Expression of the α2β1 and α(IIb)β3 integrin genes is differentially regulated during megakaryocytic differentiation of pluripotent K562 cells induced with phorbol 12,13-dibutyrate. Upon megakaryocytic differentiation, steady-state α2 mRNA increased markedly from the undetectable level present in the uninduced cells. The level of β1 mRNA did not change. Expression of α(IIb)β3 is regulated differently. β3 mRNA was undetectable in uninduced cells but increased significantly following induction. α(IIb) mRNA was detectable at a low level prior to induction, but at an increased level following differentiation. Altered mRNA stability did not contribute to changes in mRNA levels. Nuclear run-off experiments revealed a 20-fold increase in α2 gene transcription upon megakaryocytic differentiation, but no change in transcription of the β1 gene. Transcription of both the α(IIb) and β3 genes increased 10- and 5-fold, respectively. Thus, the increase in α2β1 protein which accompanies the megakaryocytic differentiation of K562 cells is a consequence of the increased steady-state level of α2 mRNA due to transcriptional activation of the α2 gene. The long-lived β1 mRNA is not altered during differentiation. In contrast, increased α(IIb)β3 protein appears due to increased steady-state levels of both α(IIb) and β3 mRNAs that result from transcriptional activation of both integrin genes.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Biological Chemistry|
|State||Published - 1992|