Coordination of chondrocyte differentiation and joint formation by alpha5beta1 integrin in the developing appendicular skeleton.
The control point by which chondrocytes take the decision between the cartilage differentiation program or the joint formation program is unknown. Here, we have investigated the effect of alpha5beta1 integrin inhibitors and bone morphogenetic protein (BMP) on joint formation. Blocking of alpha5beta1 integrin by specific antibodies or RGD peptide (arginine-glycine-aspartic acid) induced inhibition of pre-hypertrophic chondrocyte differentiation and ectopic joint formation between proliferating chondrocytes and hypertrophic chondrocytes. Ectopic joint expressed Wnt14, Gdf5, chordin, autotaxin, type I collagen and CD44, while expression of Indian hedgehog and type II collagen was downregulated in cartilage. Expression of these interzone markers confirmed that the new structure is a new joint being formed. In the presence of BMP7, inhibition of alpha5beta1 integrin function still induced the formation of the ectopic joint between proliferating chondrocytes and hypertrophic chondrocytes. By contrast, misexpression of alpha5beta1 integrin resulted in fusion of joints and formation of pre-hypertrophic chondrocytes. These facts indicate that the decision of which cell fate to make pre-joint or pre-hypertrophic is made on the basis of the presence or absence of alpha5beta1 integrin on chondrocytes.
Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
David
D
Garciadiego-Cázares
Carlos
C
Rosales
Masaru
M
Katoh
Jesús
J
Chimal-Monroy
D000818:Animals; D030801:Animals, Genetically Modified; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000494:pharmacology; D002454:Cell Differentiation; D002455:Cell Division; D048429:Cell Size; D002642:Chick Embryo; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D055428:Growth Differentiation Factor 5; D053823:Hedgehog Proteins; D006801:Humans; D039081:Integrin alpha5beta1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007596:Joints / Q000196:embryology*; D051379:Mice; D011506:Proteins / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015534:Trans-Activators / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D051153:Wnt Proteins
D000911:Antibodies, Monoclonal; C525819:BMP7 protein, human; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; C525893:GDF5 protein, human; C525894:Gdf5 protein, mouse; D055428:Growth Differentiation Factor 5; D053823:Hedgehog Proteins; D039081:Integrin alpha5beta1; D011506:Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins; C486388:Wnt9a protein, mouse