ZFIN ID: ZDB-PUB-110713-36
Spatiotemporal Expression of Bone Morphogenetic Protein Family Ligands and Receptors in the Zebrafish Ovary: A Potential Paracrine-Signaling Mechanism for Oocyte-Follicle Cell Communication
Li, C.W., and Ge, W.
Date: 2011
Source: Biology of reproduction   85(5): 977-86 (Journal)
Registered Authors: Ge, Wei
Keywords: follicular development, ovary, zebrafish, BMP, bone morphogenetic proteins
MeSH Terms:
  • Animals
  • Bone Morphogenetic Protein 2/metabolism
  • Bone Morphogenetic Protein 4/metabolism
  • Bone Morphogenetic Protein Receptors/metabolism*
  • Cell Communication/physiology*
  • Cells, Cultured
  • Female
  • Ligands
  • Models, Animal
  • Oocytes/cytology*
  • Oocytes/physiology
  • Ovarian Follicle/cytology*
  • Ovarian Follicle/physiology
  • Ovary/metabolism*
  • Paracrine Communication/physiology*
  • Phosphorylation
  • Phylogeny
  • Smad Proteins/metabolism
  • Tissue Distribution
  • Zebrafish/metabolism*
  • Zebrafish Proteins/metabolism
PubMed: 21734261 Full text @ Biol. Reprod.
The bone morphogenetic proteins (BMPs), originally identified by their abilities to induce bone and/or cartilage formation, have been reported to be involved in various growth and differentiation processes including reproduction. While mammalian models are more frequently used to study the BMP system in reproduction, we have extended the study to the zebrafish, an excellent model for studying female reproduction in teleosts. RT-PCR analysis revealed the expression of the Bmp ligands (bmp2a, bmp2b, bmp4, bmp6, and bmp7a) and the type-II Bmp receptors (bmpr2a and bmpr2b) in various tissues including the ovary. Spatiotemporal distribution of these Bmp ligands and receptors in the ovary was then investigated in this study. RT-PCR on isolated follicle layers and denuded oocytes demonstrated that all Bmp ligands examined were exclusively or abundantly expressed in the oocyte while the two receptors were expressed exclusively in the follicle layers, strongly suggesting a potential paracrine signaling from the oocyte towards the follicle layer by various Bmp ligands. This supports the current view that instead of being passively controlled and nurtured by the follicle layer for its growth and development, the oocyte may play an active role by releasing various growth differentiation factors to regulate follicle layer function. Quantitative analysis of temporal expression profiles during folliculogenesis revealed an increased expression of bmp2a, bmp2b, bmp4, and bmp6 from primary growth (PG, Stage I) to previtellogenic (PV, Stage II) stage followed by steady declines towards the end of folliculogenesis when the follicles became fully grown. On the contrast, the BMP receptors (bmpr2a and bmpr2b) consistently showed an increase in expression during folliculogenesis with the peak levels reached at the full-grown stage (FG) prior to final oocyte maturation. The spatiotemporal expression patterns of the Bmp family in the zebrafish follicles provide important insights into potential roles of Bmps during follicle development as oocyte-derived factors. Further experiment using recombinant zebrafish Bmp4 showed that Bmp4 had an inhibitory effect on spontaneous but not 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP)-induced oocyte maturation in vitro.