PHYSIOLOGY
Ihh can hone the bone
Normal growth and development of the bones rely on coordination among cartilage cell (chondrocyte) mass regulation and cartilage structure establishment. Parathyroid hormone-related protein (PTHrP) and Indian hedgehog (Ihh) are important for the precise regulation of cartilage development, but the mechanisms that guide chondrocytes during bone formation were not well understood.
In a study appearing online on June 9 in advance of the print publication of the July 1 print issue of the Journal of Clinical Investigation, Henry Kronenberg and colleagues from Massachusetts General Hospital examine the control of early chondrocyte differentiation by Ihh and the physiological role of this differentiation step in regulating chondrocyte mass and new bone composition.
The researchers analyze mice carrying multiple genetic modifications, in which expression of PTHrP, PTHrP receptor and Ihh, or combinations of these molecules were modified. Their analysis reveals that Ihh stimulates early chondrocyte differentiation, which in turn regulates the mass of proliferating chondrocytes independently of the action of PTHrP. These data provide a new model of bone growth in which Ihh, independent of any changes in PTHrP controls the conversion of early chondrocytes to more rapidly proliferating cells in the growing bones during fetal development.
Title: Indian hedgehog stimulates early chondrocyte differentiation to regulate growth plate length independently of PTHrP
AUTHOR CONTACT:
Henry M. Kronenberg
Massachusetts General Hospital, Boston MA USA
Phone: 617 726-3966; Fax: 617 726-7543; E-mail: hkronenberg@partners.org
View the PDF of this article at: https://www.the-jci.org/article.php?id=24397
IMMUNOLOGY
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Contact: Stacie Bloom
press_releases@the-jci.org
212-342-4159
Journal of Clinical Investigation
9-Jun-2005