Hydrolases from I-Cell Cultured Fibroblasts

I-cell cultured fibroblasts secrete excessive amounts of N-acetyl-fl-D-hexosaminidase and a -L-fucosidase into the culture media as compared with normal fibroblasts. Addition of tunicamycin or cycloheximide at doses that inhibit the incorporation of [3Hlmannose (60-80%) and [14C]leucine (40-50%) into trichloroacetic acid-precipitable material decreased the secretion of these I-cell hydrolases to normal values within 24h, but had no effect on the secretion of acid hydrolases from normal fibroblasts. These results indicate that I-cell cultured fibroblasts secrete at least two types of acid hydrolases: one is tunicamycinand cycloheximide-sensitive and constitutes the greater proportion of the secreted hydrolases, and a smaller proportion is insensitive to tunicamycin and cycloheximide, similar to the acid hydrolases secreted by normal cultured fibroblasts.