Function of B-Cell CLL/Lymphoma 11B in Glial Progenitor Proliferation and Oligodendrocyte Maturation

Causal gene regulatory analysis with RNA velocity reveals an interplay between slow and fast transcription factors

Single-cell expression dynamics, from differentiation trajectories or RNA velocity, have the potential to reveal causal links between transcription factors (TFs) and their target genes in gene regulatory networks (GRNs). However, existing methods either overlook these expression dynamics or necessitate that cells be ordered along a linear pseudotemporal axis, which is incompatible with branching trajectories. We introduce Velorama, an approach to causal GRN inference that represents single-cell differentiation dynamics as a directed acyclic graph of cells, constructed from pseudotime or RNA velocity measurements. Additionally, Velorama enables the estimation of the speed at which TFs influence target genes. Applying Velorama, we uncover evidence that the speed of a TF's interactions is tied to its regulatory function. For human corticogenesis, we find that slow TFs are linked to gliomas, while fast TFs are associated with neuropsychiatric diseases. We expect Velorama to become a critical part of the RNA velocity toolkit for investigating the causal drivers of differentiation and disease.

Williams-Beuren syndrome in pediatric T-cell acute lymphoblastic leukemia: A rare case report and review of literature

BACKGROUND

Williams-Beuren syndrome (WBS) is a rare genetic disorder caused by hemizygous microdeletion of contiguous genes on chromosome 7q11.23. Although the phenotype features extensive heterogeneity in severity and performance, WBS is not considered to be a predisposing factor for cancer development. Currently, hematologic cancers, mainly Burkitt lymphoma, are rarely reported in patients with WBS. Here in, we report a unique case of T-cell acute lymphoblastic leukemia in a male child with WBS.

METHODS

This retrospective study analyzed the clinical data of this case receiving chemotherapy were analyzed. This is a retrospective study.

RESULTS

The patient, who exhibited a typical WBS phenotype and presented with hemorrhagic spots. Chromosomal genome-wide chip analysis (CMA) revealed abnormalities on chromosomes 7 and 9. The fusion gene STIL-TAL1 and mutations in BCL11B, NOTCH1, and USP7 have also been found and all been associated with the occurrence of T-cell leukemia. The patient responded well to the chemotherapy.

CONCLUSION

To the best of our knowledge, this is the first reported case of WBS in T-cell acute lymphoblastic leukemia. We want to emphasize that the occurrence of leukemia in this patient might be related to the loss of 7q11.23 and microdeletion of 9p21.3 (including 3 TSGs), but the relationship between WBS and malignancy remains unclear. Further studies are required to clarify the relationship between WBS and malignancy.

Insulin signaling as a therapeutic mechanism of lithium in bipolar disorder

In this paper, we propose that lithium may exert its therapeutic effect in bipolar disorder by acting on insulin signaling pathways. Specifically, we assess the importance of the phosphatidylinositol 3-kinase/Protein Kinase B (PI3K/Akt) insulin signaling pathway and we assess how the action of lithium on both glycogen synthase kinase-3 (GSK3) and the phosphatidylinositol cycle may lead to mood stabilization mediated by PI3K/Akt insulin signaling. We also highlight evidence that several other actions of lithium (including effects on Akt, Protein kinase C (PKC), and sodium myo-inositol transporters) are putative mediators of insulin signaling. This novel mode of action of lithium is consistent with an emerging consensus that energy dysregulation represents a core deficit in bipolar disorder. It may also provide context for the significant co-morbidity between bipolar disorder, type 2 diabetes, and other forms of metabolic illness characterized by impaired glucose metabolism. It is suggested that developments in assessing neuronal insulin signaling using extracellular vesicles would allow for this hypothesis to be tested in bipolar disorder patients.

Hericium erinaceus mycelium and its small bioactive compounds promote oligodendrocyte maturation with an increase in myelin basic protein

Oligodendrocytes (OLs), myelin-producing glia in the central nervous system (CNS), produce a myelin extension that enwraps axons to facilitate action potential propagation. An effective approach to induce oligodendrogenesis and myelination is important to foster CNS development and promote myelin repair in neurological diseases. Hericium (H.) erinaceus, an edible and culinary-medicinal mushroom, has been characterized as having neuroprotective activities. However, its effect on OL differentiation has not yet been uncovered. In this study using oligodendrocyte precursor cell (OPC) cultures and an ex vivo cerebellar slice system, we found that the extract from H. erinaceus mycelium (HEM) not only promoted the differentiation of OPCs to OLs in the differentiation medium, but also increased the level of myelin basic protein (MBP) on neuronal fibers. Moreover, daily oral administration of HEM into neonatal rat pups for 7 days enhanced MBP expression and OLs in the corpus callosum of the postnatal rat brain. The effect of HEM-derived bioactive compounds, the diterpenoid xylosides erinacine A (HeA) and HeC and a sesterterpene with 5 isoprene units called HeS, were further evaluated. The results showed that HeA and HeS more potently stimulated MBP expression in OLs and increased the number of OLs. Moreover, overlap between MBP immunoreactivity and neuronal fibers in cultured cerebellar tissue slices was significantly increased in the presence of HeA and HeS. In summary, our findings indicate that HEM extract and its ingredients HeA and HeS display promising functional effects and promote OL maturation, providing insights into their potential for myelination in neurodevelopmental disorders.

Spatially mapped single-cell chromatin accessibility

High-throughput single-cell epigenomic assays can resolve cell type heterogeneity in complex tissues, however, spatial orientation is lost. Here, we present single-cell combinatorial indexing on Microbiopsies Assigned to Positions for the Assay for Transposase Accessible Chromatin, or sciMAP-ATAC, as a method for highly scalable, spatially resolved, single-cell profiling of chromatin states. sciMAP-ATAC produces data of equivalent quality to non-spatial sci-ATAC and retains the positional information of each cell within a 214 micron cubic region, with up to hundreds of tracked positions in a single experiment. We apply sciMAP-ATAC to assess cortical lamination in the adult mouse primary somatosensory cortex and in the human primary visual cortex, where we produce spatial trajectories and integrate our data with non-spatial single-nucleus RNA and other chromatin accessibility single-cell datasets. Finally, we characterize the spatially progressive nature of cerebral ischemic infarction in the mouse brain using a model of transient middle cerebral artery occlusion.

Spatial orientation of cells in an interconnected network is lost in high-throughput single-cell epigenomic assays. Here the authors present sciMAP-ATAC to produce spatially resolved single-cell ATAC-seq data.

Heterogeneity and Proliferative and Differential Regulators of NG2-glia in Physiological and Pathological States

NG2-glia, also called Oligodendrocyte Precursor Cells (OPCs), account for approximately 5%-10% of the cells in the developing and adult brain and constitute the fifth major cell population in the central nervous system. NG2-glia express receptors and ion channels involved in rapid modulation of neuronal activities and signaling with neuronal synapses, which have functional significance in both physiological and pathological states. NG2-glia participate in quick signaling with peripheral neurons via direct synaptic touches in the developing and mature central nervous system. These distinctive glia perform the unique function of proliferating and differentiating into oligodendrocytes in the early developing brain, which is critical for axon myelin formation. In response to injury, NG2-glia can proliferate, migrate to the lesions, and differentiate into oligodendrocytes to form new myelin sheaths, which wrap around damaged axons and result in functional recovery. The capacity of NG2-glia to regulate their behavior and dynamics in response to neuronal activity and disease indicate their critical role in myelin preservation and remodeling in the physiological state and in repair in the pathological state. In this review, we provide a detailed summary of the characteristics of NG2-glia, including their heterogeneity, the regulators of their proliferation, and the modulators of their differentiation into oligodendrocytes.

Bcl11b/Ctip2 in Skin, Tooth, and Craniofacial System

Ctip2/Bcl11b is a zinc finger transcription factor with dual action (repression/activation) that couples epigenetic regulation to gene transcription during the development of various tissues. It is involved in a variety of physiological responses under healthy and pathological conditions. Its role and mechanisms of action are best characterized in the immune and nervous systems. Furthermore, its implication in the development and homeostasis of other various tissues has also been reported. In the present review, we describe its role in skin development, adipogenesis, tooth formation and cranial suture ossification. Experimental data from several studies demonstrate the involvement of Bcl11b in the control of the balance between cell proliferation and differentiation during organ formation and repair, and more specifically in the context of stem cell self-renewal and fate determination. The impact of mutations in the coding sequences of Bcl11b on the development of diseases such as craniosynostosis is also presented. Finally, we discuss genome-wide association studies that suggest a potential influence of single nucleotide polymorphisms found in the 3’ regulatory region of Bcl11b on the homeostasis of the cardiovascular system.

Bioinformatic identification and expression analysis of the chicken B cell lymphoma (BCL) gene

BACKGROUND

B cell lymphoma (BCL) families play an important role in apoptosis as a growth factor, cell death programming, cytokine expression and immune-related genes expression.

OBJECTIVES

In this study, to investigate the roles of BCLs, we performed genome-wide identification, expression and functional analyses of the BCL family in chicken.

METHODS

Chicken BCLs genes were identified and analyzed by using bioinformatics approach. Expression profiles and Hierarchical cluster analysis of the BCLs genes in different chicken tissues were obtained from the genome-wide RNA-seq in the GEO, and Cluster and Java Treeview, respectively.

RESULTS

A total of 16 BCLs genes were identified from the chicken genome, which could be further classified into five distinct groups in the phylogenetic tree. On the other hand, the interaction among BCLs proteins and between BCLs proteins with NF-κB subunits are limited, indicating that the remaining the functions of BCLs protein could be investigated in chicken. Moreover, KEGG pathway analysis indicated that BCL gene family was involved in regulation of apoptotic and immune response. Finally, BCL gene family was differentially expressed in chicken tissues, pathogen infection and growth stages of early chicken early embryo.

CONCLUSION

This study provides significant insights into the potential functions of BCLs in chicken, including the regulation of apoptosis, cell death and expression of immune-related genes.

Down-regulation of interleukin-33 expression in oligodendrocyte precursor cells impairs oligodendrocyte lineage progression

Interleukin-33 (IL-33), a member of the IL1 family, has been found to be expressed in oligodendrocytes (OLGs) and released as an alarmin from injured OLGs to work on other glial cell-types in the central nervous system. However, its functional role in OLGs remains unclear. Herein, we present that IL-33 was mainly expressed in the nucleus of CC1⁺ -oligodendrocytes (OLGs) in mouse and rat corpus callosum, as well as NG2⁺ -oligodendrocyte precursor cells (OPCs). The in vitro study indicated that the amount of IL-33 expressing in OPCs was higher when compared to that detected in OLGs. Results from the experiments using lentivirus-mediated shRNA delivery against IL-33 expression (IL33-KD) in OPCs showed that IL33-KD reduced the differentiation of OLGs into mature OLGs along with the down-regulation of OLG differentiation-related genes and mature OLG marker proteins, myelin basic protein (MBP) and proteolipid protein (PLP). Alternatively, we observed reduced differentiation of OLGs that were prepared from the brains of IL-33 gene knockout (IL33-KO) mice with anxiolytic-like behavior. Observations were correlated with the results showing lower levels of MBP and PLP in IL33-KO cultures than those detected in the control cultures prepared from wildtype (WT) mice. Transmission Electron Microscopy (TEM) analysis revealed that the myelin structures in the corpus callosum of the IL33-KO mice were impaired compared to those observed in the WT mice. Overall, this study provides important evidence that declined expression of IL-33 in OPCs suppresses the maturation of OLGs. Moreover, gene deficiency of IL-33 can disrupt OLG maturation and interfere with myelin compaction. Cover Image for this issue: doi: 10.1111/jnc.14522.

Chronic exposure to high fat diet triggers myelin disruption and interleukin-33 upregulation in hypothalamus

Background

Hypothalamic inflammation including astrogliosis and microglia activation occurs after intake of high fat diet (HFD) in rodent models or in obese individuals. However, the effect of chronic HFD feeding on oligodendrocytes (OLGs), a myelin-producing glial population in the central nervous system (CNS), remains unclear. In this study, we used 8-week old male C57BL/6 mice fed by HFD for 3–6 months to induce chronic obesity.

Results

The transmission electron microscopy imaging analysis showed that the integrity of hypothalamic myelin was disrupted after HFD feeding for 4 and 6 months. Moreover, the accumulation of Iba1⁺-microglia with an amoeboid hypertrophic form was continually observed in arcuate nucleus of HFD-fed mice during the entire feeding time period. Interleukin-33 (IL-33), a tissue alarmin upon injury to the CNS, was detected with an increased level in hypothalamus after HFD feeding for 3 and 4 months. Furthermore, the in vitro study indicated that exposure of mature OLGs to IL-33 impaired OLG cell structure along with a decline in the expression of myelin basic protein.

Conclusions

Altogether, our findings demonstrate that chronic HFD feeding triggers hypothalamic myelin disruption in accompany with IL-33 upregulation and prolonged microglial activation in hypothalamus. Given that the addition of exogenous IL-33 was harmful for the maturation of OLGs, an increase in IL-33 by chronic HFD feeding might contribute to the induction of hypothalamic myelin disruption.

Electronic supplementary material

The online version of this article (10.1186/s12868-019-0516-6) contains supplementary material, which is available to authorized users.

BRCA1/BRCA2-containing complex subunit 3 controls oligodendrocyte differentiation by dynamically regulating lysine 63-linked ubiquitination

Oligodendrocytes (OLs) provide the myelin sheath surrounding axons that propagates action potentials in the central nervous system (CNS). The metabolism of myelinated membranes and proteins is strictly regulated in the OLs and is closely associated with OL differentiation and maturation. The ubiquitination-associated proteasome and endosomal system have not yet been well studied during OL differentiation and maturation. Here, we determined the functions of the Lys63-linked ubiquitination (K63Ub) and K63-specific deubiquitination (DUB) systems regulated by BRCA1/BRCA2-containing complex subunit 3 (BRCC3) during OL differentiation. The competitive inhibition of K63Ub by overexpression of mutant ubiquitin (K63R) in oligodendrocyte precursor cells (OPCs) indicated that the two major CNS myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP), were upregulated in OLs derived from K63R OPCs. In contrast, the knockdown of BRCC3 (BRCC3-KD) through the application of lentivirus-mediated shRNA delivery system into OPCs suppressed OL differentiation by decreasing MBP expression and PLP production. Further immunoprecipitation assays revealed higher levels of sphingolipid GalC, MBP, and PLP, which were associated with K63Ub-immunoprecipitants and detected in endosome/lysosomal compartments, in BRCC3-KD OLs than those in OLs transfected with the scrambled shRNA (scramble OLs). The differentiation of OLs from BRCC3-KD OPCs was impaired in the demyelinating corpus callosum of rats receiving a cuprizone-containing diet. In the demyelinating tissues from human patients suffering from multiple sclerosis, we detected a decreased number of BRCC3-expressing OLs at the lesion site, accompanied by a greater number of OLs expressing EEA1 and K63Ub at high levels. Altogether, the counterbalance of the K63Ub machinery and BRCC3-triggered DUB machinery are important for the cellular trafficking of myelin proteins and OL differentiation.