Participation of proteasomes in Xenopus embryogenesis.
We examined the effects of various protease substrates on Xenopus laevis embryogenesis. Thirty-three peptidyl-MCA substrates were added to the culture medium in which Xenopus embryos were developing. Five of the 33 substrates were found to inhibit embryogenesis at the early gastrula stage or much earlier ones. These results suggest that proteases that hydrolyze these substrates are involved in embryonic development. We found that the developmental stage of embryos is crucial for these substrates to inhibit their development. We purified a protease that hydrolyzes Pyr-Arg-Thr-Lys-Arg-MCA, a substrate that inhibits embryogenesis, from Xenopus embryos. This protease turned out to be a component of proteasomes. We found that 4 of the 5 substrates that inhibit embryogenesis are among the proteasome substrates. Thus, we concluded that proteasomes play a crucial role in the development of Xenopus embryos. Possibly, various catalytic subunits in proteasomes function independently, in stage-specific manners.
Iijima
Ryoko
R
Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113-0033.
Homma
Koichi J
KJ
Natori
Shunji
S
D000818:Animals; D003470:Culture Media; D003546:Cysteine Endopeptidases / Q000494:pharmacology*; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D005775:Gastrula / Q000187:drug effects; D007976:Leupeptins / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D012697:Serine Endopeptidases / Q000494:pharmacology; D013379:Substrate Specificity; D013997:Time Factors; D014982:Xenopus laevis / Q000196:embryology*
D003470:Culture Media; D007976:Leupeptins; D009097:Multienzyme Complexes; D011480:Protease Inhibitors; C089486:carbobenzoxy-leucyl-leucyl-norvalinal; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex