RUNX1-205, a novel splice variant of the human RUNX1 gene, has blockage effect on mesoderm-hemogenesis transition and promotion effect during the late stage of hematopoiesis

ADA2 regulates inflammation and hematopoietic stem cell emergence via the A2bR pathway in zebrafish

Deficiency of adenosine deaminase 2 (DADA2) is an inborn error of immunity caused by loss-of-function mutations in the adenosine deaminase 2 (ADA2) gene. Clinical manifestations of DADA2 include vasculopathy and immuno-hematological abnormalities, culminating in bone marrow failure. A major gap exists in our knowledge of the regulatory functions of ADA2 during inflammation and hematopoiesis, mainly due to the absence of an ADA2 orthologue in rodents. Exploring these mechanisms is essential for understanding disease pathology and developing new treatments. Zebrafish possess two ADA2 orthologues, cecr1a and cecr1b, with the latter showing functional conservation with human ADA2. We establish a cecr1b-loss-of-function zebrafish model that recapitulates the immuno-hematological and vascular manifestations observed in humans. Loss of Cecr1b disrupts hematopoietic stem cell specification, resulting in defective hematopoiesis. This defect is caused by induced inflammation in the vascular endothelium. Blocking inflammation, pharmacological modulation of the A2r pathway, or the administration of the recombinant human ADA2 corrects these defects, providing insights into the mechanistic link between ADA2 deficiency, inflammation and immuno-hematological abnormalities. Our findings open up potential therapeutic avenues for DADA2 patients.

Heterogeneous nuclear ribonucleoprotein K is overexpressed in acute myeloid leukemia and causes myeloproliferation in mice via altered Runx1 splicing

Acute myeloid leukemia (AML) is driven by numerous molecular events that contribute to disease progression. Herein, we identify hnRNP K overexpression as a recurrent abnormality in AML that negatively correlates with patient survival. Overexpression of hnRNP K in murine fetal liver cells results in altered self-renewal and differentiation potential. Further, murine transplantation models reveal that hnRNP K overexpression results in myeloproliferation in vivo. Mechanistic studies expose a direct functional relationship between hnRNP K and RUNX1-a master transcriptional regulator of hematopoiesis often dysregulated in leukemia. Molecular analyses show that overexpression of hnRNP K results in an enrichment of an alternatively spliced isoform of RUNX1 lacking exon 4. Our work establishes hnRNP K's oncogenic potential in influencing myelogenesis through its regulation of RUNX1 splicing and subsequent transcriptional activity.

Colloidal Self-Assembled Patterns Maintain the Pluripotency and Promote the Hemopoietic Potential of Human Embryonic Stem Cells

The generation of blood cells in a significant amount for clinical uses is still challenging. Human pluripotent stem cells-derived hemopoietic cells (hPSC-HCs) are a promising cell source to generate blood cells. Previously, it has been shown that the attached substrates are crucial in the maintenance or differentiation of hPSCs. In this study, a new family of artificial extracellular matrix (ECM) called colloidal self-assembled patterns (cSAPs: #1-#5) was used for the expansion of mouse and human PSCs. The optimized cSAP (i.e., #4 and #5) was selected for subsequent hemopoietic differentiation of human embryonic stem cells (hESCs). Results showed that the hematopoietic potential of hESCs was enhanced approx 3-4 folds on cSAP #5 compared to the flat control. The cell population of hematopoietic progenitors (i.e., CD34+CD43+ cells) and erythroid progenitors (i.e., CD71+GPA+ cells) were enhanced 4 folds at day 8 and 3 folds at day 14. RNA sequencing analysis of cSAP-derived hESCs showed that there were 300 genes up-regulated and 627 genes down-regulated compared to the flat control. The enriched signaling pathways, including up-regulation (i.e., Toll-like receptor, HIF-1a, and Notch) or down-regulation (i.e., FAs, MAPK, JAK/STAT, and TGF-β) were classic in the maintenance of hESC phenotype Real time PCR confirmed that the expression of focal adhesion (PTK2, VCL, and CXCL14) and MAPK signaling (CAV1) related genes was down-regulated 2-3 folds compared to the flat control. Altogether, cSAP enhances the pluripotency and the hematopoietic potential of hESCs that subsequently generates more blood-like cells. This study reveals the potential of cSAPs on the expansion and early-stage blood cell lineage differentiation of hPSCs.