title: Spatiotemporal disorder in the axial skeleton development of the Mesp2-null mouse: a model of spondylocostal dysostosis and spondylothoracic dysostosis.
abstract: Spondylocostal dysostosis (SCDO) is a genetic disorder characterized by severe malformation of the axial skeleton. Mesp2 encodes a basic helix-loop-helix type transcription factor that is required for somite formation. Its human homologue, Mesp2, is a gene affected in patients with SCDO and a related vertebral disorder, spondylothoracic dysostosis (STDO). This work investigated how the loss of Mesp2 affects axial skeleton development and causes the clinical features of SCDO and STDO. We first confirmed, by three-dimensional computed tomography scanning, that Mesp2-null mice exhibited mineralized tissue patterning resembling the radiological features of SCDO and STDO. Histological observations and in situ hybridization probing for extracellular matrix molecules demonstrated that the developing vertebral bodies in Mesp2-null mice were extensively fused with rare insertions of intervertebral tissue. Unexpectedly, the intervertebral tissues were mostly fused longitudinally in the vertebral column, instead of exhibiting extended formation, as was expected based on the caudalized properties of Mesp2-null somite derivatives. Furthermore, the differentiation of vertebral body chondrocytes in Mesp2-null mice was spatially disordered and largely delayed, with an increased cell proliferation rate. The quantitative three-dimensional immunofluorescence image analyses of phospho-Smad2 and -Smad1/5/8 revealed that these chondrogenic phenotypes were associated with spatially disordered inputs of TGF-β and BMP signaling in the Mesp2-null chondrocytes, and also demonstrated an amorphous arrangement of cells with distinct properties. Furthermore, a significant delay in ossification in Mesp2-null vertebrae was observed by peripheral quantitative computed tomography. The current observations of the spatiotemporal disorder of vertebral organogenesis in the Mesp2-null mice provide further insight into the pathogenesis of SCDO and STDO, and the physiological development of the axial skeleton.
authors.affiliation: Section of Oral Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Makino
authors.forename: Yu
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Rieko
authors.initials: R
authors.lastname: Tanabe
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Tamamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Mayu
authors.initials: M
authors.lastname: Haraikawa
authors.forename: Miwako
authors.initials: M
authors.lastname: Hamagaki
authors.forename: Kenji
authors.initials: K
authors.lastname: Hata
authors.forename: Jun
authors.initials: J
authors.lastname: Kanno
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yoneda
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Saga
authors.forename: Masae
authors.initials: M
authors.lastname: Goseki-Sone
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko
authors.forename: Akira
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Iimura
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics / Q000503:physiopathology*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000502:physiology*; D001842:Bone and Bones / Q000503:physiopathology*; D003286:Contracture / Q000235:genetics / Q000503:physiopathology*; D004195:Disease Models, Animal; D004413:Dysostoses / Q000235:genetics / Q000503:physiopathology*; D005455:Fluorescent Antibody Technique; D006330:Heart Defects, Congenital / Q000235:genetics / Q000503:physiopathology*; D006548:Hernia, Diaphragmatic / Q000235:genetics / Q000503:physiopathology*; D051379:Mice; D018345:Mice, Knockout; D010009:Osteochondrodysplasias / Q000235:genetics / Q000503:physiopathology*; D012272:Ribs / Q000002:abnormalities / Q000503:physiopathology; D013131:Spine / Q000002:abnormalities / Q000503:physiopathology; D014057:Tomography, X-Ray Computed
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; C107407:Mesp2 protein, mouse