Rac1, also known as Ras-related C3 botulinum toxin substrate 1, is a protein found in human cells. It is encoded by the RAC1gene.[1][2] This gene can produce a variety of alternatively spliced versions of the Rac1 protein, which appear to carry out different functions.[3]
Rac1 is a small (~21 kDa) signaling G protein (more specifically a GTPase), and is a member of the Rac subfamily of the family Rho family of GTPases. Members of this superfamily appear to regulate a diverse array of cellular events, including the control of GLUT4[4][5] translocation to glucose uptake, cell growth, cytoskeletal reorganization, antimicrobial cytotoxicity,[6] and the activation of protein kinases.[7]
Rac1 is a pleiotropic regulator of many cellular processes, including the cell cycle, cell-cell adhesion, motility (through the actin network), and of epithelialdifferentiation (proposed to be necessary for maintaining epidermal stem cells).
Role in cancer
Along with other subfamily of Rac and Rho proteins, they exert an important regulatory role specifically in cell motility and cell growth. Rac1 has ubiquitous tissue expression, and drives cell motility by formation of lamellipodia.[8] In order for cancer cells to grow and invade local and distant tissues, deregulation of cell motility is one of the hallmark events in cancer cell invasion and metastasis.[9] Overexpression of a constitutively active Rac1 V12 in mice caused a tumor that's phenotypically indistinguishable from human Kaposi's sarcoma.[10] Activating or gain-of-function mutations of Rac1 are shown to play active roles in promoting mesenchymal-type of cell movement assisted by NEDD9 and DOCK3 protein complex.[11] Such abnormal cell motility may result in epithelial mesenchymal transition (EMT) – a driving mechanism for tumor metastasis as well as drug-resistant tumor relapse.[12][13]
Role in glucose transport
Rac1 is expressed in significant amounts in insulin sensitive tissues, such as adipose tissue and skeletal muscle. Here Rac1 regulated the translocation of glucose transporting GLUT4 vesicles from intracellular compartments to the plasma membrane.[5][14][15] In response to insulin, this allows for blood glucose to enter the cell to lower blood glucose. In conditions of obesity and type 2 diabetes, Rac1 signaling in skeletal muscle is dysfunctional, suggesting that Rac1 contributes to the progression of the disease.
Rac1 protein is also necessary for glucose uptake in skeletal muscle activated by exercise[4][16] and muscle stretching[17]
Clinical significance
Activating mutations in Rac1 have been recently discovered in large-scale genomic studies involving melanoma[18][19][20] and non-small cell lung cancer.[21] As a result, Rac1 is considered a therapeutic target for many of these diseases.[22]
A few recent studies have also exploited targeted therapy to suppress tumor growth by pharmacological inhibition of Rac1 activity in metastatic melanoma and liver cancer as well as in human breast cancer.[23][24][25]
For example, Rac1-dependent pathway inhibition resulted in the reversal of tumor cell phenotypes, suggesting Rac1 as a predictive marker and therapeutic target for trastuzumab-resistant breast cancer.[24] However, given Rac1's role in glucose transport, drugs that inhibits Rac1 could potentially be harmful to glucose homeostasis.
↑Didsbury J, Weber RF, Bokoch GM, Evans T, Snyderman R (Oct 1989). "rac, a novel ras-related family of proteins that are botulinum toxin substrates". The Journal of Biological Chemistry. 264 (28): 16378–82. PMID2674130.
↑Jordan P, Brazåo R, Boavida MG, Gespach C, Chastre E (Nov 1999). "Cloning of a novel human Rac1b splice variant with increased expression in colorectal tumors". Oncogene. 18 (48): 6835–9. doi:10.1038/sj.onc.1203233. PMID10597294.
↑Ridley AJ (Oct 2006). "Rho GTPases and actin dynamics in membrane protrusions and vesicle trafficking". Trends in Cell Biology. 16 (10): 522–9. doi:10.1016/j.tcb.2006.08.006. PMID16949823.
↑Sanz-Moreno V, Gadea G, Ahn J, Paterson H, Marra P, Pinner S, Sahai E, Marshall CJ (Oct 2008). "Rac activation and inactivation control plasticity of tumor cell movement". Cell. 135 (3): 510–23. doi:10.1016/j.cell.2008.09.043. PMID18984162.
↑Stallings-Mann ML, Waldmann J, Zhang Y, Miller E, Gauthier ML, Visscher DW, et al. (Jul 11, 2012). "Matrix metalloproteinase induction of Rac1b, a key effector of lung cancer progression". Science Translational Medicine. 4 (142): 510–523.
↑Yang WH, Lan HY, Huang CH, Tai SK, Tzeng CH, Kao SY, Wu KJ, Hung MC, Yang MH (Apr 2012). "RAC1 activation mediates Twist1-induced cancer cell migration". Nature Cell Biology. 14 (4): 366–74. doi:10.1038/ncb2455. PMID22407364.
↑Sylow L, Kleinert M, Pehmøller C, Prats C, Chiu TT, Klip A, Richter EA, Jensen TE (Feb 2014). "Akt and Rac1 signaling are jointly required for insulin-stimulated glucose uptake in skeletal muscle and downregulated in insulin resistance". Cellular Signalling. 26 (2): 323–31. doi:10.1016/j.cellsig.2013.11.007. PMID24216610.
↑Hodis E, Watson IR, Kryukov GV, Arold ST, Imielinski M, Theurillat JP, Nickerson E, Auclair D, Li L, Place C, Dicara D, Ramos AH, Lawrence MS, Cibulskis K, Sivachenko A, Voet D, Saksena G, Stransky N, Onofrio RC, Winckler W, Ardlie K, Wagle N, Wargo J, Chong K, Morton DL, Stemke-Hale K, Chen G, Noble M, Meyerson M, Ladbury JE, Davies MA, Gershenwald JE, Wagner SN, Hoon DS, Schadendorf D, Lander ES, Gabriel SB, Getz G, Garraway LA, Chin L (Jul 2012). "A landscape of driver mutations in melanoma". Cell. 150 (2): 251–63. doi:10.1016/j.cell.2012.06.024. PMC3600117. PMID22817889.
↑Krauthammer M, Kong Y, Ha BH, Evans P, Bacchiocchi A, McCusker JP, Cheng E, Davis MJ, Goh G, Choi M, Ariyan S, Narayan D, Dutton-Regester K, Capatana A, Holman EC, Bosenberg M, Sznol M, Kluger HM, Brash DE, Stern DF, Materin MA, Lo RS, Mane S, Ma S, Kidd KK, Hayward NK, Lifton RP, Schlessinger J, Boggon TJ, Halaban R (Sep 2012). "Exome sequencing identifies recurrent somatic RAC1 mutations in melanoma". Nature Genetics. 44 (9): 1006–14. doi:10.1038/ng.2359. PMC3432702. PMID22842228.
↑Chen QY, Xu LQ, Jiao DM, Yao QH, Wang YY, Hu HZ, et al. (Nov 2011). "Silencing of Rac1 modifies lung cancer cell migration, invasion and actin cytoskeleton rearrangements and enhances chemosensitivity to antitumor drugs". International Journal of Molecular Medicine. 28 (5): 769–776.
↑ 24.024.1Dokmanovic M, Hirsch DS, Shen Y, Wu WJ (Jun 2009). "Rac1 contributes to trastuzumab resistance of breast cancer cells: Rac1 as a potential therapeutic target for the treatment of trastuzumab-resistant breast cancer". Molecular Cancer Therapeutics. 8 (6): 1557–69. doi:10.1158/1535-7163.mct-09-0140. PMID19509242.
↑Liu S, Yu M, He Y, Xiao L, Wang F, Song C, Sun S, Ling C, Xu Z (Jun 2008). "Melittin prevents liver cancer cell metastasis through inhibition of the Rac1-dependent pathway". Hepatology. 47 (6): 1964–73. doi:10.1002/hep.22240. PMID18506888.
↑Reijnders, Margot R.F.; Ansor, Nurhuda M.; Kousi, Maria; Yue, Wyatt W.; Tan, Perciliz L.; Clarkson, Katie; Clayton-Smith, Jill; Corning, Ken; Jones, Julie R.; Lam, Wayne W.K.; Mancini, Grazia M.S.; Marcelis, Carlo; Mohammed, Shehla; Pfundt, Rolph; Roifman, Maian; Cohn, Ronald; Chitayat, David; Millard, Tom H.; Katsanis, Nicholas; Brunner, Han G.; Banka, Siddharth (September 2017). "RAC1 Missense Mutations in Developmental Disorders with Diverse Phenotypes". The American Journal of Human Genetics. 101 (3): 466–477. doi:10.1016/j.ajhg.2017.08.007. PMC5591022. PMID28886345.
↑ 27.027.1Shin OH, Exton JH (Aug 2001). "Differential binding of arfaptin 2/POR1 to ADP-ribosylation factors and Rac1". Biochemical and Biophysical Research Communications. 285 (5): 1267–73. doi:10.1006/bbrc.2001.5330. PMID11478794.
↑Tarricone C, Xiao B, Justin N, Walker PA, Rittinger K, Gamblin SJ, Smerdon SJ (May 2001). "The structural basis of Arfaptin-mediated cross-talk between Rac and Arf signalling pathways". Nature. 411 (6834): 215–9. doi:10.1038/35075620. PMID11346801.
↑Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T, Figeys D (2007). "Large-scale mapping of human protein-protein interactions by mass spectrometry". Molecular Systems Biology. 3 (1): 89. doi:10.1038/msb4100134. PMC1847948. PMID17353931.
↑Grizot S, Fauré J, Fieschi F, Vignais PV, Dagher MC, Pebay-Peyroula E (Aug 2001). "Crystal structure of the Rac1-RhoGDI complex involved in nadph oxidase activation". Biochemistry. 40 (34): 10007–13. doi:10.1021/bi010288k. PMID11513578.
↑Lian LY, Barsukov I, Golovanov AP, Hawkins DI, Badii R, Sze KH, Keep NH, Bokoch GM, Roberts GC (Jan 2000). "Mapping the binding site for the GTP-binding protein Rac-1 on its inhibitor RhoGDI-1". Structure. 8 (1): 47–55. doi:10.1016/S0969-2126(00)00080-0. PMID10673424.
↑Gorvel JP, Chang TC, Boretto J, Azuma T, Chavrier P (Jan 1998). "Differential properties of D4/LyGDI versus RhoGDI: phosphorylation and rho GTPase selectivity". FEBS Letters. 422 (2): 269–73. doi:10.1016/S0014-5793(98)00020-9. PMID9490022.
↑Di-Poï N, Fauré J, Grizot S, Molnár G, Pick E, Dagher MC (Aug 2001). "Mechanism of NADPH oxidase activation by the Rac/Rho-GDI complex". Biochemistry. 40 (34): 10014–22. doi:10.1021/bi010289c. PMID11513579.
↑Fauré J, Dagher MC (May 2001). "Interactions between Rho GTPases and Rho GDP dissociation inhibitor (Rho-GDI)". Biochimie. 83 (5): 409–14. doi:10.1016/S0300-9084(01)01263-9. PMID11368848.
↑Miki H, Yamaguchi H, Suetsugu S, Takenawa T (Dec 2000). "IRSp53 is an essential intermediate between Rac and WAVE in the regulation of membrane ruffling". Nature. 408 (6813): 732–5. doi:10.1038/35047107. PMID11130076.
↑Westendorf JJ (Dec 2001). "The formin/diaphanous-related protein, FHOS, interacts with Rac1 and activates transcription from the serum response element". The Journal of Biological Chemistry. 276 (49): 46453–9. doi:10.1074/jbc.M105162200. PMID11590143.
↑ 39.039.1Zhang B, Chernoff J, Zheng Y (Apr 1998). "Interaction of Rac1 with GTPase-activating proteins and putative effectors. A comparison with Cdc42 and RhoA". The Journal of Biological Chemistry. 273 (15): 8776–82. doi:10.1074/jbc.273.15.8776. PMID9535855.
↑Kuroda S, Fukata M, Kobayashi K, Nakafuku M, Nomura N, Iwamatsu A, Kaibuchi K (Sep 1996). "Identification of IQGAP as a putative target for the small GTPases, Cdc42 and Rac1". The Journal of Biological Chemistry. 271 (38): 23363–7. doi:10.1074/jbc.271.38.23363. PMID8798539.
↑Fukata M, Watanabe T, Noritake J, Nakagawa M, Yamaga M, Kuroda S, Matsuura Y, Iwamatsu A, Perez F, Kaibuchi K (Jun 2002). "Rac1 and Cdc42 capture microtubules through IQGAP1 and CLIP-170". Cell. 109 (7): 873–85. doi:10.1016/S0092-8674(02)00800-0. PMID12110184.
↑Katoh H, Negishi M (Jul 2003). "RhoG activates Rac1 by direct interaction with the Dock180-binding protein Elmo". Nature. 424 (6947): 461–4. doi:10.1038/nature01817. PMID12879077.
↑Seoh ML, Ng CH, Yong J, Lim L, Leung T (Mar 2003). "ArhGAP15, a novel human RacGAP protein with GTPase binding property". FEBS Letters. 539 (1–3): 131–7. doi:10.1016/S0014-5793(03)00213-8. PMID12650940.
↑ 49.049.1Noda Y, Takeya R, Ohno S, Naito S, Ito T, Sumimoto H (Feb 2001). "Human homologues of the Caenorhabditis elegans cell polarity protein PAR6 as an adaptor that links the small GTPases Rac and Cdc42 to atypical protein kinase C". Genes to Cells. 6 (2): 107–19. doi:10.1046/j.1365-2443.2001.00404.x. PMID11260256.
↑Qiu RG, Abo A, Steven Martin G (Jun 2000). "A human homolog of the C. elegans polarity determinant Par-6 links Rac and Cdc42 to PKCzeta signaling and cell transformation". Current Biology. 10 (12): 697–707. doi:10.1016/S0960-9822(00)00535-2. PMID10873802.
↑Zhao C, Ma H, Bossy-Wetzel E, Lipton SA, Zhang Z, Feng GS (Sep 2003). "GC-GAP, a Rho family GTPase-activating protein that interacts with signaling adapters Gab1 and Gab2". The Journal of Biological Chemistry. 278 (36): 34641–53. doi:10.1074/jbc.M304594200. PMID12819203.
↑Moon SY, Zang H, Zheng Y (Feb 2003). "Characterization of a brain-specific Rho GTPase-activating protein, p200RhoGAP". The Journal of Biological Chemistry. 278 (6): 4151–9. doi:10.1074/jbc.M207789200. PMID12454018.
↑Simon AR, Vikis HG, Stewart S, Fanburg BL, Cochran BH, Guan KL (Oct 2000). "Regulation of STAT3 by direct binding to the Rac1 GTPase". Science. 290 (5489): 144–7. doi:10.1126/science.290.5489.144. PMID11021801.
↑Worthylake DK, Rossman KL, Sondek J (Dec 2000). "Crystal structure of Rac1 in complex with the guanine nucleotide exchange region of Tiam1". Nature. 408 (6813): 682–8. doi:10.1038/35047014. PMID11130063.
↑Gao Y, Xing J, Streuli M, Leto TL, Zheng Y (Dec 2001). "Trp(56) of rac1 specifies interaction with a subset of guanine nucleotide exchange factors". The Journal of Biological Chemistry. 276 (50): 47530–41. doi:10.1074/jbc.M108865200. PMID11595749.
Further reading
Benitah SA, Frye M, Glogauer M, Watt FM (Aug 2005). "Stem cell depletion through epidermal deletion of Rac1". Science. 309 (5736): 933–5. doi:10.1126/science.1113579. PMID16081735.
Ramakers GJ (Apr 2002). "Rho proteins, mental retardation and the cellular basis of cognition". Trends in Neurosciences. 25 (4): 191–9. doi:10.1016/S0166-2236(00)02118-4. PMID11998687.
Esufali S, Charames GS, Bapat B (Oct 2007). "Suppression of nuclear Wnt signaling leads to stabilization of Rac1 isoforms". FEBS Letters. 581 (25): 4850–6. doi:10.1016/j.febslet.2007.09.013. PMID17888911.