GATA-6 induces p21(Cip)¹ expression and G₁ cell cycle arrest

GATA transcription factors represent a family of highly conserved zinc finger proteins with tissue-specific expression patterns. Previous studies have shown that GATA-6 is expressed in vascular smooth muscle cells (VSMCs) and rapidly down-regulated when VSMCs are induced to proliferate. Here we investigated whether the GATA-6 transcription factor can modulate cellular proliferation. Transient transfection with a GATA-6 expression vector inhibited S-phase entry in VSMCs and in mouse embryonic fibroblasts (MEFs) lacking both p53 alleles. The GATA-6-induced growth arrest correlated with a marked increase in the expression of the general cyclin-dependent kinase (Cdk) inhibitor p21. In contrast to p53-deficient MEFs and VSMCs, MEFs null for both p21 alleles were refractory to the GATA-6-induced growth inhibition. These data demonstrate that elevated GATA-6 expression can promote the quiescent phenotype in VSMCs.