TY - JOUR
T1 - Inhibition of protein synthesis and hormone-sensitive steroidogenesis in response to hydrogen peroxide in rat luteal cells
AU - Musicki, Biljana
AU - Aten, Raymond F.
AU - Behrman, Harold R.
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1994/2
Y1 - 1994/2
N2 - Hydrogen peroxide (H2O2) is generated in the corpus luteum at functional luteal regression and produces rapid antigonadotropic effects in rat luteal cells. However, the mechanism by which peroxide interrupts LH- and cAMP- sensitive progesterone synthesis is unknown. The post-cAMP site of H2O2 action is due to the reduced cholesterol availability in mitochondria, and this process is well known to be dependent on protein synthesis. Therefore, we examined whether H2O2 may interfere with protein and RNA synthesis, and whether such responses may be associated with inhibition of steroidogenesis. Incorporation of radiolabeled amino acids into luteal proteins was inhibited in response to H2O2 in a time- and dose-dependent manner, and these doses are similar to those that inhibit progesterone synthesis, shown earlier in the identical paradigm. The inhibitory effect of H2O2 on amino acid incorporation was not due to increased protein degradation, impaired transport of amino acids, or depletion of cellular ATP levels. H2O2 also inhibited RNA synthesis, increased RNA degradation, and impaired the efficiency of mRNA as a translation template. The time course for the inhibitory effect of H2O2 on protein and RNA synthesis was very rapid and coincident with inhibition of steroidogenesis. Inhibition of protein and RNA synthesis and steroidogenesis were reversed by preincubation of cells with the cell-permeable metal chelator o-phenanthroline, which implicates metal- dependent radical generation as the probable mediator of these actions of H2O2. We conclude that the target of the post-cAMP site of peroxide- induced inhibition of cAMP-dependent steroidogenesis is the inhibition of rapidly inducible proteins that are known to mediate translocation of cholesterol within mitochondria, where it is used as a substrate for pregnenolone synthesis.
AB - Hydrogen peroxide (H2O2) is generated in the corpus luteum at functional luteal regression and produces rapid antigonadotropic effects in rat luteal cells. However, the mechanism by which peroxide interrupts LH- and cAMP- sensitive progesterone synthesis is unknown. The post-cAMP site of H2O2 action is due to the reduced cholesterol availability in mitochondria, and this process is well known to be dependent on protein synthesis. Therefore, we examined whether H2O2 may interfere with protein and RNA synthesis, and whether such responses may be associated with inhibition of steroidogenesis. Incorporation of radiolabeled amino acids into luteal proteins was inhibited in response to H2O2 in a time- and dose-dependent manner, and these doses are similar to those that inhibit progesterone synthesis, shown earlier in the identical paradigm. The inhibitory effect of H2O2 on amino acid incorporation was not due to increased protein degradation, impaired transport of amino acids, or depletion of cellular ATP levels. H2O2 also inhibited RNA synthesis, increased RNA degradation, and impaired the efficiency of mRNA as a translation template. The time course for the inhibitory effect of H2O2 on protein and RNA synthesis was very rapid and coincident with inhibition of steroidogenesis. Inhibition of protein and RNA synthesis and steroidogenesis were reversed by preincubation of cells with the cell-permeable metal chelator o-phenanthroline, which implicates metal- dependent radical generation as the probable mediator of these actions of H2O2. We conclude that the target of the post-cAMP site of peroxide- induced inhibition of cAMP-dependent steroidogenesis is the inhibition of rapidly inducible proteins that are known to mediate translocation of cholesterol within mitochondria, where it is used as a substrate for pregnenolone synthesis.
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U2 - 10.1210/en.134.2.588
DO - 10.1210/en.134.2.588
M3 - Article
C2 - 7507829
AN - SCOPUS:0028140273
SN - 0013-7227
VL - 134
SP - 588
EP - 595
JO - Endocrinology
JF - Endocrinology
IS - 2
ER -