Tom70 prevents fibrotic activation of aortic valve interstitial cells via EPA-activated Autophagic flux

Abstract

Background: Translocase of outer mitochondrial membrane 70 (Tom70) has been implicated in the development of various cardiovascular diseases. However, its role in aortic valve fibrosis, an important feature of calcific aortic valve disease (CAVD), remains unclear.

Objective: This study aims to explore the potential role of Tom70 in aortic valve fibrosis, with a view to providing new insights into the clinical management of CAVD.

Methods: Proteomics, metabolomics and enrichment analysis were used to screen for differential molecules and signaling pathways. Western Blot (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to detect the expression levels of Tom70 and autophagy-related proteins. Gain- and loss-of-function experiments of Tom70 were conducted both in vivo and vitro to investigate its role in aortic valve fibrosis. Immunofluorescence staining, Masson staining, etc. were used to evaluate fibrosis. Confocal microscopy and transmission electron microscope (TEM) were utilized to detect autophagic flux.

Results: The expression of Tom70 was significantly downregulated in fibrocalcific aortic valve tissues from patients and in aortic valve interstitial cells (AVICs) following TGF-β1 stimulation. In vivo experiments revealed that Tom70 knockout exacerbated aortic valve fibrosis in rat. Mechanistic studies in rat AVICs indicated that impaired autophagic flux accelerates fibrotic activation in AVICs, and Tom70 modulates fibrotic activation through the regulation of autophagic flux. In addition, we identified eicosapentaenoic acid (EPA) as a key regulator of autophagic flux influenced by Tom70.

Conclusion: Overall, our study unveils a novel role of Tom70 in aortic valve fibrosis and elucidates its regulatory relationship with autophagic flux, providing new insights into the molecular mechanisms underlying CAVD.

Keywords: Autophagic flux; Calcific aortic valve disease; Tom70; Valve interstitial cell.