BAP1 shapes the bone marrow niche for lymphopoiesis by fine-tuning epigenetic profiles in endosteal mesenchymal stromal cells

Histone H2A deubiquitinase BAP1 is essential for endothelial cell differentiation from human pluripotent stem cells

Polycomb group proteins (PcGs) add repressive post translational histone modifications such as H2AK119ub1, and histone H2A deubiquitinases remove it. Mice lacking histone H2A deubiquitinases such as Usp16 and Bap1 die in embryonic stage, while mice lacking Usp3, Mysm1, Usp12, and Usp21 have been shown to be deficient in hematopoietic lineage differentiation, cell cycle regulation, and DNA repair. Thus, it is likely that histone deubiquitinases may also be required for human endothelial cell differentiation; however, there are no reports about the role of histone H2A deubiquitinase BAP1 in human endothelial cell development. We differentiated human pluripotent stem cells into the endothelial lineage which expressed stable inducible shRNA against BAP1. Our results show that BAP1 is required for human endothelial cell differentiation.

Identification of mitophagy-related hub genes during the progression of spinal cord injury by integrated multinomial bioinformatics analysis

Spinal cord injury (SCI) is a disturbance of peripheral and central nerve conduction that causes disability in sensory and motor function. Currently, there is no effective treatment for SCI. Mitophagy plays a vital role in mitochondrial quality control during various physiological and pathological processes. The study aimed to elucidate the role of mitophagy and identify potential mitophagy-related hub genes in SCI pathophysiology. Two datasets (GSE15878 and GSE138637) were analyzed. Firstly, the differentially expressed genes (DEGs) were identified and mitophagy-related genes were obtained from GeneCards, then the intersection between SCI and mitophagy-related genes was determined. Next, we performed gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), protein-protein interaction network (PPI network), least absolute shrinkage and selection operator (LASSO), and cluster analysis to identify and define the hub genes in SCI. Finally, the link between hub genes and infiltrating immune cells was investigated and the potential transcriptional regulation/small molecular compounds to target hub genes were predicted. In total, SKP1 and BAP1 were identified as hub genes of mitophagy-related DEGs during SCI development and regulatory T cells (Tregs)/resting NK cells/activated mast cells may play an essential role in the progression of SCI. LINC00324 and SNHG16 may regulate SKP1 and BAP1, respectively, through miRNAs. Eleven and eight transcriptional factors (TFs) regulate SKP1 and BAP1, respectively, and six small molecular compounds target BAP1. Then, the mRNA expression levels of BAP1 and SKP1 were detected in the injured sites of spinal cord of SD rats at 6 h and 72 h after injury using RT-qPCR, and found that the level were decreased. Therefore, the pathways of mitophagy are downregulated during the pathophysiology of SCI, and SKP1 and BAP1 could be accessible targets for diagnosing and treating SCI.

B-cell intrinsic regulation of antibody mediated immunity by histone H2A deubiquitinase BAP1

Introduction

BAP1 is a deubiquitinase (DUB) of the Ubiquitin C-terminal Hydrolase (UCH) family that regulates gene expression and other cellular processes, through its direct catalytic activity on the repressive epigenetic mark histone H2AK119ub, as well as on several other substrates. BAP1 is also a highly important tumor suppressor, expressed and functional across many cell types and tissues. In recent work, we demonstrated a cell intrinsic role of BAP1 in the B cell lineage development in murine bone marrow, however the role of BAP1 in the regulation of B cell mediated humoral immune response has not been previously explored.

Methods and results

In the current study, we demonstrate that a B-cell intrinsic loss of BAP1 in activated B cells in the Bap1 fl/fl Cγ1-cre murine model results in a severe defect in antibody production, with altered dynamics of germinal centre B cell, memory B cell, and plasma cell numbers. At the cellular and molecular level, BAP1 was dispensable for B cell immunoglobulin class switching but resulted in an impaired proliferation of activated B cells, with genome-wide dysregulation in histone H2AK119ub levels and gene expression.

Conclusion and discussion

In summary, our study establishes the B-cell intrinsic role of BAP1 in antibody mediated immune response and indicates its central role in the regulation of the genome-wide landscapes of histone H2AK119ub and downstream transcriptional programs of B cell activation and humoral immunity.

Aged mesenchymal stem cells and inflammation: from pathology to potential therapeutic strategies

Natural ageing of organisms and corresponding age-related diseases result mainly from stem cell ageing and "inflammaging". Mesenchymal stem cells (MSCs) exhibit very high immune-regulating capacity and are promising candidates for immune-related disease treatment. However, the effect of MSC application is not satisfactory for some patients, especially in elderly individuals. With ageing, MSCs undergo many changes, including altered cell population reduction and differentiation ability, reduced migratory and homing capacity and, most important, defective immunosuppression. It is necessary to explore the relationship between the "inflammaging" and aged MSCs to prevent age-related diseases and increase the therapeutic effects of MSCs. In this review, we discuss changes in naturally ageing MSCs mainly from an inflammation perspective and propose some ideas for rejuvenating aged MSCs in future treatments.

The quest for the holy grail: overcoming challenges in expanding human hematopoietic stem cells for clinical use

Hematopoietic stem cell (HSC) transplantation has been the golden standard for many hematological disorders. However, the number of HSCs obtained from several sources, including umbilical cord blood (UCB), often is insufficient for transplantation. For decades, maintaining or even expanding HSCs for therapeutic purposes has been a "holy grail" in stem cell biology. Different methods have been proposed to improve the efficiency of cell expansion and enhance homing potential such as co-culture with stromal cells or treatment with specific agents. Recent progress has shown that this is starting to become feasible using serum-free and well-defined media. Some of these protocols to expand HSCs along with genetic modification have been successfully applied in clinical trials and some others are studied in preclinical and clinical studies. However, the main challenges regarding ex vivo expansion of HSCs such as limited growth potential and tendency to differentiate in culture still need improvements. Understanding the biology of blood stem cells, their niche and signaling pathways has provided possibilities to regulate cell fate decisions and manipulate cells to optimize expansion of HSCs in vitro. Here, we review the plethora of HSC expansion protocols that have been proposed and indicate the current state of the art for their clinical application.

Epigenetic regulation in hematopoiesis and its implications in the targeted therapy of hematologic malignancies

Hematologic malignancies are one of the most common cancers, and the incidence has been rising in recent decades. The clinical and molecular features of hematologic malignancies are highly heterogenous, and some hematologic malignancies are incurable, challenging the treatment, and prognosis of the patients. However, hematopoiesis and oncogenesis of hematologic malignancies are profoundly affected by epigenetic regulation. Studies have found that methylation-related mutations, abnormal methylation profiles of DNA, and abnormal histone deacetylase expression are recurrent in leukemia and lymphoma. Furthermore, the hypomethylating agents and histone deacetylase inhibitors are effective to treat acute myeloid leukemia and T-cell lymphomas, indicating that epigenetic regulation is indispensable to hematologic oncogenesis. Epigenetic regulation mainly includes DNA modifications, histone modifications, and noncoding RNA-mediated targeting, and regulates various DNA-based processes. This review presents the role of writers, readers, and erasers of DNA methylation and histone methylation, and acetylation in hematologic malignancies. In addition, this review provides the influence of microRNAs and long noncoding RNAs on hematologic malignancies. Furthermore, the implication of epigenetic regulation in targeted treatment is discussed. This review comprehensively presents the change and function of each epigenetic regulator in normal and oncogenic hematopoiesis and provides innovative epigenetic-targeted treatment in clinical practice.