Rescue of bmp15 deficiency in zebrafish by mutation of inha reveals mechanisms of BMP15 regulation of folliculogenesis

Yue Zhai; Xin Zhang; Cheng Zhao; Ruijing Geng; Kun Wu; Mingzhe Yuan; Nana Ai; Wei Ge

doi:10.1371/journal.pgen.1010954

Rescue of bmp15 deficiency in zebrafish by mutation of inha reveals mechanisms of BMP15 regulation of folliculogenesis

PLoS Genet. 2023 Sep 15;19(9):e1010954. doi: 10.1371/journal.pgen.1010954. eCollection 2023 Sep.

Authors

Yue Zhai¹, Xin Zhang¹, Cheng Zhao¹, Ruijing Geng¹, Kun Wu¹, Mingzhe Yuan¹, Nana Ai¹, Wei Ge¹

Affiliation

¹ Department of Biomedical Sciences and Centre of Reproduction, Development and Aging (CRDA), Faculty of Health Sciences, University of Macau, Taipa, Macau SAR, China.

Abstract

As an oocyte-specific growth factor, bone morphogenetic protein 15 (BMP15) plays a critical role in controlling folliculogenesis. However, the mechanism of BMP15 action remains elusive. Using zebrafish as the model, we created a bmp15 mutant using CRISPR/Cas9 and demonstrated that bmp15 deficiency caused a significant delay in follicle activation and puberty onset followed by a complete arrest of follicle development at previtellogenic (PV) stage without yolk accumulation. The mutant females eventually underwent female-to-male sex reversal to become functional males, which was accompanied by a series of changes in secondary sexual characteristics. Interestingly, the blockade of folliculogenesis and sex reversal in bmp15 mutant could be partially rescued by the loss of inhibin (inha-/-). The follicles of double mutant (bmp15-/-;inha-/-) could progress to mid-vitellogenic (MV) stage with yolk accumulation and the fish maintained their femaleness without sex reversal. Transcriptome analysis revealed up-regulation of pathways related to TGF-β signaling and endocytosis in the double mutant follicles. Interestingly, the expression of inhibin/activin βAa subunit (inhbaa) increased significantly in the double mutant ovary. Further knockout of inhbaa in the triple mutant (bmp15-/-;inha-/-;inhbaa-/-) resulted in the loss of yolk granules again. The serum levels of estradiol (E2) and vitellogenin (Vtg) both decreased significantly in bmp15 single mutant females (bmp15-/-), returned to normal in the double mutant (bmp15-/-;inha-/-), but reduced again significantly in the triple mutant (bmp15-/-;inha-/-;inhbaa-/-). E2 treatment could rescue the arrested follicles in bmp15-/-, and fadrozole (a nonsteroidal aromatase inhibitor) treatment blocked yolk accumulation in bmp15-/-;inha-/- fish. The loss of inhbaa also caused a reduction of Vtg receptor-like molecules (e.g., lrp1ab and lrp2a). In summary, the present study provided comprehensive genetic evidence that Bmp15 acts together with the activin-inhibin system in the follicle to control E2 production from the follicle, Vtg biosynthesis in the liver and its uptake by the developing oocytes.

Copyright: © 2023 Zhai et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Activins / genetics
Animals
Bone Morphogenetic Protein 15* / genetics
Bone Morphogenetic Protein 15* / metabolism
Female
Inhibins* / genetics
Inhibins* / metabolism
Male
Mutation
Zebrafish Proteins* / genetics
Zebrafish Proteins* / metabolism
Zebrafish* / genetics
Zebrafish* / metabolism

Substances

Activins
Bone Morphogenetic Protein 15
Inhibins
Zebrafish Proteins

Grants and funding

This study was supported by grants from the University of Macau (MYRG2019-00123-FHS, MYRG2020-00192-FHS and CPG2023-00029-FHS) and The Macau Fund for Development of Science and Technology (FDCT173/2017/A3, FDCT0132/2019/A3 and NSFC-FDCT0086/2022/AFJ) to WG. NA and KW are supported by the FDCT Postdoctoral Funding Scheme (FDCT0029/APD/2021) and the Macau Young Scholars Program (AM2020025), respectively. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.