Bone anabolic effects of sonic/indian hedgehog are mediated by bmp-2/4-dependent pathways in the neonatal rat metatarsal model.
A neonatal rat metatarsal organ culture model has been employed to study the anabolic effects of Sonic/Indian hedgehog and BMP-4. In this culture system, a significant increase in endochondral ossification is measured by an increase in length of mineralized bone, after daily treatment for 7 days with Sonic hedgehog protein (Shh-N). Previous evidence indicated that PTH related protein (PTHrP) is a critical target of hedgehog function in endochondral ossification. Using a PTHrP blocking antibody, it is shown that hedgehog mediates this activity via pathways other than through PTHrP. A dose-related increase in endochondral ossification is observed when metatarsals are treated with 25 ng/ml recombinant human bone morphogenetic protein 4 (BMP-4). However, this activity is not evident at higher doses of BMP-4 (200 ng/ml). High doses of BMP-4 resulted in increased expression of noggin messenger RNA and cotreatment of noggin and Shh-N resulted in reversal of the anabolic action of Shh-N. This observation suggests that BMP-4 signaling can influence the Shh-N mediated increase in endochondral ossification. Finally, we show that the Shh-N and BMP-4 mediated increase in endochondral ossification is reversed by treatment with antisense oligonucleotides targeted against Cbfa1. Thus, this report identifies Shh-N as an inducer of endochondral ossification that mediates its effect via BMP-4 and Cbfa1-dependent pathways.
Krishnan
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Endocrinology Division, Eli Lilly & Co., Lilly Corporate Center, Indianapolis, Indiana 46285, USA. krishnan_Gary@lilly.com
Ma
Y
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Moseley
J
J
Geiser
A
A
Friant
S
S
Frolik
C
C
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology / Q000502:physiology*; D050659:Core Binding Factor Alpha 1 Subunit; D004305:Dose-Response Relationship, Drug; D053823:Hedgehog Proteins; D006801:Humans; D008682:Metatarsal Bones / Q000187:drug effects* / Q000378:metabolism*; D009363:Neoplasm Proteins; D009924:Organ Culture Techniques; D011506:Proteins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors / Q000502:physiology; D016212:Transforming Growth Factor beta
C525718:BMP2 protein, human; C525809:BMP4 protein, human; C525720:Bmp2 protein, rat; C525811:Bmp4 protein, rat; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D050659:Core Binding Factor Alpha 1 Subunit; D053823:Hedgehog Proteins; D009363:Neoplasm Proteins; D011506:Proteins; D011994:Recombinant Proteins; C509239:SHH protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2