Blocked O-GlcNAc cycling disrupts mouse hematopoeitic stem cell maintenance and early T cell development

Lara K Abramowitz,Christelle Harly,Avinash Bhandoola,Arundhoti Das,John A Hanover

doi:10.1038/s41598-019-48991-8

Abstract

Small numbers of hematopoietic stem cells (HSCs) balance self-renewal and differentiation to produce the diversity and abundance of cell types that make up the blood system. How nutrients are recruited to support this massive differentiation and proliferation process remains largely unknown. The unique metabolism of adult HSCs, which rely on glycolysis and glutaminolysis, suggests a potential role for the post-translational modification O-GlcNAc as a critical nutrient signal in these cells. Glutamine, glucose, and other metabolites drive the hexosamine biosynthetic pathway (HBP) ultimately leading to the O-GlcNAc modification of critical intracellular targets. Here, we used a conditional targeted genetic deletion of the enzyme that removes O-GlcNAc, O-GlcNAcase (OGA), to determine the consequences of blocked O-GlcNAc cycling on HSCs. Oga deletion in mouse HSCs resulted in greatly diminished progenitor pools, impaired stem cell self-renewal and nearly complete loss of competitive repopulation capacity. Further, early T cell specification was particularly sensitive to Oga deletion. Loss of Oga resulted in a doubling of apoptotic cells within the bone marrow and transcriptional deregulation of key genes involved in adult stem cell maintenance and lineage specification. These findings suggest that O-GlcNAc cycling plays a critical role in supporting HSC homeostasis and early thymocyte development.

Highlights

The mammalian hematopoietic system is comprised of diverse cell types that each have unique functions
Because O-GlcNAc cycling is a crucial feature in cell populations reliant on glycolysis and glutaminolysis, we anticipated that stable O-GlcNAcylation would disrupt hematopoietic stem cells (HSCs) homeostasis
Previous inquiries into the role of O-GlcNAc cycling in stem cells have largely focused on altering Oga or Ogt in cultured embryonic stem cells

Summary

Introduction

The mammalian hematopoietic system is comprised of diverse cell types that each have unique functions. Added to proteins by O-GlcNAc transferase (OGT) and removed by O-GlcNAcase (OGA), O-GlcNAc cycling integrates nutrient availability with molecular processes like transcription, translation, proteostasis and signaling[4] Because it plays diverse roles in cell physiology, O-GlcNAcylation is poised to influence cells reliant on glycolysis and glutaminolysis like HSCs and T cells. Loss of Oga resulted in an increase in apoptosis and transcriptional analysis revealed that nutrient transport and FGF signaling likely contributed to HSC dysfunction in mutant HSCs. Our data suggested that the processes of O-GlcNAc addition and removal each play a key part in regulating critical steps of hematopoiesis. Our data suggested that the processes of O-GlcNAc addition and removal each play a key part in regulating critical steps of hematopoiesis These findings have important implications for the role of hexosamine signaling in the maintenance of stem cell populations giving rise to immune homeostasis

Methods

Results

Conclusion