title: Shh signaling from the nucleus pulposus is required for the postnatal growth and differentiation of the mouse intervertebral disc.
abstract: Intervertebral discs (IVD) are essential components of the vertebral column. They maintain separation, and provide shock absorbing buffers, between adjacent vertebrae, while also allowing movements between them. Each IVD consists of a central semi-liquid nucleus pulposus (NP) surrounded by a multi-layered fibrocartilagenous annulus fibrosus (AF). Although the IVDs grow and differentiate after birth along with the vertebral column, little is known about the mechanism of this. Understanding the signals that control normal IVD growth and differentiation would also provide potential therapies for degenerative disc disease, which is the major cause of lower back pain and affects a large proportion of the population. In this work, we show that during postnatal growth of the mouse, Sonic hedgehog (Shh) signaling from the NP cells controls many aspects of growth and differentiation of both the NP cells themselves and of the surrounding AF, and that it acts, at least partly, by regulating other signaling pathways in the NP and AF. Recent studies have shown that the NP cells arise from the embryonic notochord, which acts as a major signaling center in the embryo. This work shows that this notochord-derived tissue continues to carry out a major signaling function in the postnatal body and that the IVDs are signaling centers, in addition to their already known functions in the mechanics of vertebral column function.
authors.affiliation: Division of Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA. Chitra.Dahia@cchmc.org
authors.forename: Chitra Lekha
authors.initials: CL
authors.lastname: Dahia
authors.forename: Eric
authors.initials: E
authors.lastname: Mahoney
authors.forename: Christopher
authors.initials: C
authors.lastname: Wylie
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D017353:Gene Deletion; D006132:Growth Plate / Q000187:drug effects / Q000473:pathology; D053823:Hedgehog Proteins / Q000378:metabolism*; D006984:Hypertrophy; D019426:Integrases / Q000378:metabolism; D007403:Intervertebral Disc / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D010641:Phenotype; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014704:Veratrum Alkaloids / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D053823:Hedgehog Proteins; D011994:Recombinant Proteins; C465570:Shh protein, mouse; D014704:Veratrum Alkaloids; C514061:ihh protein, mouse; C045073:Cre recombinase; D019426:Integrases; C000541:cyclopamine