title: A fluorescence spotlight on the clockwork development and metabolism of bone.
abstract: Biological phenomena that exhibit periodic activity are often referred as biorhythms or biological clocks. Among these, circadian rhythms, cyclic patterns reflecting a 24-h cycle, are the most obvious in many physiological activities including bone growth and metabolism. In the late 1990s, several clock genes were isolated and their primary structures and functions were identified. The feedback loop model of transcriptional factors was proposed to work as a circadian core oscillator not only in the suprachiasmatic nuclei of the anterior hypothalamus, which is recognized as the mammalian central clock, but also in various peripheral tissues including cartilage and bone. Looking back to embryonic development, the fundamental architecture of skeletal patterning is regulated by ultradian clocks that are defined as biorhythms that cycle more than once every 24 h. As post-genomic approaches, transcriptome analysis by micro-array and bioimaging assays to detect luminescent and fluorescent signals have been exploited to uncover a more comprehensive set of genes and spatio-temporal regulation of the clockwork machinery in animal models. In this review paper, we provide an overview of topics related to these molecular clocks in skeletal biology and medicine, and discuss how fluorescence imaging approaches can contribute to widening our views of this realm of biomedical science.
authors.affiliation: Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan. iimura.gcoe@tmd.ac.jp
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Iimura
authors.forename: Ayako
authors.initials: A
authors.lastname: Nakane
authors.forename: Mayu
authors.initials: M
authors.lastname: Sugiyama
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sato
authors.forename: Yuji
authors.initials: Y
authors.lastname: Makino
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Takagi
authors.forename: Rika
authors.initials: R
authors.lastname: Numano
authors.forename: Akira
authors.initials: A
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000235:genetics / Q000502:physiology*; D019521:Body Patterning; D001842:Bone and Bones / Q000033:anatomy & histology / Q000196:embryology / Q000378:metabolism*; D023281:Genomics; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence
chemical_list: D018398:Homeodomain Proteins