Stimulation of growth of serum-deprived chick embryo fibroblasts by 3',5'-phosphodiesterase. |
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Authors: | D A Lawrence P Jullien |
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Institution: | Fondation Curie, Institut du Radium, Section de Biologie, F-91405 Orsay, et Unité de Physiologie Cellulaire, INSERM, Paris, France |
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Abstract: | In chick embryo fibroblasts (CEF) deprived of serum, DNA synthesis is reduced to a basal level in about 12 h, cell division ceases after 24–36 h and their morphology changes to a rounded, less refringent form. During several days without serum the cAMP content of the cells showed a slow increase or a maintenance of the level found before serum was removed. When CEF deprived of serum for 24 h were treated with beef heart 3′,5′-phosphodiesterase (PHD) the cAMP level fell about 40% after 3 h, 3H-thymidine incorporation into DNA was strongly stimulated with a peak of incorporation at 12 h after the start of PHD treatment, cell morphology returned to that observed before serum deprivation, and at 24 h there was an evident growth in cell population, with a parallel increase in protein content. The growth stimulation by PHD is transitory: after cells had been deprived of serum for 4 days the PHD effect was no longer noticeable on the above parameters. Theophylline (1 mM and 4 mM) inhibited the PHD-mediated stimulation of 3H-TdR incorporation, this could well have been due to its general toxic effect on the cells (see Discussion). |
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