Oral Presentation 2019 Hunter Cell Biology Meeting

SART3 genetic variants are a novel cause of gonadal dysgenesis and intellectual disability (#9)

Katie Ayers 1 2 , Stefanie Eggers 3 , Ingrid Knarston 1 , Ben Rollo 4 , Josephine Bowles 5 , Gorjana Robevska 1 , Jocelyn van den Bergen 1 , Liang Zhao 5 , Katherine Smith 6 , Melanie Bahlo 6 , Ann Jorgenson 7 , Steve Petrou 4 , Gary Hime 8 , Peter Koopman 5 , Melissa Little 1 2 , Kenneth McElreavey 9 10 , Naomi Weintrob 11 , Bruria Ben Zeev 12 , Andrew Sinclair 1 2 3
  1. Murdoch Children’s Research Institute, Melbourne, Australia
  2. Department of Paediatrics, The University of Melbourne, Melbourne, Australia
  3. Victorian Clinical Genetics Services, Melbourne, Australia
  4. The Florey Institute, Melbourne, Australia
  5. The University of Queensland, St Lucia, Australia
  6. Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
  7. Department of Growth and Reproduction, Copenhagen University Hospital, Denmark
  8. Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne
  9. L’institut Pasteur, Paris, France
  10. L’institut Pasteur, Paris, France
  11. Sackler school of Medicine, Tel-Aviv University, Israel
  12. Safra Pedatric Hospital, Chaim Sheba Medical Center, Ramat-Gan, Israel

Human congenital disorders affecting brain and gonadal development are particularly distressing for patients and their families. Very little is known about what causes these rare disorders, and in most cases a genetic diagnosis cannot be made. We have identified three families where children with gonadal dysgenesis (46,XY females), intellectual disability (ID) and agenesis of the corpus callosum carry homozygous variants in the novel disease gene SART3.  SART3 is important for spliceosome assembly and double-stranded DNA break repair, but a specific role for SART3 in brain and gonad development has not been established; particularly since studies on this gene have been hampered by mouse mutant lethality. We are now working to elucidate the role of SART3 in embryogenesis. Using RNAi mediated knockdown in Drosophila we have found that the fly SART3 homolog, Rnp4f, is required for development, and its knockdown in embryonic neurons causes severe CNS defects leading to lethality. However, knockdown in embryonic glia had no effect on embryogenesis. Interestingly, we found that this gene is also required for fly male fertility, and targeted knockdown in the testis triggers defects in meiosis.  Together these data suggest that SART3 plays a conserved role in neuronal and testicular development. To model the variants found in our patients we have created induced pluripotent stem (iPS) cell lines carrying these mutations. Preliminary results show that these mutant iPS cells fail to efficiently differentiate into neurons, and undergo apoptosis. In addition, using a novel in vitro method for differentiation of human stem cells to embryonic gonadal cells, we found that the patient SART3 variant does indeed disrupt normal gonadal differentiation, perhaps through disrupted SART3 auto-regulation and defects in spliceosome assembly. This work identifies SART3 as a key regulator of neuronal and gonadal cell types in the developing embryo, and establishes SART3 as a novel cause of developmental disorders affecting these two tissues.