Transcriptional Activity of Erythroid Kruppel-like Factor (EKLF/KLF1) Modulated by Protein Inhibitor of Activated STAT3 (PIAS3) [Cell Biology]

February 24th, 2015 by Siatecka, M., Soni, S., Planutis, A., Bieker, J. J.

Erythroid Kruppel-like factor (EKLF or KLF1) is a transcription factor crucial for red cell development that is directly involved in regulation of a large number of erythroid genes. EKLF serves mostly as an activator of expression of these genes; however, it can act also as a repressor. Here, we present evidence that EKLF interacts with proteins from the PIAS (protein inhibitor of activated STAT) family that convey repressive activity to EKLF in the absence of sumoylation. Our studies identify PIAS3 as a transcriptional corepressor of EKLF for at least a subset of its target genes during erythropoiesis (e.g. β-globin, α-hemoglobin stabilizing protein). We demonstrate an interaction between EKLF and PIAS proteins confirmed by in vivo coimmunoprecipitation assays with both exogenous and endogenous proteins. We identified an LXXLL signature motif located near the N-terminus of PIAS proteins that, although not involved in the EKLF-PIAS3 interaction, is required for the transrepression activity. Knockdown of endogenous PIAS3 accelerates differentiation of both the Murine erythroleukemia (MEL) cells as well as the fetal liver cells, while an increase in PIAS3 levels inhibits this increase. Using chromatin immunoprecipitation assays we show that PIAS3 preferentially occupies the β-globin promoter in undifferentiated MEL cells. Together these results demonstrate that an interaction between EKLF and PIAS3 provides a novel mode of regulation of EKLF activity in the absence of sumoylation, and furthermore show an important involvement of PIAS proteins in erythropoiesis.
  • Posted in Journal of Biological Chemistry, Publications
  • Comments Off on Transcriptional Activity of Erythroid Kruppel-like Factor (EKLF/KLF1) Modulated by Protein Inhibitor of Activated STAT3 (PIAS3) [Cell Biology]