Figure 1. Detection of a truncated MMP-2 isoform in mitochondrial-enriched fractions from murine hearts and cardiomyoblast H9C2 cells.

I. A. Western blot analysis for MMP-2 expression in mitochondrial-enriched fractions from left ventricles of four and twelve month old wild type CD-1 mice (n = 4 for each group). MMP-2 bands with apparent molecular masses of 65 kDa are detected in the mitochondrial fractions from the twelve month old mice, but not in the fractions from four month old mice. (rMMP-2: recombinant full-length 68 kDa MMP-2 protein). I. B. Western blot analysis of mitochondrial-enriched fractions from left ventricles of hypomorphic SR-BI KO/ApoER61^h/h mice fed a normal diet or a high fat atherogenic diet for 30 days (n = 3–4). MMP-2 bands of 65 kDa and 62 kDa are detected in the mitochondrial fractions of mice fed an atherogenic diet. (Figure S2 shows a mitochondrial fraction run in parallel with recombinant 68 kDa MMP-2). II. In vitro model of transient inhibition of oxidative phosphorylation (OxPhosI). Partial OxPhosI was induced by incubation for 15 minutes in mitochondrial substrate glucose/pyruvate-free DMEM as detailed in Methods, followed by restoration in complete medium. More complete OxPhosI was induced by inclusion of antimycin A (2 µM) and 2-deoxyglucose (10 mM) in substrate-free medium. Westerns blots of mitochondrial-enriched fractions were performed at 24, 48 and 72 hours following OxPhosI. The 65 kDa MMP-2 isoform was detected in the mitochondria-enriched fractions from the H9C2 cells subjected to partial inhibition of OxPhosI and this was increased in the fractions from cells subjected to more complete OxPhosI with antimycin A and 2-deoxyglucose. (rMMP2: recombinant full-length 68 kDa MMP-2).