Functional Analysis of Mutations at Codon 127 of the <b><i>SRY</i></b> Gene Associated with 46,XY Complete Gonadal Dysgenesis

Abstract

Complete gonadal dysgenesis (CGD) is characterized by an incomplete differentiation of the genital organs in a patient with a 46,XY karyotype. It is induced by mutations in the sex-determining region Y (SRY) gene which plays a key role in testis-determining pathways. The aim of this study was to investigate the possible pathogenic nature of a novel SRY mutation (p.Y127H) identified in a 46,XY female patient. To determine the effect of this mutation on SRY function, we studied its impact on DNA interaction by electrophoretic mobility shift assays. Since tyrosine 127 is close to the C-terminal nuclear localization signal of SRY, we conducted HA-SRY protein expression to observe the impact of the mutation on the nuclear import function in transfected cells. Our results showed that the Y127H mutation nearly abolishes the DNA-binding capacity of SRY and strongly impairs the nuclear localization of the mutated protein. Together with a previously described mutation analyzed in parallel in this paper (p.Y127C), our results highlight this tyrosine residue as a crucial structural determinant of the high mobility group box domain. This is the first report to explain the molecular mechanism of the Y127H mutation causing sex reversal and gives new insights for clinical practice to benefit patients with disorders of sex development.

Tenuous Transcriptional Threshold of Human Sex Determination. I. SRY and Swyer Syndrome at the Edge of Ambiguity

“…Such attenuated DNA bending must represent a transmitted effect of the mutations as the WT side chain, and presumably also the variant side chains, is not in direct contact with the bent DNA site. These DNA bend angles each fall, however, within the range of WT species variation (60), so altered DNA bending is unlikely to be responsible for either the variant proteins' loss of transcriptional activity in cell culture or associated DSD phenotypes (44,45).…”

“…(B) Rigid-body substitution of mutant side chains at box position 72 (sticks) in an otherwise transparent CPK model. Models of the three clinical mutants ( 34 , 44 , 45 ): Y127C in red, Y127F in orange and Y127H in green.…”

Prenatal diagnosis of a 46,XY karyotype female fetus with an SRY-associated gonadal dysgenesis, conceived through an intracytoplasmic sperm injection: a case report

“…SRY pathogenic variants affect DNA binding, bending or cellular localization of the TDF. Impaired nucleus transportation of the TDF and failure of a transcriptional complex assembly result in a disrupted sex differentiation cascade [ 10 ]. Patients with SRY -associated complete gonadal dysgenesis commonly have a female phenotype.…”

The Deleterious F109S Mutation Disrupts Binding of Sex-Determining Region Y with DNA

“…Whatever the pattern nsSNPs take in the interruption of SRY activity, these three risky nsSNPs were found to be associated with several sex reversal issues [62,65,66]. However, I90M and Y127F undergo their deleterious tasks by a straightforward effect on structure, function, and stability without being intervened in the modulation of SRY binding with its DNA receptor.…”