title: Molecular characterization of mitocalcin, a novel mitochondrial Ca2+-binding protein with EF-hand and coiled-coil domains.
abstract: Here we have identified and characterized a novel mitochondrial Ca2+-binding protein, mitocalcin. Western blot analysis demonstrated that mitocalcin was widely expressed in mouse tissues. The expression in brain was increased during post-natal to adult development. Further analyses were carried out in newly established neural cell lines. The protein was expressed specifically in neurons but not in glial cells. Double-labeling studies revealed that mitocalcin was colocalized with mitochondria in neurons differentiated from 2Y-3t cells. In addition, mitocalcin was enriched in the mitochondrial fraction purified from the cells. Immunohistochemical studies on mouse cerebellum revealed that the expression pattern of mitocalcin in glomeruli of the internal granular and molecular layers was well overlapped by the distribution pattern of mitochondria. Immunogold electron microscopy showed that mitocalcin was associated with mitochondrial inner membrane. Overexpression of mitocalcin in 2Y-3t cells resulted in neurite extension. Inhibition of the expression in 2Y-3t cells caused suppression of neurite outgrowth and then cell death. These findings suggest that mitocalcin may play roles in neuronal differentiation and function through the control of mitochondrial function.
authors.affiliation: Department of Biological Science and Technology and Tissue Engineering Research Center, Tokyo University of Science, Noda, Chiba, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Tominaga
authors.forename: Hidetake
authors.initials: H
authors.lastname: Kurihara
authors.forename: Shinya
authors.initials: S
authors.lastname: Honda
authors.forename: Genta
authors.initials: G
authors.lastname: Amakawa
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Sakai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tomooka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D020832:EF Hand Motifs / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016501:Neurites / Q000648:ultrastructure; D009474:Neurons / Q000502:physiology; D010957:Plasmids / Q000235:genetics; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection
chemical_list: D002135:Calcium-Binding Proteins; D024101:Mitochondrial Proteins; C507752:mitocalcin, mouse; D002118:Calcium