Hypoxia-inducible factor-1 drives the motility of the erythroid progenitor cell line, UT-7/Epo, via autocrine motility factor

WRN protein as a novel erythroblast immunohistochemical marker with applications for the diagnosis of Werner syndrome

Genetic testing for mutations in the WRN gene is critical for the diagnosis of Werner syndrome (WS); however, these tests cannot be performed in a clinical setting. Nearly all of the WRN mutations result in expression of truncated WRN proteins that are missing the C-terminal nuclear localization signal. We evaluated the use of WRN protein immunohistochemistry for diagnosing WS using paraffin-embedded bone marrow sections. Using a well-defined commercially available polyclonal antibody against the C terminus of WRN, we found that of all the cell types tested, bone marrow erythroid precursors showed the strongest nuclear expression of WRN. Immunohistochemical analysis of bone marrow samples from 120 patients with non-WS hematological disorders (age range, 7 days-90 years) revealed WRN staining of the nuclei of CD71-positive early and late erythroid precursors. Erythroblasts negative for WRN immunostaining were only observed in two patients, both of whom were diagnosed with WS: one with concomitant myelodysplastic syndrome and the other with erythroleukemia with overexpression of TP53. Western blot analysis and immunocytochemistry indicated WRN was localized in the nuclei of the four positive control cell lines from non-WS patients but not in the five cell lines from WS patients, who had three different types of WRN mutations. Thus, immunohistochemical detection of WRN in erythroblasts from bone marrow paraffin sections could be useful in screening of WS cases and worthy of further molecular confirmation.

Involvement of miRNA in erythroid differentiation

miRNAs are a family of small ncRNAs that regulate gene expression by targeting mRNAs in a sequence-specific manner, inducing translational repression or mRNA degradation. In this review, we present and discuss the available literature on the expression of miRNAs in erythroid cells. There are several experimental systems that can be employed for studies focusing on the relationship between miRNAs and erythroid differentiation, including human embryonic stem cells forced to erythroid differentiation, K562 and UT-7 cells induced to hemoglobin production by chemical compounds, erythropoietin-treated erythroid precursor cells from normal subjects or patients affected by hematological disease and in vivo systems, such as zebrafish embryos. Several miRNAs were identified as deeply involved in the erythroid phenotype, including miR-15a, miR-16-1, miR-126, miR-144, miR-451 and miR-210. Several functions related with erythroid cells were demonstrated to be regulated by these miRNAs, including maturation and proliferation of early erythroid cells, expression of fetal γ-globin genes and enucleation. These identified erythroid specific miRNAs represent the starting point to develop new protocols for miRNA therapeutics, based on both anti-miR molecules or miRNA replacement.

Establishment and characterization of chronic-hypoxia-resistant gastric cancer cell line MNK45/HYP

The chronic-hypoxia-resistant gastric cancer cell line was established, and its biological characteristics were explored and compared with the parental cell line. Gastric cancer cell lines were cultured under the degressive oxygen concentration. Cell doubling time was calculated by cell counting method. Chemo-resistance ability of cells was tested by MTT assay. Irradiation tolerance of cells was evaluated by colony forming method. Cell cycle distribution was tested with flow cytometry. Invasive ability was tested by Transwell method. The expression levels of GLUT-1 and HIF-1α were detected by using Western blot. MNK45/HYP cells successfully survived under the 1% concentration of oxygen and its cell doubling time was 35.01±1.02 h, while that of MNK45 was 27.35±0.83 h (P<0.01). The percentage of MNK45/HYP cells in G(0)/G(1) stage was (58.3±6.1)%, and that of MNK45 cells was (42.2±6.0)% (P<0.05). Comparing with the parental cells MNK45, drug resistance indexes of 5-Fu, PTX, OXA, Sn38, GEM and VP16 in MNK45/HYP cells were respectively 5.3, 1.3, 3.6, 2.2, 4.8 and 4.4. Colony forming ability of MNK45/HYP cells after irradiation was also significantly higher than MNK45 cells. The invasive number of MNK45/HYP cells was 107.7±17.5, while that of MNK45 cells was 59.0±9.9. The expression levels of GLUT-1 and HIF-1α in MNK45/HYP cells were significantly higher than those in MNK45 cells. MNK45/HYP cells hold biological characteristics of hypoxia tumor with good tolerance to chronic hypoxia, and can be used for the research of solid tumor under chronic hypoxia condition.

Low oxygen concentration as a general physiologic regulator of erythropoiesis beyond the EPO-related downstream tuning and a tool for the optimization of red blood cell production ex vivo

OBJECTIVE

The control of mature erythroid progenitors and precursors' production via erythropoietin (EPO) is the major systemic regulatory mechanism in erythropoiesis. However, hypoxia seems to influence erythropoiesis beyond this well-known mechanism. The aim of our study is to test this hypothesis adapting the oxygenation level to each stage of erythropoiesis.

MATERIALS AND METHODS

We exploited the newly developed ex vivo three-phase protocol for red blood cell (RBC) production starting from the steady-state peripheral blood and cord blood CD34(+) cells exposed to adapted O(2) concentrations. Differentiation and maturation were followed by functional tests, morphology, immunophenotype, and analysis of molecular markers' expression.

RESULTS

We report here an enhancement of total RBC production if low O(2) concentrations (1.5-5%) were applied, instead of 20% O(2), during the first phase of culture. This results from a comprehensive action of low-O(2) concentration on: 1) amplification of erythroid progenitors, 2) acceleration of their proliferation, 3) differentiation, and 4) maturation of erythroid precursors. In addition, arterial blood O(2) concentration (13%) is critical for stromal cells to fully sustain the differentiation of erythroid precursors. These effects were associated with upregulation of erythroid 5-aminolevulinate synthase and gamma-globin gene expression.

CONCLUSION

These results imply that integral regulation of erythropoiesis is operated by low O(2) concentrations, beyond the EPO/EPO-responsive cells loop and provide a tool to optimize the technology for ex vivo production of RBC.

Expression of hypoxia-inducible factor 1alpha in mononuclear phagocytes infected with Leishmania amazonensis

Increasing evidence indicates that hypoxia-inducible factor 1alpha (HIF-1alpha) can be upregulated in different cell types by nonhypoxic stimuli such as growth factors, cytokines, nitric oxide, lipopolysaccharides and a range of infectious microorganisms. In this study, the ability of the following mononuclear phagocytes to express HIF-1alpha is reported: mouse macrophages (mMPhi), human macrophages (hMPhi) and human dendritic cells (DC), parasitized in vitro with Leishmania amazonensis; as assessed by immunofluorescence microscopy. A logical explanation for HIF-1alpha expression might be that the mononuclear phagocytes became hypoxic after L. amazonensis infection. Using the hypoxia marker pimonidazole, observation revealed that L. amazonensis-infected cells were not hypoxic. In addition, experiments using a HIF-1alpha inhibitor, CdCl(2), to treat L. amazonensis-infected macrophage cultures showed reduced parasite survival. These studies indicated that HIF-1alpha could play a role in adaptative and immune responses of mononuclear phagocytes presenting infection by the parasite L. amazonensis.