Modification of GATA-2 Transcriptional Activity in Endothelial Cells by the SUMO E3 Ligase PIASy

Abstract

Abstract-GATA sequences are required for the optimal expression of endothelial cell-specific genes, including endothelin-1 (ET-1). We have identified PIASy in a search for new GATA-2 interacting proteins that can regulate GATA-2-mediated endothelial gene expression. Notably, among the cell populations comprising vascular walls, PIASy mRNA is selectively expressed in endothelial cells, and its expression can be regulated by angiogenic growth factors. We show that GATA-2 is covalently modified by small ubiquitin-like modifier (SUMO)-1 and -2 and that PIASy, through its E3 SUMO ligase activity, preferentially enhances the conjugation of SUMO-2 to GATA-2. Through a functional analysis, we demonstrate that PIASy potently suppresses the activity of the GATA-2-dependent human ET-1 promoter in endothelial cells. The suppressive effect of PIASy requires the GATA-binding site in the ET-1 promoter and depends on its interaction with GATA-2, which requires both N-terminal (amino acids 1-183) and C-terminal (amino acids 414-510) sequences in PIASy. We conclude that PIASy enhances the conjugation of SUMO-2 to GATA-2 and that the interaction of PIASy with GATA-2 can modulate GATA-mediated ET-1 transcription activity in endothelial cells through a RING-like domain-independent mechanism. (Circ Res. 2003;92:1201-1208.)

Modification of the erythroid transcription factor GATA-1 by SUMO-1

“…Recently, it has been reported that PIASy enhances SUMO conjugation to GATA-2, a member of the GATA family that is expressed in primitive hematopoietic cells and is critical for survival and growth of multipotential progenitors (42,43). GATA-2 is also present in adult endothelia, and overexpression of PIASy inhibits GATA-2-dependent transcription in endothelial cell lines.…”

“…Even in the case of GATA-2, PIASy-mediated repression does not appear to require sumoylation (43), suggesting that PIASy's inhibitory effect on both GATA proteins might involve a common mechanism, which awaits investigation. PIASy is detected in many tissues and cell lines (43,44), so it is tempting to hypothesize some functional interplay between PIASy and GATA proteins in regulating the fate of hematopoietic cells.…”

Adipogenesis

“…GATA2 and -3 can also associate with C/EBPa and -b to disrupt their transcriptional activity (Tong et al 2005), suggesting that GATA can attenuate adipogenesis via multiple pathways. GATA proteins can be regulated posttranslationally by acetylation, SUMOylation, and phosphorylation (Boyes et al 1998;Chun et al 2003;Menghini et al 2005). Akt phosphorylation of GATA results in cytosolic sequestering and inhibition of nuclear translocation (Menghini et al 2005).…”

Small Ubiquitin-like Modifier (SUMO) Modification of the Androgen Receptor Attenuates Polyglutamine-mediated Aggregation

“…UBC9, which interacts directly with specific substrates (24), catalyzes the formation of an isopeptide bond between the C terminus of SUMO and the amino group of the target lysine. This step is facilitated by SUMO E3 ligases such as RanBP2 and members of the protein inhibitor of activated STAT (PIAS) family (25)(26)(27). SUMOylation is reversible, and specific isopeptidases release the SUMO moiety (28).…”

“…In contrast, SC motifs are functionally silent when activators are bound to a single site (36,40,41). Through multiple approaches, we (26,36,39,42) and others (37,(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53) have demonstrated that SC motifs exert their effects by serving as sites for SUMO modification. Furthermore, recent functional and structural studies by our group as well as concordant findings of others indicate that once conjugated, individual SUMO isoforms mediate their transcriptional effects through a conserved effector surface (42, 54 -57).…”