The Effects of cAMP on the Expression of Glycolytic Isozymes in Activated Peripheral Human T Lymphocytes

Forskolin, an activator of adenylate cyclase, inhibits mitogen induction of glycolytic isozymes in human peripheral T cells. Inhibition of lactate dehydrogenase isozyme activity is correlated with lowered mRNA levels, suggesting a transcriptional block in the presence of increased cAMP. Forskolin added with the mitogen, or 12-24 h after the mitogen, strongly inhibits isozyme expression and DNA synthesis, and causes cells to accumulate in the GO or early Gi phase of the cell cycle. The data suggest that DNA synthesis and isozyme expression are both inhibited by a cAMP-sensitive step(s) in the early activation or progression phase.