A nickel-binding serpin, pNiXa, induces maturation of Xenopus oocytes and shows synergism with oncogenic ras-p21 protein.
A nickel-binding serine proteinase inhibitor, pNiXa (43 kDa), was isolated from Xenopus ovary and assayed for effects on oocyte maturation. Microinjection of pNiXa (0.12 pmol/50 nl) induced maturation in 60% of Xenopus oocytes, beginning at 4 hours and reaching completion by 9 hours. Microinjection of oncogenic ras-p21 protein (0.12 pmol/50 nl) induced maturation in 79% of oocytes, beginning at 6 hours and reaching completion by 12 hours. Microinjection of pNiXa in combination with ras-p21 protein had a synergistic effect on maturation, which occurred in 92% of oocytes, beginning at 4 hours and reaching completion by 9 hours. Oocyte maturation did not occur in control oocytes, which received a microinjection of bovine serum albumin. In oocytes exposed to a combination of pNiXa (0.12 pmol/50 nl, by microinjection) and progesterone (10 micrograms/ml, in the medium), maturation was intermediate (68% at 9 hours) between that induced by pNiXa (60%) or progesterone (85%) alone. This study shows (a) that pNiXa is a potent inducer of oocyte maturation, (b) that pNiXa's effect is synergistic with that of oncogenic ras-p21 protein, and (c) that pNiXa partially antagonizes progesterone induction of oocyte maturation.
Haspel
J
J
Department of Pathology, SUNY Health Science Center, Syracuse 13210.
Sunderman
F W
FW
Hofper
S M
SM
Henjum
D C
DC
Brandt-Rauf
P W
PW
Weinstein
I B
IB
Nishimura
S
S
Yamaizumi
Z
Z
Pincus
M R
MR
D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D009532:Nickel; D015689:Oncogene Protein p21(ras) / Q000494:pharmacology*; D009865:Oocytes / Q000502:physiology*; D010053:Ovary / Q000737:chemistry; D011374:Progesterone / Q000494:pharmacology; D015843:Serpins; D029867:Xenopus Proteins; D014982:Xenopus laevis
D002352:Carrier Proteins; D015843:Serpins; D029867:Xenopus Proteins; C077804:SERPINA6 protein, Xenopus; D011374:Progesterone; D009532:Nickel; D015689:Oncogene Protein p21(ras)