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Cathepsin A contributes to left ventricular remodeling by degrading the antioxidant enzyme extracellular superoxide dismutase

ABSTRACT: In the heart, the serine carboxypeptidase cathepsin A (CatA) is distributed between lysosomes and the extracellular matrix (ECM). CatA-mediated degradation of extracellular peptides may contribute to ECM-remodeling and left ventricular (LV) dysfunction. This study aimed to evaluate the effects of CatA overexpression on LV remodeling. A proteomic analysis of the secretome of adult mouse cardiac fibroblasts upon digestion by CatA identified the extracellular antioxidant enzyme superoxide dismutase (EC-SOD) as a novel substrate of CatA (5-fold decreased abundance; p=0.0001). In vitro, cardiomyocytes and cardiac fibroblasts expressed and secreted CatA protein. EC-SOD protein was expressed and secreted only by cardiac fibroblasts. Cardiomyocyte-specific over-expression of CatA and increased activity in the LV of transgenic mice (CatA-TG) reduced EC-SOD protein levels by 43% (p<0.001). Loss of EC-SOD-mediated anti-oxidative protection resulted in accumulation of superoxide radicals (WT: 4.54±1.2 vs. CatA-TG: 8.62±2.3µmol/mg tissue/min; p=0.0012), increased inflammation, myocyte hypertrophy (WT: 19.8±1.0 vs. CatA-TG: 21.9±1.8µm; p=0.024), cellular apoptosis, and elevated mRNA expression of hypertrophy-related and pro-fibrotic marker genes, without effecting intracellular detoxifying proteins. In CatA-TG mice LV interstitial fibrosis formation was enhanced by 19% (p=0.028) and type I/type III collagen ratio was shifted towards higher abundance of collagen I fibers (p=0.026). Cardiac remodeling in CatA-TG was accompanied by increased LV weight/body weight and LV enddiastolic volume (WT: 50.8±5.8 vs. CatA-TG: 61.9±6.2 µl; p=0.018). Thus, in the heart CatA-mediated reduction of EC-SOD protein contributes to increased oxidative stress, myocyte hypertrophy, ECM remodeling and inflammation. This implicates CatA as a potential therapeutic target to prevent ventricular remodeling.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Cell Culture, Fibroblast Of Cardiac Tissue

SUBMITTER: Xiaoke Yin

LAB HEAD: Manuel Mayr

PROVIDER: PXD019895 | Pride | 2020-07-10

REPOSITORIES: Pride

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Cathepsin A contributes to left ventricular remodeling by degrading the antioxidant enzyme extracellular superoxide dismutase

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