2020年 · 第02卷第04期

Sickle cell disease (SCD) affects nearly 100,000 people in the United States of America and the sickle gene is present in approximately 8% of black Americans. Among Africans, the prevalence of sickle cell trait (heterozygosity) is as high as 30%. While SCD occurs among varying racial and ethnic groups, it is more commonly prevalent in individuals of African or African-American descent. This inherited blood disorder causes varying symptoms and complications among affected children and adults and early diagnosis and treatment are essential to help reduce mortality rates. Because there is no cure for SCD, management is vital to survival. Hence, there are different approaches in use to aid those living with SCD; thus, this paper provides insight into the current methods that are implemented in the management and maintenance of this disease.

The hematopoietic function of HOXC4 has not been extensively investigated. Our research indicated that induction of HOXC4 in co-culture system from D10 significantly promoted productions of most hematopoietic progenitor cells. CD34-CD43+ cells could be clearly classified into CD34-CD43^low and CD34-CD43^high sub-populations at D14. The former cells had greater myelogenic potential, and their production was not significantly influenced by induction of HOXC4. By contrast, the latter cells had greater potential to differentiate into megakaryocytes and erythroid cells, and thus had properties of erythroid-megakaryocyte common progenitors, which abundance was increased by ~2-fold when HOXC4 was induced from D10. For CD34-CD43^low, CD34+CD43+, and CD34-CD43^high sub-populations, CD43 level served as a natural index for the tendency to undergo hematopoiesis. Induction of HOXC4 from D10 caused more CD43+ cells sustain in S-phase with up-regulation of NF-κB signaling, which could be counteracted by inhibition of NF-κB signaling. These observations suggested that promotion of hematopoiesis by HOXC4 is closely related to NF-κB signaling and a change in cell-cycle status, which containing potential of clinical applications.

Ten-eleven translocation 2 (TET2) functions as a methylcytosine dioxygenase that catalyzes the iterative oxidation of 5-methylcytosine to 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxylcytosine. TET2 has been shown to be crucial for the maintenance and differentiation of hematopoietic stem cells, and its deletion and/or mutations results in the expansion of HSPCs, and leads to hematological malignancies. TET2 mutations were found in a variety of hematological disorders such as CMML (60%), MDS(30%), MPN (13%) and AML (20%). Interestingly, it was shown that CMML patients with TET2 mutation exhibited fewer platelets than CMML patients without TET2 mutation. However, the role and function of TET2 in platelet hemostasis and thrombogenesis is not well defined. Here in this study, using a genetically engineered Tet2 deletion mouse model, we found that the absence of Tet2 caused a decrease in the proportion of MEP cells and hyperploid megakaryocytes. Additionally, Tet2-deficient mice displayed impaired platelet activation and aggregation under stimulation of ADP and low concentrations of thrombin, although the modestly compromised platelet function and MEP differentiation in Tet2-deficient mice could be compensated without affecting blood coagulation function. Our study indicate that Tet2 deficiency leads to mild impairment of platelet function and thrombopoiesis in mice.

ALKBH3, a demethylase responsible for demethylating N1-methyladenosine (m¹A) in mRNA and N1-methyldeoxyadenosine in single-stranded DNA, plays an important role in DNA repair and cancer cell proliferation. However, its function in hematopoietic stem cells (HSCs) is unknown. In this study, we generated Alkbh3 knockout mice and observed that the deletion of Alkbh3 does not impair the reconstitution capacity of HSCs in both primary and secondary transplantation. Aged hematopoietic stem and progenitor cells exhibit increased expression of ALKBH3. Forced ALKBH3 rescued the differentiation skewing without affecting the reconstitution capacity of aged HSCs. In brief, our study for the first time investigated the functional role of ALKBH3 in hematopoietic system, and observed that ALKBH3 is dispensable for HSCs maintenance and differentiation, but overexpression of ALKBH3 rectified the differentiation skewing of aged HSCs.