Glial cell-line derived neurotrophic factor-mediated RET signaling regulates spermatogonial stem cell fate.
Normal spermatogenesis is essential for reproduction and depends on proper spermatogonial stem cell (SSC) function. Genes and signaling pathways that regulate SSC function have not been well defined. We report that glial cell-line-derived neurotrophic factor (GDNF) signaling through the RET tyrosine kinase/GFRA1 receptor complex is required for spermatogonial self-renewal in mice. GFRA1 and RET expression was identified in a subset of gonocytes at birth, was restricted to SSCs during normal spermatogenesis, and RET expressing cells were abundant in a cryptorchid model of SSC self-renewal. We used the whole-testis transplantation technique to overcome the limitation of neonatal lethality of Gdnf-, Gfra1-, and Ret-deficient mice and found that each of these genes is required for postnatal spermatogenesis and not for embryological testes development. Each mutant testis shows severe SSC depletion by Postnatal Day 7 during the first wave of spermatogenesis. These defects were due to lack of SSC proliferation and an inability of SSCs to maintain an undifferentiated state. Our results demonstrate that GDNF-mediated RET signaling is critical for the fate of undifferentiated spermatogonia and that abnormalities in this pathway may contribute to male infertility and testicular germ cell tumors.
Naughton
Cathy K
CK
Division of Urology, Washington University School of Medicine, St. Louis, Missouri 63110, USA. naughtonc@msnotes.wustl.edu
Jain
Sanjay
S
Strickland
Amy M
AM
Gupta
Akshay
A
Milbrandt
Jeffrey
J
D000818:Animals; D005786:Gene Expression Regulation; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013091:Spermatogenesis / Q000235:genetics; D013093:Spermatogonia / Q000166:cytology* / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013737:Testis / Q000637:transplantation; D019737:Transplants
D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D051096:Proto-Oncogene Proteins c-ret