Role of interferon and 2',5'-oligoadenylate synthetase in erythroid differentiation of Friend leukemia cells. Studies with interferon-sensitive and -resistant variants.
Résumé
It has been suggested that the interferon (IFN)-induced 2',5'-oligoadenylate (2-5A) synthetase, which polymerizes ATP into a series of 2',5'-linked oligomers with the general formula pppA(2'p5'A)n, plays a general role in cell growth and terminal differentiation. For instance, an increase in 2-5A synthetase activity has been described during dimethyl sulfoxide (Me2SO)-induced erythroid differentiation of Friend leukemia cells (FLC). 2-5A synthetase has been measured in two Friend leukemia cell sublines by various techniques including a radioimmunoassay of its products which would detect 10(-16) mol of 2-5A cores. Although cells of both sublines fully differentiate (as measured by benzidine staining), only in one subline was there an increase in 2-5A synthetase activity upon treatment with Me2SO. Hexamethylenebisacetamide, another potent agent of differentiation in this system, did not increase 2-5A synthetase activity in either of these two sublines. An IFN-resistant FLC variant differentiated normally upon treatment with Me2SO or hexamethylenebisacetamide while it was noninducible for 2-5A synthetase activity by exogenous IFN or by the inducers themselves. A similar situation has been observed with regard to the level of phosphorylation of the IFN-induced Mr = 67,000 protein band. In addition, treatment of IFN-sensitive and resistant FLC sublines with mouse alpha beta IFN antiserum did not affect differentiation. Even though we have duplicated previous findings on the increase of 2-5A synthetase activity in Me2SO-induced FLC, the lack of any such increase with other inducers or other sublines indicates that there is no causal relationship between the enzyme activation and FLC differentiation.
Domaines
Sciences du Vivant [q-bio]
Origine : Fichiers éditeurs autorisés sur une archive ouverte
