The mammalian ovarian follicle presents a remarkable example of how cells communicate to regulate the cell cycle within a complex tissue. In particular, the somatic cells that surround the oocyte send a signal to the oocyte that maintains meiotic prophase arrest, and then in response to luteinizing hormone (LH), these same somatic cells send an opposite signal, causing meiosis to resume. Recent work from this laboratory has shown that the maintenance of prophase arrest requires the activity of a heterotrimeric G protein of the Gs family, and a Gs-linked receptor, GPR3, both located in the oocyte. The proposed studies will investigate the function of GPR3 in maintaining prophase arrest, as well as in restarting the meiotic cell cycle.
Aim one is to examine the expression of Gpr3 during oogenesis, to further characterize the phenotype of a Gpr3 knockout mouse, and to determine whether the Gpr3 requirement for the maintenance of meiotic arrest is due entirely to GPR3 in the oocyte.
Aim two is to investigate whether and how the presence of the somatic cells maintains the activities of Gs and GPR3 in follicle-enclosed oocytes at levels greater than those in isolated oocytes.
Aim three is to investigate whether and how signals from the somatic cells decrease the activities of Gs and GPR3 during LH-induced reinitiation of meiosis. These studies will provide important new insights into the function of G-protein linked receptors in cell-cell signaling and cell cycle regulation. Ultimately, this knowledge concerning the regulation of the normal cell cycle may be applicable to treatment of pathological conditions in which cell cycle control is lost.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK073499-02
Application #
7048682
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Blondel, Olivier
Project Start
2005-04-15
Project End
2008-03-31
Budget Start
2006-04-01
Budget End
2007-03-31
Support Year
2
Fiscal Year
2006
Total Cost
$205,468
Indirect Cost
Name
University of Connecticut
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
022254226
City
Farmington
State
CT
Country
United States
Zip Code
06030
Norris, Rachael P; Ratzan, William J; Freudzon, Marina et al. (2009) Cyclic GMP from the surrounding somatic cells regulates cyclic AMP and meiosis in the mouse oocyte. Development 136:1869-78
DiLuigi, Andrea; Weitzman, Vanessa N; Pace, Margaret C et al. (2008) Meiotic arrest in human oocytes is maintained by a Gs signaling pathway. Biol Reprod 78:667-72
Norris, Rachael P; Freudzon, Leon; Freudzon, Marina et al. (2007) A G(s)-linked receptor maintains meiotic arrest in mouse oocytes, but luteinizing hormone does not cause meiotic resumption by terminating receptor-G(s) signaling. Dev Biol 310:240-9
Mehlmann, Lisa M; Kalinowski, Rebecca R; Ross, Lavinia F et al. (2006) Meiotic resumption in response to luteinizing hormone is independent of a Gi family G protein or calcium in the mouse oocyte. Dev Biol 299:345-55
Mehlmann, Lisa M (2005) Oocyte-specific expression of Gpr3 is required for the maintenance of meiotic arrest in mouse oocytes. Dev Biol 288:397-404
Freudzon, Leon; Norris, Rachael P; Hand, Arthur R et al. (2005) Regulation of meiotic prophase arrest in mouse oocytes by GPR3, a constitutive activator of the Gs G protein. J Cell Biol 171:255-65