||Tetsuya Sakurai*, Takehito Uruno*, Yuki Sugiura, Takaaki Tatsuguchi, Kazuhiko Yamamura, Miho Ushijima, Yuko Hattori, Mutsuko Kukimoto-Niino, Chiemi Mishima-Tsumagari, Mayuki Watanabe, Makoto Suematsu, and Yoshinori Fukui, Cholesterol sulfate is a DOCK2 inhibitor that mediates tissue-specific immune evasion in the eye, Science Signaling, 10.1126/scisignal.aao4874, 11, 541, eaao4874, 2018.07, Although immune responses are essential to protect the body from infection, they can also harm tissues. Certain tissues and organs, including the eye, constitute specialized microenvironments that locally inhibit immune reactivity. Dedicator of cytokinesis protein 2 (DOCK2) is a Rac-specific guanine nucleotide exchange factor (GEF) that is predominantly found in hematopoietic cells. DOCK2 plays a key role in immune surveillance because it is essential for the activation and migration of leukocytes. DOCK2 mutations cause severe immunodeficiency in humans. We found that DOCK2-mediated Rac activation and leukocyte migration were effectively inhibited by cholesterol sulfate (CS), but not by cholesterol or other sulfated steroids. CS bound to the catalytic domain of DOCK2 and suppressed its GEF activity. Mass spectrometric quantification revealed that CS was most abundantly produced in the Harderian gland, which provides the lipids that form the oily layer of the tear film. Sulfation of cholesterol is mediated by the sulfotransferases SULT2B1b and, to a lesser extent, SULT2B1a, which are produced from the same gene through alternative splicing. By genetically inactivating Sult2b1, we showed that the lack of CS in mice augmented ultraviolet- and antigen-induced ocular surface inflammation, which was suppressed by administration of eye drops containing CS. Thus, CS is a naturally occurring DOCK2 inhibitor and contributes to the generation of the immunosuppressive microenvironment in the eye.
||Hirotada Tajiri*, Takehito Uruno*, Takahiro Shirai, Daisuke Takaya, Shigeki Matsunaga, Daiki Setoyama, Mayuki Watanabe, Miho Ushijima, Fumiyuki Sanematsu, Mutsuko Niino, Honma Teuki, Ken Shirabe, Yoshihiko Maehara, Dongchon Kang, Jean-François Côté, Shigeyuki Yokoyama, Yoshinori Fukui, Targeting Ras-driven cancer cell survival and invasion through selective inhibition of DOCK1, Cell Reports, 19, 969-980, 2017.05, Oncogenic Ras plays a key role in cancer initiation but also contributes to malignant phenotypes by stimulating nutrient uptake and promoting invasive migration. Because these latter cellular responses require Rac-mediated remodeling of the actin cytoskeleton, we hypothesized that molecules involved in Rac activation may be valuable targets for cancer therapy. We report that genetic inactivation of the Rac-specific guanine nucleotide exchange factor DOCK1 ablates both macropinocytosis-dependent nutrient uptake and cellular invasion in Ras-transformed cells. By screening chemical libraries, we have identified 1-(2-(3'-(trifluoromethyl)-[1,1'-biphenyl]-4-yl)-2-oxoethyl)-5-pyrrolidinylsulfonyl-2(1H)-pyridone (TBOPP) as a selective inhibitor of DOCK1. TBOPP dampened DOCK1-mediated invasion, macropinocytosis, and survival under the condition of glutamine deprivation without impairing the biological functions of the closely related DOCK2 and DOCK5 proteins. Furthermore, TBOPP treatment suppressed cancer metastasis and growth in vivo in mice. Our results demonstrate that selective pharmacological inhibition of DOCK1 could be a therapeutic approach to target cancer cell survival and invasion.
||Takahiro Tomino, Hirotada Tajiri, Takaaki Tatsuguchi, Takahiro Shirai, Kounosuke Oisaki, Shigeki Matsunaga, Fumiyuki Sanematsu, Daiji Sakata, Tomoharu Yoshizumi, Yoshihiko Maehara, Motomu Kanai, Jean François Cote, Yoshinori Fukui, Takehito Uruno*, DOCK1 inhibition suppresses cancer cell invasion and macropinocytosis induced by self-activating Rac1P29S mutation, Biochemical and Biophysical Research Communications, 497, 1, 298-304, 2018.02.
||Kazuhiko Yamamura, Takehito Uruno, Akira Shiraishi, Yoshihiko Tanaka, Miho Ushijima, Takeshi Nakahara, Mayuki Watanabe, Makiko Kido-Nakahara, Ikuya Tsuge, Masutaka Furue, Yoshinori Fukui, The transcription factor EPAS1 links DOCK8 deficiency to atopic skin inflammation via IL-31 induction, Nature Communications, 8, 13946, 2017.01.
||Miho Ushijima, Takehito Uruno*, Akihiko Nishikimi, Fumiyuki Sanematsu, Yasuhisa Kamikaseda, Kazufumi Kunimura, Daiji Sakata, Takaharu Okada, Yoshinori Fukui, The Rac activator DOCK2 mediates plasma cell differentiation and IgG antibody production, Frontiers in Immunology, 9, 243, 2018.02.
||Akihiko Nishikimi*, Takehito Uruno* et al., "Blockade of inflammatory responses by a small -molecule inhibitor of the Rac activator DOCK2.", Chemistry and Biology, 2012.04.
||Adam Zwolak*, Takehito Uruno*, Grzegorz Piszczek, John A. Hammer III, Nico Tjandra, "Molecular basis for barbed end uncapping by CARMIL homology domain 3 of mouse CARMIL-1.", Journal of Biological Chemistry, 285, 37, 29014-29026, 2010.09.
||Takehito Uruno, Kirsten Remmert, John A. Hammer, "CARMIL is a potent capping protein antagonist: identification of a conserved CARMIL domain that inhibits the activity of capping protein and uncaps capped actin filaments.", Journal of Biological Chemistry, 281, 15, 10635, 2006.04.
||Takehito Uruno, Jiali Liu, YanSong Li, Nicole Smith, Zhan Xi, "Sequential interaction of actin-related proteins 2 and 3 (Arp2/3) complex with neural Wiscott-Aldrich syndrome protein (N-WASP) and cortactin during branched actin filament network formation.", Journal of Biological Chemistry, 278, 26086, 2003.07.
||Takehito Uruno, Jiali Liu, Peijun Zhang, Ying-xin Fan, Coumaran Egile, Rong Li, Susette C. Mueller, Zhan Xi, "Activation of Arp2/3 complex-mediated actin polymerization by cortactin.", Nature Cell Biology, 3, 3, 259-266, 2001.03.