Oral Presentation ESA-SRB-NZSE-CaSR 2026 in conjunction with ENSA

Insights into sirtuin 1 as a potential regulator of spermatogonial stem cell function and chemotherapy resistance (143512)

Jess M Lyons 1 2 , Shannon P Smyth 1 2 3 , Elizabeth Bromfield 1 2 3 , Tessa Lord 1 2
  1. Centre for Reproductive Science, College of Engineering, Science and Environment, The University of Newcastle, Newcastle, NSW, Australia
  2. Reproductive and Family Health Program, Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
  3. School of Biosciences, Faculty of Science, Biol21 Institute, The University of Melbourne, Parkville, VIC, Australia
  1. Background

Spermatogonial stem cells (SSCs) are the key to fertility preservation pipelines for paediatric cancer patients. Due to their rarity in testicular tissue, harvested SSCs will require robust expansion prior to clinical use. Expansion of SSCs in vitro remains inefficient due to our incomplete understanding of how epigenetic and protein modifications govern SSC function. Further, it is unclear how molecular pathways in homeostatic SSCs are altered in response to cytotoxic insult, although regenerating SSCs display a unique transcriptomic profile. Identifying these pathways will enable the development of effective protocols to promote SSC expansion or prevent their endogenous destruction.

  1. Methods

We produced a novel transgenic mouse line possessing a SIRT1 overexpression construct (SIRT1-OE) and a Id4-eGFP reporter transgene that labels SSCs and progenitor spermatogonia. Cultures of SIRT1-OE and control spermatogonia were collected for RNAseq. Genes ±log2FC 0.585 and p<0.05 were considered significantly differently expressed (n=3). Ingenuity Pathway Analysis (IPA) was used to predict upstream regulators. For chemotherapy experiments, SIRT1-OE and littermate controls were treated with 20mg/kg busulfan and analysed 3-days post treatment via flow cytometry (n=2-3, ongoing). Statistical analyses were performed using a Student’s t-test.

  1. Results

Proteomic profiling of SSCs and progenitor spermatogonia identified expression of six SIRT family members and predicted SIRT1 as a potential upstream regulator. Our bulk-RNAseq comparison of control and SIRT1-OE spermatogonia revealed 697 significantly downregulated and 257 significantly upregulated genes due to SIRT1-OE. IPA analysis predicted upstream regulators linked to SSC self-renewal, apoptosis, and cell-cycle control. 3-days post-busulfan, SIRT1-OE testes had 14.6% higher testis-to-bodyweight ratios (p=0.0876), reduced apoptotic cells, reduced depletion of spermatogonia and an elevated proportion of spermatogonia in S/G2/M phase in comparison to littermate controls.

  1. Conclusions

Our data suggest a functional role for SIRT1-driven deacetylation in modulating SSC fate dynamics, while potentially conferring chemoprotective and regenerative properties that enhance SSC resilience following cytotoxic stress.