Expression of endothelin type B receptors (EDNRB) on smooth muscle cells is controlled by MKL2, ternary complex factors, and actin dynamics

Abstract

Endothelin signaling plays an important role in physiology and disease and one of the endothelin receptors, the type B receptor (ETB or EDNRB), is known to be highly plastic, being upregulated in smooth muscle cells by arterial injury and following organ culture in vitro. Herein, we hypothesized that this transcriptional plasticity may arise in part because EDNRB is controlled by ternary complex factors and by the myocardin family coactivator MKL2. In line with this hypothesis we found significant correlations between the ternary complex factors ELK3, FLI1 and EDNRB, and between MKL2 and EDNRB at the mRNA level in human arteries. Overexpression of MKL2 in human coronary artery smooth muscle cells (HCASMC) led to a 30‐ fold induction of EDNRB, and this effect was antagonized by myocardin (MYOCD) which also correlated negatively with EDNRB at the tissue level. Overexpression of ELK3 and FLI1 induced expression of EDNRB, whereas the expression of classical smooth muscle markers was reduced. Depolymerization of actin using latrunculin B (LatB) increased EDNRB on both mRNA and protein levels, and increased calcium responses on stimulation with the ETB‐selective agonist sarafotoxin 6c (S6c) and endothelin 1 (ET‐1). Pretreatment with LatB in organ culture increased S6c and ET‐1‐induced contraction. We also found that ROCK inhibition using Y27632 induced EDNRB expression, and that the effect of LatB is antagonized by MAP‐kinase inhibition. Transcript‐specific primers and promoter reporter assays showed that the EDNRB_2 isoform is regulated by LatB in HCASMC. We finally demonstrate that the mRNA level of EDNRB is increased in rat carotid lesions and human carotid plaques, and that ELK3/FLI1 induction closely parallels EDNRB induction. In all, these studies uncover transcriptional control mechanisms for the endothelin type B receptor (EDNRB) that may explain its plasticity and could be targeted for therapy. Support or Funding Information This study was supported by grants from the Medical Faculty and The Royal Physiographic Society. KKK was supported by Marie Curie ITN Small Artery Remodelling of European Union. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Epigenetic Alteration of Smooth Muscle Cells Regulates Endothelin-Dependent Blood Pressure and Hypertensive Arterial Remodeling

“…We identify that H3K27me3 enrichment at EDNRB, ACTA2, TAGLN, CNN1, and MYH11 gene promoters is regulated by JMJD3, and future studies will determine how H3K27me3 at these promoters changes in the setting of hypertension. Our identification of EDNRB as a direct transcriptional target of JMJD3 is consistent with reports that have identified that EDNRB expression is positively regulated by transcription factors (e.g., MKL2) and mechanisms that regulate SMC-specific gene expression [54]. Upon disease progression, decreased JMJD3 expression further leads to repression of the SMC gene program (via increased endothelin-ERK signaling and H3K27me3 at SMC promoters), thereby promoting vascular remodeling in the setting of long-standing hypertension.…”

Regulation of the Muscarinic M3 Receptor by Myocardin-Related Transcription Factors

“…Numerous recent studies have cataloged genes that are activated by overexpression of wild type and constitutively active MRTFs using RNA-sequencing (Zhao et al, 2016;Kim et al, 2017;Hu et al, 2019), but GPCRs and ion channels are often underrepresented in such dataset (Miano et al, 2007), and many of these datasets have limited sample sizes. Polymerase chain reaction (PCR)-based studies with larger sample sizes have demonstrated that MRTFs may play a role for GPCR expression (Krawczyk et al, 2018).…”

Decreased expression of the GLP-1 receptor after segmental artery injury in mice

“…In rats, ET B receptors are expressed in kidney VSMCs of afferent arterioles mediating contraction and by endothelial cells of the efferent arteriole mediating vasodilatation, thus playing an important role in maintenance of vascular tone (Inscho et al 2005). The contractile ET B receptor is known to be upregulated in the dedifferentiated VSMC phenotype in vivo after acute vessel injury and in organ culture (Adner et al 1998, Krawczyk et al 2018, Skovsted et al 2019. The time point of 6 h was based on the rapid reaction of VSMC in organ culture leading to changes in transcription of the ET B receptor previously shown in coronary arteries from rats (Skovsted et al 2012).…”