J. Biol. Chem., Vol. 265, Issue 13, 7216-7220, May, 1990
Stabilization of the mRNA follows transcriptional activation of type II collagen gene in differentiating chicken chondrocyte
B Dozin, R Quarto, F Rossi and R Cancedda
Laboratorio di Differenziamento Cellulare, Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
The differentiation of chicken endochondral chondrocyte can be induced in
vitro by transferring to suspension culture dedifferentiated chondrocytes
grown as adherent cells. During the differentiation process, the synthesis
of type I collagen is repressed while the genes encoding type II, IX, and X
collagens are gradually activated. The changes in the steady-state levels
of the mRNAs for type I, IX, and X collagens were shown to be fully
accounted for by proportional modifications in the rates of specific gene
transcription (Castagnola, P., Dozin, B., Moro, G., and Cancedda, R. (1988)
J. Cell Biol. 106, 461- 467). In the present report, we demonstrate that
the cellular accumulation of type II collagen mRNA in differentiating
chondrocyte is regulated not only at the transcription level but also
through a stabilization of the RNA transcript as shown by the enhanced
half-life of the mRNA in differentiated cells treated with actinomycin D.
We also give evidence that this additional mechanism: 1) is specific for
type II collagen, 2) does not occur at an early stage of differentiation
when type II collagen mRNA starts accumulating, 3) affects only the
cytoplasmic form of the RNA transcript.