Substance P receptor signaling contributes to host maladaptive responses during enteric bacterial infection.

Immune responses in the intestine are intricately balanced to prevent pathogen entry without inducing immunopathology. The nervous system is well-established to interface with the immune system to fine-tune immunity in various organ systems including the gastrointestinal tract. Specialized sensory neurons can detect bacteria, bacterial products, and the resulting inflammation, to coordinate the immune response in the gastrointestinal tract. These sensory neurons release peptide neurotransmitters such as Substance P (SP), to induce both neuronal signaling and localized responses in non-neuronal cells. With this in mind, we assessed the immunoregulatory roles of SP receptor signaling during enteric bacterial infection with the non-invasive pathogen Citrobacter rodentium . Pharmacological antagonism of the SP receptor significantly reduced bacterial burden and prevented colonic crypt hyperplasia. Mice with SP receptor signaling blockade had significantly reduced inflammation and recruitment of T-cells in the colon. Reduced colonic T-cell recruitment is due to reduced expression of adhesion molecules on colonic endothelial cells in SP receptor antagonist-treated mice. Using SP receptor T-cell conditional knockout mice, we further confirmed SP receptor signaling enhanced select aspects of T-cell responses. Our data demonstrates that SP receptor signaling can significantly reduce inflammation and prevent host-maladaptive responses without impinging upon host protection.

PHF2 regulates genome topology and DNA replication in neural stem cells via cohesin.

Cohesin plays a crucial role in the organization of topologically-associated domains (TADs), which influence gene expression and DNA replication timing. Whether epigenetic regulators may affect TADs via cohesin to mediate DNA replication remains elusive. Here, we discover that the histone demethylase PHF2 associates with RAD21, a core subunit of cohesin, to regulate DNA replication in mouse neural stem cells (NSC). PHF2 loss impairs DNA replication due to the activation of dormant replication origins in NSC. Notably, the PHF2/RAD21 co-bound genomic regions are characterized by CTCF enrichment and epigenomic features that resemble efficient, active replication origins, and can act as boundaries to separate adjacent domains. Accordingly, PHF2 loss weakens TADs and chromatin loops at the co-bound loci due to reduced RAD21 occupancy. The observed topological and DNA replication defects in PHF2 KO NSC support a cohesin-dependent mechanism. Furthermore, we demonstrate that the PHF2/RAD21 complex exerts little effect on gene regulation, and that PHF2's histone-demethylase activity is dispensable for normal DNA replication and proliferation of NSC. We propose that PHF2 may serve as a topological accessory to cohesin for cohesin localization to TADs and chromatin loops, where cohesin represses dormant replication origins directly or indirectly, to sustain DNA replication in NSC.

TRPV1 controls innate immunity during Citrobacter rodentium enteric infection.

Mucosal immunity is critical to host protection from enteric pathogens and must be carefully controlled to prevent immunopathology. Regulation of immune responses can occur through a diverse range of mechanisms including bi-directional communication with neurons. Among which include specialized sensory neurons that detect noxious stimuli due to the expression of transient receptor potential vanilloid receptor 1 (TRPV1) ion channel and have a significant role in the coordination of host-protective responses to enteric bacterial pathogens. Here we have used the mouse-adapted attaching and effacing pathogen Citrobacter rodentium to assess the specific role of TRPV1 in coordinating the host response. TRPV1 knockout (TRPV1-/-) mice had a significantly higher C. rodentium burden in the distal colon and fecal pellets compared to wild-type (WT) mice. Increased bacterial burden was correlated with significantly increased colonic crypt hyperplasia and proliferating intestinal epithelial cells in TRPV1-/- mice compared to WT. Despite the increased C. rodentium burden and histopathology, the recruitment of colonic T cells producing IFNγ, IL-17, or IL-22 was similar between TRPV1-/- and WT mice. In evaluating the innate immune response, we identified that colonic neutrophil recruitment in C. rodentium infected TRPV1-/- mice was significantly reduced compared to WT mice; however, this was independent of neutrophil development and maturation within the bone marrow compartment. TRPV1-/- mice were found to have significantly decreased expression of the neutrophil-specific chemokine Cxcl6 and the adhesion molecules Icam1 in the distal colon compared to WT mice. Corroborating these findings, a significant reduction in ICAM-1 and VCAM-1, but not MAdCAM-1 protein on the surface of colonic blood endothelial cells from C. rodentium infected TRPV1-/- mice compared to WT was observed. These findings demonstrate the critical role of TRPV1 in regulating the host protective responses to enteric bacterial pathogens, and mucosal immune responses.

TRPV1 controls innate immunity during Citrobacter rodentium enteric infection.

Mucosal immunity is critical to host protection from enteric pathogens and must be carefully controlled to prevent immunopathology. Regulation of immune responses can occur through a diverse range of mechanisms including bi-directional communication with the neurons. Among which include specialized sensory neurons that detect noxious stimuli due to the expression of transient receptor potential vanilloid receptor 1 (TRPV1) ion channel and have a significant role in the coordination of host-protective responses to enteric bacterial pathogens. Here we have used the mouse-adapted attaching and effacing pathogen Citrobacter rodentium to assess the specific role of the TRPV1 channel in coordinating the host response. TRPV1 knockout (TRPV1-/-) mice had a significantly higher C. rodentium burden in the distal colon and fecal pellets compared to wild-type (WT) mice. Increased bacterial burden was correlated with significantly increased colonic crypt hyperplasia and proliferating intestinal epithelial cells in TRPV1-/- mice compared to WT. Despite the increased C. rodentium burden and histopathology, the recruitment of colonic T cells producing IFNγ, IL-17, or IL-22 was similar between TRPV1-/- and WT mice. In evaluating the innate immune response, we identified that colonic neutrophil recruitment in C. rodentium infected TRPV1-/- mice was significantly reduced compared to WT mice; however, this was independent of neutrophil development and maturation within the bone marrow compartment. TRPV1-/- mice were found to have significantly decreased expression of the neutrophil-specific chemokine Cxcl6 and the adhesion molecules Icam1 in the distal colon compared to WT mice. Corroborating these findings, a significant reduction in ICAM-1 and VCAM-1, but not MAdCAM-1 protein on the surface of colonic blood endothelial cells from C. rodentium infected TRPV1-/- mice compared to WT was observed. These findings demonstrate the critical role of TRPV1 in regulating the host protective responses to enteric bacterial pathogens, and mucosal immune responses.

CAMK2D serves as a molecular scaffold for RNF8-MAD2 complex to induce mitotic checkpoint in glioma.

MAD2 is a spindle assembly checkpoint protein that participates in the formation of mitotic checkpoint complex, which blocks mitotic progression. RNF8, an established DNA damage response protein, has been implicated in mitotic checkpoint regulation but its exact role remains poorly understood. Here, RNF8 proximity proteomics uncovered a role of RNF8-MAD2 in generating the mitotic checkpoint signal. Specifically, RNF8 competes with a small pool of p31comet for binding to the closed conformer of MAD2 via its RING domain, while CAMK2D serves as a molecular scaffold to concentrate the RNF8-MAD2 complex via transient/weak interactions between its p-Thr287 and RNF8's FHA domain. Accordingly, RNF8 overexpression impairs glioma stem cell (GSC) mitotic progression in a FHA- and RING-dependent manner. Importantly, low RNF8 expression correlates with inferior glioma outcome and RNF8 overexpression impedes GSC tumorigenicity. Last, we identify PLK1 inhibitor that mimics RNF8 overexpression using a chemical biology approach, and demonstrate a PLK1/HSP90 inhibitor combination that synergistically reduces GSC proliferation and stemness. Thus, our study has unveiled a previously unrecognized CAMK2D-RNF8-MAD2 complex in regulating mitotic checkpoint with relevance to gliomas, which is therapeutically targetable.

The diversity of neuroimmune circuits controlling lung inflammation.

It is becoming increasingly appreciated that the nervous and immune systems communicate bidirectionally to regulate immunological outcomes in a variety of organs including the lung. Activation of neuronal signaling can be induced by inflammation, tissue damage, or pathogens to evoke or reduce immune cell activation in what has been termed a neuroimmune reflex. In the periphery, these reflexes include the cholinergic anti-inflammatory pathway, sympathetic reflex, and sensory nociceptor-immune cell pathways. Continual advances in neuroimmunology in peripheral organ systems have fueled small-scale clinical trials that have yielded encouraging results for a range of immunopathologies such as rheumatoid arthritis. Despite these successes, several limitations should give clinical investigators pause in the application of neural stimulation as a therapeutic for lung inflammation, especially if inflammation arises from a novel pathogen. In this review, the general mechanisms of each reflex, the evidence for these circuits in the control of lung inflammation, and the key knowledge gaps in our understanding of these neuroimmune circuits will be discussed. These limitations can be overcome not only through a better understanding of neuroanatomy but also through a systematic evaluation of stimulation parameters using immune activation in lung tissues as primary readouts. Our rapidly evolving understanding of the nervous and immune systems highlights the importance of communication between these cells in health and disease. This integrative approach has tremendous potential in the development of targeted therapeutics if specific challenges can be overcome.

E2F and STAT3 provide transcriptional synergy for histone variant H2AZ activation to sustain glioblastoma chromatin accessibility and tumorigenicity.

The histone variant H2AZ is overexpressed in diverse cancer types where it facilitates the accessibility of transcriptional regulators to the promoters of cell cycle genes. However, the molecular basis for its dysregulation in cancer remains unknown. Here, we report that glioblastomas (GBM) and glioma stem cells (GSCs) preferentially overexpress H2AZ for their proliferation, stemness and tumorigenicity. Chromatin accessibility analysis of H2AZ2 depleted GSC revealed that E2F1 occupies the enhancer region within H2AZ2 gene promoter, thereby activating H2AZ2 transcription. Exploration of other H2AZ2 transcriptional activators using a customized "anti-H2AZ2" query signature for connectivity map analysis identified STAT3. Co-targeting E2F and STAT3 synergistically reduced the levels of H2AZ, histone 3 lysine 27 acetylation (H3K27ac) and cell cycle gene transcription, indicating that E2F1 and STAT3 synergize to activate H2AZ gene transcription in GSCs. Remarkably, an E2F/STAT3 inhibitor combination durably suppresses GSC tumorigenicity in an orthotopic GBM xenograft model. In glioma patients, high STAT3 signaling is associated with high E2F1 and H2AZ2 expression. Thus, GBM has uniquely opted the use of E2F1- and STAT3-containing "enhanceosomes" that integrate multiple signaling pathways to achieve H2AZ gene activation, supporting a translational path for the E2F/STAT3 inhibitor combination to be applied in GBM treatment.

A chemical biology approach reveals a dependency of glioblastoma on biotin distribution.

Glioblastoma (GBM) is a uniformly lethal disease driven by glioma stem cells (GSCs). Here, we use a chemical biology approach to unveil previously unknown GBM dependencies. By studying sulconazole (SN) with anti-GSC properties, we find that SN disrupts biotin distribution to the carboxylases and histones. Transcriptomic and metabolomic analyses of SN-treated GSCs reveal metabolic alterations that are characteristic of biotin-deficient cells, including intracellular cholesterol depletion, impairment of oxidative phosphorylation, and energetic crisis. Furthermore, SN treatment reduces histone biotinylation, histone acetylation, and expression of superenhancer-associated GSC critical genes, which are also observed when biotin distribution is genetically disrupted by holocarboxylase synthetase (HLCS) depletion. HLCS silencing impaired GSC tumorigenicity in an orthotopic xenograft brain tumor model. In GBM, high HLCS expression robustly indicates a poor prognosis. Thus, the dependency of GBM on biotin distribution suggests that the rational cotargeting of biotin-dependent metabolism and epigenetic pathways may be explored for GSC eradication.

Epigenetic plasticity and redox regulation of neural stem cell state and fate.

The neural stem cells (NSCs) are essential for normal brain development and homeostasis. The cell state (i.e. quiescent versus activated) and fate (i.e. the cell lineage of choice upon differentiation) of NSCs are tightly controlled by various redox and epigenetic regulatory mechanisms. There is an increasing appreciation that redox and epigenetic regulations are intimately linked, but how this redox-epigenetics crosstalk affects NSC activity remains poorly understood. Another unresolved topic is whether the NSCs actually contribute to brain ageing and neurodegenerative diseases. In this review, we aim to 1) distill concepts that underlie redox and epigenetic regulation of NSC state and fate; 2) provide examples of the redox-epigenetics crosstalk in NSC biology; and 3) highlight potential redox- and epigenetic-based therapeutic opportunities to rescue NSC dysfunctions in ageing and neurodegenerative diseases.

Mitochondrial Dysfunction at the Center of Cancer Therapy.

Significance: Mitochondria undergo constant morphological changes through fusion, fission, and mitophagy. As the key organelle in cells, mitochondria are responsible for numerous essential cellular functions such as metabolism, regulation of calcium (Ca2+), generation of reactive oxygen species, and initiation of apoptosis. Unsurprisingly, mitochondrial dysfunctions underlie many pathologies including cancer. Recent Advances: Currently, the gold standard for cancer treatment is chemotherapy, radiation, and surgery. However, the efficacy of these treatments varies across different cancer cells. It has been suggested that mitochondria may be at the center of these diverse responses. In the past decade, significant advances have been made in understanding distinct types of mitochondrial dysfunctions in cancer. Through investigations of underlying mechanisms, more effective treatment options are developed. Critical Issues: We summarize various mitochondria dysfunctions in cancer progression that have led to the development of therapeutic options. Current mitochondrial-targeted therapies and challenges are discussed. Future Directions: To address the "root" of cancer, utilization of mitochondrial-targeted therapy to target cancer stem cells may be valuable. Investigation of other areas such as mitochondrial trafficking may offer new insights into cancer therapy. Moreover, common antibiotics could be explored as mitocans, and synthetic lethality screens can be utilized to overcome the plasticity of cancer cells.

Neurogenesis and prolongevity signaling in young germ-free mice transplanted with the gut microbiota of old mice.

The gut microbiota evolves as the host ages, yet the effects of these microbial changes on host physiology and energy homeostasis are poorly understood. To investigate these potential effects, we transplanted the gut microbiota of old or young mice into young germ-free recipient mice. Both groups showed similar weight gain and skeletal muscle mass, but germ-free mice receiving a gut microbiota transplant from old donor mice unexpectedly showed increased neurogenesis in the hippocampus of the brain and increased intestinal growth. Metagenomic analysis revealed age-sensitive enrichment in butyrate-producing microbes in young germ-free mice transplanted with the gut microbiota of old donor mice. The higher concentration of gut microbiota-derived butyrate in these young transplanted mice was associated with an increase in the pleiotropic and prolongevity hormone fibroblast growth factor 21 (FGF21). An increase in FGF21 correlated with increased AMPK and SIRT-1 activation and reduced mTOR signaling. Young germ-free mice treated with exogenous sodium butyrate recapitulated the prolongevity phenotype observed in young germ-free mice receiving a gut microbiota transplant from old donor mice. These results suggest that gut microbiota transplants from aged hosts conferred beneficial effects in responsive young recipients.