PRMT3-Mediated Arginine Methylation Stabilizes PCSK9 to Promote Aortic Valve Calcification

09 Mar 20264 min read0 viewsJournal Feed

GIST

Circulation, Ahead of Print. BACKGROUND:Aortic valve calcification increases leaflet stiffness and contributes to the development of calcific aortic valve disease.

The molecular and cellular mechanisms underlying calcification remain unclear. Here, we aimed to investigate the role of PRMT3 (protein arginine methyltransferase 3) in valvular calcification and calcific aortic valve disease progression.METHODS:Both aortic valve leaflets and valvular interstitial cells from patients were used to evaluate the expression pattern and investigate the underlying mechanism of PRMT3 in calcific aortic valve disease pathogenesis.

High-cholesterol diet–fed Apoe (apolipoprotein E)–deficient (ApoE−/−) mice withPrmt3haploinsufficiency were used to examine the role of PRMT3 in aortic valve calcification. The effects of PRMT3 inhibition (SGC707) and degradation (PROTAC compound 11) on aortic valve calcification were investigated in vivo.

To elucidate the mechanisms underlying the procalcific effects of PRMT3, we performed immunoprecipitation coupled with liquid chromatography–tandem mass spectrometry and coimmunoprecipitation assays with an enzymatically inactive PRMT3 variant as well as arginine-to-lysine and lysine-to-alanine substitution PCSK9 variants.RESULTS:We found that PRMT3 expression was significantly upregulated during aortic valve calcification.

Clinical Editorial

Context and Objective

The study investigates the role of protein arginine methyltransferase 3 (PRMT3) in the pathogenesis of calcific aortic valve disease (CAVD), focusing on valve calcification as a driver of leaflet stiffness.

Study Design and Experimental Scope

Tissue and cell platforms: Aortic valve leaflets and valvular interstitial cells from human sources were examined to define PRMT3 expression patterns and probe mechanisms behind calcification.
In vivo model: Hyperlipidemic, high-cholesterol diet-fed Apoe−/− mice with Prmt3 haploinsufficiency were used to evaluate the influence of reduced PRMT3 activity on valvular calcification.
Interventions: The study assessed the impact of pharmacologic PRMT3 inhibition (SGC707) and targeted PRMT3 degradation (PROTAC) on aortic valve calcification in vivo.
Mechanistic approaches: Immunoprecipitation coupled with LC-MS/MS, along with co-immunoprecipitation using an enzymatically inactive PRMT3 and PCSK9 variants (arginine-to-lysine and lysine-to-alanine substitutions), were employed to elucidate PRMT3’s substrate network and posttranslational effects.

Key Findings on PRMT3 and Calcification

Expression dynamics: PRMT3 levels were upregulated in the context of aortic valve calcification.
Regulatory axis: RUNX2 recruits P300 to promote PRMT3 expression via histone H3K27 acetylation, linking transcriptional control to the calcific process.
Genetic and pharmacologic modulation: Reducing PRMT3 activity, either by haploinsufficiency or through pharmacologic inhibition/degradation, attenuated calcification phenotypes in mice, with accompanying improvements in echocardiographic metrics and reductions in osteogenic markers.
Osteogenic influence: PRMT3 enhances osteogenic differentiation of human valvular interstitial cells through its enzymatic function.

Molecular Mechanism: PCSK9 Stabilization via Arginine Methylation

Posttranslational modification: PRMT3 catalyzes asymmetric dimethylation of PCSK9 at arginine 582 (R582).
Consequence for PCSK9 stability: The modification is associated with a prolonged half-life for PCSK9.
Interaction with degradation pathways: Methylation impedes binding of the E3 ligase CHIP to PCSK9 at lysine 575 (K575), reducing ubiquitination-mediated degradation and thereby sustaining procalcific signaling driven by PCSK9.

Contextual and Practical Implications

The study identifies a novel posttranslational mechanism by which PRMT3 modulates PCSK9 stability in valvular interstitial cells, linking arginine methylation to lipid–osteogenic coupling in valve disease.
It provides preclinical evidence that targeting PRMT3 can influence valve calcification progression, supported by both genetic and pharmacologic approaches.
Limitations or uncertainties: While comprehensive in model systems, the direct translational applicability to humans requires cautious interpretation; detailed human clinical correlations beyond tissue and cellular analyses are not described in the provided summary.

Open questions

The relative contribution of PRMT3-mediated PCSK9 stabilization to human CAVD progression versus parallel pathways remains to be fully delineated.
Longitudinal effects and safety of sustained PRMT3 inhibition or degradation in valve biology warrant further investigation.