A connexin/ifi30 pathway bridges HSCs with their niche to dampen oxidative stress

Pietro Cacialli,Patrizia Bordignon,Tim Petzold,Julien Y Bertrand,Christopher B Mahony,Anne-Laure Rougemont

doi:10.1038/s41467-021-24831-0

Abstract

Reactive oxygen species (ROS) represent a by-product of metabolism and their excess is toxic for hematopoietic stem and progenitor cells (HSPCs). During embryogenesis, a small number of HSPCs are produced from the hemogenic endothelium, before they colonize a transient organ where they expand, for example the fetal liver in mammals. In this study, we use zebrafish to understand the molecular mechanisms that are important in the caudal hematopoietic tissue (equivalent to the mammalian fetal liver) to promote HSPC expansion. High levels of ROS are deleterious for HSPCs in this niche, however this is rescued by addition of antioxidants. We show that Cx41.8 is important to lower ROS levels in HSPCs. We also demonstrate a new role for ifi30, known to be involved in the immune response. In the hematopoietic niche, Ifi30 can recycle oxidized glutathione to allow HSPCs to dampen their levels of ROS, a role that could be conserved in human fetal liver.

Highlights

Reactive oxygen species (ROS) represent a by-product of metabolism and their excess is toxic for hematopoietic stem and progenitor cells (HSPCs)
This was accompanied by a decrease in HSPC proliferation at 48 hpf, as measured by anti-phospho-Histone 3 staining after exposure to H2O2 (Fig. 1c, d), showing that ROS have a toxic effect on HSPCs in the caudal hematopoietic tissue (CHT)
We evaluated the impact of the glutathione synthesis inhibitor buthionine sulfoximine (BSO, 10 μM) and oxidized glutathione GSSG (10 μM) treatments on HSPCs in the CHT

Summary

Introduction

Reactive oxygen species (ROS) represent a by-product of metabolism and their excess is toxic for hematopoietic stem and progenitor cells (HSPCs). We use zebrafish to understand the molecular mechanisms that are important in the caudal hematopoietic tissue (equivalent to the mammalian fetal liver) to promote HSPC expansion. Ifi[30] can recycle oxidized glutathione to allow HSPCs to dampen their levels of ROS, a role that could be conserved in human fetal liver. The very few HSPCs that are produced colonize a niche where they can expand, the fetal liver and the caudal hematopoietic tissue (CHT)[3], in mammals and zebrafish, respectively This embryonic niche is the only niche where HSPCs actively expand during the whole life of an animal[4], understanding the microenvironmental signals required at the non-cell-autonomous level for HSPC expansion may allow better expansion of human HSPCs ex vivo, improving our current clinical protocols. Zebrafish ifi[30] encodes a protein very similar to the mammalian Gilt/Ifi[30], with a thioredoxin-like C-X-X-C motif that forms the reductase active site[30] and mutations of either or both cysteines in the active-site abolish thiol-reductase activity of Gilt/Ifi[30 24]

Methods

Results

Conclusion