Investigating the role of Cnot3 subunit of the CCR4-NOT complex in the hematopoietic system

Hematopoietic stem cells (HSCs) are a diverse population of cells found in bone marrow, which generate blood cells throughout our lifetime. Little is known regarding how post-transcriptional regulation of gene expression influences HSCs and hematopoiesis. We observed that Cnot3, a scaffold subunit of the CCR4-NOT (CNOT) RNA deadenylation complex, is highly expressed in HSCs and downregulated in differentiated cells. To examine the consequences of Cnot3 loss of function in HSCs and hematopoiesis, we generated a blood-specific Mx1-Cre Cnot3 conditional knockout mice. Cnot3 ablation resulted in anemia, reduced bone marrow (BM) cellularity and enlarged spleen. Multiparameter flow cytometry analysis of BM cells revealed a complete loss of HSCs coupled with an expansion of downstream progenitors in Cnot3 KO mice. In vivo transplantation demonstrated that Cnot3-depelted BM cells failed to reconstitute hematopoietic systems of lethally irradiated recipient animals. Altogether, our results indicate that Cnot3 is essential for normal hematopoiesis and maintenance of HSCs.