Herpud1 deficiency alleviates homocysteine-induced aortic valve calcification

Abstract

Objectives: To evaluate the role and therapeutic value of homocysteine (hcy)-inducible endoplasmic reticulum stress (ERS) protein with ubiquitin like domain 1 (Herpud1) in hcy-induced calcific aortic valve disease (CAVD).

Background: The morbidity and mortality rates of calcific aortic valve disease (CAVD) remain high while treatment options are limited.

Methods: In vivo, we use the low-density lipoprotein receptor (LDLR) and Herpud1 double knockout (LDLR-/-/Herpud1-/-) mice and used high methionine diet (HMD) to assess of aortic valve calcification lesions, ERS activation, autophagy, and osteogenic differentiation of aortic valve interstitial cells (AVICs). In vitro, the role of Herpud1 in the Hcy-related osteogenic differentiation of AVICs was investigated by manipulating of Herpud1 expression.

Results: Herpud1 was highly expressed in calcified human and mouse aortic valves as well as primary aortic valve interstitial cells (AVICs). Hcy increased Herpud1 expression through the ERS pathway and promoted CAVD progression. Herpud1 deficiency inhibited hcy-induced CAVD in vitro and in vivo. Herpud1 silencing activated cell autophagy, which subsequently inhibited hcy-induced osteogenic differentiation of AVICs. ERS inhibitor 4-phenyl butyric acid (4-PBA) significantly attenuated aortic valve calcification in HMD-fed low-density lipoprotein receptor-/- (LDLR-/-) mice by suppressing ERS and subsequent Herpud1 biosynthesis.

Conclusions: These findings identify a previously unknown mechanism of Herpud1 upregulation in Hcy-related CAVD, suggesting that Herpud1 silencing or inhibition is a viable therapeutic strategy for arresting CAVD progression.

Highlights: • Herpud1 is upregulated in the leaflets of Hcy-treated mice and patients with CAVD. • In mice, global knockout of Herpud1 alleviates aortic valve calcification and Herpud1 silencing activates cell autophagy, inhibiting osteogenic differentiation of AVICs induced by Hcy. • 4-PBA suppressed Herpud1 expression to alleviate AVIC calcification in Hcy treated AVICs and to mitigate aortic valve calcification in mice.

Keywords: 4-phenyl butyric acid; Autophagy; Calcific aortic valve disease; Endoplasmic reticulum stress; Herpud1; Homocysteine.