Ectopic expression of C/EBPalpha and ID1 is sufficient to restore defective neutrophil development in low-risk myelodysplasia

The involvement of krüppel-like transcription factor 2 in megakaryocytic differentiation induction by phorbol 12-myrestrat 13-acetate

BACKGROUND

Megakaryocytic differentiation is a complicated process regulated by a series of transcription factors in a context- and stage-dependent manner. Recent studies have suggested that krüppel-like transcription factor 2 (KLF2) is involved in the control of embryonic erythroid precursor cell differentiation and maturation. However, the function and mechanism of KLF2 in regulating megakaryocytic differentiation remain unclear.

METHODS

The expression patterns of krüppel-like transcription factors (KLFs) during megakaryocytic differentiation were identified from public databases. Phorbol 12-myristate 13-acetate (PMA) treatment of the myeloid-erythroid-leukemic cell lines K562 and HEL were used as cellular megakaryocytic differentiation models. A lentiviral transduction system was utilized to achieve the goal of amplifying or reducing KLF2. The expression of KLF2 was examined using real-time PCR and western blot. The impact of KLF2 on the megakaryocytic differentiation of K562 cells was examined by flow cytometry, Giemsa staining, Phalloidin staining and western blot. RNA-sequencing (RNA-seq) and chromatin immunoprecipitation-sequencing (ChIP-seq) technologies were used to identify the KLF2-regulated targets.

RESULTS

KLF2 is increased in the maturation process of megakaryocytes. KLF2 overexpression accelerated the PMA-induced megakaryocytic differentiation, as reflected by an increased percentage of CD41/CD61 cells, an increased number of polyploid cells, and an elevated expression of P21 and P27. KLF2 knockdown exhibited the opposite results, indicating that KLF2 knockdown suppressed the megakaryocytic differentiation. Further, combination of the RNA-seq and ChIP-seq results suggested that chimerin 1 (CHN1) and potassium voltage-gated channel subfamily Q member 5 (KCNQ5) may be target genes regulated of KLF2. Both CHN1 and KCNQ5 knockdown could block the megakaryocytic differentiation to some content.

CONCLUSION

This study implicated a regulatory role of KLF2 in megakaryocytic differentiation, which may suggest KLF2 as a target for illness with abnormal megakaryocytic differentiation.

An AhR-Ovol1-Id1 regulatory axis in keratinocytes promotes skin homeostasis against atopic dermatitis

Skin is our outer permeability and immune defense barrier against myriad external assaults. Aryl hydrocarbon receptor (AhR) senses environmental factors and regulates barrier robustness and immune homeostasis. AhR agonist is in clinical trial for atopic dermatitis (AD) treatment, but the underlying mechanism of action remains ill-defined. Here we report OVOL1/Ovol1 as a conserved and direct transcriptional target of AhR in epidermal keratinocytes. We show that OVOL1/Ovol1 impacts AhR regulation of keratinocyte gene expression, and Ovol1 deletion in keratinocytes hampers AhR's barrier promotion function and worsens AD-like inflammation. Mechanistically, we identify Ovol1's direct downstream targets genome-wide, and provide in vivo evidence for Id1's critical role in barrier maintenance and disease suppression. Furthermore, our findings reveal an IL-1/dermal γδT cell axis exacerbating both type 2 and type 3 immune responses downstream of barrier perturbation in Ovol1 -deficient AD skin. Finally, we present data suggesting the clinical relevance of OVOL1 and ID1 function in human AD. Our study highlights a keratinocyte-intrinsic AhR-Ovol1-Id1 regulatory axis that promotes both epidermal and immune homeostasis against AD-like inflammation, implicating new therapeutic targets for AD.

Targeting cancer cell plasticity by HDAC inhibition to reverse EBV-induced dedifferentiation in nasopharyngeal carcinoma

Application of differentiation therapy targeting cellular plasticity for the treatment of solid malignancies has been lagging. Nasopharyngeal carcinoma (NPC) is a distinctive cancer with poor differentiation and high prevalence of Epstein-Barr virus (EBV) infection. Here, we show that the expression of EBV latent protein LMP1 induces dedifferentiated and stem-like status with high plasticity through the transcriptional inhibition of CEBPA. Mechanistically, LMP1 upregulates STAT5A and recruits HDAC1/2 to the CEBPA locus to reduce its histone acetylation. HDAC inhibition restored CEBPA expression, reversing cellular dedifferentiation and stem-like status in mouse xenograft models. These findings provide a novel mechanistic epigenetic-based insight into virus-induced cellular plasticity and propose a promising concept of differentiation therapy in solid tumor by using HDAC inhibitors to target cellular plasticity.

Recurrent Abnormal Clones in Myelodysplastic Syndrome Marrow Originate from Cells at a Pluripotent Stem Level and Maintain Their Early Differentiation Potency

OBJECTIVE

The present study aimed to investigate the origins and differentiation potencies of 4 common malignant clonal cell types (+8, 5q-/-5, 20q-/-20, 7q-/-7) in myelodysplastic syndrome (MDS) and to investigate whether the trisomy of chromosome 8 occurs subsequently to other chromosomal abnormalities.

METHODS

The present study analyzed a total of 46 cases of chromosomal abnormalities in MDS patients. The magnetic activated cell sorting technique (MACS) was used to sort the CD34(+)CD38(-) (pluripotent hematopoietic stem cells) and CD34(+)CD38(+) cells (committed progenitor cells) from the bone marrow mononuclear cells (BMNCs) of these patients; the sorted cells were then individually smeared. Meanwhile, cytospins were prepared from the remaining CD34(-) BMNCs after cell sorting. The clonal cell proportions in these three types of smears were detected by fluorescence in situ hybridization (FISH). Cases in which +8 was associated with another abnormality (2 cases each in combination with abnormalities in chromosomes 7, 5, and 20) were dually hybridized with the cep8 probe and another corresponding probe.

RESULTS

(1) for abnormalities of +8, 5q-/-5, 20q-/-20 or chromosome 7 involvements, clonal cells above the baseline level were detected in the pluripotent stem cell level. (2) The average clonal cell proportion in the committed progenitor cells of the 46 cases increased to 75.3% from 57.3% at the level of stem cell (p < 0.001). The groups with +8 and chromosome 5 abnormalities showed a statistically significant increase in clonal cells at the progenitor cell stage. At the individual level, 33 of 46 cases showed significant increases in clonal cells at the progenitor cell stage relative to the stem cell stage, whereas the clonal cell proportion in the CD34(-) BMNCs generally did not increase relative to the committed progenitor cell population. (3) The dual hybridization analysis showed that if +8 and another abnormality were present in the same abnormal clone according to G-banding, +8 always coexisted with the other chromosomal abnormality at the single cell level; there were no situations in which +8 occurred later than the other chromosomal abnormality.

CONCLUSION

It seems that the all malignant MDS clones originated at the pluripotent hematopoietic stem cell stage and that the proliferation and differentiation potencies were retained partly in these clonal cells. The present study failed to confirm that the trisomy 8 occurred subsequently to the other abnormalities, but some in vitro or transplant experiments maybe prove the succession of clonal origination.

Id1 suppresses anti-tumour immune responses and promotes tumour progression by impairing myeloid cell maturation

A central mechanism of tumour progression and metastasis involves the generation of an immunosuppressive ‘macroenvironment' mediated in part through tumour-secreted factors. Here we demonstrate that upregulation of the Inhibitor of Differentiation 1 (Id1), in response to tumour-derived factors, such as TGFβ, is responsible for the switch from dendritic cell (DC) differentiation to myeloid-derived suppressor cell expansion during tumour progression. Genetic inactivation of Id1 largely corrects the myeloid imbalance, whereas Id1 overexpression in the absence of tumour-derived factors re-creates it. Id1 overexpression leads to systemic immunosuppression by downregulation of key molecules involved in DC differentiation and suppression of CD8 T-cell proliferation, thus promoting primary tumour growth and metastatic progression. Furthermore, advanced melanoma patients have increased plasma TGFβ levels and express higher levels of ID1 in myeloid peripheral blood cells. This study reveals a critical role for Id1 in suppressing the anti-tumour immune response during tumour progression and metastasis.

Tumour progression is promoted by the generation of an immunosuppressive macroenvironment. Here, the authors demonstrate that the Inhibitor of Differentiation 1 promotes the switch from dendritic cell differentiation towards myeloid-derived suppressor cell expansion during tumour progression.

The gene signature in CCAAT-enhancer-binding protein α dysfunctional acute myeloid leukemia predicts responsiveness to histone deacetylase inhibitors

C/EPBα proteins, encoded by the CCAAT-enhancer-binding protein α gene, play a crucial role in granulocytic development, and defects in this transcription factor have been reported in acute myeloid leukemia. Here, we defined the C/EBPα signature characterized by a set of genes up-regulated upon C/EBPα activation. We analyzed expression of the C/EBPα signature in a cohort of 525 patients with acute myeloid leukemia and identified a subset characterized by low expression of this signature. We referred to this group of patients as the C/EBPα dysfunctional subset. Remarkably, a large percentage of samples harboring C/EBPα biallelic mutations clustered within this subset. We hypothesize that re-activation of the C/EBPα signature in the C/EBPα dysfunctional subset could have therapeutic potential. In search for small molecules able to reverse the low expression of the C/EBPα signature we applied the connectivity map. This analysis predicted positive connectivity between the C/EBPα activation signature and histone deacetylase inhibitors. We showed that these inhibitors reactivate expression of the C/EBPα signature and promote granulocytic differentiation of primary samples from the C/EBPα dysfunctional subset harboring biallelic C/EBPα mutations. Altogether, our study identifies histone deacetylase inhibitors as potential candidates for the treatment of certain leukemias characterized by down-regulation of the C/EBPα signature.

Kinase AKT1 negatively controls neutrophil recruitment and function in mice

Neutrophils are critically involved in host defense and inflammatory injury. However, intrinsic signaling mechanisms controlling neutrophil recruitment and activities are poorly defined. In this article, we showed that protein kinase AKT1 (also known as PKBα) is the dominant isoform expressed in neutrophils and is downregulated upon bacterial infection and neutrophil activation. AKT1 deficiency resulted in severe disease progression accompanied by recruitment of neutrophils and enhanced bactericidal activity in the acute inflammatory lung injury (ALI) and the Staphylococcus aureus infection mouse models. Moreover, the depletion of neutrophils efficiently reversed the aggravated inflammatory response, but adoptive transfer of AKT1(-/-) neutrophils could potentiate the inflammatory immunity, indicating an intrinsic effect of the neutrophil in modulating inflammation in AKT1(-/-) mice. In the ALI model, the infiltration of neutrophils into the inflammatory site was associated with enhanced migration capacity, whereas inflammatory stimuli could promote neutrophil apoptosis. In accordance with these findings, neutralization of CXCR2 attenuated neutrophil infiltration and delayed the occurrence of inflammation. Finally, the enhanced bactericidal activity and inflammatory immunity of AKT-deficient neutrophils were mediated by a STAT1-dependent, but not a mammalian target of rapamycin-dependent, pathway. Thus, our findings indicated that the AKT1-STAT1 signaling axis negatively regulates neutrophil recruitment and activation in ALI and S. aureus infection in mice.

Id1: a novel therapeutic target for patients with atherosclerotic plaque rupture

Plaque neovascularization and inflammation are responsible for plaque destabilization and rupture. However, the precise triggers for inflammation and neovascularization in atherosclerosis are largely unknown. Id1 (inhibitor of DNA-binding) protein is a helix-loop-helix transcription factor and plays an important role in angiogenesis and inflammation. The expression of Id1 can be up-regulated by plaque formation factors such as vascular endothelial growth factor (VEGF), hypoxia, NAD(P)H oxidase, and TNF-alpha. Moreover, Id1 is critical to endothelial progenitor cell (EPC) population formation and angiogenesis. Evidence from diverse sources has suggested that Id1 may affect plaque destabilization through angiogenesis and inflammation. Herein we hypothesize that Id1 is an important protein for the development and progression of atherosclerotic plaque destabilization and hence blocking the expression of Id1 may serve as new targets for antiatherogenic therapy.