EXPRESSION OF N-ACETYLGLUCOSAMINYLTRANSFERASE-V MESSENGER-RNA IN MAMMALIAN-TISSUES AND CELL-LINES

The expression of N-acetylglucosaminyltransferase V (GlcNAc-T V) is in creased in many oncogenically transformed cells and in cell lines whic h are induced to proliferate, In order to characterize the regulation of GlcNAc-T V at the molecular level, we have examined the expression of GlcNAc-T V mRNAs in a number of mouse tissues and in several human and rodent cell lines, The GlcNAc-T V mRNA is expressed in different a mounts in the various mouse tissues, with the greatest amount observed in brain, followed by thymus, kidney, lung, intestine, heart and stom ach, and no transcripts detected in liver or skeletal muscle. Measurem ents of GlcNAc-T V enzymatic activity, by contrast, show brain to have lower levels of activity than several of the other tissues, suggestin g possible post-translational regulation, We find that there are two G lcNAc-T V transcripts in most of the RNAs analysed, The rodent cell li nes all express both a 7.5 and a 9.5 kb mRNA, with the smaller transcr ipt being more abundant. The human cells have mRNAs of 4.5 and 9.5 kb, Both mRNAs are expressed in HepG2 and MCF-7 cells, while A431 cells e xpress only the 4.5 kb mRNA and HL60 cells express only the 9.5 kb tra nscript, Furthermore, only the 9.5 kb mRNA appears to be increased, al ong with activity, when HepG2 cells are stimulated to proliferate, sug gesting that the two mRNAs may be under different regulatory controls, Also, a GlcNAc-T V-deficient, mutant lymphoma cell line, PHAR(2.1), w as found to express mRNAs which are larger than the normal mRNAs, poss ibly due to an insertion or aberrant splicing, resulting in a defectiv e mRNA.