Cloning of a second nm23-M1 cDNA: expression in the central nervous systemof adult mouse and comparison with nm23-M2 mRNA distribution

Nm23 has been identified as a gene family encoding different isoforms of th e nucleoside diphosphate kinase. This protein is a key enzyme in the contro l of cellular concentrations of nucleoside triphosphates. Moreover, it has been shown to play important roles in various cellular functions such as di fferentiation and metastasis. In the present study, a second cDNA for nucle oside diphosphate kinase A (Nm23-M1) was isolated from a cDNA Library of mo use embryonic stem cells. This clone encodes the same putative 152 aminoaci ds long protein as an already published cDNA but is longer in both its 5' a nd 3' untranslated regions. Tissue and cellular distribution of nm23-M1 mRN A was investigated by using Northern blot analysis and in situ hybridizatio n. Nm23-iM1 transcripts were found to be widely distributed throughout the mouse central nervous system with prominent expression in several restricte d areas. No differences were noticed between the distribution of long and s hort transcripts. Furthermore, a similar pattern of expression was describe d in the central nervous system for nm23-M2 mRNA, encoding a second isoform of the nucleoside diphosphate kinase. However, the transcript of this isof orm displayed a wider distribution and was expressed in all organs analysed by northern blotting. The possible involvement of nm23-M1 in differentiati on of mouse nervous system is further discussed. (C) 1999 Elsevier Science B.V. All rights reserved.