ABSTRACT
A central issue in stem cell biology is a better understanding of the molecular mechanisms that regulate self-renewal of human hematopoietic stem cells (HSCs). Control of the specific function of HSCs like self-renewal and differentiation might be regulated by a common set of critical genes. However, the regulation among these genes is yet to be elucidated. Here, we show that activation by a novel human GPI-linked glycoprotein ACA at the surface of human peripheral blood progenitor cells induces via PI3K/Akt/mTor/PTEN upregulation of WNT, Notch1, Bmi-1 and HoxB4 genes thus, promoting self-renewal and generation of primitive HSCs. ACA-generated self-renewing cells retained their lympho-myeloid repopulating potential in NOD/SCID mouse xeno-transplantation model with long term functional capacity. We conclude that ACA is an essential regulator of the genes involved in maintaining hematopoiesis and its use in clinical praxis could overcome many of the barriers present so far in transplantation medicine.
Subject(s)
Blood Proteins/physiology , Hematopoiesis , Membrane Glycoproteins/physiology , Animals , Antigens, CD34/metabolism , Cell Proliferation , Cells, Cultured , Fetal Blood/cytology , Hematopoietic Stem Cell Transplantation , Hematopoietic Stem Cells/physiology , Heterografts , Humans , Leukocytes, Mononuclear/physiology , Mice , Mice, Inbred NOD , Mice, SCID , Phosphorylation , Protein Processing, Post-Translational , Up-Regulation , Wnt Signaling PathwayABSTRACT
Reprogramming of human somatic cells by transcription factors to pluripotent state holds great promise for regenerative medicine. However, low efficiencies of current reprogramming methods, immunogenicity and lack of understanding regarding the molecular mechanisms responsible for their generation, limits their utilization and raises questions regarding safety for therapeutic application. Here we report that ACA signaling via PI3K/Akt/mTor induces sustained de-differentiation of human blood progenitor cells leading to generation of ACA pluripotent stem cells. Blood-derived pluripotent stem cells differentiate in vitro into cell types of all three germ layers, exhibiting neuronal, liver, or endothelial characteristics. Our results reveal insight into the molecular events regulating cellular reprogramming and also indicate that pluripotency might be controlled in vivo through binding of a natural ligand(s) to ACA receptor enabling reprogramming through defined pathway(s) and providing a safe and efficient method for generation of pluripotent stem cells which could be a breakthrough in human therapeutics.
