Abstract
Vascular pathologies, such as thrombosis or atherosclerosis, are leading causes of death worldwide and are strongly associated with the dysfunction of vascular endothelial cells. In this context, the extracellular endonuclease Ribonuclease 1 (RNase1) acts as an essential protective factor in regulation and maintenance of vascular homeostasis. However, long-term inflammation causes strong repression of RNase1 expression, thereby promoting endothelial cell dysfunction. This inflammation-mediated downregulation of RNase1 in human endothelial cells is facilitated via histone deacetylase (HDAC) 2, although the underlying molecular mechanisms are still unknown. Here, we report that inhibition of c-Jun N-terminal kinase by small chemical compounds in primary human endothelial cells decreased physiological RNase1 mRNA abundance, while p38 kinase inhibition restored repressed RNase1 expression upon proinflammatory stimulation with tumor necrosis factor alpha (TNF-α) and poly I:C. Moreover, blocking of the p38 kinase- and HDAC2-associated kinase casein kinase 2 (CK2) by inhibitor as well as small interfering RNA (siRNA)-knockdown restored RNase1 expression upon inflammation of human endothelial cells. Further downstream, siRNA-knockdown of chromodomain helicase DNA binding protein (CHD) 3 and 4 of the nucleosome remodeling and deacetylase (NuRD) complex restored RNase1 repression in TNF-α treated endothelial cells implicating its role in the HDAC2-containing repressor complex involved in RNase1 repression. Finally, chromatin immunoprecipitation in primary human endothelial cells confirmed recruitment of the CHD4-containing NuRD complex and subsequent promoter remodeling via histone deacetylation at the RNASE1 promoter in a p38-dependent manner upon human endothelial cell inflammation. Altogether, our results suggest that endothelial RNase1 repression in chronic vascular inflammation is regulated by a p38 kinase-, CK2-, and NuRD complex-dependent pathway resulting in complex recruitment to the RNASE1 promoter and subsequent promoter remodeling.
Highlights
Endothelial cells (ECs) significantly participate in regulation and control of vascular homeostasis and are rapidly activated upon inflammation to support the immune system
TBB inhibitor treatment and CSNK2A1/A2 doubleknockdown indicated an important role of casein kinase 2 (CK2) kinase in TNFα-mediated Ribonuclease 1 (RNase1) repression in inflamed human ECs
We identified a regulatory mechanism by which proinflammatory stimulation, such as tumor necrosis factor (TNF)-α or polycytidylic acid (poly I):C, activated p38 mitogen-activated protein kinase (MAPK), CK2 kinase, and subsequent recruitment of the HDAC2 containing nucleosome remodeling and deacetylase (NuRD)/CHD4 co-repressor complex to the RNASE1 promoter
Summary
Endothelial cells (ECs) significantly participate in regulation and control of vascular homeostasis and are rapidly activated upon inflammation to support the immune system. Despite the necessity of these processes to ensure a sufficient immune response, prolonged inflammation may destruct the homeostatic functions of the endothelium This further promotes progression of vascular diseases, like thrombosis or atherosclerosis (Poredos, 2002; Sitia et al, 2010; Zernecke and Preissner, 2016). Upon long-term inflammation, accumulating eRNA enhances immune cell recruitment to the vascular wall and secretion of proinflammatory cytokines like tumor necrosis factor (TNF)-α or interleukin (IL)-1β. These cytokines further act on the EC layer via recruitment of histone deacetylase (HDAC) 2 to the RNASE1 promoter, resulting in massive RNase repression (Gansler et al, 2014; Bedenbender et al, 2019). This study aims to investigate the underlying signaling cascade involved
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