PUBLICATION
Cloning, regulation of mRNA expression and function of a new isoform of Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) in the zebrafish ovary
- Authors
- Wang, Y., Wong A.O., and Ge, W.
- ID
- ZDB-PUB-030911-6
- Date
- 2003
- Source
- Endocrinology 144(11): 4799-4810 (Journal)
- Registered Authors
- Keywords
- none
- MeSH Terms
-
- Neuropeptides/genetics
- Neuropeptides/physiology*
- Tissue Extracts/pharmacology
- Time Factors
- Chorionic Gonadotropin/pharmacology
- PubMed
- 12959988 Full text @ Endocrinology
Abstract
Increasing evidence suggests that pituitary adenylate cyclase-activating polypeptide (PACAP) acts as a local factor in the ovary of mammals. In non-mammalian vertebrates, although the expression of PACAP has also been demonstrated in the ovary, the information on its functions and regulation is limited. In the present study, we identified a new type of PACAP, zfPACAP38-2, from the zebrafish ovary. The precursor of GHRH-zfPACAP38-2 consists of 175 amino acids with only 64% homology with another type of zebrafish PACAP, zfPACAP38-1. RT-PCR analysis detected two messengers of zfPACAP38-2 in the zebrafish ovary. The short product was more abundant and it encodes zfPACAP38-2 only, while the long form codes for both zfPACAP38-2 and GHRH. Using a primary culture of zebrafish follicle cells, we demonstrated that gonadotropin (hCG and goldfish pituitary extract) significantly stimulated zfPACAP38-2 expression within 2 h; however, the effect decreased to the control level after 8 h of treatment. The stimulation of zfPACAP38-2 expression by gonadotropin could be mimicked by cAMP analogs and forskolin but suppressed by H89 (10 micro M), suggesting the involvement of cAMP-PKA signaling pathway. We also examined the expression of PACAP receptor VPAC2-R in the zebrafish ovary. Unlike zfPACAP38-2 which showed a trend of increase during follicle development, the expression of VPAC2-R mRNA in the follicles showed no significant stage-dependent variation, and its expression in the follicle cells did not respond to gonadotropin treatment. Our studies further demonstrated that synthetic zfPACAP38-2 stimulated oocyte maturation and increased the expression of follistatin in zebrafish ovarian follicle cells. These results suggest that zfPACAP38-2 is a potential ovarian factor that mediates gonadotropin actions in paracrine/autocrine manners, and its functional roles are likely, to some extent, related to the ovarian activin/follistatin system.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping