Dataset Information

Optic Atrophy 1 (OPA1) overexpression promotes dyslipidemia and atherosclerosis coupled to altered aortic VSMC function in LDL-R deficient mice

ABSTRACT: OPA1 (Optic Atrophy 1), a mitochondrial inner membrane protein involved in mitochondrial cellular metabolism, energy production, calcium homeostasis, and sterol and bile acids (BAs) synthesis. Mitochondria are plastic organelles continuously undergoing biogenesis, fusion, fission, and mitophagy. On these premises, we tested how the overexpression of OPA1, an inner mitochondrial membrane fusion protein, impacts lipids, lipoprotein metabolism, and atherosclerosis development in LDL-R deficient mice (LDLR KO). Methods: OPA1TG/LDLR KO and OPA1ΔHep /LDLR KO were generated and fed with a Western-type diet (WTD) for 12 weeks. Atherosclerosis development was compared to that of LDLR KO mice. In humans, OPA1 expression was investigated in samples from 78 asymptomatic and symptomatic human subjects within the Carotid Plaque Imaging Project (CPIP). Results: OPA1TG/LDLR KO mice showed a significant increase in plasma cholesterol levels mainly in VLDL and LDL fractions. OPA1TG/LDLR KO display a reduction of unconjugated bile acids and higher percentage of conjugated bile acids leading to an increased lipid adsorption. This phenotype was associated with increased atherosclerosis in the aortic root. OPA1 overexpression affects also vascular smooth muscle cell cellular metabolism, leading to an increase in the synthetic vs the proliferative phenotype. Vice versa, hepatocyte deletion of OPA1 improved systemic lipoprotein metabolism and protected from atherosclerosis. The analysis of human atherosclerotic samples indicated that a higher OPA1 expression in the plaque is associated with a reduced degradation of extracellular matrix as well as the expression of markers of cell migration and differentiation. Conclusion: Mitochondrial fusion mediated by OPA1 plays a key role in atherosclerosis by affecting lipoprotein metabolism as well as vascular smooth muscle cell biology.

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Liver

SUBMITTER: Monika Svecla

LAB HEAD: Giuseppe Danilo Norata

PROVIDER: PXD060450 | Pride | 2025-10-27

REPOSITORIES: Pride

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Increased mitochondrial fusion via systemic OPA1 overexpression promotes dyslipidemia and atherosclerosis in LDLR deficient mice.

Da Dalt Lorenzo L Fantini Francesca F Giancane Giulia G Moregola Annalisa A Roda Silvia S Svecla Monika M Pedretti Silvia S Vingiani Giovanni Battista GB Sun Jiangming J Edsfeldt Andreas A Goncalves Isabel I Uboldi Patrizia P Donetti Elena E Baragetti Andrea A Mitro Nico N Scorrano Luca L Norata Giuseppe Danilo GD

Molecular metabolism 20250922

<h4>Objective</h4>Mitochondria are involved in cellular metabolism, energy production, calcium homeostasis, and the synthesis of sterols and bile acids (BAs). Emerging evidence suggests that mitochondrial dynamics including biogenesis, fusion, fission, and mitophagy critically influence cardiometabolic diseases, yet their role in atherogenesis remain poorly understood. Mitochondrial fusion ensures metabolic flexibility and stress adaptation, processes highly relevant to lipid handling and vascul ...[more]

PMID: 40992730

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Project description:Background: The low-density lipoprotein receptor (LDLR) in the liver plays a crucial role in clearing low-density lipoprotein cholesterol (LDL-C) from the bloodstream. This process takes place mainly in the liver. Under atherogenic conditions, Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9), secreted by the liver, binds to LDLR on hepatocytes, preventing its recycling and enhancing its lysosomal degradation. This process reduces LDL-C clearance, promoting hypercholesterolemia. Epsins, a family of ubiquitin-binding endocytic adaptors, are key regulators of atherogenesis in lesional cells, including endothelial cells and macrophages. Given epsins' canonical role in regulating endocytosis of cell surface receptors, we aimed to determine whether and how liver epsins contribute to PCSK9-mediated LDLR endocytosis and degradation, thereby impairing LDL-C clearance and accelerating atherosclerosis. Methods: Liver-specific epsin knockout (Liver-DKO) atherosclerotic models were generated in ApoE-/- and PCSK9-AAV8-induced atheroprone mice fed on a Western diet. We utilized single-cell RNA sequencing, along with molecular, cellular, and biochemical analyses, to investigate the physiological role of liver epsins in PCSK9-mediated LDLR degradation. Additionally, we explored the therapeutic potential of nanoparticle-encapsulated siRNAs targeting epsins 1 and 2 in ApoE-/- mice with established atherosclerosis. Results: Western diet (WD)-induced atherosclerosis was significantly attenuated in ApoE-/-/Liver-DKO mice compared with ApoE-/- controls, as well as in PCSK9-AAV8-induced Liver-DKO mice compared with PCSK9-AAV8-induced wild-type (WT) mice accompanied by reductions in blood cholesterol and triglyceride levels. Mechanistically, single-cell RNA sequencing of hepatocytes and aortas isolated from atherosclerotic ApoE-/- and ApoE-/-/Liver-DKO mice revealed epsin-deficient Ldlrhi hepatocytes with diminished lipogenic potential. Notably, pathway analysis of hepatocytes showed increased LDL particle clearance and enhanced LDLR-cholesterol interactions under WD treatment in ApoE-/-/Liver-DKO mice compared with ApoE-/- controls, correlating with decreased plasma LDL-C levels. Furthermore, pathway analysis of the aortas showed attenuated inflammation and endothelial activation, coupled with reduced lipid uptake, and enhanced cholesterol efflux under WD treatment in ApoE-/-/Liver-DKO mice compared with ApoE-/- controls. Moreover, the absence of liver epsins led to an upregulation of LDLR protein expression in hepatocytes. We further demonstrated that epsins bind LDLR via the ubiquitin-interacting motif (UIM), enabling PCSK9-mediated LDLR degradation. Depleting epsins abolished this degradation, thereby preventing atheroma progression. Lastly, targeting liver epsins with nanoparticle-encapsulated epsins siRNAs effectively ameliorates dyslipidemia and inhibits atherosclerosis progression. These results are consistent with findings showing an increased epsin1 and epsin2 expression in atherosclerotic cardiovascular disease patients. Conclusions: Liver epsins drive atherogenesis by promoting PCSK9-mediated LDLR degradation, thereby elevating circulating LDL-C levels and heightening lesional inflammation. As such, targeting epsins in the liver represents a promising therapeutic strategy to mitigate atherosclerosis by preserving LDLR and enhancing LDL-C clearance in the liver.

			Action	DRS
	LDLR_KO_01.mzML	Mzml
	LDLR_KO_01.mzTab	Mztab
	LDLR_KO_01.raw	Raw
	LDLR_KO_02.mzML	Mzml
	LDLR_KO_02.mzTab	Mztab