title: Intercellular signaling via cyclic GMP diffusion through gap junctions restarts meiosis in mouse ovarian follicles.
abstract: Meiosis in mammalian oocytes is paused until luteinizing hormone (LH) activates receptors in the mural granulosa cells of the ovarian follicle. Prior work has established the central role of cyclic GMP (cGMP) from the granulosa cells in maintaining meiotic arrest, but it is not clear how binding of LH to receptors that are located up to 10 cell layers away from the oocyte lowers oocyte cGMP and restarts meiosis. Here, by visualizing intercellular trafficking of cGMP in real-time in live follicles from mice expressing a FRET sensor, we show that diffusion of cGMP through gap junctions is responsible not only for maintaining meiotic arrest, but also for rapid transmission of the signal that reinitiates meiosis from the follicle surface to the oocyte. Before LH exposure, the cGMP concentration throughout the follicle is at a uniformly high level of ∼2-4 μM. Then, within 1 min of LH application, cGMP begins to decrease in the peripheral granulosa cells. As a consequence, cGMP from the oocyte diffuses into the sink provided by the large granulosa cell volume, such that by 20 min the cGMP concentration in the follicle is uniformly low, ∼100 nM. The decrease in cGMP in the oocyte relieves the inhibition of the meiotic cell cycle. This direct demonstration that a physiological signal initiated by a stimulus in one region of an intact tissue can travel across many layers of cells via cyclic nucleotide diffusion through gap junctions could provide a general mechanism for diverse cellular processes.
authors.affiliation: Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030;
authors.forename: Leia C
authors.initials: LC
authors.lastname: Shuhaibar
authors.affiliation: Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030;
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Egbert
authors.affiliation: Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109;
authors.forename: Rachael P
authors.initials: RP
authors.lastname: Norris
authors.affiliation: Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98109;
authors.forename: Paul D
authors.initials: PD
authors.lastname: Lampe
authors.affiliation: Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany; and.
authors.forename: Viacheslav O
authors.initials: VO
authors.lastname: Nikolaev
authors.affiliation: Interfakultäres Institut für Biochemie, University of Tübingen, 72076 Tübingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Thunemann
authors.affiliation: Interfakultäres Institut für Biochemie, University of Tübingen, 72076 Tübingen, Germany.
authors.forename: Lai
authors.initials: L
authors.lastname: Wen
authors.affiliation: Interfakultäres Institut für Biochemie, University of Tübingen, 72076 Tübingen, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Feil
authors.affiliation: Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06030; ljaffe@uchc.edu.
authors.forename: Laurinda A
authors.initials: LA
authors.lastname: Jaffe
mesh_terms: D000818:Animals; D006152:Cyclic GMP / Q000235:genetics / Q000378:metabolism*; D005260:Female; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism*; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*
chemical_list: D007986:Luteinizing Hormone; D006152:Cyclic GMP
keywords: cyclic GMP; gap junctions; luteinizing hormone; oocyte meiosis; ovarian follicle