Glial cell line-derived neurotrophic factor (GDNF) induced migration of spermatogonial cells in vitro via MEK and NF-kB pathways

• Recombinant GDNF or supernatant from Sertoli cells of one-week-old mice induced migration of spermatogonial cells in vitro.
• This effect was significantly reduced by addition of inhibitors to MEK, NF-kB or IkB protease inhibitor.
• The levels of GDNF and GFR-α1 were higher in testicular tissue of one-week-old mice compared to other older ages.
• Only Sertoli cell cultures from one-week-old mice produced GDNF. However, peritubular cells from any age did not produce GDNF.
• Our results may suggest a novel role for GDNF in the regulation SSC niches and spermatogenesis.

Glial cell line-derived neurotrophic factor (GDNF) regulates spermatogonial stem cell (SSC) maintenance. In the present study, we examined the levels and the cellular origin of GDNF in mouse testes during age-development, and the capacity of GDNF to induce migration of enriched GFR-α1 positive cells in vitro. The involvement of MAP kinase (MEK) and NF-kB signal pathways were examined. Our results show high levels of GDNF in testicular tissue of one-week-old mice which significantly decreased with age when examined by ELISA, real time PCR (qPCR) and immunofluorescence staining (IF) analysis. GDNF receptor (GFR-α1) expression was similar to GDNF when examined by qPCR analysis. Only Sertoli cell cultures (SCs) from one-week-old mice produced GDNF compared to SCs from older mice. However, peritubular cells from all the examined ages did not produce GDNF. The addition of recombinant GDNF (rGDNF) or supernatant from SCs from one-week-old mice to GFR-α1 positive cells induced their migration in vitro. This effect was significantly reduced by the addition of inhibitors to MEK (PD98059, U0126), NF-kB (PDTC) and IkB protease inhibitor (TPCK).Our results show for the first time the capacity of rGDNF and supernatant from SCs to induce migration of enriched GFR-α1 positive cells, and the possible involvement of MEK, NF-kB and IkB in this process. This study may suggest a novel role for GDNF in the regulation SSC niches and spermatogenesis.