Pluripotency of mouse spermatogonial stem cells maintained by IGF-1- dependent pathway.
Recent studies indicate that neonatal spermatogonial stem cells (SSCs) possess pluripotency. However, the mechanisms that regulate the pluripotent differentiation capacity of SSCs remain unclear. Here, we describe a new method to clonally derive pluripotent SSCs from neonatal mouse testis. By coculturing with testicular stromal cells, SSCs can be maintained and expanded in serum-free conditions. Unlike endogenous SSCs, these in vitro expanded SSCs showed strong alkaline phosphatase (AP) activity and displayed characteristics of embryonic stem cells and primordial germ cells, which were therefore designated as AP(+) germline stem cells (AP(+)GSCs). The pluripotency of AP(+)GSCs was confirmed by in vitro differentiation toward hepatic and neuronal lineages and formation of embryonic chimeras after injection into blastocysts. Further investigation revealed that insulin-like growth factor-1 (IGF-1) secreted from Leydig cells was a key factor involved in maintaining the pluripotency of AP(+)GSCs. The blockage of IGF-1 receptor phosphorylation and its downstream PI3K pathway by PPP or LY294002 dramatically reduced their AP activity and expression of pluripotent genes, such as Oct-4, Blimp1, and Nanog. In conclusion, the present study demonstrated that IGF-1 secreted by testicular Leydig cells plays an important role in maintaining the pluripotency of SSCs in culture, which provides an insight into the molecular mechanism underlying germ cell pluripotency.
Huang
Yen-Hua
YH
Department of Biochemistry, Graduate Institute of Medical Sciences, School of Medicine, Taipei Medical University, Taipei, Taiwan. rita1204@tmu.edu.tw
Chin
Cheng-Chieh
CC
Ho
Hong-Nerng
HN
Chou
Chuan-Kai
CK
Shen
Chia-Ning
CN
Kuo
Hung-Chih
HC
Wu
Tsai-Jung
TJ
Wu
Yu-Chih
YC
Hung
Yu-Ching
YC
Chang
Chih-Cheng
CC
Ling
Thai-Yen
TY
D000818:Animals; D000831:Animals, Newborn; D019070:Cell Lineage; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000502:physiology; D007985:Leydig Cells / Q000378:metabolism; D008297:Male; D051379:Mice; D019899:Paracrine Communication; D039904:Pluripotent Stem Cells / Q000166:cytology*; D013093:Spermatogonia / Q000166:cytology*; D013737:Testis / Q000166:cytology
D007334:Insulin-Like Growth Factor I