Behzadi, P. | Search bioRxiv

bioRxiv2025

Progranulin deficiency aggravates aging-induced vascular injury

SignificanceVascular aging is a major contributor to cardiovascular disease, yet the molecular mechanisms of age-associated vascular dysfunction remain incompletely defined. This study reveals a critical role for progranulin (PGRN) in regulating vascular senescence, function, and remodeling during aging. MethodsWe assessed PGRN expression in human and mouse arteries and senescent vascular smooth muscle cells (VSMCs). Functional vascular studies were performed in PGRN-deficient (PGRN-/-) mice. Senescence was modulated pharmacologically using the senolytic agent navitoclax (ABT-263), and vascular phenotype was evaluated in adult (6-month-old) and aged mice (18-month-old). ResultsPGRN expression increased with age in human and mouse arteries, correlating with elevated p21 expression. PGRN deficiency in adult mice induced endothelial dysfunction, increased vasoconstriction, and induced vascular inflammation and remodeling. Transcriptomic analysis of PGRN-/- VSMCs revealed a senescence-associated signature, including perturbed oxidative phosphorylation, altered epigenetic regulation, and collagen pathways. Pharmacological clearance of senescent cells improved endothelial function but increased vascular contractility in PGRN-/- mice. In aged mice, PGRN deficiency aggravated vascular dysfunction, remodeling, and renal injury without further increasing senescence markers--suggesting premature, rather than progressive, senescence in the PGRN-/- mice. ConclusionPGRN is a novel regulator of vascular aging, coordinating senescence, inflammation, and remodeling. While endothelial senescence contributes to dysfunction, VSMCs senescence may serve an adaptive role in modulating vascular tone. Targeting PGRN or senescence pathways may offer therapeutic opportunities for age-related vascular diseases, especially in patients with PGRN mutations associated with frontotemporal dementia.

cell biology↗

bioRxiv2024

Rapamycin increases murine lifespan but does not reduce mineral volume in the Matrix GLA Protein (MGP) knockout mouse model of medial arterial calcification.

Peripheral artery disease (PAD) is the narrowing of the arteries that carry blood to the lower extremities. PAD has been traditionally associated with atherosclerosis. However, recent studies have found that thrombotic events triggered by medial arterial calcification (MAC) is the primary cause of chronic limb ischemia below the knee. MAC is localized around the elastic fibers surrounding smooth muscle cells (SMCs) in arteries. Matrix GLA protein (MGP) binds circulating calcium and prevents hydroxyapatite mineral deposition, while also modulating proosteogenic signaling by attenuating BMP-2-mediated activation of Runx2 gene expression. Mgp-/- mice develop severe MAC and die around 8 weeks after birth due to aortic rupture or heart failure. We previously discovered a rare genetic disease Arterial Calcification due to Deficiency of CD73 (ACDC), in which patients present with extensive MAC in their lower extremity arteries. Using a patient-specific induced pluripotent stem cell model, we found that rapamycin inhibited calcification. Here we investigated whether rapamycin could reduce MAC in vivo using the Mgp-/- murine model. Mgp+/+ and Mgp-/- mice received 5mg/kg rapamycin or vehicle. Calcification content was assessed via microCT, and vascular morphology and extracellular matrix content were assessed histologically. Immunostaining and western blot analysis were used to examine SMC phenotype and extracellular matrix content. Rapamycin prolonged Mgp-/- mice lifespan, decreased mineral density in the arteries, maintained SMC contractile phenotype, and improved vessel structure, however, calcification volume was unchanged. Mgp-/- mice with SMC-specific deletion of Raptor or Rictor did not recapitulate treatment with rapamycin. These findings suggest rapamycin promotes beneficial vascular remodeling in vessels with MAC. NEWS AND NOTEWORTHYPeripheral artery disease (PAD) is associated with medial arterial calcification (MAC), which involves calcification of arterial elastic fibers and smooth muscle cells (SMCs). Matrix GLA protein (MGP) inhibits vascular calcification, and Mgp-/- mice develop severe MAC. Using this model, we found rapamycin prolonged lifespan, reduced arterial mineral density, maintained SMC contractile phenotype, and improved vessel structure, though calcification volume remained unchanged. Findings highlight rapamycins potential for vascular remodeling in MAC.

physiology↗