Selective assembly of connexin37 into heterocellular gap junctions at the oocyte/granulosa cell interface.
Studies of mice with targeted disruptions of specific connexin genes have revealed that at least two connexins, connexin37 (Cx37) and connexin43 (Cx43), play essential roles in ovarian follicle development. To explore the respective roles of these two connexins in gap-junctional communication between the developing murine oocyte and its surrounding cumulus granulosa cells, we used confocal immunofluorescence microscopy and oocyte preloading functional assays. Immunofluorescence microscopy located Cx37 within gap-junction plaques between granulosa cells and the oocyte, and Cx43 between surrounding granulosa cells. Preloading assays combining denuded oocytes and cultured granulosa cells expressing or lacking Cx37 or Cx43 revealed that Cx37 must be present in both cell types for the establishment of heterocellular gap-junctional coupling. Furthermore, immunofluorescence microscopy of cultured granulosa cells after incubation with denuded oocytes showed that the oocyte induces the formation of gap junctions containing Cx37 at the surface of granulosa cells. Continuous Cx37 expression in granulosa cells was confirmed using RT-PCR. Together, these results indicate that the growing murine oocyte is functionally coupled with granulosa cells by homotypic gap junctions composed of Cx37, and that the formation and/or stabilization of Cx37 junctions is selectively induced at the oocyte-granulosa interface by cell contact.
Veitch
Gregory I
GI
Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario N6A 5C1, Canada.
Gittens
Joanne E I
JE
Shao
Qing
Q
Laird
Dale W
DW
Kidder
Gerald M
GM
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D017630:Connexins / Q000378:metabolism*; D005260:Female; D005456:Fluorescent Dyes; D017629:Gap Junctions / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors; D006107:Granulosa Cells / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007546:Isoquinolines; D051379:Mice; D018345:Mice, Knockout; D008845:Microinjections; D008856:Microscopy, Fluorescence; D009865:Oocytes / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097006:Gap Junction alpha-4 Protein
D017630:Connexins; D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D007546:Isoquinolines; D011994:Recombinant Proteins; D000097006:Gap Junction alpha-4 Protein; C017475:lucifer yellow