Adenosine 5'-monophosphate-activated protein kinase regulates progesterone secretion in rat granulosa cells.
The AMP-activated protein kinase (AMPK) is a major regulator of energy metabolism involved in fatty acid and cholesterol synthesis. In the ovary, cholesterol plays a key role in steroid production. We report the presence of AMPK in rat ovaries, and we have investigated its role in granulosa cells. We show using RT-PCR and Western blot that the mRNAs for the alpha1/2 and beta1/2 subunits and the proteins are found in the ovaries. Immunohistochemistry localized the alpha1 AMPK subunit in granulosa cells, corpus luteum, and oocyte and less abundantly in theca cells. Treatment with 1 mm 5-amino-imidazole-4-carboxyamide-1-beta-D-ribofuranoside (AICAR), an activator of AMPK, increased dose-dependent and time-dependent phosphorylation of AMPKalpha1 on Thr172 in primary granulosa cells. Simultaneously, phosphorylation of acetyl-coenzyme A carboxylase at Ser79 was also increased. AICAR treatment for 48 h halved progesterone secretion, 3beta-HSD protein and mRNA levels, and phosphorylation of both basal MAPK ERK1/2 and p38 and in response to IGF-I and/or FSH in granulosa cells. AICAR treatment (1 mM) had no detectable effect on basal and FSH- and/or IGF-I-induced estradiol production and on granulosa cell proliferation or viability. Adenovirus-mediated expression of dominant negative AMPK totally abolished the effects of AICAR on progesterone secretion, 3beta-HSD protein production, and MAPK ERK1/2 and p38 phosphorylation. Moreover, we showed using specific in- hibitors of ERK1/2 and p38 MAPK that the MAPK ERK1/2 and not p38 is involved in progesterone secretion and 3beta-HSD expression, strongly suggesting that the activation of AMPK in response to AICAR reduces progesterone production through the MAPK ERK1/2 signaling pathway in rat granulosa cells.
Tosca
Lucie
L
Unité de Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, Nouzilly, 37380, France.
Froment
Pascal
P
Solnais
Patricia
P
Ferré
Pascal
P
Foufelle
Fabienne
F
Dupont
Joëlle
J
D055372:AMP-Activated Protein Kinases; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D004054:Diethylstilbestrol / Q000494:pharmacology; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D012756:Sheep
D017931:DNA Primers; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D011374:Progesterone; D004054:Diethylstilbestrol; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases