Abstract P142: Progranulin Controls Vascular Proliferation And Migration Via Regulating Autophagy Flux

Progranulin controls vascular proliferation and migration via regulating autophagy flux Shubhnita Singh, Ariane Bruder-Nascimento, Thiago Bruder-Nascimento Vascular smooth muscle cells (VSMC) play a critical role in the genesis of varied cardiovascular diseases by controlling the integrity of the arterial wall. Progranulin (PGRN) is a protein expressed in multiple cell types, including VSMC, which regulates repair and inflammation. Deficiency in PGRN leads to frontotemporal dementia, but whether such ablation can interfere on VSMC biology is not understood. We tested the hypothesis that PGRN maintains the VSMC homeostasis by regulating autophagy flux. Experiments were performed in aortic VSMC (aVSMC) and arteries isolated from wild-type (PGRN+/+) and PGRN deficient mice (PGRN-/-). PGRN-/- aVSMC showed increase in proliferation and migration measured by Ki67 and PCNA expressions and scratch assay, respectively. An RNA-sequencing in aortae revealed a suppression in autophagy pathway in PGRN-/-. To analyze whether such reduction is associated with impaired autophagy flux, we analyzed the p62 and LC3A/B expression, PGRN-/- aVSMC displayed reduced p62 (2-fold less) and more accumulation of LC3B/A ratio, which was further accentuated by pre-treating the PGRN-/- aVSMC with Bafilomycin A1. Spermidine (autophagy inducer) restored the vascular proliferation and migration, as well as reduces Erk1/2 phosphorylation. In ex vivo experiments, we studied whether impaired autophagy flux in PGRN-/- mice is associated with vascular dysfunction, interestingly we observed that intact aortae from PGRN-/- presented an elevated vascular constriction to norepinephrine (maximal response in mN, PGRN+/+: 4.5 ± 0.4 vs PGRN-/-: 5.3 ± 0.3*, *P<0.05) and thromboxane A2 analogue (maximal response in mN, PGRN+/+: 5.2 ± 0.3 vs PGRN-/-: 6.0 ± 0.5*, *P<0.05), which was abolished by treating the mice with spermidine for 7 consecutive days (4mM in drinking water). Our findings indicate that PGRN regulates the vascular physiology by regulating autophagy flux and propound PGRN deficiency as a risk factor for cardiovascular disease.