A distinct expression pattern in mammalian testes indicates a conserved role for NANOG in spermatogenesis.
BACKGROUND
NANOG is a key player in pluripotency and its expression is restricted to pluripotent cells of the inner cell mass, the epiblast and to primordial germ cells. Spermatogenesis is closely associated with pluripotency, because through this process highly specialized sperm cells are produced that contribute to the formation of totipotent zygotes. Nevertheless, it is unknown if NANOG plays a role in this process.


RESULTS
In the current study, NANOG expression was examined in testes of various mammals, including mouse and human. Nanog mRNA and NANOG protein were detected by RT-PCR, immunohistochemistry, and western blotting. Furthermore, eGFP expression was detected in the testis of a transgenic Nanog eGFP-reporter mouse. Surprisingly, although NANOG expression has previously been associated with undifferentiated cells with stem cell potential, expression in the testis was observed in pachytene spermatocytes and in the first steps of haploid germ cell maturation (spermiogenesis). Weak expression in type A spermatogonia was also observed.


CONCLUSIONS
The findings of the current study strongly suggest a conserved role for NANOG in meiotic and post-meiotic stages of male germ cell development.
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
Ewart W
EW
Kuijk
Jeffrey
J
de Gier
Susana M Chuva de Sousa
SM
Lopes
Ian
I
Chambers
Ans M M
AM
van Pelt
Ben
B
Colenbrander
Bernard A J
BA
Roelen
D000818:Animals; D004285:Dogs; D020869:Gene Expression Profiling; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D000071317:Nanog Homeobox Protein; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013091:Spermatogenesis / Q000502:physiology*; D013737:Testis / Q000378:metabolism*
D018398:Homeodomain Proteins; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse