Coordinated regulation of Rel expression by MAP3K4, CBP, and HDAC6 controls phenotypic switching

Abstract

Coordinated gene expression is required for phenotypic switching between epithelial and mesenchymal phenotypes during normal development and in disease states. Trophoblast stem (TS) cells undergo epithelial-mesenchymal transition (EMT) during implantation and placentation. Mechanisms coordinating gene expression during these processes are poorly understood. We have previously demonstrated that MAP3K4-regulated chromatin modifiers CBP and HDAC6 each regulate thousands of genes during EMT in TS cells. Here we show that CBP and HDAC6 coordinate expression of only 183 genes predicted to be critical regulators of phenotypic switching. The highest-ranking co-regulated gene is the NF-κB family member Rel. Although NF-κB is primarily regulated post-transcriptionally, CBP and HDAC6 control Rel transcript levels by binding Rel regulatory regions and controlling histone acetylation. REL re-expression in mesenchymal-like TS cells induces a mesenchymal-epithelial transition. Importantly, REL forms a feedback loop, blocking HDAC6 expression and nuclear localization. Together, our work defines a developmental program coordinating phenotypic switching.

MAP3K4 promotes fetal and placental growth by controlling the receptor tyrosine kinases IGF1R/IR and Akt signaling pathway

“…Examination of our previously published sequencing data supported our new findings that Igf1r is coregulated in TS cells by MAP3K4, CBP, and HDAC6 in a H2BK5Ac dependent manner (60). Previous work showed that inactivation of MAP3K4 kinase activity results in reduced JNK dependent activation of CBP and increased abundance of HDAC6 by disrupting its ubiquitination and destruction in TS cells (17,59).…”

“…Inactivation of MAP3K4 activity results in loss of CBP activity and increased expression and activity of HDAC6 ( 17 , 59 ). These changes in these key epigenetic regulators resulted in reduced histone acetylation on the promoters of many genes related to maintenance of the epithelial state ( 17 , 59 , 60 ). Based on these previous studies, we predicted that CBP and/or HDAC6 may control Igf1r and Pdpk1 expression.…”

“…Placental lysates were then spun at 16,200 g for 10 min at 4 °C. Nuclear extracts were isolated as previously described ( 16 , 17 , 60 ). Lysates were blotted with the indicated antibodies described in Table S5 .…”

MAP3K4 kinase action and dual role in cancer

“…HDAC6 deacetylates the promoter regions of the genes that code for proteins that make up tight junctions, which reduces cell–cell adhesion and is a hallmark of the mesenchymal phenotype. HDAC6 expression and activity are both elevated in TS cells with the loss of MAP3K4 operation, and HDAC6 is silenced to restore epithelial characteristics [ 57 ]. MAP3K4 collectively oversees the fundamental selection of TS cells to either engage in renewal for stem cell maintenance or initiate a program of increased motility, invasiveness, and differentiation for placental development.…”