A role for the lysosomal protease cathepsin B in zebrafish follicular apoptosis.
This study presents evidence that cathepsin B, a lysosomal protease, may be involved in the regulation of apoptosis during serum-starvation in teleost follicles. Zebrafish vitellogenic follicles were isolated, incubated under serum-free conditions and homogenized. The follicle extracts demonstrated caspase-3-like activity using the fluorogenic substrate DEVD-AMC, indicating the onset of apoptosis. Cathepsin B activity as measured using the fluorogenic cathepsin B substrate, Z-Arg-Arg-AMC was elevated within the first 6h of incubation in serum-free media and coincided with the onset of apoptosis. This increase in cathepsin B activity was sensitive to the cathepsin B inhibitor, CA-074-ME. Furthermore, adding CA-074-ME to the follicle incubation blocked caspase-3-like activation, suggesting that cathepsin B activity is a positive regulator of the apoptotic cascade during serum-starvation. Interestingly, the increase in cathepsin-B-like activity was not preceded by an increase in cathepsin B mRNA transcription, suggesting that regulation of this enzyme is at a level other than of the gene. These results suggest a regulatory role for cathepsin B during follicular apoptosis in zebrafish ovarian follicles.
Eykelbosh
Angela J
AJ
Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Van Der Kraak
Glen
G
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002401:Cathepsin B / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003001:Cloning, Molecular; D016895:Culture Media, Serum-Free; D004151:Dipeptides / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D008247:Lysosomes / Q000187:drug effects / Q000201:enzymology*; D006080:Ovarian Follicle / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism
C400541:CA 074 methyl ester; D006063:Chorionic Gonadotropin; D016895:Culture Media, Serum-Free; D004151:Dipeptides; D012333:RNA, Messenger; D029961:Zebrafish Proteins; D004958:Estradiol; D053148:Caspase 3; D002401:Cathepsin B