HLA-B35 and dsRNA Induce Endothelin-1 via Activation of ATF4 in Human Microvascular Endothelial Cells

Stefania Lenna, Izabela Chrobak, G. Alessandra Farina, Fernando Rodriguez-Pascual, Santiago Lamas, Robert Lafyatis, Raffaella Scorza, Maria Trojanowska

Research output: Contribution to journalArticle

Abstract

Endothelin 1 (ET-1) is a key regulator of vascular homeostasis. We have recently reported that the presence of Human antigen class I, HLA-B35, contributes to human dermal microvascular endothelial cell (HDMEC) dysfunction by upregulating ET-1 and proinflammatory genes. Likewise, a Toll-like receptor 3 (TLR3) ligand, Poly(I:C), was shown to induce ET-1 expression in HDMECs. The goal of this study was to determine the molecular mechanism of ET-1 induction by these two agonists. Because HLA-B35 expression correlated with induction of Binding Immunoglobulin Protein (BiP/GRP78) and several heat shock proteins, we first focused on ER stress and unfolded protein response (UPR) as possible mediators of this response. ER stress inducer, Thapsigargin (TG), HLA-B35, and Poly(I:C) induced ET-1 expression with similar potency in HDMECs. TG and HLA-B35 activated the PERK/eIF2α/ATF4 branch of the UPR and modestly increased the spliced variant of XBP1, but did not affect the ATF6 pathway. Poly(I:C) also activated eIF2α/ATF4 in a protein kinase R (PKR)-dependent manner. Depletion of ATF4 decreased basal expression levels of ET-1 mRNA and protein, and completely prevented upregulation of ET-1 by all three agonists. Additional experiments have demonstrated that the JNK and NF-κB pathways are also required for ET-1 upregulation by these agonists. Formation of the ATF4/c-JUN complex, but not the ATF4/NF-κB complex was increased in the agonist treated cells. The functional role of c-JUN in responses to HLA-B35 and Poly(I:C) was further confirmed in ET-1 promoter assays. This study identified ATF4 as a novel activator of the ET-1 gene. The ER stress/UPR and TLR3 pathways converge on eIF2α/ATF4 during activation of endothelial cells.

Original languageEnglish
Article numbere56123
JournalPLoS One
Volume8
Issue number2
DOIs
Publication statusPublished - Feb 18 2013

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

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    Lenna, S., Chrobak, I., Farina, G. A., Rodriguez-Pascual, F., Lamas, S., Lafyatis, R., Scorza, R., & Trojanowska, M. (2013). HLA-B35 and dsRNA Induce Endothelin-1 via Activation of ATF4 in Human Microvascular Endothelial Cells. PLoS One, 8(2), [e56123]. https://doi.org/10.1371/journal.pone.0056123