Study on the mechanism of TSC22D3 regulating the stability of P53 to promote the quiescence of hematopoietic stem cells

In adults, human hematopoietic stem cells (HSCs) are mostly in a quiescent state (G0 stage) and show multilineage reconstruction. When the cell cycle is activated, HSCs gradually lose the hematopoietic reconstruction ability. It indicates that the maintenance of the quiescent state of HSPCs has very important physiological significance. However, the maintenance and regulation mechanism of the quiescent state of HSCs has not yet been clarified. We found that TSC22D3 was highly enriched in quiescent state HSCs but downregulated in culture with the activation of the cell cycle. We further confirmed that stabilizing TSC22D3 expression in HSCs could promote the maintenance of the quiescent state and provide balanced multilineage reconstitution in primary mouse recipients.We found that overexpression of TSC22D3 can promote the maintenance of the resting state of HSCs and the ability of hematopoietic reconstitution by inhibiting the expression of cell cycle-related kinases. Also we confirmed that TSC22D3 can promote the accumulation of p53 protein in cells and up-regulate the expression of p21, p27 and other proteins by qPCR and western blot. Therefore, we speculate that TSC22D3 can promote the resting state of HSCs by regulating the stability of p53. It remains elusive that how TSC22D3 plays a role in the regulation of the maintenance of HSCs in vitro, therefore, further investigations are required to depict its underlying mechanism. On this basis, We firstly plan to analyze the potential downstream targets of TSC22D3 in the maintenance of HSCs in vitro through RNA-seq based transcriptome comparison; then, we will verify the predicted targets of TSC22D3 through Co-IP, gene overexpression, gene knockdown, and signaling pathway activation/inhibition. Our project could contribute to an in-depth understanding of the quiescent maintenance mechanisms of HSPCs in vitro and provide ideas for the treatment of leukemia and other malignant hematological diseases.