TY - JOUR
T1 - Constitutive myc expression impairs hypertrophy and calcification in cartilage
AU - Quarto, Rodolfo
AU - Dozin, Beatrice
AU - Tacchetti, Carlo
AU - Robino, Grazia
AU - Zenke, Martin
AU - Campanile, Giuliano
AU - Cancedda, Ranieri
PY - 1992
Y1 - 1992
N2 - The myc oncogene is expressed by proliferating quail embryo chondrocytes (QEC) grown as adherent cells and is repressed in QEC maintained in suspension culture. To investigate the interference of myc expression during chondrocyte differentiation, QEC were infected with a retrovirus carrying the v-myc oncogene (QEC-v-myc). Uninfected or helper virus-infected QEC were used as control. In adherent culture, QEC-v-myc displayed a chondrocytic phenotype and synthesized type II collagen and Ch21 protein, while control chondrocytes synthesized type I and type II collagen with no Ch21 protein detected as long as the attachment to the plastic was kept. In suspension culture, QEC-v-myc readily aggregated and within 1 week the cell aggregates released small single cells; still they secreted only type II collagen and Ch21 protein. In the same conditions control cell aggregates released hypertrophic chondrocytes producing type II and type X collagens and Ch21 protein. In the appropriate culture conditions, QEC-v-myc reconstituted a tissue defined as nonhypertrophic, noncalcifying cartilage by the high cellularity, the low levels of alkaline phosphatase enzymatic activity, and the absence of type X collagen synthesis and of calcium deposition. We conclude that the constitutive expression of the v-myc oncogene keeps chondrocytes in stage I (active proliferation and synthesis of type II collagen) and prevents these cells from reconstituting hypertrophic calcifying cartilage.
AB - The myc oncogene is expressed by proliferating quail embryo chondrocytes (QEC) grown as adherent cells and is repressed in QEC maintained in suspension culture. To investigate the interference of myc expression during chondrocyte differentiation, QEC were infected with a retrovirus carrying the v-myc oncogene (QEC-v-myc). Uninfected or helper virus-infected QEC were used as control. In adherent culture, QEC-v-myc displayed a chondrocytic phenotype and synthesized type II collagen and Ch21 protein, while control chondrocytes synthesized type I and type II collagen with no Ch21 protein detected as long as the attachment to the plastic was kept. In suspension culture, QEC-v-myc readily aggregated and within 1 week the cell aggregates released small single cells; still they secreted only type II collagen and Ch21 protein. In the same conditions control cell aggregates released hypertrophic chondrocytes producing type II and type X collagens and Ch21 protein. In the appropriate culture conditions, QEC-v-myc reconstituted a tissue defined as nonhypertrophic, noncalcifying cartilage by the high cellularity, the low levels of alkaline phosphatase enzymatic activity, and the absence of type X collagen synthesis and of calcium deposition. We conclude that the constitutive expression of the v-myc oncogene keeps chondrocytes in stage I (active proliferation and synthesis of type II collagen) and prevents these cells from reconstituting hypertrophic calcifying cartilage.
UR - http://www.scopus.com/inward/record.url?scp=0026580527&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026580527&partnerID=8YFLogxK
U2 - 10.1016/0012-1606(92)90273-J
DO - 10.1016/0012-1606(92)90273-J
M3 - Article
C2 - 1728587
AN - SCOPUS:0026580527
VL - 149
SP - 168
EP - 176
JO - Developmental Biology
JF - Developmental Biology
SN - 0012-1606
IS - 1
ER -