PUBLICATION

Characterization of Inhibin {alpha} Subunit (inha) in the Zebrafish - Evidence for a Potential Feedback Loop between the Pituitary and Ovary

Authors
Poon, S.K., So, W.K., Yu, X., Liu, L., and Ge, W.
ID
ZDB-PUB-090716-27
Date
2009
Source
Reproduction (Cambridge, England)   138(4): 709-719 (Journal)
Registered Authors
Ge, Wei
Keywords
none
MeSH Terms
  • Amino Acid Sequence
  • Animals
  • CHO Cells
  • Cloning, Molecular
  • Cricetinae
  • Cricetulus
  • Feedback, Physiological/physiology*
  • Female
  • Follicle Stimulating Hormone/metabolism
  • Follicle Stimulating Hormone/pharmacology
  • Gene Expression Regulation/drug effects
  • Goldfish
  • Humans
  • Inhibins/genetics
  • Inhibins/metabolism
  • Inhibins/physiology*
  • Models, Biological
  • Molecular Sequence Data
  • Ovary/metabolism
  • Ovary/physiology*
  • Phylogeny
  • Pituitary Gland/metabolism
  • Pituitary Gland/physiology*
  • Protein Subunits/genetics
  • Protein Subunits/metabolism
  • Protein Subunits/physiology
  • Sequence Homology, Amino Acid
  • Zebrafish/genetics*
  • Zebrafish/metabolism
PubMed
19602521 Full text @ Reproduction
Abstract
Inhibin and activin are closely related disulphide-linked dimmers that belong to the transforming growth factor beta (TGF-beta) superfamily. Although inhibin has been extensively studied in mammals, the information about its existence and function in lower vertebrates is very scarce. Using zebrafish as the model, the present study demonstrated that the inhibin-specific alpha subunit (inha) was predominantly expressed in the gonads and no transcript could be detected in other tissues including the pituitary and brain. In the ovary, the expression of inha was restricted to the somatic follicle cells surrounding the oocyte, together with the beta subunits (inhbaa and inhbb). This was further supported by the absence of its expression in the ovulated unfertilized eggs. During folliculogenesis, inha expression in the follicles slightly but steadily increased from primary growth (PG) to mid-vitellogenic (MV) stage; however, its expression surged dramatically at full-grown (FG) stage. Interestingly, the expression level of inha decreased significantly in the follicles whose oocytes were undergoing spontaneous maturation or germinal vesicle breakdown (GVBD). When tested on cultured ovarian fragments, both goldfish pituitary extract and forskolin significantly stimulated inha expression. Further experiments showed that recombinant zebrafish FSH but not LH significantly increased inha expression in the same assay system. When tested in vitro, human inhibin A exhibited a slight but significant inhibitory effect on DHP-induced oocyte maturation after 4-h incubation. The stimulation of inha expression by FSH and the potential inhibition of FSH by inhibin suggest a possible existence of a negative feedback loop between the pituitary and ovary in the zebrafish.
Genes / Markers
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Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping