Role of central nervous system and ovarian insulin receptor substrate 2 signaling in female reproductive function in the mouse.
Insulin receptor signaling regulates female reproductive function acting in the central nervous system and ovary. Female mice that globally lack insulin receptor substrate (IRS) 2, which is a key mediator of insulin receptor action, are infertile with defects in hypothalamic and ovarian functions. To unravel the tissue-specific roles of IRS2, we examined reproductive function in female mice that lack Irs2 only in the neurons. Surprisingly, these animals had minimal defects in pituitary and ovarian hormone levels, ovarian anatomy and function, and breeding performance, which indicates that the central nervous system IRS2 is not an obligatory signaling component for the regulation of reproductive function. Therefore, we undertook a detailed analysis of ovarian function in a novel Irs2 global null mouse line. Comparative morphometric analysis showed reduced follicle size, increased numbers of atretic follicles, as well as impaired oocyte growth and antral cavity development in Irs2 null ovaries. Granulosa cell proliferation was also defective in the Irs2 null ovaries. Furthermore, the insulin- and eCG-stimulated phosphoinositide-3-OH kinase signaling events, which included phosphorylation of Akt/protein kinase B and glycogen synthase kinase 3-beta, were impaired, whereas mitogen-activated protein kinase signaling was preserved in Irs2 null ovaries. These abnormalities were associated with reduced expression of cyclin D2 and increased CDKN1B levels, which indicates dysregulation of key components of the cell cycle apparatus implicated in ovarian function. Our data suggest that ovarian rather than central nervous system IRS2 signaling is important in the regulation of female reproductive function.
Neganova
Irina
I
Centre for Diabetes and Endocrinology, Rayne Institute, University College London, London WC1E 6JJ, United Kingdom.
Al-Qassab
Hind
H
Heffron
Helen
H
Selman
Colin
C
Choudhury
Agharul I
AI
Lingard
Steven J
SJ
Diakonov
Ivan
I
Patterson
Michael
M
Ghatei
Mohammad
M
Bloom
Stephen R
SR
Franks
Stephen
S
Huhtaniemi
Ilpo
I
Hardy
Kate
K
Withers
Dominic J
DJ
D000818:Animals; D049109:Cell Proliferation; D002490:Central Nervous System / Q000378:metabolism*; D056742:Cyclin D2; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006107:Granulosa Cells / Q000166:cytology; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009928:Organ Specificity; D010053:Ovary / Q000196:embryology / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012098:Reproduction / Q000502:physiology*; D015398:Signal Transduction
C486196:Ccnd2 protein, mouse; C493961:Cdkn1b protein, mouse; D056742:Cyclin D2; D016213:Cyclins; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526295:Irs1 protein, mouse; C526298:Irs2 protein, mouse; D010750:Phosphoproteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019869:Phosphatidylinositol 3-Kinases