A bioenergetic shift is required for spermatogonial differentiation

A bioenergetic balance between glycolysis and mitochondrial respiration is particularly important for stem cell fate specification. It however remains to be determined whether undifferentiated spermatogonia switch their preference of bioenergy production during differentiation. In this study, we found that ATP generation in spermatogonia was gradually increased upon retinoic acid-induced differentiation. To accommodate this elevated energy demand, retinoic acid signaling concomitantly switched ATP production in spermatogonia from glycolysis to mitochondrial respiration, accompanied by increased levels of reactive oxygen species. In addition, inhibition of glucose conversion to glucose-6-phosphate or pentose phosphate pathway blocked the formation of c-Kit+ differentiating germ cells, suggesting that metabolites produced from glycolysis are required for spermatogonial differentiation. We further demonstrated that the expression levels of several metabolic regulators and enzymes were significantly altered upon retinoic acid-induced differentiation by both RNA-seq analyses and quantitative proteomics. Taken together, our data unveil a critically regulated bioenergetic balance between glycolysis and mitochondrial respiration which is required for spermatogonial proliferation and differentiation.