Wtapblock Cell Differentiation of Hematopoietic Stem and Progenitor Cells

Wilms' tumor 1-associating protein (WTAP) is a ubiquitously expressed nuclear protein has been associated with regulation of cell proliferation, apoptosis, embryonic development, cell cycle, RNA splicing and stabilization, N6-Methyladenosine RNA modification in various physiological processes. Recently,WTAPwas reported to promoter tumorigenicity in Glioblastoma and cholangiocarcinoma. Besides solid tumors,WTAPplays an important role in abnormal proliferation and arrested differentiation in acute myeloid leukemia (AML) cell, suggesting its oncogenic activity. For its promising novel therapeutic target in AML, a systematic investigation of the roles ofWTAPin normal hematopoiesis is warranted.To investigate the function ofWTAPin normal hematopoietic system, we firstly determined the mRNA level ofWTAPin different hematopoietic stem and progenitor cells (HSPCs) and several mature populations in C57/B6 mouse bone marrow (BM).WTAPwas ubiquitously expressed in different cell populations and especially elevated in HSPCs. For WTAP-null and heterozygous caused early embryonic lethality, we generated endothelial system conditional knockout (cKO) mice by crossing WTAP floxed mice with poly (I:C) induced Mx1-Cre transgenic mice. In poly (I:C) inducedWTAP^fl/fl-Mx1-Cre, WTAP deficiency lead to approximately 2-fold increase in HSC and LSK pool size, and modest expansion of HPC, CLP and LMPP population. In competitive BM transplantation assay, lossWTAPshowed a significantly decreased repopulation capacity. WhileWTAPknockout did not significantly affect the proliferation, cell cycle and apoptosis of HSPCs tested by Brdu, Ki67 and Annexin-V straining assay. Mechanistically, deletion ofWTAPin HSC resulted in decreased transcription of myeloid cell and erythrocyte differentiation gene (including Jak3, Jun and Junb) and genes regulating pluripotency of stem cells (induding Akt2, Fzd1/9 and Mapk3).Collectively, we speculateWTAPplay important role in blocking cell differentiation of HSPCs. Currently, we are conducting a series of studies to reveal the underlying molecular mechanism(s) ofWTAPregulating normal hematopoiesis.