Investigating the combined action of delta and epsilon tubulin in the microtubule cytoskeleton during spermatogenesis — ASN Events
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  3. Investigating the combined action of delta and epsilon tubulin in the microtubule cytoskeleton during spermatogenesis

Investigating the combined action of delta and epsilon tubulin in the microtubule cytoskeleton during spermatogenesis (#539)

Tao Tang 1 2 , Moira O'Bryan 1 2 , Gemma Stathatos 1 2 , Jessica Dunleavy 1 2
  1. Bio21 Molecular Sciences and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
  2. School of Bioscience, The University of Melbourne, Melbourne, VIC, Australia

Introduction

Delta and epsilon tubulin are two non-canonical tubulin isotypes that are required for the stability of complex microtubule structures. They are evolutionarily co-conserved and interact in vitro (1). Previously, we have revealed that the individual functions of delta and epsilon tubulin are essential for the microtubule-based male germ cell development (2, 3). Whether they achieve these functions in partnership, or if they have distinct modes of action, however, is unknown.

Methods

To explore the combined role of delta and epsilon tubulin in spermatogenesis, we generated a delta and epsilon tubulin double germ cell knockout mouse model (Tubd1/e1GCKO).For all analysis n≥3/genotype were analysed, and quantitiative data were anlaysed by two-tailed unpaired Welch's t-test.

Results

Fertility characterisation demonstrated that Tubd1/e1GCKO males were infertile with a more severe phenotype compared to the single GCKO male mice (2, 3). The testicular and epididymal weights reduced by 79.8% (65.83% in Tubd1GCKO, 64.72% in Tube1GCKO) and 38.3%, respectively. Daily sperm production was further reduced by 96.8% (97.24% in Tubd1GCKO, 80.48% in Tube1GCKO) and epididymal sperm counts were reduced by 99.9%. Histology analysis revealed a hypo-spermatogenesis (28.2% Tubd1/e1GCKO; 70.79% in Tubd1GCKO, 59.85% in Tube1GCKO) or Sertoli cells only (68.03% in Tubd1/e1GCKO; 27.34% in Tubd1GCKO, 28.22% in Tube1GCKO) morphology in most seminiferous tubules. Similar, to the single Tubd1GCKO and Tube1GCKO mice the majority of H&E-stained sperm presented with abnormal head shapes, due to disrupted manchette movement during spermiogenesis.

 

Conclusion

Collectively, the additive degree of the phenotypes observed in the Tubd1/e1GCKO relative to the single Tubd1GCKO and Tube1GCKO mice, and the absence of dramatic additional phenotypes, suggests that TUBD1 and TUBE1 likely perform similar, yet independent functions in spermatogenesis. Defining their precise molecular functions in regulating the microtubule cytoskeleton and their interacting network in male germ cells is ongoing.

 

  1. Wang JT, Kong D, Hoerner CR, Loncarek J, Stearns T. Centriole triplet microtubules are required for stable centriole formation and inheritance in human cells. Elife. 2017;6.
  2. Stathatos GG, Merriner DJ, O'Connor AE, Zenker J, Dunleavy JEM, O'Bryan MK. Delta tubulin stabilizes male meiotic kinetochores and aids microtubule remodeling and fertility. Journal of Cell Biology. 2025;224(9).
  3. Stathatos GG, Merriner DJ, O'Connor AE, Zenker J, Dunleavy JEM, O'Bryan MK. Epsilon tubulin is an essential determinant of microtubule-based structures in male germ cells. Embo Rep. 2024.