Scientific background: |
SMARCB1(SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1), also known as SNF5, INI1 or MALIGNANT RHABDOID TUMOR SUPPRESSOR, is a protein that in humans is encoded by the SMARCB1 gene. The SMARCB1 gene encodes a subunit of the SWI/SNF ATP-dependent chromatin-remodeling complex. The SMARCB1 gene maps to chromosome 22q11.2 (Versteege et al., 1998). Wu et al. (2002) noted that GADD34 (PPP1R15A) and SNF5 can coexist in a trimeric complex with chimeric leukemic HRX (MLL) fusion proteins, leading to inhibition of GADD34-mediated apoptosis. By mutation analysis, they showed that the GADD34 region homologous to the HSV-1 ICP34.5 protein was necessary for interaction with SNF5. SNF5 could bind independently with the protein phosphatase-1 (PP1) catalytic subunit (PPP1CA) and stimulate its activity in solution and in complex with GADD34. SNF5 and PP1 did not compete for GADD34 binding, but rather formed a stable trimeric complex with GADD34. Wu et al. (2002) proposed that GADD34 mediates growth suppression, at least in part, through its interaction with SNF5. They suggested that SNF5 may function as a regulatory subunit of PP1, either independently or together with GADD34. |
References: |
1. van den Munckhof, P., Christiaans, I., Kenter, S. B., Baas, F., Hulsebos, T. J. M. Germline SMARCB1 mutation predisposes to multiple meningiomas and schwannomas with preferential location of cranial meningiomas at the falx cerebri. Neurogenetics 13: 1-7, 2012.
2. Versteege, I., Sevenet, N., Lange, J., Rousseau-Merck, M.-F., Ambros, P., Handgretinger, R., Aurias, A., Delattre, O. Truncating mutations of hSNF5/INI1 in aggressive paediatric cancer. Nature 394: 203-206, 1998.
3. Wu, D. Y., Tkachuck, D. C., Roberson, R. S., Schubach, W. H. The human SNF5/INI1 protein facilitates the function of the growth arrest and DNA damage-inducible protein (GADD34) and modulates GADD34-bound protein phosphatase-1 activity. J. Biol. Chem. 277: 27706-27715, 2002.
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