Human sex reversal is caused by duplication or deletion of core enhancers upstream of SOX9

Croft B,Ayers K,Harley V,Pelosi E,Knarston I,Quinn A,Koopman P,Van Den Bergen J,Hutson J,Robevska G,Vu Dc,Corbin V,Ohnesorg T,Tan J,Sreenivasan R,Sinclair A,Bowles J,Hewitt J

doi:10.1530/ey.16.6.3

Abstract

Initial steps in the sex determination of the (human) testis depend on SRY regulating SOX9, but the exact mechanism that controls SOX9 expression remains unknown. These authors discovered four overlapping copy number variations (CNVs) upstream of SOX9 as the causes of sex reversal in two 46,XX DSD (with duplications) and two 46,XY DSD patients (with deletions). Prompted by this, they performed studies of these CNVs in cell systems and in mice, and found three essential regulatory elements for normal testis and male sex development, namely eSR-A, eSR-B and eALDI.

Highlights

In this study we redefine the upstream regulatory landscape of human SOX9
We focused on genetic intervals in the 2 Mb SOX9 upstream regulatory region that were previously associated with 46,XY and 46,XX DSD16–22
CGH-array showed these duplications overlapped with each other and the XYSR region, defining a minimum critical region of 5.2 kb (Fig. 1b). We anticipated that this redefined region would include a core gonadal enhancer for SOX9 implicated in both 46,XY and 46,XX Disorders of sex development (DSDs) (Fig. 1b)

Summary

Introduction

In this study we redefine the upstream regulatory landscape of human SOX9. We refined the 32.5 kb XYSR and 24 kb RevSex intervals and analysed the genomic regions using bioinformatic and luciferase tiling approaches, to identify three putative enhancers 5′ of SOX9. In cell-based reporter assays these enhancers responded to different combinations of testis-specific regulators including SRY, SF1 and SOX9 itself. Deletion of these three enhancers in mice resulted in different outcomes ranging from: no apparent effect to reduced Sox[9] transcription and complete sex reversal. Given that duplication or deletion of these sequences results in sex reversal in SRY-negative 46,XX males and 46,XY females, respectively, our results suggest a mechanism by which these enhancers have crucial roles in human sex development and DSD

Methods

Results

Conclusion