Endogenous bone morphogenetic proteins mediate 1alpha, 25-dihydroxyvitamin D(3)-induced expression of osteoblast differentiation markers in human dermal fibroblasts.
Human dermal fibroblasts are generally considered to be restricted to a fibroblastic lineage. Although dermal fibroblasts do not typically express markers of osteoblastic differentiation, they have previously been shown to undergo osteoinduction when stimulated with bone morphogenetic proteins (BMPs) or vitamin D(3). However, involvement of BMP signaling in vitamin D(3)-mediated osteoinduction has not been reported. In this study, human dermal fibroblasts were cultured in chemically defined medium containing vitamin D(3), in the presence of the BMP antagonist noggin or neutralizing antibodies specific for BMP-4 or BMP-6, and characterized for markers of osteoblastic differentiation. Treatment of dermal fibroblasts with vitamin D(3) induced expression of BMP-4 (1.2 +/- 0.2, 1.7 +/- 0.2, and 1.8 +/- 0.2 relative fold increase) and BMP-6 (9.1 +/- 0.3, 23.3 +/- 2.1, and 30.4 +/- 3.0 relative fold increase) at 3, 14, and 21 days, respectively. Vitamin D(3) was also shown to induce the expression of the osteoblast-specific markers, alkaline phosphatase and osteocalcin, in a dose-dependent manner in human dermal fibroblasts. Addition of noggin, BMP-4 antibodies, and BMP-6 antibodies resulted in a downregulation of alkaline phosphatase activity (by 42%, 22%, and 20%, respectively) and secreted osteocalcin (by 20%, 31%, and 49%, respectively) after 21 days in culture. However, blocking BMP signaling did not result in complete recovery of a fibroblastic phenotype. Taken together, these results suggest that BMP signaling plays a role in the induction of an osteoblastic phenotype in human dermal fibroblasts in response to vitamin D(3) stimulation.
Hee
Christopher K
CK
Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6392, USA.
Nicoll
Steven B
SB
D000906:Antibodies / Q000494:pharmacology; D015415:Biomarkers; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D055415:Bone Morphogenetic Protein 4 / Q000276:immunology / Q000378:metabolism*; D055418:Bone Morphogenetic Protein 6 / Q000276:immunology / Q000378:metabolism*; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D019070:Cell Lineage / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D020405:Dermis / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D000906:Antibodies; C525809:BMP4 protein, human; C525816:BMP6 protein, human; D015415:Biomarkers; D050071:Bone Density Conservation Agents; D055415:Bone Morphogenetic Protein 4; D055418:Bone Morphogenetic Protein 6; D002117:Calcitriol