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SRY (sex determining region Y)-box 21/Sox-21 (Gene SOX21) Homo sapiensThe SOX21 (map locus: Entrez and HGNC: 13q31-q32; Ensembl 13q32.1, Malas S, (1999)) gene product, SRY (sex determining region Y)-box 21/Sox-21 protein, is a 276 AA (28.6 kDa) high mobility group (HMG box) domain (8 to 76) containing transcription factor. HMG box domains preferentially bind to and distort DNA. Sox21 contains three polyalanine tracts; 137 to 146, 154 to 166 and 208 to 219. The Sox family members are HMG-box containing transcription factors related to mammalian testis determining factor, SRY. Sox14 and Sox21 are B2-subgroup Sox transcription factors involved primarily in gene repression, especially of neurogenesis. Sox14 and Sox21 are similar to one another but distinct from the B1-subgroup Sox proteins, Sox1, Sox2 and Sox3. Sox14 and Sox21 are viewed as opposing regulators of genes regulated by the B1 Sox factors, Uchikawa M et al. (1999). Sox21 is generally classified as a repressor gene that promotes neurogenesis, Sandberg M, et al. (2005); Ohba H, et al. (2004). The overexpression of Sox21 leads to substantial repression of NGF-induced neurite outgrowth in PC12 cells, Ohba H, et al. (2004). Sox21 is upregulated by proneural basic helix-loop-helix proteins (pHLH), Sandberg M, et al. (2005). These pHLH proteins are members of pathways that compete with the B1-subgroup stem cell maintenance promoting SOX proteins, Sox1, Sox2 and Sox3. Hence, Sox21 helps to counter the pluripotency maintenance genes and to allow neurogenesis to occur, Wegner M and Stolt CC (2005). The neurogenesis promoting activity of Sox21 is positionally restricted within the CNS, where it functions primarily as a dorsalizing factor that helps establish dorsoventral patterning, Rex M, et al. (1997). Sox21 is expressed mainly in the developing midbrain-hindbrain boundary at the onset of neurulation. Knock-out of Sox21a in zebrafish caused ventralization of the embryos, Argenton F, et al. (2004). Sox 21 mRNA is not detected in normal adult tissues, Gure AO, at al. (2000) but has been reported in a couple of cancer models. Sox21 was reported to be expressed in high-metastatic K-1735 murine melanoma cells, Tani M, et al. (1997) and by some small cell lung cancer (SCLC) cell lines, Gure AO, at al. (2000). Sigma offers antibodies, shRNAs and other products useful for the study of the SOX21 gene products. References: Argenton F, et al. (2004) Ectopic expression and knockdown of a zebrafish sox21 reveal its role as a transcriptional repressor in early development. Mech Dev. 121: 131-142. |
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