circHECTD1 promotes the silica-induced pulmonary endothelial–mesenchymal transition via HECTD1

Abstract

Excessive proliferation and migration of fibroblasts contribute to pulmonary fibrosis in silicosis, and both epithelial cells and endothelial cells participate in the accumulation of fibroblasts via the epithelial–mesenchymal transition (EMT) and the endothelial–mesenchymal transition (EndMT), respectively. A mouse endothelial cell line (MML1) was exposed to silicon dioxide (SiO2, 50 μg/cm2), and immunofluorescence and western blot analyses were performed to evaluate levels of specific endothelial and mesenchymal markers and to elucidate the mechanisms by which SiO2 induces the EndMT. Functional changes were evaluated by analyzing cell migration and proliferation. The mRNA and circular RNA (circRNA) levels were measured using qPCR and fluorescent in situ hybridization (FISH). Lung tissue samples from both Tie2-GFP mice exposed to SiO2 and silicosis patients were applied to confirm the observations from in vitro experiments. Based on the results from the current study, SiO2 increased the expression of mesenchymal markers (type I collagen (COL1A1), type III collagen (COL3A1) and alpha smooth muscle actin (α-SMA/Acta2)) and decreased the expression of endothelial markers (vascular endothelial cadherin (VE-Cad/Cdh 5) and platelet endothelial cell adhesion molecule-1 (PECAM1)), indicating the occurrence of the EndMT in response to SiO2 exposure both in vivo and in vitro. SiO2 concomitantly increased circHECTD1 expression, which, in turn, inhibited HECTD1 protein expression. SiO2-induced increases in cell proliferation, migration, and changes in marker levels were restored by either a small interfering RNA (siRNA) targeting circHECTD1 or overexpression of HECTD1 via the CRISPR/Cas9 system, confirming the involvement of the circHECTD1/HECTD1 pathway in the EndMT. Moreover, tissue samples from SiO2-exposed mice and silicosis patients confirmed the EndMT and change in HECTD1 expression. Our findings reveal a potentially new function for the circHECTD1/HECTD1 pathway and suggest a possible mechanism of fibrosis in patients with pulmonary silicosis.

The role of Ca2+/NFAT in Dysfunction and Inflammation of Human Coronary Endothelial Cells induced by Sera from patients with Kawasaki disease

“…The enhanced proliferation of HCAECs induced by KD sera in our study were due to the following reasons: (1) In the acute phase of KD, coronary endothelial cells are activated to show enhanced proliferation ability to cope with environmental changes, which is a feedback regulation to stress 32 ; (2) The sera composition is more complicated. VEGF concentration was reported to be high in KD sera which promotes endothelial proliferation [33][34][35] ; (3) The proliferation of endothelial cells is an early response to endothelial-mesenchymal changes 36 . Interestingly, we found that HCAECs incubated with sera from CAL+ KD patients did not show increased proliferation.…”

Regulatory network of two circRNAs and an miRNA with their targeted genes under astilbin treatment in pulmonary fibrosis

“…Bachmayr‐Heyda et al discovered a negative correlation of circRNA abundance and proliferation in lung fibrosis . Chao et al found that circHECTD1 promotes silica‐induced pulmonary fibrosis via HECTD1 . A recent study from our laboratory based on a circRNA microarray analysis identified 67 significantly dysregulated circRNAs in IPF patients, indicating the fundamental roles of circRNAs in pathological processes of lung fibrosis .…”

“…31 Chao et al found that circHECTD1 promotes silica-induced pulmonary fibrosis via HECTD1. 32,33 A recent study from our laboratory based on a circRNA microarray analysis identified 67 significantly dysregulated circRNAs in IPF patients, indicating the fundamental roles of circRNAs in pathological processes of lung fibrosis. 19 In this study, 145 differentially expressed circRNAs were identified under astilbin treatment using RNA sequencing.…”

The circular RNA CDR1as regulate cell proliferation via TMED2 and TMED10

“…CRISPR-mediated gene editing is a powerful technology that has been successfully used to knock out specific lncRNAs and circRNAs [31][32][33][34]. We therefore sought to use this approach to knock out CDR1as in 293 T cells, using two sgRNAs targeting the CDR1 locus containing the CDR1as sequence (Fig.…”