Loss of postnatal quiescence of neural stem cells through mTOR activation upon genetic removal of cysteine string protein-α

Significance Neural stem cells generate newborn neurons in the postnatal brain by a process known as neurogenesis. Cysteine string protein-α (CSP-α) maintains healthy nerve terminals and, when mutated in humans, causes a serious disease known as neuronal ceroid lipofuscinosis related to lysosomal pathologies. We have now found that neural stem cells without CSP-α hyperproliferate, leading to depletion of the neural stem cell pool in the mouse hippocampus. Biochemically, the hyperproliferation occurs through the hyperactivation of the mechanistic target of rapamycin (mTOR) signaling pathway. Our findings demonstrate the disruption of postnatal neurogenesis in the absence of CSP-α and unveil an intriguing signaling interaction between CSP-α and mTOR that may underlie molecular mechanisms of brain dysfunction and neurodegeneration.