Kyushu University Academic Staff Educational and Research Activities Database
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Takashi Kanematsu Last modified date:2022.06.28

Professor / Oral Biological Sciences
Department of Dental Science
Faculty of Dental Science

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 Reseacher Profiling Tool Kyushu University Pure
Molecular & Cellular Biochemistry, Faculty of Dental Science, Kyushu University .
Academic Degree
Doctor of Dental Science
Field of Specialization
Pharmacology Biochemistry MolecularBiology
Total Priod of education and research career in the foreign country
Research Interests
  • Functional analysis of a new anti-cancer molecule that promotes anti-tumor immune responses
    keyword : anti-tumor immune response
  • Studies on the connections between peripheral inflammation and type 2 diabetes
    keyword : obesity, diabetes, peripheral inflammation, miRNA
  • Studies on type 3 diabetes and Alzheimer's disease
    keyword : diabetes, Alzheimer's disease, brain inflammation, microglia
  • PRIP roles in autophagy signaling pathway
    keyword : autophagy
  • Studies on PRIP roles in insulin secretion machinery
    keyword : insulin secretion
  • Studies on the intracellular signaling of GABA(A) receptor
    keyword : GABA(A) receptor
Academic Activities
1. Kanematsu T., Mizokami A., Watanabe K., Hirata M., Regulation of GABA(A) receptor surface expression with special reference to the invilvement of GABARAP and PRIP. , J. Pharmacol. Sci., 2007.08.
2. Kanematsu T., Takeuchi H., Terunuma M., Hirata M., PRIP, a novel Ins(1,4,5)P3 binding protein, functional significance in Ca2+ signaling and extension to neuroscience and beond., Mol. Cells, 20: 305-314, 2005.01.
1. Kayo Mori, Akiko Mizokami, Tomomi Sano, Satoru Mukai, Fumitaka Hiura, Yasunori Ayukawa, Kiyoshi Koyano, Takashi Kanematsu, Eijiro Jimi, RANKL elevation activates the NIK/NF-κB pathway, inducing obesity in ovariectomized mice, Journal of Endocrinology,, 254, 1, 27-36, 2022.05, Menopausal women are susceptible to visceral obesity, which increases the risk of metabolic disorders. However, the mechanisms of menopause-induced visceral fat accumulation are not fully understood. Circulating levels of receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) are elevated in an animal model of menopause. RANKL, a multifunctional cytokine, activates the NF-κB pathway, which serves as a pivotal mediator of inflammatory responses. Here, we investigated whether RANKL-induced non-canonical NF-κB pathway activation induces inflammation and lipid accumulation in adipose tissues. RANKL induced Tnfa expression via the non-canonical NF-κB pathway in bone marrow cells. We therefore analyzed aly/aly mice, in which the non-canonical NF-κB pathway is not activated, owing to an inactive form of NF-κB-inducing kinase. A postmenopausal obesity model was generated by ovariectomy and subsequent high-fat and high-sucrose diet feeding. In aly/aly mice with postmenopausal obesity, serum RANKL levels were elevated, and hepatic lipid accumulation and adipocyte hypertrophy were suppressed, resulting in reduced macrophage infiltration and inflammatory cytokine mRNA expression in visceral adipose tissue. Furthermore, aly/aly mice showed protection from glucose intolerance and insulin resistance, which were observed in ovariectomized WT obese mice. These findings indicate that non-canonical NF-κB pathway activation via serum RANKL elevation contributes to postmenopausal obesity..
2. Jing Gao, Akiko Mizokami, Hiroshi Takeuchi, Aonan Li, Fei Huang, Haruki Nagano, Takashi Kanematsu, Eijiro Jimi, Masato Hirata, Phospholipase C-related but catalytically inactive protein acts as a positive regulator of insulin signalling in adipocytes, Journal of Cell Science,, 135, 1, jcs258584, 2022.01, Insulin signalling is tightly controlled by various factors, but the exact molecular mechanism remains incompletely understood. We have previously reported that phospholipase C-related but catalytically inactive protein (PRIP; used here to refer to both PRIP-1 and PRIP-2, also known as PLCL1 and PLCL2, respectively) interacts with Akt1, the central molecule in insulin signalling. Here, we investigated whether PRIP is involved in the regulation of insulin signalling in adipocytes. We found that insulin signalling, including insulin-stimulated phosphorylation of the insulin receptor (IR), insulin receptor substrate-1 (IRS-1) and Akt, and glucose uptake were impaired in adipocytes from PRIP double-knockout (PRIP-KO) mice compared with those from wild-type (WT) mice. The amount of IR expressed on the cell surface was decreased in PRIP-KO adipocytes. Immunoprecipitation assays showed that PRIP interacted with IR. The reduced cell surface IR in PRIP-KO adipocytes was comparable with that in WT cells when Rab5 (Rab5a, -5b and -5c) expression was silenced using specific siRNA. In contrast, the dephosphorylation of IRS-1 at serine residues, some of which have been reported to be involved in the internalisation of IR, was impaired in cells from PRIP-KO mice. These results suggest that PRIP facilitates insulin signalling by modulating the internalisation of IR in adipocytes..
3. Yuka Maetani, Satoshi Asano, Akiko Mizokami, Yosuke Yamawaki, Tomomi Sano, Masato Hirata, Masahiro Irifune, Takashi Kanematsu, Expression of PRIP, a phosphatidylinositol 4,5-bisphosphate binding protein, attenuates PI3K/AKT signaling and suppresses tumor growth in a xenograft mouse model, Biochemical and biophysical research communications,, 552, 106-113, 2021.05, Cancer is characterized by uncontrolled proliferation resulting from aberrant cell cycle progression. The activation of phosphatidylinositol 3-kinase (PI3K)/AKT signaling, a regulatory pathway for the cell cycle, stabilizes cyclin D1 in the G1 phase by inhibiting the activity of glycogen synthase kinase 3β (GSK3β) via phosphorylation. We previously reported that phospholipase C-related catalytically inactive protein (PRIP), a phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] binding protein, regulates PI3K/AKT signaling by competitively inhibiting substrate recognition by PI3K. Therefore, in this study, we investigated whether PRIP is involved in cell cycle progression. PRIP silencing in MCF-7 cells, a human breast cancer cell line, demonstrated PI(3,4,5)P3 signals accumulated at the cell periphery compared to that of the control. This suggests that PRIP reduction enhances PI(3,4,5)P3-mediated signaling. Consistently, PRIP silencing in MCF-7 cells exhibited increased phosphorylation of AKT and GSK3β which resulted in cyclin D1 accumulation. In contrast, the exogenous expression of PRIP in MCF-7 cells evidenced stronger downregulation of AKT and GSK3β phosphorylation, reduced accumulation of cyclin D1, and diminished cell proliferation in comparison to control cells. Flow cytometry analysis indicated that MCF-7 cells stably expressing PRIP attenuate cell cycle progression. Importantly, tumor growth of MCF-7 cells stably expressing PRIP was considerably prevented in an in vivo xenograft mouse model. In conclusion, PRIP expression downregulates PI3K/AKT/GSK3β-mediated cell cycle progression and suppresses tumor growth. Therefore, we propose that PRIP is a new therapeutic target for anticancer therapy..
4. Satoshi Asano, Yasuka Ikura, Mitsuki Nishimoto, Yosuke Yamawaki, Kozue Hamao, Keiju Kamijo, Masato Hirata, Takashi Kanematsu, Phospholipase C-related catalytically inactive protein regulates cytokinesis by protecting phosphatidylinositol 4,5-bisphosphate from metabolism in the cleavage furrow, Scientific reports,, 9, 1, 2019.12, Cytokinesis is initiated by the formation and ingression of the cleavage furrow. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P<sub>2</sub>] accumulation followed by RhoA translocation to the cleavage furrow are prerequisites for cytokinesis progression. Here, we investigated whether phospholipase C (PLC)-related catalytically inactive protein (PRIP), a metabolic modulator of PI(4,5)P<sub>2</sub>, regulates PI(4,5)P<sub>2</sub>-mediated cytokinesis. We found that PRIP localised to the cleavage furrow during cytokinesis. Moreover, HeLa cells with silenced PRIP displayed abnormal cytokinesis. Importantly, PI(4,5)P<sub>2</sub> accumulation at the cleavage furrow, as well as the localisation of RhoA and phospho-myosin II regulatory light chain to the cleavage furrow, were reduced in PRIP-silenced cells. The overexpression of oculocerebrorenal syndrome of Lowe-1 (OCRL1), a phosphatidylinositol-5-phosphatase, in cells decreased PI(4,5)P<sub>2</sub> levels during early cytokinesis and resulted in cytokinesis abnormalities. However, these abnormal cytokinesis phenotypes were ameliorated by the co-expression of PRIP but not by co-expression of a PI(4,5)P<sub>2</sub>-unbound PRIP mutant. Collectively, our results indicate that PRIP is a component at the cleavage furrow that maintains PI(4,5)P<sub>2</sub> metabolism and regulates RhoA-dependent progression of cytokinesis. Thus, we propose that PRIP regulates phosphoinositide metabolism correctively and mediates normal cytokinesis progression..
5. Yosuke Yamawaki, Satomi Shirawachi, Akiko Mizokami, Kanako Nozaki, Hikaru Ito, Satoshi Asano, Kana Oue, Hidenori Aizawa, Shigeto Yamawaki, Masato Hirata, Takashi Kanematsu, Phospholipase C-related catalytically inactive protein regulates lipopolysaccharide-induced hypothalamic inflammation-mediated anorexia in mice, Neurochemistry International, 131, 2019.12, Peripheral lipopolysaccharide (LPS) injection induces systemic inflammation through the activation of the inhibitor of nuclear factor kappa B (NF-κB) kinase (IKK)/NF-κB signaling pathway, which promotes brain dysfunction resulting in conditions including anorexia. LPS-mediated reduction of food intake is associated with activation of NF-κB signaling and phosphorylation of the transcription factor signal transducer and activator of transcription 3 (STAT3) in the hypothalamus. We recently reported phospholipase C-related catalytically inactive protein (PRIP) as a new negative regulator of phosphatidylinositol 3-kinase/AKT signaling. AKT regulates the IKK/NF-κB signaling pathway; therefore, this study aimed to investigate the role of PRIP/AKT signaling in LPS-mediated neuroinflammation-induced anorexia. PRIP gene (Prip1 and Prip2) knockout (Prip-KO) mice intraperitoneally (ip) administered with LPS exhibited increased anorexia responses compared with wild-type (WT) controls. Although few differences were observed between WT and Prip-KO mice in LPS-elicited plasma pro-inflammatory cytokine elevation, hypothalamic pro-inflammatory cytokines were significantly upregulated in Prip-KO rather than WT mice. Hypothalamic AKT and IKK phosphorylation and IκB degradation were significantly increased in Prip-KO rather than WT mice, indicating further promotion of AKT-mediated NF-κB signaling. Consistently, hypothalamic STAT3 was further phosphorylated in Prip-KO rather than WT mice. Furthermore, suppressor of cytokine signaling 3 (Socs3), a negative feedback regulator for STAT3 signaling, and cyclooxogenase-2 (Cox2), a candidate molecule in LPS-induced anorexigenic responses, were upregulated in the hypothalamus in Prip-KO rather than WT mice. Pro-inflammatory cytokines were upregulated in hypothalamic microglia isolated from Prip-KO rather than WT mice. Together, these findings indicate that PRIP negatively regulates LPS-induced anorexia caused by pro-inflammatory cytokine expression in the hypothalamus, which is mediated by AKT-activated NF-κB signaling. Importantly, hypothalamic microglia participate in this PRIP-mediated process. Elucidation of PRIP-mediated neuroinflammatory responses may provide novel insights into the pathophysiology of many brain dysfunctions..
6. Taka Fujita, Gentaro Kumagai, Xizhe Liu, Kanichiro Wada, Toshihiro Tanaka, Hitoshi Kudo, Toru Asari, Tatsuhiro Fukutoku, Ayako Sasaki, Yohshiro Nitobe, Yoshikazu Nikaido, Ken Ichi Furukawa, Masato Hirata, Takashi Kanematsu, Shinya Ueno, Yasuyuki Ishibashi, Poor Motor-Function Recovery after Spinal Cord Injury in Anxiety-Model Mice with Phospholipase C-Related Catalytically Inactive Protein Type 1 Knockout, Journal of Neurotrauma, 10.1089/neu.2017.5492, 35, 12, 1379-1386, 2018.06, Mice with a knockout of phospholipase C (PLC)-related inactive protein type 1 (PRIP1
mice) display anxiety-like behavior and altered γ-aminobutyric acid (GABA)
-receptor pharmacology. Here, we examined associations between anxiety and motor-function recovery in PRIP1
mice after a spinal cord injury (SCI) induced by a moderate contusion injury at the 10th thoracic level. Uninjured PRIP1
mice showed less distance than wild-type (WT) mice in the center 25% in an open field test (OFT), indicating anxiety-like behavior. Anxiety behavior increased in both WT and PRIP1
mice after SCI. WT and PRIP1
mice were completely paralyzed on day 1 after SCI, but gradually recovered until reaching a plateau at ∼4 weeks. After SCI, the PRIP1
mice had significantly greater motor dysfunction than the WT mice. In WT mice after SCI, the percentage of distance spent in the center 25% of the OFT was correlated with the OFT distance traveled and velocity, and with the reaction time in a plantar pressure-sensitivity mechanical test. In PRIP1
mice after SCI, the percentage of distance spent in the center 25% of the OFT was correlated with the OFT distance traveled and with the latency to fall in the rotarod test. Six weeks after SCI, ionized calcium binding adaptor molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP) expressions were elevated at the lesion epicenter in PRIP1
mice, and spinal cord atrophy and demyelination were more severe than in WT mice. The axonal fiber development was also decreased in PRIP1
mice, consistent with the poor motor-function recovery after SCI in these mice..
7. Satoshi Asano, Yuri Taniguchi, Yosuke Yamawaki, Jing Gao, Kae Harada, Hiroshi Takeuchi, Masato Hirata, Takashi Kanematsu, Suppression of cell migration by phospholipase C-related catalytically inactive protein-dependent modulation of PI3K signalling, Scientific reports, 10.1038/s41598-017-05908-7, 7, 1, 2017.12, The metabolic processes of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] into PI(3,4,5)P3 and the subsequent PI(3,4,5)P3 signalling are involved in cell migration. Dysfunctions in the control of this pathway can cause human cancer cell migration and metastatic growth. Here we investigated whether phospholipase C-related catalytically inactive protein (PRIP), a PI(4,5)P2-binding protein, regulates cancer cell migration. PRIP overexpression in MCF-7 and BT-549 human breast cancer cells inhibited cell migration in vitro and metastasis development in vivo. Overexpression of the PRIP pleckstrin homology domain, a PI(4,5)P2 binding motif, in MCF-7 cells caused significant suppression of cell migration. Consistent with these results, in comparison with wild-type cells, Prip-deficient mouse embryonic fibroblasts exhibited increased cell migration, and this was significantly attenuated upon transfection with a siRNA targeting p110α, a catalytic subunit of class I phosphoinositide 3-kinases (PI3Ks). PI(3,4,5)P3 production was decreased in Prip-overexpressing MCF-7 and BT-549 cells. PI3K binding to PI(4,5)P2 was significantly inhibited by recombinant PRIP in vitro, and thus the activity of PI3K was downregulated. Collectively, PRIP regulates the production of PI(3,4,5)P3 from PI(4,5)P2 by PI3K, and the suppressor activity of PRIP in PI(4,5)P2 metabolism regulates the tumour migration, suggesting PRIP as a promising target for protection against metastatic progression..
8. Yoshikazu Nikaido, Tomonori Furukawa, Shuji Shimoyama, Junko Yamada, Keisuke Migita, Kohei Koga, Tetsuya Kushikata, Kazuyoshi Hirota, Takashi Kanematsu, Masato Hirata, Shinya Ueno, Propofol anesthesia is reduced in phospholipase c-related inactive protein type-1 knockout mices, Journal of Pharmacology and Experimental Therapeutics, 10.1124/jpet.116.239145, 361, 3, 367-374, 2017.06, The GABA type A receptor (GABAA-R) is a major target of intravenous anesthetics. Phospholipase C-related inactive protein type-1 (PRIP-1) is important in GABAA-R phosphorylation and membrane trafficking. In this study, we investigated the role of PRIP-1 in general anesthetic action. The anesthetic effects of propofol, etomidate, and pentobarbital were evaluated in wild-type and PRIP-1 knockout (PRIP-1 KO) mice by measuring the latency and duration of loss of righting reflex (LORR) and loss of tail-pinch withdrawal response (LTWR). The effect of pretreatment with okadaic acid (OA), a protein phosphatase 1/2A inhibitor, on propofol- and etomidate-induced LORR was also examined. PRIP-1 deficiency provided the reduction of LORR and LTWR induced by propofol but not by etomidate or pentobarbital, indicating that PRIP-1 could determine the potency of the anesthetic action of propofol. Pre-treatment with OA recovered the anesthetic potency induced by propofol in PRIP-1 KO mice. OA injection enhanced phos-phorylation of cortical the GABAA-R β3 subunit in PRIP-1 KO mice. These results suggest that PRIP-1-mediated GABAA-R β3 subunit phosphorylation might be involved in the general anesthetic action induced by propofol but not by etomidate or pentobarbital..
9. Kana Oue, Jun Zhang, Kae Harada-Hada, Satoshi Asano, Yosuke Yamawaki, Masaki Hayashiuchi, Hisako Furusho, Takashi Takata, Masahiro Irifune, Masato Hirata, Takashi Kanematsu, Phospholipase C-related Catalytically Inactive Protein Is a New Modulator of Thermogenesis Promoted by β-Adrenergic Receptors in Brown Adipocytes, Journal of Biological Chemistry, 10.1074/jbc.M115.705723, 291, 8, 4185-4196, 2016.02, Phospholipase C-related catalytically inactive protein (PRIP) was first identified as an inositol 1,4,5-trisphosphate-binding protein, and was later found to be involved in a variety of cellular events, particularly those related to protein phosphatases. We previously reported that Prip knock-out (KO) mice exhibit a lean phenotype with a small amount of white adipose tissue. In the present study, we examined whether PRIP is involved in energy metabolism, which could explain the lean phenotype, using high-fat diet (HFD)-fed mice. Prip-KO mice showed resistance to HFD-induced obesity, resulting in protection from glucose metabolism dysfunction and insulin resistance. Energy expenditure and body temperature at night were significantly higher in Prip-KO mice than in wild-type mice. Gene and protein expression of uncoupling protein 1 (UCP1), a thermogenic protein, was up-regulated in Prip-KO brown adipocytes in ther-moneutral or cold environments. These phenotypes were caused by the promotion of lipolysis in Prip-KO brown adipocytes, which is triggered by up-regulation of phosphorylation of the lipolysis-related proteins hormone-sensitive lipase and perilipin, followed by activation of UCP1 and/or up-regulation of thermogenesis-related genes (e.g. peroxisome proliferator-activated receptor-γ coactivator-1α). The results indicate that PRIP negatively regulates UCP1-mediated thermogenesis in brown adipocytes..
10. Satoshi Asano, Tomomi Nemoto, Tomoya Kitayama, Kae Harada, Jun Zhang, Kana Harada, Isei Tanida, Masato Hirata, Takashi Kanematsu, Phospholipase C-related catalytically inactive protein (PRIP) controls KIF5B-mediated insulin secretion, Biology Open, 10.1242/bio.20147591, 3, 6, 463-474, 2014.06, We previously reported that phospholipase C-related catalytically inactive protein (PRIP)-knockout mice exhibited hyperinsulinemia. Here, we investigated the role of PRIP in insulin granule exocytosis using Prip-knockdown mouse insulinoma (MIN6) cells. Insulin release from Prip-knockdown MIN6 cells was higher than that from control cells, and Prip knockdown facilitated movement of GFP-phogrinlabeled insulin secretory vesicles. Double-immunofluorescent staining and density step-gradient analyses showed that the KIF5B motor protein co-localized with insulin vesicles in Prip-knockdown MIN6 cells. Knockdown of GABAA -receptor-associated protein (GABARAP), a microtubule-associated PRIP-binding partner, by Gabarap silencing in MIN6 cells reduced the co-localization of insulin vesicles with KIF5B and the movement of vesicles, resulting in decreased insulin secretion. However, the co-localization of KIF5B with microtubules was not altered in Prip- and Gabarap-knockdown cells. The presence of unbound GABARAP, freed either by an interference peptide or by Prip silencing, in MIN6 cells enhanced the co-localization of insulin vesicles with microtubules and promoted vesicle mobility. Taken together, these data demonstrate that PRIP and GABARAP function in a complex to regulate KIF5B-mediated insulin secretion, providing new insights into insulin exocytic mechanisms..
11. Toshiya Okumura, Kae Harada, Kana Oue, Jun Zhang, Satoshi Asano, Masaki Hayashiuchi, Akiko Mizokami, Hiroto Tanaka, Masahiro Irifune, Nobuyuki Kamata, Masato Hirata, Takashi Kanematsu, Phospholipase C-related catalytically inactive protein (PRIP) regulates lipolysis in adipose tissue by modulating the phosphorylation of hormone-sensitive lipase, PloS one, 10.1371/journal.pone.0100559, 9, 6, 2014.06, Phosphorylation of hormone-sensitive lipase (HSL) and perilipin by protein kinase A (PKA) promotes the hydrolysis of lipids in adipocytes. Although activation of lipolysis by PKA has been well studied, inactivation via protein phosphatases is poorly understood. Here, we investigated whether phospholipase C-related catalytically inactive protein (PRIP), a binding partner for protein phosphatase 1 and protein phosphatase 2A (PP2A), is involved in lipolysis by regulating phosphatase activity. PRIP knockout (PRIP-KO) mice displayed reduced body-fat mass as compared with wild-type mice fed with standard chow ad libitum. Most other organs appeared normal, suggesting that mutant mice had aberrant fat metabolism in adipocytes. HSL in PRIP-KO adipose tissue was highly phosphorylated compared to that in wild-type mice. Starvation of wild-type mice or stimulation of adipose tissue explants with the catabolic hormone, adrenaline, translocated both PRIP and PP2A from the cytosol to lipid droplets, but the translocation of PP2A was significantly reduced in PRIP-KO adipocytes. Consistently, the phosphatase activity associated with lipid droplet fraction in PRIP -KO adipocytes was significantly reduced and was independent of adrenaline stimulation. Lipolysis activity, as assessed by measurement of non-esterified fatty acids and glycerol, was higher in PRIP-KO adipocytes. When wild-type adipocytes were treated with a phosphatase inhibitor, they showed a high lipolysis activity at the similar level to PRIP-KO adipocytes. Collectively, these results suggest that PRIP promotes the translocation of phosphatases to lipid droplets to trigger the dephosphorylation of HSL and perilipin A, thus reducing PKA-mediated lipolysis. Copyright:.
12. Kae Harada-Hada, Kana Harada, Fuminori Kato, Junzo Hisatsune, Isei Tanida, Michinaga Ogawa, Satoshi Asano, Motoyuki Sugai, Masato Hirata, Takashi Kanematsu, Phospholipase C-related catalytically inactive protein participates in the autophagic elimination of Staphylococcus aureus infecting mouse embryonic fibroblasts, PloS one, 10.1371/journal.pone.0098285, 9, 5, 2014.05, Autophagy is an intrinsic host defense system that recognizes and eliminates invading bacterial pathogens. We have identified microtubule- associated protein 1 light chain 3 (LC3), a hallmark of autophagy, as a binding partner of phospholipase C-related catalytically inactive protein (PRIP) that was originally identified as an inositol trisphosphatebinding protein. Here, we investigated the involvement of PRIP in the autophagic elimination of Staphylococcus aureus in infected mouse embryonic fibroblasts (MEFs). We observed significantly more LC3-positive autophagosome-like vacuoles enclosing an increased number of S. aureus cells in PRIP-deficient MEFs than control MEFs, 3 h and 4.5 h post infection, suggesting that S. aureus proliferates in LC3-positive autophagosome-like vacuoles in PRIP-deficient MEFs. We performed autophagic flux analysis using an mRFP-GFP-tagged LC3 plasmid and found that autophagosome maturation is significantly inhibited in PRIP-deficient MEFs. Furthermore, acidification of autophagosomes was significantly inhibited in PRIP-deficient MEFs compared to the wild-type MEFs, as determined by LysoTracker staining and time-lapse image analysis performed using mRFP-GFP-tagged LC3. Taken together, our data show that PRIP is required for the fusion of S. aureus-containing autophagosome-like vacuoles with lysosomes, indicating that PRIP is a novel modulator in the regulation of the innate immune system in non-professional phagocytic host cells. Copyright:.
13. Tomoya Kitayama, Katsuya Morita, Rizia Sultana, Nami Kikushige, Keisuke Mgita, Shinya Ueno, Masato Hirata, Takashi Kanematsu, Phospholipase C-related but catalytically inactive protein modulates pain behavior in a neuropathic pain model in mice, Molecular Pain, 10.1186/1744-8069-9-23, 9, 1, 2013.05, Background: An inositol 1,4,5-trisphosphate binding protein, comprising 2 isoforms termed PRIP-1 and PRIP-2, was identified as a novel modulator for GABAA receptor trafficking. It has been reported that naive PRIP-1 knockout mice have hyperalgesic responses.Findings: To determine the involvement of PRIP in pain sensation, a hind paw withdrawal test was performed before and after partial sciatic nerve ligation (PSNL) in PRIP-1 and PRIP-2 double knockout (DKO) mice. We found that naive DKO mice exhibited normal pain sensitivity. However, DKO mice that underwent PSNL surgery showed increased ipsilateral paw withdrawal threshold. To further investigate the inverse phenotype in PRIP-1 KO and DKO mice, we produced mice with specific siRNA-mediated knockdown of PRIPs in the spinal cord. Consistent with the phenotypes of KO mice, PRIP-1 knockdown mice showed allodynia, while PRIP double knockdown (DKD) mice with PSNL showed decreased pain-related behavior. This indicates that reduced expression of both PRIPs in the spinal cord induces resistance towards a painful sensation. GABAA receptor subunit expression pattern was similar between PRIP-1 KO and DKO spinal cord, while expression of K+-Cl--cotransporter-2 (KCC2), which controls the balance of neuronal excitation and inhibition, was significantly upregulated in DKO mice. Furthermore, in the DKD PSNL model, an inhibitor-induced KCC2 inhibition exhibited an altered phenotype from painless to painful sensations.Conclusions: Suppressed expression of PRIPs induces an elevated expression of KCC2 in the spinal cord, resulting in inhibition of nociception and amelioration of neuropathic pain in DKO mice..
14. Hisanori Umebayashi, Akiko Mizokami, Miho Matsuda, Kae Harada, Hiroshi Takeuchi, Isei Tanida, Masato Hirata, Takashi Kanematsu, Phospholipase C-related catalytically inactive protein, a novel microtubule-associated protein 1 light chain 3-binding protein, negatively regulates autophagosome formation, Biochemical and Biophysical Research Communications, 10.1016/j.bbrc.2013.01.119, 432, 2, 268-274, 2013.03, Upon starvation, cells undergo autophagy, an intracellular bulk-degradation process, to provide the required nutrients. Here, we observed that phospholipase C-related catalytically inactive protein (PRIP) binds to microtubule-associated protein 1 light chain 3 (LC3), a mammalian autophagy-related initiator that regulates the autophagy pathway. Then, we examined the involvement of PRIP in the nutrient depletion-induced autophagy pathway. Enhanced colocalization of PRIP with LC3 was clearly seen in nutrient-starved mouse embryonic fibroblasts under a fluorescent microscope, and interaction of the proteins was revealed by immunoprecipitation experiments with an anti-LC3 antibody. Under starvation conditions, there were more green fluorescent protein fused-LC3 dots in mouse embryonic fibroblasts from PRIP-deficient mice than in fibroblasts from wild type cells. The formation of new dots in a single cell increased, as assessed by time-lapse microscopy. Furthermore, the increase in autophagosome formation in PRIP-deficient cells was notably inhibited by exogenously overexpressed PRIP. Taken together, PRIP is a novel LC3-binding protein that acts as a negative modulator of autophagosome formation..
15. Akiko Mizokami, Hiroto Tanaka, Hitoshi Ishibashi, Hisanori Umebayashi, Kiyoko Fukami, Tadaomi Takenawa, Keiichi I. Nakayama, Takeshi Yokoyama, Junichi Nabekura, Takashi Kanematsu, Masato Hirata, GABAA receptor subunit alteration-dependent diazepam insensitivity in the cerebellum of phospholipase C-related inactive protein knockout mice, Journal of Neurochemistry, 10.1111/j.1471-4159.2010.06754.x, 114, 1, 302-310, 2010.07, The GABAA receptor, a pentamer composed predominantly of α, β, and γ subunits, mediates fast inhibitory synaptic transmission. We have previously reported that phospholipase C-related inactive protein (PRIP) is a modulator of GABAA receptor trafficking and that knockout (KO) mice exhibit a diazepam-insensitive phenotype in the hippocampus. The α subunit affects diazepam sensitivity; α1, 2, 3, and 5 subunits assemble with any form of β and the γ2 subunits to produce diazepam-sensitive receptors, whereas α4 or α6/β/γ2 receptors are diazepam-insensitive. Here, we investigated how PRIP is implicated in the diazepam-insensitive phenotype using cerebellar granule cells in animals expressing predominantly the α6 subunit. The expression of α1/β/γ2 diazepam-sensitive receptors was decreased in the PRIP-1 and 2 double KO cerebellum without any change in the total number of benzodiazepine-binding sites as assessed by radioligand-binding assay. Since levels of the α6 subunit were increased, the α1/β/γ2 receptors might be replaced with α6 subunit-containing receptors. Then, we further performed autoradiographic and electrophysiologic analyses. These results suggest that the expression of α6/δ receptors was decreased in cerebellar granule neurons, while that of α6/γ2 receptors was increased. PRIP-1 and 2 double KO mice exhibit a diazepam-insensitive phenotype because of a decrease in diazepam-sensitive (α1/γ2) and increase in diazepam-insensitive (α6/γ2) GABAA receptors in the cerebellar granule cells..
16. Makoto Fujii, Takashi Kanematsu, Hitoshi Ishibashi, Kiyoko Fukami, Tadaomi Takenawa, Keiichi I. Nakayama, Stephen J. Moss, Junichi Nabekura, Masato Hirata, Phospholipase C-related but catalytically inactive protein is required for insulin-induced cell surface expression of γ-aminobutyric acid type A receptors, Journal of Biological Chemistry, 10.1074/jbc.M109.070045, 285, 7, 4837-4846, 2010.02, The γ-aminobutyric acid type A (GABAA) receptors play a pivotal role in fast synaptic inhibition in the central nervous system. One of the key factors for determining synaptic strength is the number of receptors on the postsynaptic membrane, which is maintained by the balance between cell surface insertion and endocytosis of the receptors. In this study, we investigated whether phospholipase C-related but catalytically inactive protein (PRIP) is involved in insulin-induced GABAA receptor insertion. Insulin potentiated the GABA-induced Cl- current (IGABA) by about 30% in wild-type neurons, but not in PRIP1 and PRIP2 double-knock-out (DKO) neurons, suggesting that PRIP is involved in insulin-induced potentiation. The phosphorylation level of the GABAA receptor β-subunit was increased by about 30% in the wild-type neurons but not in the mutant neurons, which were similar to the changes observed in IGABA. We also revealed that PRIP recruited active Akt to the GABAA receptors by forming a ternary complex under insulin stimulation. The disruption of the binding between PRIP and the GABAA receptor β-subunit by PRIP interference peptide attenuated the insulin potentiation of IGABA. Taken together, these results suggest that PRIP is involved in insulin-induced GABAA receptor insertion by recruiting active Akt to the receptor complex..
17. Takashi Kanematsu, Makoto Fujii, Akiko Mizokami, Josef T. Kittler, Junichi Nabekura, Stephen J. Moss, Masato Hirata, Phospholipase C-related inactive protein is implicated in the constitutive internalization of GABAA receptors mediated by clathrin and AP2 adaptor complex, Journal of Neurochemistry, 10.1111/j.1471-4159.2006.04399.x, 101, 4, 898-905, 2007.05, A mechanism for regulating the strength of synaptic inhibition is enabled by altering the number of GABAA receptors available at the cell surface. Clathrin and adaptor protein 2 (AP2) complex-mediated endocytosis is known to play a fundamental role in regulating cell surface GABAA receptor numbers. Very recently, we have elucidated that phospholipase C-related catalytically inactive protein (PRIP) molecules are involved in the phosphorylation-dependent regulation of the internalization of GABAA receptors through association with receptor β subunits and protein phosphatases. In this study, we examined the implications of PRIP molecules in clathrin-mediated constitutive GABAA receptor endocytosis, independent of phospho-regulation. We performed a constitutive receptor internalization assay using human embryonic kidney 293 (HEK293) cells transiently expressed with GABAA receptor α/β/γ subunits and PRIP. PRIP was internalized together with GABAA receptors, and the process was inhibited by PRIP-binding peptide which blocks PRIP binding to β subunits. The clathrin heavy chain, μ2 and β2 subunits of AP2 and PRIP-1, were complexed with GABAA receptor in brain extract as analyzed by co-immunoprecipitation assay using anti-PRIP-1 and anti-β2/3 GABAA receptor antibody or by pull-down assay using β subunits of GABAA receptor. These results indicate that PRIP is primarily implicated in the constitutive internalization of GABAA receptor that requires clathrin and AP2 protein complex..
18. Akiko Mizokami, Takashi Kanematsu, Hitoshi Ishibashi, Taku Yamaguchi, Isei Tanida, Kei Takenaka, Keiichi I. Nakayama, Kiyoko Fukami, Tadaomi Takenawa, Eiki Kominami, Stephen J. Moss, Tsuneyuki Yamamoto, Junichi Nabekura, Masato Hirata, Phosholipase C-related inactive protein is involved in trafficking of γ2 subunit-containing GABAA receptors to the cell surface, Journal of Neuroscience, 10.1523/JNEUROSCI.3155-06.2007, 27, 7, 1692-1701, 2007.02, The subunit composition of GABAA receptors is known to be associated with distinct physiological and pharmacological properties. Previous studies that used phospholipase C-related inactive protein type 1 knock-out (PRIP-1 KO) mice revealed that PRIP-1 is involved in the assembly and/or the trafficking of γ2 subunit-containing GABAA receptors. There are two PRIP genes in mammals; thus the roles of PRIP-1 might be compensated partly by those of PRIP-2 in PRIP-1 KO mice. Here we used PRIP-1 and PRIP-2 double knock-out (PRIP-DKO) mice and examined the roles for PRIP in regulating the trafficking of GABAA receptors. Consistent with previous results, sensitivity to diazepam was reduced in electrophysiological and behavioral analyses of PRIP-DKO mice, suggesting an alteration of γ2 subunit-containing GABAA receptors. The surface numbers of diazepam binding sites (α/γ2 subunits) assessed by [3H]flumazenil binding were reduced in the PRIP-DKO mice as compared with those of wild-type mice, whereas the cell surface GABA binding sites (α/β subunits, assessed by [3H]muscimol binding) were increased in PRIP-DKO mice. The association between GABAA receptors and GABAA receptor-associated protein (GABARAP) was reduced significantly in PRIP-DKO neurons. Disruption of the direct interaction between PRIP and GABAA receptor β subunits via the use of a peptide corresponding to the PRIP-1 binding site reduced the cell surface expression of γ2 subunit-containing GABAA receptors in cultured cell lines and neurons. These results suggest that PRIP is implicated in the trafficking of γ2 subunit-containing GABAA receptors to the cell surface, probably by acting as a bridging molecule between GABARAP and the receptors..
19. Takashi Kanematsu, Atsushi Yasunaga, Yoshito Mizoguchi, Akiko Kuratani, Josef T. Kittler, Jasmina N. Jovanovic, Kei Takenaka, Keiichi I. Nakayama, Kiyoko Fukami, Tadaomi Takenawa, Stephen J. Moss, Junichi Nabekura, Masato Hirata, Modulation of GABAA receptor phosphorylation and membrane trafficking by phospholipase C-related inactive protein/protein phosphatase 1 and 2A signaling complex underlying brain-derived neurotrophic factor-dependent regulation of GABAergic inhibition, Journal of Biological Chemistry, 10.1074/jbc.M603118200, 281, 31, 22180-22189, 2006.08, Brain-derived neurotrophic factor (BDNF) modulates several distinct aspects of synaptic transmission, including GABAergic transmission. Exposure to BDNF alters properties of GABAA receptors and induces changes in the expression level at the cell surface. Although phospholipase C-related inactive protein-1 (PRIP-1) plays an important role in GABAA receptor trafficking and function, its role in BDNF-dependent modulation of these receptors, together with the role of PRIP-2, was investigated using neurons cultured from PRIP double knock-out mice. The BDNF-dependent inhibition of whole cell GABA-evoked currents observed in wild type neurons was not detected in neurons cultured from knock-out mice. Instead, a gradual increase in GABA-evoked currents in these neurons correlated with a gradual increase in phosphorylation of GABAA receptor β3 subunit in response to BDNF. To characterize the specific role(s) that PRIP plays as components of underlying molecular machinery, we examined the recruitment of protein phosphatase(s) to GABAA receptors. We demonstrate that PRIP associates with phosphatases as well as with β subunits. PRIP was found to colocalize with GABAA receptor clusters in cultured neurons and with recombinant GABAA receptors when co-expressed in HEK293 cells. Importantly, a peptide mimicking a domain of PRIP involved in binding to β subunits disrupted the co-localization of these proteins in HEK293 cells and potently inhibited the BDNF-mediated attenuation of GABAA receptor currents in wild type neurons. Together, the results suggest that PRIP plays an important role in BDNF-dependent regulation of GABAA receptors by mediating the specific association between β subunits of these receptors with protein phosphatases..
20. Miho Terunuma, Il Sung Jang, Sang Hoon Ha, Josef T. Kittler, Takashi Kanematsu, Jasmina N. Jovanovic, Keiichi I. Nakayama, Norio Akaike, Sung Ho Ryu, Stephen J. Moss, Masato Hirata, GABAA receptor phospho-dependent modulation is regulated by phospholipase C-related inactive protein type 1, a novel protein phosphatase 1 anchoring protein, Journal of Neuroscience, 10.1523/JNEUROSCI.1323-04.2004, 24, 32, 7074-7084, 2004.08, GABAA receptors are critical in controlling neuronal activity. Here, we examined the role for phospholipase C-related inactive protein type 1 (PRIP-1), which binds and inactivates protein phosphatase 1α (PP1α) in facilitating GABAA receptor phospho-dependent regulation using PRIP-1-/- mice. In wild-type animals, robust phosphorylation and functional modulation of GABAA receptors containing β3 subunits by cAMP-dependent protein kinase was evident, which was diminished in PRIP-1-/- mice. PRIP-1-/- mice exhibited enhanced PP1α activity compared with controls. Furthermore, PRIP-1 was able to interact directly with GABAA receptor β subunits, and moreover, these proteins were found to be PP1α substrates. Finally, phosphorylation of PRIP-1 on threonine 94 facilitated the dissociation of PP1α-PRIP-1 complexes, providing a local mechanism for the activation of PP1α. Together, these results suggest an essential role for PRIP-1 in controlling GABAA receptor activity via regulating subunit phosphorylation and thereby the efficacy of neuronal inhibition mediated by these receptors..
21. Takashi Kanematsu, Il Sung Jang, Taku Yamaguchi, Hiroyasu Nagahama, Kenji Yoshimura, Kiyoshi Hidaka, Miho Matsuda, Hiroshi Takeuchi, Yoshio Misumi, Keiko Nakayama, Tsuneyuki Yamamoto, Norio Akaike, Masato Hirata, Keiichi Nakayama, Role of the PLC-related, catalytically inactive protein p130 in GABAA receptor function, EMBO Journal, 10.1093/emboj/21.5.1004, 21, 5, 1004-1011, 2002.03, The protein p130 was isolated from rat brain as an inositol 1, 4, 5-trisphosphate-binding protein with a domain organization similar to that of phospholipase C-δ1 but lacking PLC activity. We show that p130 plays an important role in signaling by the type A receptor for γ-aminobutyric acid (GABA). Yeast two-hybrid screening identified GABARAP (GABAA receptor-associated protein), which is proposed to contribute to the sorting, targeting or clustering of GABAA receptors, as a protein that interacts with p130. Furthermore, p130 competitively inhibited the binding of the γ2 subunit of the GABAA receptor to GABARAP in vitro. Electrophysiological analysis revealed that the modulation of GABA-induced Cl-current by Zn2+ or diazepam, both of which act at GABAA receptors containing γ subunits, is impaired in hippocampal neurons of p130 knockout mice. Moreover, behavioral analysis revealed that motor coordination was impaired and the intraperitoneal injection of diazepam induced markedly reduced sedative and antianxiety effects in the mutant mice. These results indicate that p130 is essential for the function of GABAA receptors, especially in response to the agents acting on a γ2 subunit..
22. Kenji Yoshimura, Hiroshi Takeuchi, Osamu Sato, Kiyoshi Hidaka, Naoko Doira, Miho Terunuma, Kae Harada, Yasuo Ogawa, Yushi Ito, Takashi Kanematsu, Masato Hirata, Interaction of p130 with, and Consequent Inhibition of, the Catalytic Subunit of Protein Phosphatase 1α, Journal of Biological Chemistry, 10.1074/jbc.M009677200, 276, 21, 17908-17913, 2001.01, The protein p130 was originally isolated from rat brain as an inositol 1,4,5-trisphosphate-binding protein with a domain organization similar to that of phospholipase C-δ1 but which lacks phospholipase C activity. Yeast two-hybrid screening of a human brain cDNA library for clones that encode proteins that interact with p130 has now led to the identification of the catalytic subunit of protein phosphatase 1α (PP1cα) as a p130-binding protein. The association between p130 and PP1cα was also confirmed in vitro by an overlay assay, a "pull-down" assay, and surface plasmon resonance analysis. The interaction of p130 with PP1cα resulted in inhibition of the catalytic activity of the latter in a p130 concentration-dependent manner. Immunoprecipitation and immunoblot analysis of COS-1 cells that stably express p130 and of mouse brain extract with antibodies to p130 and to PP1cα also detected the presence of a complex of p130 and PP1cα. The activity of glycogen phosphorylase, which is negatively regulated by dephosphorylation by PP1cα, was higher in COS-1 cells that stably express p130 than in control COS-1 cells. These results suggest that, in addition to its role in inositol 1,4,5-trisphosphate and Ca2+ signaling, p130 might also contribute to regulation of protein dephosphorylation through its interaction with PP1cα..
23. Takashi Kanematsu, Kenji Yoshimura, Kiyoshi Hidaka, Hiroshi Takeuchi, Matilda Katan, Masato Hirata, Domain organization of p130, PLC-related catalytically inactive protein, and structural basis for the lack of enzyme activity, European Journal of Biochemistry, 10.1046/j.1432-1327.2000.01291.x, 267, 9, 2731-2737, 2000.05, The 130-kDa protein (p130) was isolated as a novel inositol 1,4,5- trisphosphate [Ins(1,4,5)P3)-binding protein similar to phospholipase C-δ1 (PLC-δ1), but lacking catalytic activity [Kanematsu, T., Takeya, H., Watanabe, Y., Ozaki, S., Yoshida, M., Koga, T., Iwanaga, S. and Hirata, M. (1992) J. Biol. Chem. 267, 6518-6525, Kanematsu, T., Misumi, Y., Watanabe, Y., Ozaki, S., Koga, T., Iwanaga, S., Ikehara, Y. and Hirata, M. (1996) Biochem, J. 313, 319-3251. To test experimentally the domain organization of p130 and structural basis for lack of PLC activity, we subjected p130 to limited proteolysis and also constructed a number of chimeras with PLC-δ1. Trypsin treatment of p130 produced four major polypeptides with molecular misses of 86 kDa, 55 kDa, 33 kDa and 25 kDa. Two polypeptides of 86 kDa and 55 kDa started at Lys93 and were CalCulated to end at Arg851 and Arg568, respectively. Using the same approach, it has been found that the polypeptides of 33 kDa and 25 kDa are likely to correspond to regions between Val569 and Arg851 and Lys869 and Leu1096, respectively. All the proteolytic sites were in interconnecting regions between the predicted domains, therefore supporting domain organization based on sequence similarity to PLC- δ1 and demonstrating that all domains of p130, including the unique region at the C-terminus, are stable, tightly folded structures. p130 truncated at either or both the N-terminus (94 amino acids) and C-terminus (851-1096 amino acids) expressed in COS-1 cells showed no catalytic activity, indicating that p130 has intrinsically no PLC activity. A number of chimeric molecules between p130 and PLC-δ1 were constructed and assayed for PLC activity. It was shown that structural differences in interdomain interactions exist between the two proteins, as only some domains of p130 could replace the corresponding structures in PLC-δ1 to form a functional enzyme. These results suggest that p130 and the related proteins could represent a new protein family that may play some distinct role in cells due to the capability of binding Ins(1,4,5)P3 but the lack of catalytic activity..
24. Xin H.B., Rogers K., Qi Y., Kanematsu T. & Fleischer S., Three amino acid residues determine selective binding of FK506-binding protein 12.6 to the cardiac ryanodine., Journal of Biological Chemistry , 274, 15315~15319, 1999.01.
25. Hiroshi Takeuchi, Takashi Kanematsu, Yoshio Misumi, Hassan Bin Yaakob, Hitoshi Yagisawa, Yukio Ikehara, Yutaka Watanabe, Zheng Tan, Stephen B. Shears, Masato Hirata, Localization of a high-affinity inositol 1,4,5-trisphosphate/inositol 1,4,5,6-tetrakisphosphate binding domain to the pleckstrin homology module of a new 130 KDa protein
Characterization of the determinants of structural specificity, Biochemical Journal, 10.1042/bj3180561, 318, 2, 561-568, 1996.09, We have previously identified a novel 130 kDa protein (p130) which binds Ins(1,4,5)P3 and shares 38% sequence identity with phospholipase C-δ1 [Kanematsu, Misumi, Watanabe, Ozaki, Koga, Iwanaga, Ikehara and Hirata (1996) Biochem. J. 313, 319-325]. We have now transfected COS-1 cells with genes encoding the entire length of the molecule or one of several truncated mutants, in order to locate the region for binding of Ins(1,4,5)P3. Deletion of N-terminal residues 116-232, the region which corresponds to the pleckstrin homology (PH) domain of the molecule, completely abolished binding activity. This result was confirmed when the PH domain itself (residues 95-232), isolated from a bacterial expression system, was found to bind [3H]Ins(1,4,5)P3. We also found that Ins(1,4,5,6)P4 was as efficacious as Ins(1,4,5)P3 in displacing [3H]Ins(1,4,5)P3, suggesting that these two polyphosphates bind to p130 with similar affinity. This conclusion was confirmed by direct binding studies using [3H]Ins(1,4,5,6)P4 with high specific radioactivity which we prepared ourselves. Binding specificity was also examined with a variety of inositol phosphate derivatives. As is the case with other PH domains characterized to date, we found that the 4,5-vicinal phosphate pair was an essential determinant of ligand specificity. However, the PH domain of p130 exhibited some novel features. For example, the 3- and/or 6-phosphates could also contribute to overall binding; this contrasts with some other PH domains where these phosphate groups decrease ligand affinity by imposing a steric constraint. Secondly, a free monoester 1-phosphate substantially increased binding affinity, which is a situation so far unique to the PH domain of p130..
26. Takashi Kanematsu, Yoshio Misumi, Yutaka Watanabe, Shoichiro Ozaki, Toshitaka Koga, Sadaaki Iwanaga, Yukio Ikehara, Masato Hirata, A new inositol 1,4,5-trisphosphate binding protein similar to phospholipase C-δ1, Biochemical Journal, 10.1042/bj3130319, 313, 1, 319-325, 1996.01, We have reported that two inositol 1,4,5-trisphosphate binding proteins, with molecular masses of 85 and 130 kDa, were purified from rat brain; the former protein was found to be the δ1-isoenzyme of phospholipase C (PLC-δ1) and the latter was an unidentified novel protein [Kanematsu, Takeya, Watanabe, Ozaki, Yoshida, Koga, Iwanaga and Hirata (1992) J. Biol. Chem. 267, 6518-6525]. Here we describe the isolation of the full-length cDNA for the 130 kDa Ins(1,4,5)P3 binding protein, which encodes 1096 amino acids. The predicted sequence of the 130 kDa protein had 38.2% homology to that of PLC-δ1. Three known domains of PLC-δ1 (pleckstrin homology and putative catalytic X and Y domains) were located at residues 110-222, 377-544 and 585-804 with 35.2%, 48.2% and 45.8% homologies respectively. However, the protein showed no PLC activity to phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol. The 130 kDa protein expressed by transfection in COS-1 cells bound Ins(1,4,5)P3 in the same way as the molecule purified from brain. Thus the 130 kDa protein is a novel Ins(1,4,5)P3 binding protein homologous to PLC-δ1, but with no catalytic activity. The functional significance of the 130 kDa protein is discussed..
27. Masako Yoshida, Takashi Kanematsu, Yutaka Watanabe, Toshitaka Koga, Shoichiro Ozaki, Sadaaki Iwanaga, Masato Hirata, D-myo-inositol 1,4,5-trisphosphate-binding proteins in rat brain membranes, Journal of biochemistry, 10.1093/oxfordjournals.jbchem.a124447, 115, 5, 973-980, 1994.01, Rat brain membrane fractions obtained using Triton X-100 were applied to a D-myo-inositol 1,4,5-trisphosphate [D-Ins(1,4,5)P3] immobilized column, followed by gel filtration and anion-exchange chromatography. Two proteins with molecular masses of 130 and 85 kDa, as assessed by SDS-polyacrylamide gel electrophoresis, were purified to apparent homogeneity as D-[3H] Ins(1,4,5)P3-binding proteins with no D-Ins(1,4,5)P3-metabolizing activity. Partial amino acid sequence determinations of these proteins revealed that the 130 kDa protein appears to be a new D-Ins(1,4,5)P3-binding protein and the 85 kDa protein is δ1-isozyme of phospholipase C. We have previously purified 130 and 85 kDa proteins, as D-[3H]Ins(1, 4, 5)P3-binding proteins, from rat brain cytosol fraction. Antibodies against the 130 kDa protein from the cytosol cross-reacted with the membrane 130 kDa protein purified in this study, suggesting that the membrane 130 kDa protein is likely to be the same as the protein from the cytosol fraction. The inhibition of D-[3H]Ins(1,4,5)P3 binding by D-isomers of inositol phosphates available clarified that the 130 kDa protein has a similar affinity for D-Ins(1,4,5,6)P4 to that for D-Ins(1,4,5)P3, while the 85 kDa protein is specific to D-Ins(1,4,5)P3..
28. T. Kanematsu, H. Takeya, Y. Watanabe, S. Ozaki, M. Yoshida, T. Koga, S. Iwanaga, M. Hirata, Putative inositol 1,4,5-trisphosphate binding proteins in rat brain cytosol, Journal of Biological Chemistry, 267, 10, 6518-6525, 1992.01, In previous works, we synthesized a series of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) analogs, with a substituent on the second carbon of the inositol ring. Using these analogs, the Ins(1,4,5)P3 affinity media were also synthesized (Hirata, M., Watanabe, Y., Ishimatsu, T., Yanaga, F., Koga, T., and Ozaki, S. (1990) Biochem. Biophys. Res. Commun. 168, 379-386). When the cytosol fraction from the rat brain was applied to an Ins(1,4,5)P3 affinity column, an eluate with a 2 M NaCl solution was found to have remarkable Ins(1,4,5)P3-binding activity. The active fraction was further fractionated with gel filtration chromatography, and two proteins with an apparent molecular mass of 130 or 85 kDa were found to be Ins(1,4,5)P3- binding proteins but with no Ins(1,4,5)P3 metabolizing activities. Partial amino acid sequences determined after proteolysis and reversed-phase chromatography revealed that the protein with an apparent molecular mass of 85 kDa is the δ-isozyme of phospholipase C and that of 130 kDa has no sequence the same as the Ins(1,4,5)P3-recognizing proteins hitherto examined. Ins(1,4,5)P3 at concentrations greater than 1 μM strongly inhibited 85-kDa phospholipase Cδ activity, without changing its dependence on the concentrations of free Ca2+ and H+. Among inositol phosphates examined, Ins(3,4,5,6)P4 inhibited the binding of [3H]Ins(1,4,5)P3 to the 130-kDa protein at much the same concentrations as seen with Ins(1,4,5)P3. This report seems to be the first evidence for the presence of soluble Ins(1,4,5)P3-binding proteins in the rat brain, one of which is the δ isozyme of phospholipase C..
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