CONSTITUTIVE EXPRESSION OF BETA-N-ACETYLHEXOSAMINIDASE IN A MICROGLIAL CELL-LINE - TRANSCRIPTIONAL MODULATION BY LIPOPOLYSACCHARIDE AND SERUM FACTORS

We investigated the expression of the alpha- and beta-subunits of the lysosomal enzyme beta-N-acetylhexosaminidase in the BV-2 microglial ce ll line under different culture conditions, beta-N-acetylhexosaminidas e from BV-2 microglia cells was separated into its constituent isoenzy mes on diethylaminoethyl (DEAE) cellulose, and its activity was monito red with 4-methylumbelliferyl-beta-N-acetylglucosamine and 4-methylumb elliferyl-beta-N-acetylglucosamine substrates, Forms corresponding to the mouse isoenzymes A and B were present in the cells incubated in se rum-supplemented medium as well as in serum-free medium, Lipopolysacch aride, a well-known activator of microglia in vitro, added to the BV-2 cells in serum-supplemented medium induced a decrease in the specific enzymatic activity determined with the 4-methylumbelliferyl-beta-N-ac etylglucosamine substrate, Lipopolysaccharide had no effect on hexosam inidase isoenzyme pattern of BV-2 cells in serum-supplemented medium. The level of alpha-subunit mRNA was increased and the level of beta-su bunit mRNA was decreased in BV-2 cells incubated in serum-supplemented medium plus lipopolysaccharide, In the cells incubated in a serum-fre e medium no significant changes in the hexosaminidase-specific activit ies towards the above substrates were observed, Interestingly, increas ed expression of alpha- and beta-subunit mRNA was evident in compariso n with cultures in serum-supplemented medium, The present results sugg est that the BV-2 cell line may be a useful tool to study the possible role of microglia in the metabolism of brain glycolipids. (C) 1997 Wi ley-Liss, Inc.