ERK signaling in the pituitary is required for female but not male fertility.
Males and females require different patterns of pituitary gonadotropin secretion for fertility. The mechanisms underlying these gender-specific profiles of pituitary hormone production are unknown; however, they are fundamental to understanding the sexually dimorphic control of reproductive function at the molecular level. Several studies suggest that ERK1 and -2 are essential modulators of hypothalamic GnRH-mediated regulation of pituitary gonadotropin production and fertility. To test this hypothesis, we generated mice with a pituitary-specific depletion of ERK1 and 2 and examined a range of physiological parameters including fertility. We find that ERK signaling is required in females for ovulation and fertility, whereas male reproductive function is unaffected by this signaling deficiency. The effects of ERK pathway ablation on LH biosynthesis underlie this gender-specific phenotype, and the molecular mechanism involves a requirement for ERK-dependent up-regulation of the transcription factor Egr1, which is necessary for LHbeta expression. Together, these findings represent a significant advance in elucidating the molecular basis of gender-specific regulation of the hypothalamic-pituitary-gonadal axis and sexually dimorphic control of fertility.
Bliss
Stuart P
SP
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
Miller
Andrew
A
Navratil
Amy M
AM
Xie
Jianjun
J
McDonough
Sean P
SP
Fisher
Patricia J
PJ
Landreth
Gary E
GE
Roberson
Mark S
MS
D000818:Animals; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005298:Fertility / Q000235:genetics*; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D009928:Organ Specificity / Q000235:genetics; D010060:Ovulation / Q000235:genetics / Q000378:metabolism; D010902:Pituitary Gland / Q000201:enzymology / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013480:Superovulation / Q000235:genetics; D013961:Thyroid Gland / Q000502:physiology
D037101:Luteinizing Hormone, beta Subunit; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3