Dynamin-related protein 1 inhibition reduces hepatic PCSK9 secretion

Maximillian A. Rogers, Joshua D. Hutcheson, Takehito Okui, Claudia Goettsch, Sasha A. Singh, Arda Halu, Florian Schlotter, Hideyuki Higashi, Lixiang Wang, Mary C. Whelan, Andrew K. Mlynarchik, Alan Daugherty, Masatoshi Nomura, Masanori Aikawa, Elena Aikawa

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Aims: Proteostasis maintains protein homeostasis and participates in regulating critical cardiometabolic disease risk factors including proprotein convertase subtilisin/kexin type 9 (PCSK9). Endoplasmic reticulum (ER) remodeling through release and incorporation of trafficking vesicles mediates protein secretion and degradation. We hypothesized that ER remodeling that drives mitochondrial fission participates in cardiometabolic proteostasis. Methods and results: We used in vitro and in vivo hepatocyte inhibition of a protein involved in mitochondrial fission, dynamin-related protein 1 (DRP1). Here, we show that DRP1 promotes remodeling of select ER microdomains by tethering vesicles at ER. A DRP1 inhibitor, mitochondrial division inhibitor 1 (mdivi-1) reduced ER localization of a DRP1 receptor, mitochondrial fission factor, suppressing ER remodeling-driven mitochondrial fission, autophagy, and increased mitochondrial calcium buffering and PCSK9 proteasomal degradation. DRP1 inhibition by CRISPR/Cas9 deletion or mdivi-1 alone or in combination with statin incubation in human hepatocytes and hepatocyte-specific Drp1-deficiency in mice reduced PCSK9 secretion (-78.5%). In HepG2 cells, mdivi-1 increased low-density lipoprotein receptor via c-Jun transcription and reduced PCSK9 mRNA levels via suppressed sterol regulatory binding protein-1c. Additionally, mdivi-1 reduced macrophage burden, oxidative stress, and advanced calcified atherosclerotic plaque in aortic roots of diabetic Apoe-deficient mice and inflammatory cytokine production in human macrophages. Conclusions: We propose a novel tethering function of DRP1 beyond its established fission function, with DRP1-mediated ER remodeling likely contributing to ER constriction of mitochondria that drives mitochondrial fission. We report that DRP1-driven remodeling of select ER micro-domains may critically regulate hepatic proteostasis and identify mdivi-1 as a novel small molecule PCSK9 inhibitor.

Original languageEnglish
Pages (from-to)2340-2353
Number of pages14
JournalCardiovascular Research
Volume117
Issue number11
DOIs
StatePublished - Oct 1 2021

Bibliographical note

Publisher Copyright:
© 2021 Published on behalf of the European Society of Cardiology. All rights reserved.

Keywords

  • Cardiometabolic
  • DRP1
  • Endoplasmic reticulum
  • Liver
  • Mitochondria
  • PCSK9
  • Proteostasis

ASJC Scopus subject areas

  • General Medicine

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