Brain milieu induces early microglial maturation through the BAX-Notch axis

Low lipid levels caused by bisphenol S exposure trigger neuroinflammation and apoptosis in the brain of zebrafish

Bisphenol S (BPS), as an environmental pollutant, is known to reduce brain lipid levels and induce neurotoxicity. However, whether brain lipid imbalance can induce neurotoxicity has not yet been clarified. Here, wild-type zebrafish and apoEb mutant zebrafish were used to investigate the effect of BPS on the macrophages proliferation and microglia mobilization caused by the decrease of cerebral lipids and its potential neurotoxic effects. The zebrafish exposed to BPS (1, 10, or 100 μg/L) from 2 hours after fertilization (hpf) to 3 days after fertilization (dpf) displayed microglial aggregation, as well as a decrease in brain lipid content. Lipidomic analyses of the brains and plasma of 50 dpf zebrafish exposed to BPS were used to identify key lipids, including lysophosphatidylcholine and phosphatidylcholine in brain and phosphatidylcholine in plasma. The apoEb mutant zebrafish as a hyperlipidemia model was used to further demonstrate that BPS-induced lipid reduction increased the number of microglia in the brain. Our data provide new insight into the mechanism by which pollutants cause neurotoxicity.

The BCL2 family: from apoptosis mechanisms to new advances in targeted therapy

The B cell lymphoma 2 (BCL2) protein family critically controls apoptosis by regulating the release of cytochrome c from mitochondria. In this cutting-edge review, we summarize the basic biology regulating the BCL2 family including canonical and non-canonical functions, and highlight milestones from basic research to clinical applications in cancer and other pathophysiological conditions. We review laboratory and clinical development of BH3-mimetics as well as more recent approaches including proteolysis targeting chimeras (PROTACs), antibody-drug conjugates (ADCs) and tools targeting the BH4 domain of BCL2. The first BCL2-selective BH3-mimetic, venetoclax, showed remarkable efficacy with manageable toxicities and has transformed the treatment of several hematologic malignancies. Following its success, several chemically similar BCL2 inhibitors such as sonrotoclax and lisaftoclax are currently under clinical evaluation, alone and in combination. Genetic analysis highlights the importance of BCL-XL and MCL1 across different cancer types and the possible utility of BH3-mimetics targeting these proteins. However, the development of BH3-mimetics targeting BCL-XL or MCL1 has been more challenging, with on-target toxicities including thrombocytopenia for BCL-XL and cardiac toxicities for MCL1 inhibitors precluding clinical development. Tumor-specific BCL-XL or MCL1 inhibition may be achieved by novel targeting approaches using PROTACs or selective drug delivery strategies and would be transformational in many subtypes of malignancy. Taken together, we envision that the targeting of BCL2 proteins, while already a success story of translational research, may in the foreseeable future have broader clinical applicability and improve the treatment of multiple diseases.

Low Selenium Diet Inhibited CaMKII Activation via miR-365-3p/SelT Signaling Axis, Resulting in Myoblast Differentiation Disorders and Skeletal Muscle Damage in Broilers

Selenium (Se) mainly functions in the form of selenoproteins. Low Se diet causes skeletal muscle injury and expression changes in miRNA and selenoprotein. Selenoprotein T (SelT) is reported to be a key molecule in Ca2+/CaMKII signaling. But the role of SelT/Ca2+/CaMKII signals in low Se diet induced skeletal muscle damage of broilers and their underlying mechanisms remain poorly investigated. Here, we randomly divided 40 1-day-old Ross 308 male broilers into two groups, feeding them either a low-selenium diet or a normal diet for 42 days, to establish control and selenium-deficient broiler models. In vitro, we established chicken embryo models, and cultured chicken primary myoblasts. We showed that Se deficiency resulted in skeletal muscle damage and atrophy in broilers, and the protein level of SelT was decreased significantly (p < 0.05). Mechanistically, myotube formation depended on SelT-mediated p-CaMKII upregulation. The absence of SelT suppressed CaMKII activation and impaired myotube development by decreasing the ER-Ca2+ content (p < 0.05). On the contrary, overexpressing SelT by pCDNA-SelT transfection induced robust myotube growth, manifested by a marked increase of MHC abundance, yet KN-93 treatment could block this process (p < 0.05). In addition, in this work, we first identified miR-365-3p, a microRNA which targets SelT mRNA to inhibit myoblast differentiation by disrupting Ca2+ homeostasis (p < 0.05). In summary, our findings revealed that SelT deletion-mediated Ca2+ level downregulation caused by low Se diet hindered myoblast differentiation and myotube formation through suppressing CaMKII activation. Our study provides an attractive target for the cultivated meat industry.

Brominated Flame Retardant HBCD and Artificial Light at Night Synergically Caused Visual Disorder and Sleep Difficulty in Zebrafish Larvae

Sleep difficulty is a widespread health concern exacerbated by factors such as light and chemical pollution. Artificial light at night (ALAN) can disrupt natural sleep-wake cycles, whereas chemical pollutants can impair sleep-related processes. The prevalence of ALAN increases the health risk of coexposure, yet it has not gained sufficient attention. Meanwhile, visual inputs are important for sleep regulation, especially the non-image-forming circadian visual system centered around melanopsin. This study evaluated the light perception ability and sleep performance of zebrafish larvae exposed to flame retardant hexabromocyclododecanes (HBCDs) at environmentally relevant concentrations (2.5 and 25 μg/L) and to cotreatment of HBCD and ALAN. HBCD induced a longer sleep latency of 34.59 min under 25 μg/L (p < 0.01) versus control (26.04 min). The situation was intensified by coexposure with low-level ALAN (10 lx) to 48.04 min. Similar synergic effects were observed for upregulations of Xenopus-related melanopsin genes and downregulations of the melatonin synthesis gene aanat2, suggesting a melanopsin-aanat2-sleep retina-brain pathway. Image-forming opsins (opn1sw1 and opn1sw2) were also activated by HBCD to 1.29-1.53-fold (p < 0.05), together with elevated retina glutamate, but without synergic effects. Collectively, we found that HBCD and ALAN coexposure caused synergic effects on the non-image-forming visual system and caused sleep difficulty in zebrafish larvae.

The embryonic zebrafish brain is exclusively colonized by pu.1-dependent and lymphatic-independent population of microglia

Microglia, the crucial immune cells inhabiting the central nervous system (CNS), perform a range of vital functions, encompassing immune defense and neuronal regulation. Microglia subsets with diverse functions and distinct developmental regulations have been identified recently. It is generally accepted that all microglia originate from hematopoiesis and depend on the myeloid transcription factor PU.1. However, a recent study reported the existence of mrc1+ microglia in zebrafish embryos, which are seemingly independent of Pu.1 and reliant on lymphatic vessels, sparking great interest in the possibility of lymphatic-originated microglia. To address this, we took advantage of a pu.1 knock-in zebrafish allele for a detailed investigation. Our results conclusively showed that almost all zebrafish embryonic microglia (~95% on average) express pu.1. Further, lineage tracing and mutant analysis revealed that these microglia neither emerged from nor depended on lymphatic vessels. In essence, our study refutes the presence of pu.1-independent but lymphatic-dependent microglia.

Central Causation of Autism/ASDs via Excessive [Ca2+]i Impacting Six Mechanisms Controlling Synaptogenesis during the Perinatal Period: The Role of Electromagnetic Fields and Chemicals and the NO/ONOO(-) Cycle, as Well as Specific Mutations

The roles of perinatal development, intracellular calcium [Ca2+]i, and synaptogenesis disruption are not novel in the autism/ASD literature. The focus on six mechanisms controlling synaptogenesis, each regulated by [Ca2+]i, and each aberrant in ASDs is novel. The model presented here predicts that autism epidemic causation involves central roles of both electromagnetic fields (EMFs) and chemicals. EMFs act via voltage-gated calcium channel (VGCC) activation and [Ca2+]i elevation. A total of 15 autism-implicated chemical classes each act to produce [Ca2+]i elevation, 12 acting via NMDA receptor activation, and three acting via other mechanisms. The chronic nature of ASDs is explained via NO/ONOO(-) vicious cycle elevation and MeCP2 epigenetic dysfunction. Genetic causation often also involves [Ca2+]i elevation or other impacts on synaptogenesis. The literature examining each of these steps is systematically examined and found to be consistent with predictions. Approaches that may be sed for ASD prevention or treatment are discussed in connection with this special issue: The current situation and prospects for children with ASDs. Such approaches include EMF, chemical avoidance, and using nutrients and other agents to raise the levels of Nrf2. An enriched environment, vitamin D, magnesium, and omega-3s in fish oil may also be helpful.

Human stem cell transplantation models of Alzheimer's disease

Alzheimer's disease (AD) is the most frequent form of dementia. It is characterized by pronounced neuronal degeneration with formation of neurofibrillary tangles and deposition of amyloid β throughout the central nervous system. Animal models have provided important insights into the pathogenesis of AD and they have shown that different brain cell types including neurons, astrocytes and microglia have important functions in the pathogenesis of AD. However, there are difficulties in translating promising therapeutic observations in mice into clinical application in patients. Alternative models using human cells such as human induced pluripotent stem cells (iPSCs) may provide significant advantages, since they have successfully been used to model disease mechanisms in neurons and in glial cells in neurodegenerative diseases in vitro and in vivo. In this review, we summarize recent studies that describe the transplantation of human iPSC-derived neurons, astrocytes and microglial cells into the forebrain of mice to generate chimeric transplantation models of AD. We also discuss opportunities, challenges and limitations in using differentiated human iPSCs for in vivo disease modeling and their application for biomedical research.