Oral Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

Investigating a role for Sirtuin 1 in governing spermatogonial stem cell function (128605)

Jess Lyons 1 , Tessa Lord 1 , Shannon Smyth 2 , Elizabeth Bromfield 2
  1. Discipline of Biological Sciences, College of Engineering, Science and Environment, The University of Newcastle, Newcastle, NSW, Australia
  2. School of Biosciences, Faculty of Science, The University of Melbourne, Parkville, VIC, Australia

Spermatogonial stem cells (SSCs) are indispensable for continued male fertility but are exceptionally vulnerable to damage by chemotherapy. SSC destruction is particularly problematic for prepubertal oncology patients, as no mechanism exists to safeguard their reproductive potential, given that they cannot produce sperm for cryopreservation. In vitro SSC therapies and treatments to promote regeneration of chemotherapy-resistant SSCs in vivo offer promising strategies but require an understanding of molecular mechanisms governing SSC regeneration.

Recently, a proteomic comparison of SSCs and progenitor spermatogonia performed by our group identified expression of 6 SIRT isoforms, and Ingenuity Pathway Analysis (IPA) predicted regulation by SIRT1. Additionally, in an RNAseq dataset that compared undifferentiated spermatogonia in steady-state and regenerative conditions (post-chemotherapy)1, IPA analysis also predicted SIRT1 as an upstream regulator of the regenerative response. We have produced a novel transgenic mouse line possessing a sirtuin 1-overexpression construct (SIRT1-OE) as well as an Id4-eGFP reporter transgene that labels SSCs and progenitor spermatogonia. Immunoblotting analysis confirmed a 2.5-fold increase in SIRT1 expression in the OE testis when compared to controls (p<0.05), and immunofluorescence identified SIRT1 expression within the nucleus and cytoplasm of spermatogonia. Breeding studies using SIRT-OE/ID4-eGFP males and control females revealed normal fertility (, and the number of undifferentiated spermatogonia per seminiferous tubule remained equivalent

To explore the effects of SIRT1 overexpression on SSCs in regenerative conditions, chemotherapy exposure and in vitro culture studies have been initiated. At 14 days post-busulfan treatment (n=2, ongoing), testis-to-bodyweight ratios remained equivalent between control and SIRT-OE/ID4-eGFP animals. However, a 36% reduction in the total number of spermatogonia in the OE testis has been identified. In undifferentiated spermatogonia cultures, cell counts and the percentage of ID4-eGFPBright SSCs have remained equivalent over two passages, albeit prolonged studies are required to reveal a true regenerative effect.

 

 

 

 

 

 

 

  1. 1. La, H. M. et al. Distinctive molecular features of regenerative stem cells in the damaged male germline. Nature Communications 13, 2500, doi:10.1038/s41467-022-30130-z (2022).