标题：Regulation of Adenosine 3′:5′-Cyclic Monophosphate Phosphodiesterase Activity in Fibroblasts by Intracellular Concentrations of Cyclic Adenosine Monophosphate
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：2
页码：459-462
DOI：10.1073/pnas.69.2.459
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Cyclic AMP-phosphodiesterase is present in various mouse fibroblasts. Contact-inhibited 3T3 cells contain two forms of the enzyme, one with a Km of 2.5 {micro}M and the second with a Km of 71 {micro}M. As 3T3 cells grow to confluency and cAMP concentrations rise, the activity of the first enzyme increases, whereas that of the second is unchanged. A line of SV40-transformed 3T3 cells with low cAMP concentration also has low levels of the cAMP-phosphodiesterase with a Km of 2.5 {micro}M. Treatment of 3T3 and SV40-transformed 3T3 cells with dibutyryl cAMP and theophylline increases cAMP-phosphodiesterase accumulation. This accumulation is blocked by cycloheximide and actinomycin D. The newly formed enzyme resembles the higher affinity enzyme present in unstimulated cells, since it has a Km of 1.2-2.0 {micro}M, and is stimulated by snake venom. In L cells in which cAMP concentrations are elevated by treatment with prostaglandin E1, cAMP phosphodiesterase also accumulates. We conclude that intracellular concentrations of cAMP regulate the synthesis of cAMP-phosphodiesterase, and that cAMP functions as an inducer of the enzyme.
