| 1. |
Yumiko Ono, Kenji Matsuzawa, Junichi Ikenouchi, mTORC2 suppresses cell death induced by hypo-osmotic stress by promoting sphingomyelin transport, The Journal of Cell Biology, 10.1083/jcb.202106160, 221(4), 2022.01. |
| 2. |
Yuma Cho, Daichi Haraguchi, Kenta Shigetomi, Kenji Matsuzawa, Seiichi Uchida, Junichi Ikenouchi, Tricellulin secures the epithelial barrier at tricellular junctions by interacting with actomyosin, The Journal of Cell Biology, 10.1083/jcb.202009037, 221(4), 2022.01. |
| 3. |
Takashi Watanabe, Jun Noritake, Mai Kakeno, Toshinori Matsui, Takumi Harada, Shujie Wang, Norimichi Itoh, Kazuhide Sato, Kenji Matsuzawa, Akihiro Iwamatsu, Niels Galjart, Kozo Kaibuchi, Phosphorylation of CLASP2 by GSK-3beta regulates its interaction with IQGAP1, EB1 and microtubules., Journal of cell science, 10.1242/jcs.046649, 122, Pt 16, 2969-79, 2009.08, Polarised cell migration is required for various cell behaviours and functions. Actin and microtubules are coupled structurally and distributed asymmetrically along the front-rear axis of migrating cells. CLIP-associating proteins (CLASPs) accumulate near the ends of microtubules at the front of migrating cells to control microtubule dynamics and cytoskeletal coupling. Regional inhibition of GSK-3beta is responsible for this asymmetric distribution of CLASPs. However, it is not known how GSK-3beta regulates the activity of CLASPs for linkage between actin and microtubules. Here we identified IQGAP1, an actin-binding protein, as a novel CLASP-binding protein. GSK-3beta directly phosphorylates CLASP2 at Ser533 and Ser537 within the region responsible for the IQGAP1 binding. Phosphorylation of CLASP2 results in the dissociation of CLASP2 from IQGAP1, EB1 and microtubules. At the leading edges of migrating fibroblasts, CLASP2 near microtubule ends partially colocalises with IQGAP1. Expression of active GSK-3beta abrogates the distribution of CLASP2 on microtubules, but not that of a nonphosphorylatable CLASP2 mutant. The phosphorylated CLASP2 does not accumulate near the ends of microtubules at the leading edges. Thus, phosphorylation of CLASP2 by GSK-3beta appears to control the regional linkage of microtubules to actin filaments through IQGAP1 for cell migration.. |
| 4. |
Kazuhide Sato, Takashi Watanabe, Shujie Wang, Mai Kakeno, Kenji Matsuzawa, Toshinori Matsui, Keiko Yokoi, Kiyoko Murase, Ikuko Sugiyama, Masayuki Ozawa, Kozo Kaibuchi, Numb controls E-cadherin endocytosis through p120 catenin with aPKC., Molecular biology of the cell, 10.1091/mbc.E11-03-0274, 22, 17, 3103-19, 2011.09, Cadherin trafficking controls tissue morphogenesis and cell polarity. The endocytic adaptor Numb participates in apicobasal polarity by acting on intercellular adhesions in epithelial cells. However, it remains largely unknown how Numb controls cadherin-based adhesion. Here, we found that Numb directly interacted with p120 catenin (p120), which is known to interact with E-cadherin and prevent its internalization. Numb accumulated at intercellular adhesion sites and the apical membrane in epithelial cells. Depletion of Numb impaired E-cadherin internalization, whereas depletion of p120 accelerated internalization. Expression of the Numb-binding fragment of p120 inhibited E-cadherin internalization in a dominant-negative fashion, indicating that Numb interacts with the E-cadherin/p120 complex and promotes E-cadherin endocytosis. Impairment of Numb induced mislocalization of E-cadherin from the lateral membrane to the apical membrane. Atypical protein kinase C (aPKC), a member of the PAR complex, phosphorylated Numb and inhibited its association with p120 and α-adaptin. Depletion or inhibition of aPKC accelerated E-cadherin internalization. Wild-type Numb restored E-cadherin internalization in the Numb-depleted cells, whereas a phosphomimetic mutant or a mutant with defective α-adaptin-binding ability did not restore the internalization. Thus, we propose that aPKC phosphorylates Numb to prevent its binding to p120 and α-adaptin, thereby attenuating E-cadherin endocytosis to maintain apicobasal polarity.. |
| 5. |
Shujie Wang, Takashi Watanabe, Kenji Matsuzawa, Akira Katsumi, Mai Kakeno, Toshinori Matsui, Feng Ye, Kazuhide Sato, Kiyoko Murase, Ikuko Sugiyama, Kazushi Kimura, Akira Mizoguchi, Mark H Ginsberg, John G Collard, Kozo Kaibuchi, Tiam1 interaction with the PAR complex promotes talin-mediated Rac1 activation during polarized cell migration., The Journal of cell biology, 10.1083/jcb.201202041, 199, 2, 331-45, 2012.10, Migrating cells acquire front-rear polarity with a leading edge and a trailing tail for directional movement. The Rac exchange factor Tiam1 participates in polarized cell migration with the PAR complex of PAR3, PAR6, and atypical protein kinase C. However, it remains largely unknown how Tiam1 is regulated and contributes to the establishment of polarity in migrating cells. We show here that Tiam1 interacts directly with talin, which binds and activates integrins to mediate their signaling. Tiam1 accumulated at adhesions in a manner dependent on talin and the PAR complex. The interactions of talin with Tiam1 and the PAR complex were required for adhesion-induced Rac1 activation, cell spreading, and migration toward integrin substrates. Furthermore, Tiam1 acted with talin to regulate adhesion turnover. Thus, we propose that Tiam1, with the PAR complex, binds to integrins through talin and, together with the PAR complex, thereby regulates Rac1 activity and adhesion turnover for polarized migration.. |
| 6. |
Takashi Watanabe, Mai Kakeno, Toshinori Matsui, Ikuko Sugiyama, Nariko Arimura, Kenji Matsuzawa, Aya Shirahige, Fumiyoshi Ishidate, Tomoki Nishioka, Shinichiro Taya, Mikio Hoshino, Kozo Kaibuchi, TTBK2 with EB1/3 regulates microtubule dynamics in migrating cells through KIF2A phosphorylation., The Journal of cell biology, 10.1083/jcb.201412075, 210, 5, 737-51, 2015.08, Microtubules (MTs) play critical roles in various cellular events, including cell migration. End-binding proteins (EBs) accumulate at the ends of growing MTs and regulate MT end dynamics by recruiting other plus end-tracking proteins (+TIPs). However, how EBs contribute to MT dynamics through +TIPs remains elusive. We focused on tau-tubulin kinase 2 (TTBK2) as an EB1/3-binding kinase and confirmed that TTBK2 acted as a +TIP. We identified MT-depolymerizing kinesin KIF2A as a novel substrate of TTBK2. TTBK2 phosphorylated KIF2A at S135 in intact cells in an EB1/3-dependent fashion and inactivated its MT-depolymerizing activity in vitro. TTBK2 depletion reduced MT lifetime (facilitated shrinkage and suppressed rescue) and impaired HeLa cell migration, and these phenotypes were partially restored by KIF2A co-depletion. Expression of nonphosphorylatable KIF2A, but not wild-type KIF2A, reduced MT lifetime and slowed down the cell migration. These findings indicate that TTBK2 with EB1/3 phosphorylates KIF2A and antagonizes KIF2A-induced depolymerization at MT plus ends for cell migration.. |
| 7. |
Toshinori Matsui, Takashi Watanabe, Kenji Matsuzawa, Mai Kakeno, Nobumasa Okumura, Ikuko Sugiyama, Norimichi Itoh, Kozo Kaibuchi, PAR3 and aPKC regulate Golgi organization through CLASP2 phosphorylation to generate cell polarity., Molecular biology of the cell, 10.1091/mbc.E14-09-1382, 26, 4, 751-61, 2015.02, The organization of the Golgi apparatus is essential for cell polarization and its maintenance. The polarity regulator PAR complex (PAR3, PAR6, and aPKC) plays critical roles in several processes of cell polarization. However, how the PAR complex participates in regulating the organization of the Golgi remains largely unknown. Here we demonstrate the functional cross-talk of the PAR complex with CLASP2, which is a microtubule plus-end-tracking protein and is involved in organizing the Golgi ribbon. CLASP2 directly interacted with PAR3 and was phosphorylated by aPKC. In epithelial cells, knockdown of either PAR3 or aPKC induced the aberrant accumulation of CLASP2 at the trans-Golgi network (TGN) concomitantly with disruption of the Golgi ribbon organization. The expression of a CLASP2 mutant that inhibited the PAR3-CLASP2 interaction disrupted the organization of the Golgi ribbon. CLASP2 is known to localize to the TGN through its interaction with the TGN protein GCC185. This interaction was inhibited by the aPKC-mediated phosphorylation of CLASP2. Furthermore, the nonphosphorylatable mutant enhanced the colocalization of CLASP2 with GCC185, thereby perturbing the Golgi organization. On the basis of these observations, we propose that PAR3 and aPKC control the organization of the Golgi through CLASP2 phosphorylation.. |
| 8. |
Kana Aoki, Shota Harada, Keita Kawaji, Kenji Matsuzawa, Seiichi Uchida, Junichi Ikenouchi, STIM-Orai1 signaling regulates fluidity of cytoplasm during membrane blebbing., Nature communications, 10.1038/s41467-020-20826-5, 12, 1, 480-480, 2021.01, The cytoplasm in mammalian cells is considered homogeneous. In this study, we report that the cytoplasmic fluidity is regulated in the blebbing cells; the cytoplasm of rapidly expanding membrane blebs is more disordered than the cytoplasm of retracting blebs. The increase of cytoplasmic fluidity in the expanding bleb is caused by a sharp rise in the calcium concentration. The STIM-Orai1 pathway regulates this rapid and restricted increase of calcium in the expanding blebs. Conversely, activated ERM protein binds to Orai1 to inhibit the store-operated calcium entry in retracting blebs, which results in decreased in cytoplasmic calcium, rapid reassembly of the actin cortex.. |
| 9. |
Kenji Matsuzawa, Hayato Ohga, Kenta Shigetomi, Tomohiro Shiiya, Masanori Hirashima, Junichi Ikenouchi, MAGIs regulate aPKC to enable balanced distribution of intercellular tension for epithelial sheet homeostasis., Communications Biology, 10.1038/s42003-021-01874-z, 4, 1, 337-337, 2021.03, Constriction of the apical plasma membrane is a hallmark of epithelial cells that underlies cell shape changes in tissue morphogenesis and maintenance of tissue integrity in homeostasis. Contractile force is exerted by a cortical actomyosin network that is anchored to the plasma membrane by the apical junctional complexes (AJC). In this study, we present evidence that MAGI proteins, structural components of AJC whose function remained unclear, regulate apical constriction of epithelial cells through the Par polarity proteins. We reveal that MAGIs are required to uniformly distribute Partitioning defective-3 (Par-3) at AJC of cells throughout the epithelial monolayer. MAGIs recruit ankyrin-repeat-, SH3-domain- and proline-rich-region-containing protein 2 (ASPP2) to AJC, which modulates Par-3-aPKC to antagonize ROCK-driven contractility. By coupling the adhesion machinery to the polarity proteins to regulate cellular contractility, we propose that MAGIs play essential and central roles in maintaining steady state intercellular tension throughout the epithelial cell sheet.. |
| 10. |
Kenji Matsuzawa, Takuya Himoto, Yuki Mochizuki, Junichi Ikenouchi, α-Catenin Controls the Anisotropy of Force Distribution at Cell-Cell Junctions during Collective Cell Migration., Cell reports, 10.1016/j.celrep.2018.05.070, 23, 12, 3447-3456, 2018.06, Adherens junctions (AJs) control epithelial cell behavior, such as collective movement and morphological changes, during development and in disease. However, the molecular mechanism of AJ remodeling remains incompletely understood. Here, we report that the conformational activation of α-catenin is the key event in the dynamic regulation of AJ remodeling. α-catenin activates RhoA to increase actomyosin contractility at cell-cell junctions. This leads to the stabilization of activated α-catenin, in part through the recruitment of the actin-binding proteins, vinculin and afadin. In this way, α-catenin regulates force sensing, as well as force transmission, through a Rho-mediated feedback mechanism. We further show that this is important for stable directional alignment of multiple cells during collective cell movement by both experimental observation and mathematical modeling. Taken together, our findings demonstrate that α-catenin controls the establishment of anisotropic force distribution at cell junctions to enable cooperative movement of the epithelial cell sheet.. |
| 11. |
Kenji Matsuzawa, Hiroki Akita, Takashi Watanabe, Mai Kakeno, Toshinori Matsui, Shujie Wang, Kozo Kaibuchi, PAR3-aPKC regulates Tiam1 by modulating suppressive internal interactions., Molecular biology of the cell, 10.1091/mbc.E15-09-0670, 27, 9, 1511-23, 2016.05, Tiam1 is one of the most extensively analyzed activators of the small GTPase Rac. However, fundamental aspects of its regulation are poorly understood. Here we demonstrate that Tiam1 is functionally suppressed by internal interactions and that the PAR complex participates in its full activation. The N-terminal region of Tiam1 binds to the protein-binding and catalytic domains to inhibit its localization and activation. Atypical PKCs phosphorylate Tiam1 to relieve its intramolecular interactions, and the subsequent stabilization of its interaction with PAR3 allows it to exert localized activity. By analyzing Tiam1 regulation by PAR3-aPKC within the context of PDGF signaling, we also show that PAR3 directly binds PDGF receptor β. Thus we provide the first evidence for the negative regulation of Tiam1 by internal interactions, elucidate the nature of Tiam1 regulation by the PAR complex, and reveal a novel role for the PAR complex in PDGF signaling.. |
