title: Mitochondrial localization of Smad5 in a human chondrogenic cell line.
abstract: Bone morphogenetic proteins (BMPs) are members of the transforming growth factor-beta (TGF-beta) superfamily and regulate the formation of cartilage and bone tissues as well as other key events during development. TGF-beta superfamily signaling is mediated intracellularly by Smad proteins, some of which can translocate into the cell nucleus and influence gene expression. Although much progress has been made in understanding how TGF-beta superfamily signaling regulates expression of target genes, little formal proof has been presented regarding the intracellular distribution of the Smad proteins before their entry into the nucleus. In the literature, non-nuclear Smad proteins are generally referred to as cytoplasmic. Using confocal microscopy, we here show for the first time that immunofluorescent labeling of Smad5, one of the Smad proteins associated with BMP signaling, colocalizes with the mitochondrion-specific probe MitoTracker, demonstrating a mitochondrial distribution of Smad5 in non-stimulated chondroprogenitor cells.
authors.affiliation: Department of Surgery, Faculty of Medicine and Health Science, University of Auckland, Room 3421, 85 Park Road, Grafton, Auckland, New Zealand.
authors.forename: Mia
authors.initials: M
authors.lastname: Jüllig
authors.forename: N Susan
authors.initials: NS
authors.lastname: Stott
mesh_terms: D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008928:Mitochondria / Q000378:metabolism*; D009930:Organic Chemicals; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D051902:Smad5 Protein; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D005456:Fluorescent Dyes; D009930:Organic Chemicals; D010750:Phosphoproteins; C497797:SMAD5 protein, human; D051902:Smad5 Protein; D015534:Trans-Activators; C107472:red dye CMXRos