title: Vasoactive intestinal peptide promotes differentiation and clock gene expression in granulosa cells from prehierarchal follicles.
abstract: Vasoactive intestinal peptide (VIP) signaling via cyclic adenosine monophosphate (cAMP) is reported to stimulate steroidogenesis in ovarian granulosa cells from a variety of vertebrate species, including the domestic hen. Prior to follicle selection in the hen ovary (i.e., cyclic recruitment) follicle-stimulating-hormone (FSH)-induced cAMP signaling is absent within the granulosa layer until immediately following follicle selection. As a consequence, granulosa cells remain in an undifferentiated state and are unable to initiate FSH-induced steroidogenesis. VIP receptors (VPAC1 and VPAC2), like the FSH receptor, are G protein-coupled receptors, so we predicted that VIP signaling in granulosa cells is also absent in follicles that have not yet been selected into the preovulatory hierarchy. Initial studies established that mRNA encoding VPAC1 and VPAC2 are expressed within the granulosa cells throughout follicle development. Nevertheless, undifferentiated granulosa cells from prehierarchal (6-8 mm) follicles do not accumulate cAMP in response to a 4-hr incubation with chicken VIP; the capacity for such receptor signaling is attained only following selection within actively differentiating granulosa cells. VIP treatment did, however, increase expression of mRNA encoding the Gallus circadian clock protein, BMAL1-but only in granulosa cells collected from selected follicles. These findings provide evidence that, at follicle selection, the acquisition of VIP-induced cAMP cell signaling helps initiate and promote the differentiation of of granulosa cells. Furthermore, we propose that VIP signaling may regulate BMAL1 expression and, thus, a daily rhythmicity within granulosa cells of preovulatory follicles. Mol. Reprod. Dev. 83: 455-463, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Center for Reproductive Biology and Health, The Pennsylvania State University, Pennsylvania.|Cell and Developmental Biology Program in the Huck Institute of Life Science, The Pennsylvania State University, Pennsylvania.
authors.forename: Dongwon
authors.initials: D
authors.lastname: Kim
authors.affiliation: Center for Reproductive Biology and Health, The Pennsylvania State University, Pennsylvania.|Cell and Developmental Biology Program in the Huck Institute of Life Science, The Pennsylvania State University, Pennsylvania.|Department of Animal Science, The Pennsylvania State University, Pennsylvania.
authors.forename: Alan L
authors.initials: AL
authors.lastname: Johnson
mesh_terms: D056930:ARNTL Transcription Factors / Q000096:biosynthesis*; D000818:Animals; D030161:Avian Proteins / Q000096:biosynthesis*; D002454:Cell Differentiation / Q000502:physiology*; D002645:Chickens / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D015290:Second Messenger Systems / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
chemical_list: D056930:ARNTL Transcription Factors; D030161:Avian Proteins; D014660:Vasoactive Intestinal Peptide; D000242:Cyclic AMP