Genetic control of typical and atypical sex development

A role for TRPC3 in mammalian testis development

SOX9 is a key transcription factor for testis determination and development. Mutations in and around the SOX9 gene contribute to Differences/Disorders of Sex Development (DSD). However, a substantial proportion of DSD patients lack a definitive genetic diagnosis. SOX9 target genes are potentially DSD-causative genes, yet only a limited subset of these genes has been investigated during testis development. We hypothesize that SOX9 target genes play an integral role in testis development and could potentially be causative genes in DSD. In this study, we describe a novel testicular target gene of SOX9, Trpc3. Trpc3 exhibits high expression levels in the SOX9-expressing male Sertoli cells compared to female granulosa cells in mouse fetal gonads between embryonic day 11.5 (E11.5) and E13.5. In XY Sox9 knockout gonads, Trpc3 expression is markedly downregulated. Moreover, culture of E11.5 XY mouse gonads with TRPC3 inhibitor Pyr3 resulted in decreased germ cell numbers caused by reduced germ cell proliferation. Trpc3 is also expressed in endothelial cells and Pyr3-treated E11.5 XY mouse gonads showed a loss of the coelomic blood vessel due to increased apoptosis of endothelial cells. In the human testicular cell line NT2/D1, TRPC3 promotes cell proliferation and controls cell morphology, as observed by xCELLigence and HoloMonitor real-time analysis. In summary, our study suggests that SOX9 positively regulates Trpc3 in mouse testes and TRPC3 may mediate SOX9 function during Sertoli, germ and endothelial cell development.

COUP-TFII regulates early bipotential gonad signaling and commitment to ovarian progenitors

BACKGROUND

The absence of expression of the Y-chromosome linked testis-determining gene SRY in early supporting gonadal cells (ESGC) leads bipotential gonads into ovarian development. However, genetic variants in NR2F2, encoding three isoforms of the transcription factor COUP-TFII, represent a novel cause of SRY-negative 46,XX testicular/ovotesticular differences of sex development (T/OT-DSD). Thus, we hypothesized that COUP-TFII is part of the ovarian developmental network. COUP-TFII is known to be expressed in interstitial/mesenchymal cells giving rise to steroidogenic cells in fetal gonads, however its expression and function in ESGCs have yet to be explored.

RESULTS

By differentiating induced pluripotent stem cells into bipotential gonad-like cells in vitro and by analyzing single cell RNA-sequencing datasets of human fetal gonads, we identified that NR2F2 expression is highly upregulated during bipotential gonad development along with markers of bipotential state. NR2F2 expression was detected in early cell populations that precede the steroidogenic cell emergence and that retain a multipotent state in the undifferentiated gonad. The ESGCs differentiating into fetal Sertoli cells lost NR2F2 expression, whereas pre-granulosa cells remained NR2F2-positive. When examining the NR2F2 transcript variants individually, we demonstrated that the canonical isoform A, disrupted by frameshift variants previously reported in 46,XX T/OT-DSD patients, is nearly 1000-fold more highly expressed than other isoforms in bipotential gonad-like cells. To investigate the genetic network under COUP-TFII regulation in human gonadal cell context, we generated a NR2F2 knockout (KO) in the human granulosa-like cell line COV434 and studied NR2F2-KO COV434 cell transcriptome. NR2F2 ablation downregulated markers of ESGC and pre-granulosa cells. NR2F2-KO COV434 cells lost the enrichment for female-supporting gonadal progenitor and acquired gene signatures more similar to gonadal interstitial cells.

CONCLUSIONS

Our findings suggest that COUP-TFII has a role in maintaining a multipotent state necessary for commitment to the ovarian development. We propose that COUP-TFII regulates cell fate during gonad development and impairment of its function may disrupt the transcriptional plasticity of ESGCs. During early gonad development, disruption of ESGC plasticity may drive them into commitment to the testicular pathway, as observed in 46,XX OT-DSD patients with NR2F2 haploinsufficiency.

Support for affirmative actions to increase inclusivity of intersex* persons at an Austrian medical university

BACKGROUND

Since the ruling handed down by the Austrian Constitutional Court in 2018 intersex variation has been recognized under Austrian law as a "third sex". In order to ensure that people with intersex variation are not discriminated against based on their group membership affirmative actions (i.e., proactive practices to avert discrimination) can be implemented. The current study explored whether students and employees at an Austrian medical university know about intersex variation. Furthermore, the study investigated what affirmative actions are practiced at the medical university to be inclusive for intersex persons and students' and employees' support for such affirmative actions.

METHODS

All students and employees of a medical university in Austria were invited by e-mail to participate at the current study that included a self-constructed knowledge test on intersex variation with ten true-false questions. On five-point Likert scales participants reported for each of twelve listed affirmative actions whether they had seen a certain affirmative action at their university and how important they thought the implementation of an affirmative action was. Finally, participants' gender, age, sexual orientation, highest level of education, and nationality was assessed. A cluster analysis was performed to determine groups of people with different degrees of support for affirmative actions for intersex persons.

RESULTS

220 students (62% cisgender women, 38% cisgender men) and 200 employees (72% cisgender women, 28% cisgender men) participated. Participants responded correctly to three out of ten knowledge test questions. The cluster analysis revealed that participants could be clustered as heterosexual cisgender women (Cluster 1; 55%), heterosexual cisgender men (Cluster 2; 30%), or sexual minority cisgender women and men (Cluster 3; 15%). Sexual minority persons knew more about intersex variation than did heterosexual participants. On average, affirmative actions for the inclusivity of intersex people have not been encountered (M = 1.5, SD = 0.4) at the studied university. Participants, especially those in Cluster 3, believed that the listed actions are moderately important.

CONCLUSIONS

At the medical university many actions should be taken to increase inclusivity for intersex people. Increasing the knowledge of university staff and students concerning intersex might help increase their support for such actions.