Iron homeostasis is critical for hematopoietic cell differentiation in a crustacean, Pacifastacus leniusculus

The importance of iron in hematopoiesis in mammals is studied almost exclusively in relation to the synthesis of red blood cells, erythrocytes, due to the need for hemoglobin. However, other roles of iron during blood cell formation in other animals are barely studied at all. Due to the lack of red blood cells in invertebrates as a whole and crustaceans, we have a unique opportunity to explore the role of iron in hematopoiesis in a freshwater crayfish, Pacifastacus leniusculs. In a recent scRNAseq analysis, we found that genes involved in iron homeostasis were specifically expressed in a small cell cluster in the hematopoietic tissue (HPT) cells and in this present study, we show that genes involved in iron metabolism are important for hematopoietic cell differentiation in the crayfish, Pacifastacus leniusculus. Iron restriction impaired hemocyte migration and altered the expression of key genes involved in iron homeostasis and as well as those participating in hemocyte differentiation. These results highlight the importance of IRP-mediated iron regulation for hemocyte differentiation and release of hemocytes from the hematopoietic tissue and demonstrate that iron availability affects mitochondrial and metabolic pathways important for immune cell development in this crustacean and possibly in other invertebrate animals as well.