Abstract
Phorbol esters caused reversible decrease in the levels of terminal deoxynucleotidyl transferase (TdT) and adenosine deaminase (ADA) mRNAs and an increase in the level of purine nucleoside phosphorylase (PNP) mRNA. The structural specificity of the phorbol esters affecting ADA, TdT and PNP mRNA levels correlates with their effectiveness in the activation of protein kinase (PKC). The effect of phorbol esters on TdT and ADA mRNA levels is attributed to an apparent decrease in stability of their mRNAs. The changes observed in ADA, TdT and PNP mRNA levels closely simulate the behaviour of these enzyme activities during T-cell differentiation in vivo. Moreover, similar changes in ADA, TdT and PNP activities were observed in immature pre-B and T-lymphoid cell lines expressing TdT activity.
The presence of high ADA and low PNP activities in immature lymphocytes may have a role in maintaining balanced intracellular dGTP/dATP pools which are required for TdT activity (Cohen, A. et al. J. Biol. Chem. 258:12334). Expression of TdT activity is a requirement for the diversification of immunoglobulin (Ig) and T-cell antigen receptor (TcR) genes. Thus, upon completion of Ig and TcR gene rearrangement PKC activation may mediate the programmed changes in these enzyme levels to those observed in mature lymphocytes.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Cohan, A., Martinez-Valdez, H. 23 COORDINATE REGULATION OF ADENOSINE DEAMINASE, PURINE NUCLEOSIDE PHOSPHORYLASE AND TERMINAL DEOXYNUCLEOTIDYL TRANSFERASE mRNA LEVELS BY PHORBOL ESTERS IN HUMAN THYMOCYTES. Pediatr Res 24, 115 (1988). https://doi.org/10.1203/00006450-198807000-00047
Issue Date:
DOI: https://doi.org/10.1203/00006450-198807000-00047