Alteration of phosphotyrosine-containing proteins during differentiation of chicken erythroleukemia cells (HD3)

✍ Scribed by Mira Grdiša

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 173 KB
• Volume: 16
• Category: Article
• ISSN: 0263-6484
• DOI: 10.1002/(sici)1099-0844(1998120)16:4<277::aid-cbf798>3.0.co;2-d

✦ Synopsis

After treatment of HD3 cells with erythroid-inducing agents (hemin and butyric acid) at 428C, the pro®le of phosphotyrosine-containing proteins was altered. Upon induction the overall level of phosphotyrosine-containing proteins increased. To examine the role of protein phosphorylation in HD3 cells dierentiation, the cells were treated with speci®c inhibitors. In the presence of okadaic acid, cell proliferation was arrested and accompanied by a marked increase in haemoglobin synthesis, a dierentiation marker of erythroid cells. Okadaic acid caused decrease of the phosphotyrosine-containing proteins, presumably to maintain a balance between phosphorylation/dephosphorylation processes in the cells. Addition of 3-isobutyl-l-methyl-xanthine, an activator of phosphatases, caused a decrease or disappearance of almost all phosphotyrosine-containing proteins and, at the same time, prevented the erythroid dierentiation of HD3 cells. Sodium orthovanadate, a speci®c inhibitor of phosphotyrosine phosphatase, increased the level of phosphotyrosine proteins and induced dierentiation of HD3 cells. These results indicate that phosphorylation of cellular proteins is coupled with a reaction(s) which is responsible for triggering the dierentiation of HD3 cells. The phosphorylation/dephosphorylation processes are associated with an early event(s) during the dierentiation of HD3 cells and may not be connected to tyrosine residues.