%0 Journal Article %A Dionna M. Kasper %A Jared Hintzen %A Yinyu Wu %A Joey J. Ghersi %A Hanna K. Mandl %A Kevin E. Salinas %A William Armero %A Zhiheng He %A Ying Sheng %A Yixuan Xie %A Daniel W. Heindel %A Eon Joo Park %A William C. Sessa %A Lara K. Mahal %A Carlito Lebrilla %A Karen K. Hirschi %A Stefania Nicoli %T The N-Glycome regulates the endothelial-to-hematopoietic transition %D 2020 %R 10.1101/602912 %J bioRxiv %P 602912 %X Hematopoietic stem and progenitor cells (HSPCs) that establish and maintain the blood system in adult vertebrates arise from the transdifferentiation of hemogenic endothelial cells (hemECs) during embryogenesis. This endothelial-to-hematopoietic transition (EHT) is tightly regulated, but the mechanisms are poorly understood. Here, we show that microRNA (miR)-223-mediated regulation of N-glycan biosynthesis in endothelial cells (ECs) regulates EHT. Single cell RNA-sequencing revealed that miR-223 is enriched in hemECs and in oligopotent nascent HSPCs. miR-223 restricts the EHT of lymphoid/myeloid lineages by suppressing the expression of mannosyltransferase alg2 and sialyltransferase st3gal2, two enzymes involved in N-linked protein glycosylation. High-throughput glycomics of ECs lacking miR-223 showed a decrease of high mannose versus sialylated complex/hybrid sugars on N-glycoproteins involved in EHT such as the metalloprotease Adam10. Endothelial-specific expression of an N-glycan Adam10 mutant or of the N-glycoenzymes phenocopied the aberrant HSPC production of miR-223 mutants. Thus, the N-glycome plays a previously unappreciated role as an intrinsic regulator of EHT, with specific mannose and sialic acid modifications serving as key endothelial determinants of their hematopoietic fate.One Sentence Summary The N-glycan “sugar code” governs the hematopoietic fate of endothelial cells and regulates blood stem cell production in vivo.Competing Interest StatementThe authors have declared no competing interest. %U https://www.biorxiv.org/content/biorxiv/early/2020/08/06/602912.full.pdf