Comparative study of satb family proteins

Abstract

SATB1 and SATB2 are members of special AT rich binding protein family a class of chromatin organizers and gene regulators SATB1 has been shown to play seminal roles in development and differentiation of T cells whereas SATB2 has been mainly implicated in development of neurons and bone These two have also been shown to play important roles in development and progression of various kinds of tumors Recently SATB1 2 have been implicated in the regulation of Nanog a pluoripotency associated gene Here we study the distinct roles of SATB1 and SATB2 using cell line and human stem cell models We show that various cells and tissues differentially express SATB1 and SATB2 Using IgH MAR reporter system we show that SATB1 and SATB2 both bind and regulate the target genes in MAR dependent manner in association with various corepressors and activators Our study further reveals that SATB1 and SATB2 interact in vivo to form heterodimeric complexes and cooperatively regulate transcription Intriguingly both SATB1 and SATB2 regulate each other 8217 s expression by directly binding to respective promoters We further dissected their roles during retinoic acid RA mediated differentiation of NT2D1 a pluripotent human testicular embryonal carcinoma cell line and that of human embryonic stem cells RA mediated differentiation of NT2D1 cells resulted in upregulation of SATB1 and SATB2 along with various differentiation markers while various pluripotency markers were downregulated Knockdown of SATB1 and SATB2 resulted in contrasting effects to that of RA mediated differentiation Interestingly we observed that Wnt signaling is upregulated upon RA mediated differentiation Activation of Wnt signaling via Wnt3a in these cells mimicked the RA mediated differentiation Knockdown of SATB1 and SATB2 resulted in the downregulation of Wnt responsive genes in NT2D1 cells indicating that SATB1 and STAB2 might target Wnt responsive genes during differentiation We extended our studies to human embryonic stem cell line hES where we used two hES