• Manning Cantrell posted an update 1 week ago

    Despite decades of progress in our understanding of hematopoiesis through the study of animal models and transplantation in humans, investigating physiological human hematopoiesis directly has remained challenging. Selleckchem Envonalkib Questions on the clonal structure of the human hematopoietic stem cell (HSC) pool, such as “how many HSCs are there?” and “do all HSC clones actively produce all blood cell types in equal proportions?” remain open. These questions have inherent value for understanding normal human physiology, but also directly inform our comprehension of the process by which the system is subverted to drive diseases of the blood, in particular blood cancers and bone marrow failure syndromes. The critical link between normal and abnormal hematopoiesis is perhaps best illustrated by the recent discovery of clonal hematopoiesis in healthy people with no abnormal blood parameters. In such individuals, large clones derived from single cells are present and are dominant relative to their normal counterparts, but their presence does not necessitate abnormal blood cell production. Intriguingly, however, these individuals are also at a significantly greater risk of developing leukemias and of cardiovascular events, underscoring the importance of understanding how blood stem cell clones compete against each other. The histone lysine demethylase KDM5 family is implicated in normal development and stem cell maintenance by epigenetic modulation of histone methylation status. Deregulation of the KDM5 family has been reported in various types of cancers, including hematological malignancies. However, their transcriptional regulatory roles in the context of leukemia remain unclear. Here, we find that KDM5B is strongly expressed in normal CD34+ hematopoietic stem/progenitor cells and chronic myeloid leukemia (CML) cells. Knockdown of KDM5B in K562 CML cells reduced leukemia colony-forming potential. Transcriptome profiling of KDM5B knockdown K562 cells revealed the deregulation of genes involved in myeloid differentiation and Toll-like receptor signaling. Through the integration of transcriptome and ChIP-seq profiling data, we show that KDM5B is enriched at the binding sites of the GATA and AP-1 transcription factor families, suggesting their collaborations in the regulation of transcription. Even though the binding of KDM5B substantially overlapped with H3K4me1 or H3K4me3 mark at gene promoters, only a small subset of the KDM5B targets showed differential expression in association with the histone demethylation activity. By characterizing the interacting proteins in K562 cells, we discovered that KDM5B recruits protein complexes involved in the mRNA processing machinery, implying an alternative epigenetic action mediated by KDM5B in gene regulation. Our study highlights the oncogenic functions of KDM5B in CML cells and suggests that KDM5B is vital to the transcriptional regulation via multiple epigenetic mechanisms. Characterization of human cells that sustain blood cell production lifelong has historically been inferred from phenotypically defined subsets of cells assayed in vitro, in transplanted immunodeficient mice, or in patients transplanted with genetically marked cells. These approaches have led to the concept of a persistent complex hierarchical process of differentiation divisions originating from a rare population of CD34+CD38-CD45RA-CD90+CD49f+ cells with an average self-renewal potential of >0.5 and an ability to produce some or all blood cell types for >1 year. However, the role of these “49f” cells in the unperturbed adult has remained poorly understood. To address this gap, somatic single-nucleotide polymorphisms (SNVs) have recently been exploited as lineage tracing markers to enumerate and characterize active hematopoietic clones in normal adults using a capture and recapture approach. We show here that the use of somatic transversions to identify somatically acquired variant alleles enabled their detection in bulk populations at frequencies of approximately 1 in 80,000 cells. We then applied this method to blood cells isolated from two normal adults (aged 31 and 53 years) over a 1- to 3-year period. The results revealed in both donors a continued clonal output of both T- and B-lymphoid cells as well as myeloid cells identified by the same unique transversions found to distinguish single 49f cells isolated from the same donors’ initial blood samples. These findings provide the first evidence of a continuing hematopoietic stem cell-derived source of all mature blood cell types in normal (unperturbed) adult humans. Pathological scar is a common complication after wound healing. One of the most important factors that affects scar formation is inflammation. During this process, macrophages play a critical role in the wound healing process, as well as in scar formation. Notch signaling is reported to participate in inflammation and fibrosis; however, whether it affects scar formation is still unclear. In this study, RBP-J knockout mice, in which Notch signaling was down-regulated, and control mice were used, and a skin incision model was established. Sirius red staining and Masson staining suggested that RBP-J knockout could significantly reduce collagen sedimentation after wound healing. Western blot analysis and RT-PCR also confirmed the results. During wound healing, the expression of inflammatory cytokines and macrophage infiltration were decreased in RBP-J knockout mice. In vitro, it was also verified that RBP-J deficiency in macrophages effectively suppressed the expression of inflammatory cytokines and chemotaxis of macrophages after LPS stimulation. In conclusion, blocking Notch signaling in macrophages effectively alleviated scar formation by suppressing the inflammatory response and collagen sedimentation. INTRODUCTION AND OBJECTIVES Hospital readmissions are a major concern in terms of both cost and quality of care. The purpose of this study was to determine which patients were more likely to experience hospital readmissions after acute myocardial infarction in order to help develop more targeted programs and policies. PATIENTS AND MATERIALS AND METHODS The 2014 Nationwide Readmissions Database was used to calculate the national readmission rate by patient characteristics. All U.S. patients who presented to the hospital with acute myocardial infarction in 2014 and incurred a readmission were included in this analysis. The main outcome of interest was the rate of readmission by obesity. Obesity was measured using the comorbidity indicator found in the dataset. National secondary data of a sample of U.S. hospital discharges was used to measure hospital readmission rates. Bivariate analysis and logistic regression were used to determine if a significant relationship existed between readmissions and the patient characteristics.