Open AccessFunctional Analysis of Mmd2 and Related PAQR Genes During Sex Determination in Mice
Author(s) -
Liang Zhao,
Ella Thomson,
Ee Ting Ng,
Enya Longmuss,
Terje Svingen,
Stefan BagheriFam,
Alexander Quinn,
Vincent R. Harley,
Leonard C. Harrison,
Emanuele Pelosi,
Peter Koopman
Publication year - 2022
Publication title -
sexual development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 44
eISSN - 1661-5433
pISSN - 1661-5425
DOI - 10.1159/000522668
Subject(s) - testis determining factor , biology , knockout mouse , gene knockout , gene , embryo , sexual differentiation , genetics , sex reversal , sertoli cell , null allele , gene expression , development of the gonads , embryogenesis , andrology , y chromosome , mutant , endocrinology , gonad , spermatogenesis , medicine
Sex determination in eutherian mammals is controlled by the Y-linked gene Sry , which drives the formation of testes in male embryos. Despite extensive study, the genetic steps linking Sry action and male sex determination remain largely unknown. Here, we focused on Mmd2 , a gene that encodes a member of the progestin and adipoQ receptor (PAQR) family. Mmd2 is expressed during the sex-determining period in XY but not XX gonads, suggesting a specific role in testis development. Methods: We used CRISPR to generate mouse strains deficient in Mmd2 and its 2 closely related PAQR family members, Mmd and Paqr8 , which are also expressed during testis development. Following characterization of Mmd2 expression in the developing testis, we studied sex determination in embryos from single knockout as well as Mmd2;Mmd and Mmd2;Paqr8 double knockout lines using quantitative RT-PCR and immunofluorescence. Results: Analysis of knockout mice deficient in Sox9 and Nr5a1 revealed that Mmd2 operates downstream of these known sex-determining genes. However, fetal testis development progressed normally in Mmd2 -null embryos. To determine if other genes might have compensated for the loss of Mmd2 , we analyzed Paqr8 and Mmd -null embryos and confirmed that in both knockout lines, sex determination occurred normally. Finally, we generated Mmd2 ; Mmd and Mmd2 ; Paqr8 double-null embryos and again observed normal testis development. Discussion: These results may reflect functional redundancy among PAQR factors, or their dispensability in gonadal development. Our findings highlight the difficulties involved in identifying genes with a functional role in sex determination and gonadal development through expression screening and loss-of-function analyses of individual candidate genes and may help to explain the paucity of genes in which variations have been found to cause human disorders/differences of sex development.