Increased trehalase expression after glucose limitation of LLC-PK1 clones

Expression of the apical membrane disaccharidase trehalase correlates with the development of a proximal tubule-specific differentiated phenotype in the LLC-PK1 cell line derived from renal epithelia. Substitution of galactose for glucose in the culture medium of confluent cultures resulted in a significant trehalase induction; a smaller induction was observed after replacement by fructose, mannose, or the nonmetabolizable sugar alpha-methyl-D-glucose. Induction was specific for trehalase among other microvillar hydrolases, reversible after replacement of glucose, and was increased as a function of decreasing glucose concentration. Stable clonal cell lines that were inducible by glucose limitation and noninducible clones were isolated nonselectively. Both types exhibited trehalase induction after exposure to the differentiation inducer N,N'-hexamethylene-bis-acetamide (HMBA). These results suggest that trehalase induction after glucose deprivation occurs by a different mechanism than that mediated by HMBA.