Uncovering the Importance of Cell Morphology, Genetic Regulation, and Neuronal Signalling in Quiescent Neural Stem Cells

Abstract

Neural stem cells (NSCs) are essential for their ability to produce new neurons during neurogenesis. These cells undergo quiescence, the state when quiescent cells are metabolically active but do not produce new neurons. Understanding and manipulating this critical state is essential due to undiscovered applications in regenerative biology and precision medicine, which lead to better outcomes in neurodegenerative diseases and cancers. The thesis aimed to understand NSCs and their regulation using three separate methods. Firstly, an investigation was performed into how the distinct quiescence features – cellular projections – regulate quiescence induction and reactivation. It revealed that projections are involved in guiding the direction of neuron generation. Secondly, a genetic analysis was performed to understand how these projections could be manipulated. The Sickie, Bero, CG1572, and Ringer were identified as promising candidates for further study due to their effects on NSC morphology and reactivation timing. In addition to the four genes, this thesis looked at the mulet gene and its role in NSC regulation. Reactivation assays suggested that increased levels of mulet mRNA accelerate microtubule depolymerisation and disrupt NSC stability, affecting the reactivation. Thirdly, the neural signalling experiment investigated how different neuron signals affect NSC reactivation and quiescence. scRNA-Seq revealed that specific neurotransmitter receptors are involved in the quiescence. Further investigation was performed on GABAergic and dopaminergic neuron manipulations to understand their impact on quiescence. The experiments revealed a clear neuronal signalling role in NSC quiescence and reactivation.