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Matrix metalloproteinase‐2 is localized to the mitochondria‐associated membrane in the heart (1154.4)
Author(s) -
Hughes Bryan,
Fan Frank,
Cho Woo Jung,
Schulz Richard
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.1154.4
Subject(s) - mitochondrion , endoplasmic reticulum , matrix metalloproteinase , microbiology and biotechnology , chaperone (clinical) , mitochondrial matrix , immunogold labelling , colocalization , biology , inner membrane , subcellular localization , inner mitochondrial membrane , calnexin , biochemistry , chemistry , cytosol , calreticulin , enzyme , pathology , ultrastructure , cytoplasm , anatomy , medicine
Intracellular matrix metalloproteinase‐2 (MMP‐2) is activated by pro‐oxidants to proteolyze intercellular targets. MMP‐2 has recently been reported in mitochondria, a critical source of cellular oxidative stress. However, the methods used to determine MMP‐2 subcellular localization could not differentiate between MMP‐2 in the mitochondria or the mitochondrial‐associated membrane (MAM), a subdomain of the endoplasmic reticulum (ER). We hypothesized that mitochondrial MMP‐2 may be situated in the MAM and therefore investigated the subcellular distribution of MMP‐2. Immunogold electron microscopy revealed MMP‐2 in mitochondria of heart sections from mice. However, HaloTagged MMP‐2 expressed in HL‐1 cardiomyocytes showed an ER‐like distribution with greater colocalization with an ER marker (protein disulfide isomerase) relative to a mitochondrial marker, MitoTracker Red. Although MMP‐2 protein and enzymatic activity were present in crude mitochondrial fractions, once these were separated into purified mitochondria and MAM, MMP‐2 was principally associated with the latter. We also found that calreticulin, an ER and MAM‐resident Ca2+ handling protein and chaperone, could be proteolyzed by MMP‐2 in vitro. Thus, although mitochondria may contain minimal levels of MMP‐2, the majority of MMP‐2 previously identified as “mitochondrial” is in fact associated with the MAM. We hypothesize that MAM‐localized MMP‐2 could affect mitochondrial function by affecting ER‐mitochondrial Ca2+ signaling. Grant Funding Source : Supported by the Canadian Institutes of Health Research