Secreted frizzled related protein 1 regulates Wnt signaling for BMP2 induced chondrocyte differentiation.
Canonical Wnt signaling (beta-catenin/TCF) has emerged as a key regulator of skeletogenesis. In this study, chondrogenesis is examined in a mouse model in which the Wnt antagonist secreted frizzled related protein 1 (sFRP1) is non-functional and results in a high bone mass phenotype and activation through the canonical pathway of the Runx2 transcription factor that is essential for bone formation. We find during the period of rapid post-natal growth, shortened height of the growth plate and increased calcification of the hypertrophic zone (HZ) in the sFRP1-/- mouse, indicating accelerated endochondral ossification. Using mouse embryo fibroblasts (MEFs) induced into the chondrogenic lineage, increased chondrogenesis and accelerating differentiation of hypertrophic chondrocytes in the sFRP1-/- MEFs was observed compared to WT cells. The induced maturation of hypertrophic chondrocytes in sFRP1(-/-) MEFs was inversely correlated to phospho-beta-catenin levels, indicating involvement of activated canonical Wnt signaling characterized by an increased expression of collagen type 2a1 and Sox 9. However, an absence of Indian hedgehog expression which occurs in WT cells was found. SFRP1-/- cells also exhibited an early induction of collagen type 10a1. Thus, these modifications in gene expression are contributing mechanism(s) for increased chondrocyte differentiation in SFRP1-/- cells. These studies have identified sFRP1 as a critical negative regulator of Wnt signaling for the normal progression of chondrocyte differentiation. Microarray gene profiling provided additional novel insights into the regulatory factors for appropriate Wnt signaling necessary for the control of chondrocyte maturation.
Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
Tripti
T
Gaur
Lillian
L
Rich
Christopher J
CJ
Lengner
Sadiq
S
Hussain
Brune
B
Trevant
David
D
Ayers
Janet L
JL
Stein
Peter V N
PV
Bodine
Barry S
BS
Komm
Gary S
GS
Stein
Jane B
JB
Lian
D000818:Animals; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000737:chemistry / Q000473:pathology* / Q000502:physiology*; D024043:Collagen Type II / Q000032:analysis / Q000235:genetics / Q000502:physiology; D024121:Collagen Type X / Q000032:analysis / Q000235:genetics / Q000502:physiology; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis / Q000235:genetics / Q000502:physiology; D005347:Fibroblasts / Q000737:chemistry / Q000473:pathology / Q000502:physiology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D006132:Growth Plate / Q000737:chemistry / Q000473:pathology / Q000503:physiopathology; D053823:Hedgehog Proteins; D006609:High Mobility Group Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology; D006984:Hypertrophy / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D015534:Trans-Activators / Q000032:analysis / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000032:analysis / Q000235:genetics / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D051153:Wnt Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D051176:beta Catenin / Q000032:analysis / Q000235:genetics / Q000502:physiology; D000094742:Secreted Frizzled-Related Proteins
D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D024043:Collagen Type II; D024121:Collagen Type X; D050659:Core Binding Factor Alpha 1 Subunit; D053823:Hedgehog Proteins; D006609:High Mobility Group Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; D015534:Trans-Activators; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; D051176:beta Catenin; C525719:Bmp2 protein, mouse; C495267:CTNNB1 protein, mouse; C447413:Col2a1 protein, mouse; C493716:Runx2 protein, mouse; C485539:Sfrp1 protein, mouse; D000094742:Secreted Frizzled-Related Proteins; C527933:Sox9 protein, mouse