Modulation of cellular glycosidase activity by hyperthermia.
We examined the effect of 45 degrees C hyperthermia on the following glycosidases in CHO cells: beta-galactosidase, beta-hexosaminidase, beta-glucuronidase and alpha-mannosidase. Among these, lysosomal alpha-mannosidase exhibited the most dramatic response to hyperthermia with an increase in activity immediately after 45 degrees C hyperthermia. The increase was linearly dose-dependent with a doubling of activity for every 20 min at 45 degrees C. In contrast to alpha-mannosidase, beta-glucuronidase, beta-galactosidase, and beta-hexosaminidase showed only minor alterations in activity, or none, after hyperthermia of 10 to 60 min at 45 degrees C. Induction of thermotolerance enhanced the heat resistance of beta-galactosidase, but caused increased heat sensitivity for alpha-mannosidase. Intracellular beta-galactosidase, measured by histochemical staining, showed a dramatic redistribution in response to mild hyperthermia (10 min, 45 degrees C); the same effect was not observed for beta-glucuronidase. The data argue against non-specific activation of lysosomes by hyperthermia, and suggest that cells contain lysosomal subpopulations that are characterized by different heat sensitivities and variable glycosidase contents.
Henle
K J
KJ
Department of Medicine, University of Arkansas for Medical Sciences, Little Rock 72205-5484.
Shmookler Reis
R J
RJ
Lumpkin
C K
CK
D000818:Animals; D002478:Cells, Cultured; D005966:Glucuronidase / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006358:Hot Temperature; D007700:Kinetics; D008247:Lysosomes / Q000201:enzymology; D008361:Mannosidases / Q000378:metabolism; D043323:alpha-Mannosidase; D001616:beta-Galactosidase / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
D006026:Glycoside Hydrolases; D008361:Mannosidases; D001616:beta-Galactosidase; D043323:alpha-Mannosidase; D005966:Glucuronidase; D001619:beta-N-Acetylhexosaminidases