CXCR4 drives lympho-myeloid fate of hematopoietic progenitors via mTOR and mitochondrial metabolic pathways

Hematopoietic stem and progenitor cells (HSPCs), including the multipotent progenitors (MPPs), are responsible for replenishing immune cells. They reside in bone marrow (BM) endosteal and (peri)-vascular niches, which provide all cellular and molecular components required for their lifelong maintenance and fate. Among them, the CXCL12 chemokine and one of its receptor, CXCR4, exert a dominant role in promoting HSPC retention and quiescence. These processes are deregulated in the WHIM Syndrome (WS), a rare immunodeficiency caused by inherited heterozygous autosomal gain-of-function CXCR4 mutations that affect homologous desensitization of the receptor. Clinically, WS is notably characterized by severe, chronic circulating lymphopenia whose mechanisms remain to be elucidated. Using a mouse model carrying a naturally occurring WS-linked Cxcr4 mutation, we explored the possibility that the lymphopenia in WS originates from defects at the MPP level in BM. The global strategy consists in performing high-throughput RNA-seq analyses of the different MPP subsets bearing or not the WS-linked Cxcr4 mutation to investigate the impact of the gain-of-Cxcr4-function on the molecular identity of MPP subsets. RNAseq data were generated from pools of 3 x 103 MPP1-4 sorted from the marrow fraction of WT and Cxcr41013-bearing mice.