A Novel Missense Mutation 224G>T (R75M) in SRY Coding Region Interferes with Nuclear Import and Results in 46, XY Complete Gonadal Dysgenesis

Abstract

SRY-mutation-caused sex reversal is a rare disease and mostly associated with a de novo mutation since the patients with defective SRY is infertile. There are many reports about SRY-mutation associated 46, XY ovarian disorder of sex development (DSD), but few described their molecular mechanism. Here we report a de novo mutation 224G>T (R75M) in SRY associated with a phenotypic female, 46, XY karyotype and dysgerminoma. The wild and mutated SRY were cloned into recombinant plasmid and expressed in cells in vitro, the result showed the mutated SRY is greatly accumulated in cytoplasm while the wild type SRY is mostly localized in nucleus. To make sure no other genes were involved, we performed the trio-based whole exome sequencing using the DNA samples from the proband and the parents, and no mutations were identified especially in DHH, NR0B1, NR5A1, SOX9 and MAP3K1, indicating the de novo mutation in SRY is the single defect responsible for the female sex reversal. We also used bioinformatics simulation analysis to predict impact of the mutation on SRY function, and find the R75 in wild type SRY can form a hydrogen bond with serine at 91 (S91) that make the SRY protein well fit into the minor groove of target DNA, while the M75 in the mutated SRY can’t. Finally, we reviewed SRY mutations based on the available references and analyzed the mutation distribution patterns according to density and continuity, which may be useful for further study of the SRY structure, function, and its relatedness with DSD.

Structural basis for nuclear import selectivity of pioneer transcription factor SOX2

“…While there are no naturally occurring mutants in the NLSs of SOX2 that have been documented, SRY mutants have been shown to impede nuclear localization and result in sex reversal. Mutations such as SRY R62G 15 , R75M 46 , and R76P 47 , located within the NLS1 (bipartite region) of SOX proteins, were shown to bind within the IMPA minor site (IMPα3 ARMs 6–8) and ARM 9 in this study. Similarly, the NLS2 region harbors mutations, such as SRY R133W 48 , shown to bind at the major site of IMPα3 (within ARM3).…”

Cellular fate of intersex differentiation

“…Mutations in these sex-determining genes and the dysregulation of relevant pathways will lead to DSDs, including 46,XY complete or partial gonadal dysgenesis, 46,XX testicular DSD, and 46,XX ovotesticular DSD. For example, mutations in the conserved HMG-box and both 5′ and 3′ regions of sexdetermining gene SRY caused XY gonadal dysgenesis/sex reversal, in which the ovarian structure was often in a degenerate state [9][10][11][12] . Mutations of WT1, NR5A1, and FOG2 caused 46,XX testicular/ovotesticular DSDs [13][14][15] .…”

NR5A1 mutations are not associated with male infertility in Indian men

“…In addition to male infertility, several NR5A1 mutations have been reported in individuals with partial to complete gonadal dysgenisis having 46,XY karyotype. (Fabbri, Ribeiro de Andrade, Maciel‐Guerra, Guerra‐Junior, & de Mello, ; Fan et al., ).…”