title: ACBD2/ECI2-Mediated Peroxisome-Mitochondria Interactions in Leydig Cell Steroid Biosynthesis.
abstract: Fatty acid metabolism and steroid biosynthesis are 2 major pathways shared by peroxisomes and mitochondria. Both organelles are in close apposition to the endoplasmic reticulum, with which they communicate via interorganelle membrane contact sites to promote cellular signaling and the exchange of ions and lipids. To date, no convincing evidence of the direct contact between peroxisomes and mitochondria was reported in mammalian cells. Hormone-induced, tightly controlled steroid hormone biosynthesis requires interorganelle interactions. Using immunofluorescent staining and live-cell imaging, we found that dibutyryl-cAMP treatment of MA-10 mouse tumor Leydig cells rapidly induces peroxisomes to approach mitochondria and form peroxisome-mitochondrial contact sites/fusion, revealed by the subcellular distribution of the endogenous acyl-coenzyme A-binding domain (ACBD)2/ECI2 isoform A generated by alternative splicing, and further validated using a proximity ligation assay. This event occurs likely via a peroxisome-like structure, which is mediated by peroxisomal and mitochondrial matrix protein import complexes: peroxisomal import receptor peroxisomal biogenesis factor 5 (PEX5), and the mitochondrial import receptor subunit translocase of outer mitochondrial membrane 20 homolog (yeast) protein. Similar results were obtained using the mLTC-1 mouse tumor Leydig cells. Ectopic expression of the ACBD2/ECI2 isoform A in MA-10 cells led to increased basal and hormone-stimulated steroid formation, indicating that ACBD2/ECI2-mediated peroxisomes-mitochondria interactions favor in the exchange of metabolites and/or macromolecules between these 2 organelles in support of steroid biosynthesis. Considering the widespread occurrence of the ACBD2/ECI2 protein, we propose that this protein might serve as a tool to assist in understanding the contact between peroxisomes and mitochondria.
authors.affiliation: The Research Institute of the McGill University Health Centre (J.F., X.L., L.I., M.C., V.P.) and Departments of Medicine (J.F., L.I., M.C., V.P.), Biochemistry (X.L., V.P.), and Pharmacology and Therapeutics (M.C., V.P.), McGill University, Montréal, Québec, Canada H4A 3J1.
authors.forename: Jinjiang
authors.initials: J
authors.lastname: Fan
authors.affiliation: The Research Institute of the McGill University Health Centre (J.F., X.L., L.I., M.C., V.P.) and Departments of Medicine (J.F., L.I., M.C., V.P.), Biochemistry (X.L., V.P.), and Pharmacology and Therapeutics (M.C., V.P.), McGill University, Montréal, Québec, Canada H4A 3J1.
authors.forename: Xinlu
authors.initials: X
authors.lastname: Li
authors.affiliation: The Research Institute of the McGill University Health Centre (J.F., X.L., L.I., M.C., V.P.) and Departments of Medicine (J.F., L.I., M.C., V.P.), Biochemistry (X.L., V.P.), and Pharmacology and Therapeutics (M.C., V.P.), McGill University, Montréal, Québec, Canada H4A 3J1.
authors.forename: Leeyah
authors.initials: L
authors.lastname: Issop
authors.affiliation: The Research Institute of the McGill University Health Centre (J.F., X.L., L.I., M.C., V.P.) and Departments of Medicine (J.F., L.I., M.C., V.P.), Biochemistry (X.L., V.P.), and Pharmacology and Therapeutics (M.C., V.P.), McGill University, Montréal, Québec, Canada H4A 3J1.
authors.forename: Martine
authors.initials: M
authors.lastname: Culty
authors.affiliation: The Research Institute of the McGill University Health Centre (J.F., X.L., L.I., M.C., V.P.) and Departments of Medicine (J.F., L.I., M.C., V.P.), Biochemistry (X.L., V.P.), and Pharmacology and Therapeutics (M.C., V.P.), McGill University, Montréal, Québec, Canada H4A 3J1.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Papadopoulos
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D064006:Dodecenoyl-CoA Isomerase / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D000074435:Peroxisome-Targeting Signal 1 Receptor / Q000378:metabolism; D020675:Peroxisomes / Q000187:drug effects / Q000378:metabolism*; D034741:RNA, Small Interfering; D013256:Steroids / Q000378:metabolism*
chemical_list: D000074435:Peroxisome-Targeting Signal 1 Receptor; C000614265:Pex5 protein, mouse; D034741:RNA, Small Interfering; D013256:Steroids; D003994:Bucladesine; D064006:Dodecenoyl-CoA Isomerase; C576300:Eci2 protein, mouse