Localization of glutamate cysteine ligase subunit mRNA within the rat ovary and relationship to follicular apoptosis.
Ovarian levels of the antioxidant tripeptide glutathione (GSH) increase following gonadotropin administration, suggesting that GSH synthesis in the ovary may be associated with follicular growth. In situ hybridization with (35)S-labeled riboprobes was used to localize ovarian mRNA expression of the catalytic and modulatory subunits of glutamate cysteine ligase (Gclc and Gclm), the rate-limiting enzyme in GSH synthesis, during each stage of the rat estrous cycle. Gclm was highly expressed in the granulosa cells and oocytes of healthy, growing follicles, not in atretic follicles. Gclc was also highly expressed in follicles; however, unlike Gclm, Gclc was also expressed in corpora lutea and interstitial cells. In a subsequent experiment, the hypothesis that GSH synthesis occurs in healthy, but not in apoptotic, follicles was tested. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to detect apoptotic cells in the ovaries, and in situ hybridization for Gclm and Gclc was performed in adjacent sections of the same ovaries. TUNEL staining was found to be significantly associated with absence of Gclm hybridization in granulosa cells and oocytes and with lack of strong Gclc hybridization in granulosa cells. These results suggest that follicular apoptosis may be associated with down-regulation of Gclm and Gclc transcription in granulosa cells and oocytes.
Luderer
Ulrike
U
Department of Medicine, Division of Occupational and Environmental Medicine, University of California, Irvine, California 96212, USA. uluderer@uci.edu
Diaz
Dolores
D
Faustman
Elaine M
EM
Kavanagh
Terrance J
TJ
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D005721:Glutamate-Cysteine Ligase / Q000235:genetics*; D017403:In Situ Hybridization; D020287:In Situ Nick-End Labeling; D006080:Ovarian Follicle / Q000166:cytology* / Q000502:physiology; D010053:Ovary / Q000201:enzymology*; D021122:Protein Subunits / Q000235:genetics; D015347:RNA Probes; D016372:RNA, Antisense; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014158:Transcription, Genetic
D021122:Protein Subunits; D015347:RNA Probes; D016372:RNA, Antisense; D012333:RNA, Messenger; D005721:Glutamate-Cysteine Ligase