GILZ-dependent modulation of mTORC1 regulates spermatogonial maintenance

Development. 2018 Sep 18;145(18):dev165324. doi: 10.1242/dev.165324.

Abstract

Male fertility is dependent on spermatogonial stem cells (SSCs) that self-renew and produce differentiating germ cells. Growth factors produced within the testis are essential for SSC maintenance but intrinsic factors that dictate the SSC response to these stimuli are poorly characterised. Here, we have studied the role of GILZ, a TSC22D family protein and spermatogenesis regulator, in spermatogonial function and signalling. Although broadly expressed in the germline, GILZ was prominent in undifferentiated spermatogonia and Gilz deletion in adults resulted in exhaustion of the GFRα1+ SSC-containing population and germline degeneration. GILZ loss was associated with mTORC1 activation, suggesting enhanced growth factor signalling. Expression of deubiquitylase USP9X, an mTORC1 modulator required for spermatogenesis, was disrupted in Gilz mutants. Treatment with an mTOR inhibitor rescued GFRα1+ spermatogonial failure, indicating that GILZ-dependent mTORC1 inhibition is crucial for SSC maintenance. Analysis of cultured undifferentiated spermatogonia lacking GILZ confirmed aberrant activation of ERK MAPK upstream mTORC1 plus USP9X downregulation and interaction of GILZ with TSC22D proteins. Our data indicate an essential role for GILZ-TSC22D complexes in ensuring the appropriate response of undifferentiated spermatogonia to growth factors via distinct inputs to mTORC1.

Keywords: GILZ; Spermatogenesis; Spermatogonial stem cells; TSC22D family; mTORC1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • DNA-Binding Proteins
  • Endopeptidases / biosynthesis
  • Gene Expression Regulation, Developmental / genetics
  • Glial Cell Line-Derived Neurotrophic Factor Receptors / metabolism
  • Infertility, Male / genetics
  • Male
  • Mechanistic Target of Rapamycin Complex 1 / antagonists & inhibitors
  • Mechanistic Target of Rapamycin Complex 1 / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Spermatogenesis / genetics
  • Spermatogenesis / physiology*
  • Spermatogonia / cytology*
  • Stem Cells / cytology
  • Transcription Factors / metabolism*
  • Ubiquitin Thiolesterase

Substances

  • DNA-Binding Proteins
  • Dsip1 protein, mouse
  • Gfra1 protein, mouse
  • Glial Cell Line-Derived Neurotrophic Factor Receptors
  • TSC22D2 protein, mouse
  • Transcription Factors
  • Mechanistic Target of Rapamycin Complex 1
  • Endopeptidases
  • Ubiquitin Thiolesterase
  • Usp9x protein, mouse