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Evidence of a mitochondrial lactate oxidation complex at mitochondrial inner membrane in mammalian skeletal muscle cells
Author(s) -
Hashimoto Takeshi,
Hussien Rajaa,
Brooks George A
Publication year - 2006
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.20.4.a816-b
Subject(s) - skeletal muscle , mitochondrion , cytochrome c oxidase , lactate dehydrogenase , biochemistry , microbiology and biotechnology , blot , biology , intracellular , immunoprecipitation , cytosol , inner mitochondrial membrane , chemistry , enzyme , endocrinology , gene
Results of previous studies suggested a role of mitochondria (MI) in an Intracellular Lactate Shuttle. Therefore, using confocal laser‐scanning microscopy (CLSM) we examined the cellular locations of mitochondria, lactate dehydrogenase (LDH), the lactate/pyruvate transporter MCT1, and CD147, a purported chaperone protein for MCT1 in rat‐derived L6 skeletal muscle cell line and rat plantaris muscle. As well, the interaction of MCT1 and related proteins was confirmed by Western blotting of mitochondrial (MI) cell fractions and by immunoprecipitation from L6 lysates followed by immunoblotting. CLSM showed that LDH, MCT1 and CD147 are co‐localized with the mitochondrial reticulum in L6 cells and rat plantaris muscle. Western blots showed that cytochrome oxidase (COX), NADH‐dehydrogenase (NADH‐dh), LDH, MCT1 and CD147 are abundant in MI fractions of L6 cells. Interactions among cytochrome oxidase (COX), MCT1 and CD147 in mitochondria was confirmed by immunoblotting after immunoprecipitation in L6 cells. However, we did not find association between NADH‐dh and MCT1 and LDH in L6 cells. These findings further our understanding of the mitochondrial role in cellular lactate oxidation and may be interpreted to indicate presence of a terminal mitochondrial electron transport chain component, the lactate oxidation complex, in mammalian skeletal muscle. Supported by NIH grant AR050459