Publication Date:
1996-08-02
Description:
Proper regulation of chondrocyte differentiation is necessary for the morphogenesis of skeletal elements, yet little is known about the molecular regulation of this process. A chicken homolog of Indian hedgehog (Ihh), a member of the conserved Hedgehog family of secreted proteins that is expressed during bone formation, has now been isolated. Ihh has biological properties similar to those of Sonic hedgehog (Shh), including the ability to regulate the conserved targets Patched (Ptc) and Gli. Ihh is expressed in the prehypertrophic chondrocytes of cartilage elements, where it regulates the rate of hypertrophic differentiation. Misexpression of Ihh prevents proliferating chondrocytes from initiating the hypertrophic differentiation process. The direct target of Ihh signaling is the perichondrium, where Gli and Ptc flank the expression domain of Ihh. Ihh induces the expression of a second signal, parathyroid hormone-related protein (PTHrP), in the periarticular perichondrium. Analysis of PTHrP (-/-) mutant mice indicated that the PTHrP protein signals to its receptor in the prehypertrophic chondrocytes, thereby blocking hypertrophic differentiation. In vitro application of Hedgehog or PTHrP protein to normal or PTHrP (-/-) limb explants demonstrated that PTHrP mediates the effects of Ihh through the formation of a negative feedback loop that modulates the rate of chondrocyte differentiation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vortkamp, A -- Lee, K -- Lanske, B -- Segre, G V -- Kronenberg, H M -- Tabin, C J -- DK47038/DK/NIDDK NIH HHS/ -- DK4723/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1996 Aug 2;273(5275):613-22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8662546" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Base Sequence
;
*Bone Development
;
Cartilage/*cytology/metabolism
;
Cell Differentiation
;
Cell Division
;
Chick Embryo
;
Cloning, Molecular
;
Culture Techniques
;
Extremities/embryology
;
Feedback
;
Gene Expression Regulation
;
Growth Plate/*cytology/metabolism
;
Hedgehog Proteins
;
Mice
;
Molecular Sequence Data
;
Morphogenesis
;
*Osteogenesis
;
Parathyroid Hormone
;
Parathyroid Hormone-Related Protein
;
Phenotype
;
Proteins/pharmacology/*physiology
;
Receptor, Parathyroid Hormone, Type 1
;
Receptors, Parathyroid Hormone/physiology
;
Signal Transduction
;
*Trans-Activators
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
