DMRT1 repression using a novel approach to genetic manipulation induces testicular dysgenesis in human fetal gonads

• Published in: Human reproduction (Oxford) 2018-11, Vol.33 (11), p.2107-2121
• Main Authors: Macdonald, Joni, Kilcoyne, Karen R, Sharpe, Richard M, Kavanagh, Áine, Anderson, Richard A, Brown, Pamela, Smith, Lee B, Jørgensen, Anne, Mitchell, Rod T
• Format: Article
• Language: English
• Subjects: Animals; Down-Regulation; Gene Knockdown Techniques; Gonadal Dysgenesis - embryology; Gonadal Dysgenesis - genetics; Humans; Male; Mice; Mice, Nude; MicroRNAs; Original; Sertoli Cells - metabolism; Testis - embryology; Transcription Factors - metabolism
• ISSN: 0268-1161; 1460-2350
• DOI: 10.1093/humrep/dey289

Abstract STUDY QUESTION Does loss of DMRT1 in human fetal testis alter testicular development and result in testicular dysgenesis? SUMMARY ANSWER DMRT1 repression in human fetal testis alters the expression of key testicular and ovarian determining genes, and leads to focal testicular dysgenesis. WHAT IS KNOWN ALREADY Testicular dysgenesis syndrome (TDS) is associated with common testicular disorders in young men, but its etiology is unknown. DMRT1 has been shown to play a role in the regulation of sex differentiation in the vertebrate gonad. Downregulation of DMRT1 in male mice results in trans-differentiation of Sertoli cells into granulosa (FOXL2+) cells resulting in an ovarian gonadal phenotype. STUDY DESIGN, SIZE, DURATION To determine the effect of DMRT1 repression on human fetal testes, we developed a novel system for genetic manipulation, which utilizes a Lentivral delivered miRNA during short-term in vitro culture (2 weeks). A long-term (4-6 weeks) ex vivo xenograft model was used to determine the subsequent effects of DMRT1 repression on testicular development and maintenance. We included first and second-trimester testis tissue (8-20 weeks gestation; n = 12) in the study. PARTICIPANTS/MATERIALS, SETTING, METHODS Human fetal testes were cultured in vitro and exposed to either of two DMRT1 miRNAs (miR536, miR641), or to scrambled control miRNA, for 24 h. This was followed by a further 14 days of culture (n = 3-4), or xenografting (n = 5) into immunocompromised mice for 4-6 weeks. Tissues were analyzed by histology, immunohistochemistry, immunofluorescence and quantitative RT-PCR. Endpoints included histological evaluation of seminiferous cord integrity, mRNA expression of testicular, ovarian and germ cell genes, and assessment of cell number and protein expression for proliferation, apoptosis and pluripotency factors. Statistical analysis was performed using a linear mixed effect model. MAIN RESULTS AND THE ROLE OF CHANCE DMRT1 repression (miR536/miR641) resulted in a loss of DMRT1 protein expression in a sub-population of Sertoli cells of first trimester (8-11 weeks gestation) human fetal testis; however, this did not affect the completion of seminiferous cord formation or morphological appearance. In second-trimester testis (12-20 weeks gestation), DMRT1 repression (miR536/miR641) resulted in disruption of seminiferous cords with absence of DMRT1 protein expression in Sertoli (SOX9+) cells. No differences in proliferation (Ki67+) were observed a