8eq5

Structural highlights

Disease

KS6A3_HUMAN Coffin-Lowry syndrome;X-linked nonsyndromic intellectual deficit. Defects in RPS6KA3 are the cause of Coffin-Lowry syndrome (CLS) [MIM:303600. A X-linked mental retardation associated with facial and digital dysmorphisms, progressive skeletal malformations, growth retardation, hearing deficit and paroxysmal movement disorders.^{[1] [2] [3] [4] [5] [6]} Defects in RPS6KA3 are the cause of mental retardation X-linked type 19 (MRX19) [MIM:300844. MRX19 is a non-syndromic form of mild to moderate mental retardation. Mental retardation is characterized by significantly below average general intellectual functioning associated with impairments in adaptative behavior and manifested during the developmental period. In contrast to syndromic or specific X-linked mental retardation which also present with associated physical, neurological and/or psychiatric manifestations, intellectual deficiency is the only primary symptom of non-syndromic X-linked mental retardation.^{[7] [8]}

Function

KS6A3_HUMAN Serine/threonine-protein kinase that acts downstream of ERK (MAPK1/ERK2 and MAPK3/ERK1) signaling and mediates mitogenic and stress-induced activation of the transcription factors CREB1, ETV1/ER81 and NR4A1/NUR77, regulates translation through RPS6 and EIF4B phosphorylation, and mediates cellular proliferation, survival, and differentiation by modulating mTOR signaling and repressing pro-apoptotic function of BAD and DAPK1. In fibroblast, is required for EGF-stimulated phosphorylation of CREB1 and histone H3 at 'Ser-10', which results in the subsequent transcriptional activation of several immediate-early genes. In response to mitogenic stimulation (EGF and PMA), phosphorylates and activates NR4A1/NUR77 and ETV1/ER81 transcription factors and the cofactor CREBBP. Upon insulin-derived signal, acts indirectly on the transcription regulation of several genes by phosphorylating GSK3B at 'Ser-9' and inhibiting its activity. Phosphorylates RPS6 in response to serum or EGF via an mTOR-independent mechanism and promotes translation initiation by facilitating assembly of the preinitiation complex. In response to insulin, phosphorylates EIF4B, enhancing EIF4B affinity for the EIF3 complex and stimulating cap-dependent translation. Is involved in the mTOR nutrient-sensing pathway by directly phosphorylating TSC2 at 'Ser-1798', which potently inhibits TSC2 ability to suppress mTOR signaling, and mediates phosphorylation of RPTOR, which regulates mTORC1 activity and may promote rapamycin-sensitive signaling independently of the PI3K/AKT pathway. Mediates cell survival by phosphorylating the pro-apoptotic proteins BAD and DAPK1 and suppressing their pro-apoptotic function. Promotes the survival of hepatic stellate cells by phosphorylating CEBPB in response to the hepatotoxin carbon tetrachloride (CCl4). Is involved in cell cycle regulation by phosphorylating the CDK inhibitor CDKN1B, which promotes CDKN1B association with 14-3-3 proteins and prevents its translocation to the nucleus and inhibition of G1 progression. In LPS-stimulated dendritic cells, is involved in TLR4-induced macropinocytosis, and in myeloma cells, acts as effector of FGFR3-mediated transformation signaling, after direct phosphorylation at Tyr-529 by FGFR3. Phosphorylates DAPK1.^{[9] [10] [11] [12] [13] [14] [15]}

See Also

• Ribosomal protein S6 kinase 3D structures

References

1. ↑ Trivier E, De Cesare D, Jacquot S, Pannetier S, Zackai E, Young I, Mandel JL, Sassone-Corsi P, Hanauer A. Mutations in the kinase Rsk-2 associated with Coffin-Lowry syndrome. Nature. 1996 Dec 12;384(6609):567-70. PMID:8955270 doi:10.1038/384567a0
2. ↑ Jacquot S, Merienne K, De Cesare D, Pannetier S, Mandel JL, Sassone-Corsi P, Hanauer A. Mutation analysis of the RSK2 gene in Coffin-Lowry patients: extensive allelic heterogeneity and a high rate of de novo mutations. Am J Hum Genet. 1998 Dec;63(6):1631-40. PMID:9837815 doi:S0002-9297(07)61607-3
3. ↑ Abidi F, Jacquot S, Lassiter C, Trivier E, Hanauer A, Schwartz CE. Novel mutations in Rsk-2, the gene for Coffin-Lowry syndrome (CLS). Eur J Hum Genet. 1999 Jan;7(1):20-6. PMID:10094187 doi:10.1038/sj.ejhg.5200231
4. ↑ Manouvrier-Hanu S, Amiel J, Jacquot S, Merienne K, Moerman A, Coeslier A, Labarriere F, Vallee L, Croquette MF, Hanauer A. Unreported RSK2 missense mutation in two male sibs with an unusually mild form of Coffin-Lowry syndrome. J Med Genet. 1999 Oct;36(10):775-8. PMID:10528858
5. ↑ Martinez-Garay I, Ballesta MJ, Oltra S, Orellana C, Palomeque A, Molto MD, Prieto F, Martinez F. Intronic L1 insertion and F268S, novel mutations in RPS6KA3 (RSK2) causing Coffin-Lowry syndrome. Clin Genet. 2003 Dec;64(6):491-6. PMID:14986828
6. ↑ Facher JJ, Regier EJ, Jacobs GH, Siwik E, Delaunoy JP, Robin NH. Cardiomyopathy in Coffin-Lowry syndrome. Am J Med Genet A. 2004 Jul 15;128A(2):176-8. PMID:15214012 doi:10.1002/ajmg.a.30056
7. ↑ Merienne K, Jacquot S, Pannetier S, Zeniou M, Bankier A, Gecz J, Mandel JL, Mulley J, Sassone-Corsi P, Hanauer A. A missense mutation in RPS6KA3 (RSK2) responsible for non-specific mental retardation. Nat Genet. 1999 May;22(1):13-4. PMID:10319851 doi:10.1038/8719
8. ↑ Field M, Tarpey P, Boyle J, Edkins S, Goodship J, Luo Y, Moon J, Teague J, Stratton MR, Futreal PA, Wooster R, Raymond FL, Turner G. Mutations in the RSK2(RPS6KA3) gene cause Coffin-Lowry syndrome and nonsyndromic X-linked mental retardation. Clin Genet. 2006 Dec;70(6):509-15. PMID:17100996 doi:10.1111/j.1399-0004.2006.00723.x
9. ↑ Sutherland C, Leighton IA, Cohen P. Inactivation of glycogen synthase kinase-3 beta by phosphorylation: new kinase connections in insulin and growth-factor signalling. Biochem J. 1993 Nov 15;296 ( Pt 1):15-9. PMID:8250835
10. ↑ De Cesare D, Jacquot S, Hanauer A, Sassone-Corsi P. Rsk-2 activity is necessary for epidermal growth factor-induced phosphorylation of CREB protein and transcription of c-fos gene. Proc Natl Acad Sci U S A. 1998 Oct 13;95(21):12202-7. PMID:9770464
11. ↑ Sassone-Corsi P, Mizzen CA, Cheung P, Crosio C, Monaco L, Jacquot S, Hanauer A, Allis CD. Requirement of Rsk-2 for epidermal growth factor-activated phosphorylation of histone H3. Science. 1999 Aug 6;285(5429):886-91. PMID:10436156
12. ↑ Anjum R, Roux PP, Ballif BA, Gygi SP, Blenis J. The tumor suppressor DAP kinase is a target of RSK-mediated survival signaling. Curr Biol. 2005 Oct 11;15(19):1762-7. PMID:16213824 doi:10.1016/j.cub.2005.08.050
13. ↑ Wingate AD, Campbell DG, Peggie M, Arthur JS. Nur77 is phosphorylated in cells by RSK in response to mitogenic stimulation. Biochem J. 2006 Feb 1;393(Pt 3):715-24. PMID:16223362 doi:10.1042/BJ20050967
14. ↑ Roux PP, Shahbazian D, Vu H, Holz MK, Cohen MS, Taunton J, Sonenberg N, Blenis J. RAS/ERK signaling promotes site-specific ribosomal protein S6 phosphorylation via RSK and stimulates cap-dependent translation. J Biol Chem. 2007 May 11;282(19):14056-64. Epub 2007 Mar 14. PMID:17360704 doi:10.1074/jbc.M700906200
15. ↑ Carriere A, Cargnello M, Julien LA, Gao H, Bonneil E, Thibault P, Roux PP. Oncogenic MAPK signaling stimulates mTORC1 activity by promoting RSK-mediated raptor phosphorylation. Curr Biol. 2008 Sep 9;18(17):1269-77. doi: 10.1016/j.cub.2008.07.078. Epub 2008, Aug 21. PMID:18722121 doi:10.1016/j.cub.2008.07.078