Wolframin is a novel regulator of tau pathology and neurodegeneration

A Single-cell and Spatial RNA-seq Database for Alzheimer's Disease (ssREAD)

Alzheimer's Disease (AD) pathology has been increasingly explored through single-cell and single-nucleus RNA-sequencing (scRNA-seq & snRNA-seq) and spatial transcriptomics (ST). However, the surge in data demands a comprehensive, user-friendly repository. Addressing this, we introduce a single-cell and spatial RNA-seq database for Alzheimer's disease (ssREAD). It offers a broader spectrum of AD-related datasets, an optimized analytical pipeline, and improved usability. The database encompasses 1,053 samples (277 integrated datasets) from 67 AD-related scRNA-seq & snRNA-seq studies, totaling 7,332,202 cells. Additionally, it archives 381 ST datasets from 18 human and mouse brain studies. Each dataset is annotated with details such as species, gender, brain region, disease/control status, age, and AD Braak stages. ssREAD also provides an analysis suite for cell clustering, identification of differentially expressed and spatially variable genes, cell-type-specific marker genes and regulons, and spot deconvolution for integrative analysis. ssREAD is freely available at https://bmblx.bmi.osumc.edu/ssread/.

The role of TRPV4 in programmed cell deaths

Programmed cell death is a major life activity of both normal development and disease. Necroptosis is early recognized as a caspase-independent form of programmed cell death followed obviously inflammation. Apoptosis is a gradually recognized mode of cell death that is characterized by a special morphological changes and unique caspase-dependent biological process. Ferroptosis, pyroptosis and autophagy are recently identified non-apoptotic regulated cell death that each has its own characteristics. The transient receptor potential vanilloid 4 (TRPV4) is a kind of nonselective calcium-permeable cation channel, which is received more and more attention in biology studies. It is widely expressed in human tissues and mainly located on the membrane of cells. Several researchers have identified that the influx Ca2+ from TRPV4 acts as a key role in the loss of cells by apoptosis, ferroptosis, necroptosis, pyroptosis and autophagy via mediating endoplasmic reticulum (ER) stress, oxidative stress and inflammation. This effect is bad for the normal function of organs on the one hand, on the other hand, it is benefit for anticancer activities. In this review, we will summarize the current discovery on the role and impact of TRPV4 in these programmed cell death pathological mechanisms to provide a new prospect of gene therapeutic target of related diseases.

Treatment with the dual-incretin agonist DA-CH5 demonstrates potent therapeutic effect in a rat model of Wolfram Syndrome

Aim

Wolfram Syndrome (WS) is a rare condition caused by mutations in Wfs1, with a poor prognosis and no cure. Mono-agonists targeting the incretin glucagon-like-peptide 1 (GLP-1) have demonstrated disease-modifying potential in pre-clinical and clinical settings. Dual agonists that target GLP-1 and glucose-dependent insulinotropic polypeptide (GIP-1) are reportedly more efficacious; hence, we evaluated the therapeutic potential of dual incretin agonism in a loss-of-function rat model of WS.

Methods

Eight-month-old Wfs1 knock-out (KO) and wild-type control rats were continuously treated with either the dual agonist DA-CH5 or saline for four months. Glycemic profile, visual acuity and hearing sensitivity were longitudinally monitored pre-treatment, and then at 10.5 and 12 months. Pancreata and retina were harvested for immunohistological analysis.

Results

DA-CH5 therapy reversed glucose intolerance in KO rats and provided lasting anti-diabetogenic protection. Treatment also reversed intra-islet alterations, including reduced endocrine islet area and β-cell density, indicating its regenerative potential. Although no rescue effect was noted for hearing loss, visual acuity and retinal ganglion cell density were better preserved in DA-CH5-treated rats.

Conclusion

We present preclinical evidence for the pleiotropic therapeutic effects of long-term dual incretin agonist treatment; effects were seen despite treatment beginning after symptom-onset, indicating reversal of disease progression. Dual incretins represent a promising therapeutic avenue for WS patients.

Spatial transcriptomics in development and disease

The proper functioning of diverse biological systems depends on the spatial organization of their cells, a critical factor for biological processes like shaping intricate tissue functions and precisely determining cell fate. Nonetheless, conventional bulk or single-cell RNA sequencing methods were incapable of simultaneously capturing both gene expression profiles and the spatial locations of cells. Hence, a multitude of spatially resolved technologies have emerged, offering a novel dimension for investigating regional gene expression, spatial domains, and interactions between cells. Spatial transcriptomics (ST) is a method that maps gene expression in tissue while preserving spatial information. It can reveal cellular heterogeneity, spatial organization and functional interactions in complex biological systems. ST can also complement and integrate with other omics methods to provide a more comprehensive and holistic view of biological systems at multiple levels of resolution. Since the advent of ST, new methods offering higher throughput and resolution have become available, holding significant potential to expedite fresh insights into comprehending biological complexity. Consequently, a rapid increase in associated research has occurred, using these technologies to unravel the spatial complexity during developmental processes or disease conditions. In this review, we summarize the recent advancement of ST in historical, technical, and application contexts. We compare different types of ST methods based on their principles and workflows, and present the bioinformatics tools for analyzing and integrating ST data with other modalities. We also highlight the applications of ST in various domains of biomedical research, especially development and diseases. Finally, we discuss the current limitations and challenges in the field, and propose the future directions of ST.

Genomics of Wolfram Syndrome 1 (WFS1)

Wolfram Syndrome (WFS) is a rare, autosomal, recessive neurogenetic disorder that affects many organ systems. It is characterised by diabetes insipidus, diabetes mellites, optic atrophy, and deafness and, therefore, is also known as DIDMOAD. Nearly 15,000-30,000 people are affected by WFS worldwide, and, on average, patients suffering from WFS die at 30 years of age, usually from central respiratory failure caused by massive brain atrophy. The more prevalent of the two kinds of WFS is WFS1, which is a monogenic disease and caused by the loss of the WFS1 gene, whereas WFS2, which is more uncommon, is caused by mutations in the CISD2 gene. Currently, there is no treatment for WFS1 to increase the life expectancy of patients, and the treatments available do not significantly improve their quality of life. Understanding the genetics and the molecular mechanisms of WFS1 is essential to finding a cure. The inability of conventional medications to treat WFS1 points to the need for innovative strategies that must address the fundamental cause: the deletion of the WFS1 gene that leads to the profound ER stress and disturbances in proteostasis. An important approach here is to understand the mechanism of the cell degeneration after the deletion of the WFS1 gene and to describe the differences in these mechanisms for the different tissues. The studies so far have indicated that remarkable clinical heterogeneity is caused by the variable vulnerability caused by WFS1 mutations, and these differences cannot be attributed solely to the positions of mutations in the WFS1 gene. The present review gives a broader overview of the results from genomic studies on the WFS1 mouse model.

Spatially resolved transcriptomic analysis of the germinating barley grain

Seeds are a vital source of calories for humans and a unique stage in the life cycle of flowering plants. During seed germination, the embryo undergoes major developmental transitions to become a seedling. Studying gene expression in individual seed cell types has been challenging due to the lack of spatial information or low throughput of existing methods. To overcome these limitations, a spatial transcriptomics workflow was developed for germinating barley grain. This approach enabled high-throughput analysis of spatial gene expression, revealing specific spatial expression patterns of various functional gene categories at a sub-tissue level. This study revealed over 14 000 genes differentially regulated during the first 24 h after imbibition. Individual genes, such as the aquaporin gene family, starch degradation, cell wall modification, transport processes, ribosomal proteins and transcription factors, were found to have specific spatial expression patterns over time. Using spatial autocorrelation algorithms, we identified auxin transport genes that had increasingly focused expression within subdomains of the embryo over time, suggesting their role in establishing the embryo axis. Overall, our study provides an unprecedented spatially resolved cellular map for barley germination and identifies specific functional genomics targets to better understand cellular restricted processes during germination. The data can be viewed at https://spatial.latrobe.edu.au/.

Neuroprotection from protein misfolding in cerebral hypoperfusion concurrent with metabolic syndrome. A translational perspective

Based on clinical and experimental evidence, metabolic syndrome (MetS) and type 2 diabetes (T2D) are considered risk factors for chronic cerebral hypoperfusion (CCH) and neurodegeneration. Scientific evidence suggests that protein misfolding is a potential mechanism that explains how CCH can lead to either Alzheimer's disease (AD) or vascular cognitive impairment and dementia (VCID). Over the last decade, there has been a significant increase in the number of experimental studies regarding this issue. Using several animal paradigms and different markers of CCH, scientists have discussed the extent to which MetSor T2D causes a decrease in cerebral blood flow (CBF). In addition, different models of CCH have explored how long-term reductions in oxygen and energy supply can trigger AD or VCID via protein misfolding and aggregation. Research that combines two or three animal models could broaden knowledge of the links between these pathological conditions. Recent experimental studies suggest novel neuroprotective properties of protein-remodeling factors. In this review, we present a summarized updated revision of preclinical findings, discussing clinical implications and proposing new experimental approaches from a translational perspective. We are confident that research studies, both clinical and experimental, may find new diagnostic and therapeutic tools to prevent neurodegeneration associated with MetS, diabetes, and any other chronic non-communicable disease (NCD) associated with diet and lifestyle risk factors.

Disrupting pathologic phase transitions in neurodegeneration

Solid-like protein deposits found in aged and diseased human brains have revealed a relationship between insoluble protein accumulations and the resulting deficits in neurologic function. Clinically diverse neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, frontotemporal lobar degeneration, and amyotrophic lateral sclerosis, exhibit unique and disease-specific biochemical protein signatures and abnormal protein depositions that often correlate with disease pathogenesis. Recent evidence indicates that many pathologic proteins assemble into liquid-like protein phases through the highly coordinated process of liquid-liquid phase separation. Over the last decade, biomolecular phase transitions have emerged as a fundamental mechanism of cellular organization. Liquid-like condensates organize functionally related biomolecules within the cell, and many neuropathology-associated proteins reside within these dynamic structures. Thus, examining biomolecular phase transitions enhances our understanding of the molecular mechanisms mediating toxicity across diverse neurodegenerative diseases. This Review explores the known mechanisms contributing to aberrant protein phase transitions in neurodegenerative diseases, focusing on tau and TDP-43 proteinopathies and outlining potential therapeutic strategies to regulate these pathologic events.

Δ8-THC Protects against Amyloid Beta Toxicity Modulating ER Stress In Vitro: A Transcriptomic Analysis

Alzheimer’s disease (AD) represents the most common form of dementia, characterized by amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs). It is characterized by neuroinflammation, the accumulation of misfolded protein, ER stress and neuronal apoptosis. It is of main importance to find new therapeutic strategies because AD prevalence is increasing worldwide. Cannabinoids are arising as promising neuroprotective phytocompounds. In this study, we evaluated the neuroprotective potential of Δ8-THC pretreatment in an in vitro model of AD through transcriptomic analysis. We found that Δ8-THC pretreatment restored the loss of cell viability in retinoic acid-differentiated neuroblastoma SH-SY5Y cells treated with Aβ1-42. Moreover, the transcriptomic analysis provided evidence that the enriched biological processes of gene ontology were related to ER functions and proteostasis. In particular, Aβ1-42 upregulated genes involved in ER stress and unfolded protein response, leading to apoptosis as demonstrated by the increase in Bax and the decrease in Bcl-2 both at gene and protein expression levels. Moreover, genes involved in protein folding and degradation were also deregulated. On the contrary, Δ8-THC pretreatment reduced ER stress and, as a consequence, neuronal apoptosis. Then, the results demonstrated that Δ8-THC might represent a new neuroprotective agent in AD.

Chronic Stress Alters Hippocampal Renin-Angiotensin-Aldosterone System Component Expression in an Aged Rat Model of Wolfram Syndrome

Biallelic mutations in the gene encoding WFS1 underlie the development of Wolfram syndrome (WS), a rare neurodegenerative disorder with no available cure. We have previously shown that Wfs1 deficiency can impair the functioning of the renin-angiotensin-aldosterone system (RAAS). The expression of two key receptors, angiotensin II receptor type 2 (Agtr2) and bradykinin receptor B1 (Bdkrb1), was downregulated both in vitro and in vivo across multiple organs in a rat model of WS. Here, we show that the expression of key RAAS components is also dysregulated in neural tissue from aged WS rats and that these alterations are not normalized by pharmacological treatments (liraglutide (LIR), 7,8-dihydroxyflavone (7,8-DHF) or their combination). We found that the expression of angiotensin II receptor type 1a (Agtr1a), angiotensin II receptor type 1b (Agtr1b), Agtr2 and Bdkrb1 was significantly downregulated in the hippocampus of WS animals that experienced chronic experimental stress. Treatment-naïve WS rats displayed different gene expression patterns, underscoring the effect of prolonged experiment-induced stress. Altogether, we posit that Wfs1 deficiency disturbs RAAS functioning under chronic stressful conditions, thereby exacerbating neurodegeneration in WS.

Case Report: A novel mutation in WFS1 gene (c.1756G>A p.A586T) is responsible for early clinical features of cognitive impairment and recurrent ischemic stroke

Wolfram syndrome 1 (WFS1) gene mutations can be dominantly or recessively inherited, and the onset of the clinical picture is highly heterogeneity in both appearance and degree of severity. Different types of WFS1 mutations have been identified. Autosomal recessive mutations in the WFS1 gene will underlie Wolfram syndrome 1 (WS1), a rare and severe neurodegenerative disease characterized by diabetes insipidus, diabetes mellitus, optic atrophy, deafness, and other neurological, urological and psychiatric abnormalities. Other WFS1-related disorders such as low-frequency sensorineural hearing impairment (LFSNHI) and Wolfram syndrome-like disease with autosomal dominant transmission have been described. It is difficult to establish genotype-phenotype correlations because of the molecular complexity of wolframin protein. In this report, we presented a case of WSF1 gene mutation-related disease with cognitive impairment as the initial symptom and recurrent cerebral infarction in the course of the disease. Brain structural imaging results suggested decreased intracranial volume, dramatically reduced in cerebral cortex and cerebellum regions. Multimodal molecular imaging results suggested Tau protein deposition in the corresponding brain regions without Aβ pathology changes. These pathological changes may indicate a role of WFS1 in neuronal vulnerability to tau pathology associated with neurodegeneration and ischemia-induced damage.

MCT1-dependent energetic failure and neuroinflammation underlie optic nerve degeneration in Wolfram syndrome mice

Wolfram syndrome 1 (WS1) is a rare genetic disorder caused by mutations in the WFS1 gene leading to a wide spectrum of clinical dysfunctions, among which blindness, diabetes, and neurological deficits are the most prominent. WFS1 encodes for the endoplasmic reticulum (ER) resident transmembrane protein wolframin with multiple functions in ER processes. However, the WFS1-dependent etiopathology in retinal cells is unknown. Herein, we showed that Wfs1 mutant mice developed early retinal electrophysiological impairments followed by marked visual loss. Interestingly, axons and myelin disruption in the optic nerve preceded the degeneration of the retinal ganglion cell bodies in the retina. Transcriptomics at pre-degenerative stage revealed the STAT3-dependent activation of proinflammatory glial markers with reduction of the homeostatic and pro-survival factors glutamine synthetase and BDNF. Furthermore, label-free comparative proteomics identified a significant reduction of the monocarboxylate transport isoform 1 (MCT1) and its partner basigin that are highly enriched on retinal glia and myelin-forming oligodendrocytes in optic nerve together with wolframin. Loss of MCT1 caused a failure in lactate transfer from glial to neuronal cell bodies and axons leading to a chronic hypometabolic state. Thus, this bioenergetic impairment is occurring concurrently both within the axonal regions and cell bodies of the retinal ganglion cells, selectively endangering their survival while impacting less on other retinal cells. This metabolic dysfunction occurs months before the frank RGC degeneration suggesting an extended time-window for intervening with new therapeutic strategies focused on boosting retinal and optic nerve bioenergetics in WS1.

Wolfram syndrome 1b mutation suppresses Mauthner-cell axon regeneration via ER stress signal pathway

Wolfram Syndrome (WS) is a fatal human inherited disease with symptoms of diabetes, vision decreasing, and neurodegeneration caused by mutations in the endoplasmic reticulum (ER)-resident protein WFS1. WFS1 has been reported to play an important role in glucose metabolism. However, the role of WFS1 in axonal regeneration in the central nervous system has so far remained elusive. Herein, we established a model of the wfs1b globally deficient zebrafish line. wfs1b deficiency severely impeded the Mauthner-cell (M-cell) axon regeneration, which was partly dependent on the ER stress response. The administration of ER stress inhibitor 4-Phenylbutyric acid (4-PBA) promoted M-cell axon regeneration in wfs1b^-/- zebrafish larvae, while the ER stress activator Tunicamycin (TM) inhibited M-cell axon regeneration in wfs1b^+/+ zebrafish larvae. Moreover, complementation of wfs1b at the single-cell level stimulated M-cell axon regeneration in the wfs1b^-/- zebrafish larvae. Altogether, our results revealed that wfs1b promotes M-cell axon regeneration through the ER stress signal pathway and provide new evidence for a therapeutic target for WS and axon degeneration.

The cGAS-STING-autophagy pathway: Novel perspectives in neurotoxicity induced by manganese exposure

Chronic high-level heavy metal exposure increases the risk of developing different neurodegenerative diseases. Chronic excessive manganese (Mn) exposure is known to lead to neurodegenerative diseases. In addition, some evidence suggests that autophagy dysfunction plays an important role in the pathogenesis of various neurodegenerative diseases. Over the past decade, the DNA-sensing receptor cyclic GMP-AMP synthase (cGAS) and its downstream signal-efficient interferon gene stimulator (STING), as well as the molecular composition and regulatory mechanisms of this pathway have been well understood. The cGAS-STING pathway has emerged as a crucial mechanism to induce effective innate immune responses by inducing type I interferons in mammalian cells. Moreover, recent studies have found that Mn²⁺ is the second activator of the cGAS-STING pathway besides dsDNA, and inducing autophagy is a primitive function for the activation of the cGAS-STING pathway. However, overactivation of the immune response can lead to tissue damage. This review discusses the mechanism of neurotoxicity induced by Mn exposure from the cGAS-STING-autophagy pathway. Future work exploiting the cGAS-STING-autophagy pathway may provide a novel perspective for manganese neurotoxicity.

Activity disruption causes degeneration of entorhinal neurons in a mouse model of Alzheimer's circuit dysfunction

Neurodegenerative diseases are characterized by selective vulnerability of distinct cell populations; however, the cause for this specificity remains elusive. Here, we show that entorhinal cortex layer 2 (EC2) neurons are unusually vulnerable to prolonged neuronal inactivity compared with neighboring regions of the temporal lobe, and that reelin + stellate cells connecting EC with the hippocampus are preferentially susceptible within the EC2 population. We demonstrate that neuronal death after silencing can be elicited through multiple independent means of activity inhibition, and that preventing synaptic release, either alone or in combination with electrical shunting, is sufficient to elicit silencing-induced degeneration. Finally, we discovered that degeneration following synaptic silencing is governed by competition between active and inactive cells, which is a circuit refinement process traditionally thought to end early in postnatal life. Our data suggests that the developmental window for wholesale circuit plasticity may extend into adulthood for specific brain regions. We speculate that this sustained potential for remodeling by entorhinal neurons may support lifelong memory but renders them vulnerable to prolonged activity changes in disease.

Spread of pathological human Tau from neurons to oligodendrocytes and loss of high-firing pyramidal neurons in aging mice

Intracellular aggregation of hyperphosphorylated Tau (pTau) in the brain is associated with cognitive and motor impairments, and ultimately neurodegeneration. We investigate how human pTau affects cells and network activity in the hippocampal formation of the THY-Tau22 tauopathy model mice in vivo. We find that pTau preferentially accumulates in deep-layer pyramidal neurons, leading to neurodegeneration, and we establish that pTau spreads to oligodendrocytes. During goal-directed virtual navigation in aged transgenic mice, we detect fewer high-firing prosubicular pyramidal cells, but the firing population retains its coupling to theta oscillations. Analysis of network oscillations and firing patterns of pyramidal and GABAergic neurons recorded in head-fixed and freely moving mice suggests preserved neuronal coordination. In spatial memory tests, transgenic mice have reduced short-term familiarity, but spatial working and reference memory are surprisingly normal. We hypothesize that unimpaired subcortical network mechanisms maintain cortical neuronal coordination, counteracting the widespread pTau aggregation, loss of high-firing cells, and neurodegeneration.

NCS1 overexpression restored mitochondrial activity and behavioral alterations in a zebrafish model of Wolfram syndrome

Wolfram syndrome (WS) is a rare neurodegenerative disease resulting in deafness, optic atrophy, diabetes, and neurological disorders. Currently, no treatment is available for patients. The mutated gene, WFS1, encodes an endoplasmic reticulum (ER) protein, Wolframin. We previously reported that Wolframin regulated the ER-mitochondria Ca²⁺ transfer and mitochondrial activity by protecting NCS1 from degradation in patients' fibroblasts. We relied on a zebrafish model of WS, the wfs1ab ^KO line, to analyze the functional and behavioral impact of NCS1 overexpression as a novel therapeutic strategy. The wfs1ab ^KO line showed an increased locomotion in the visual motor and touch-escape responses. The absence of wfs1 did not impair the cellular unfolded protein response, in basal or tunicamycin-induced ER stress conditions. In contrast, metabolic analysis showed an increase in mitochondrial respiration in wfs1ab ^KO larvae. Interestingly, overexpression of NCS1 using mRNA injection restored the alteration of mitochondrial respiration and hyperlocomotion. Taken together, these data validated the wfs1ab ^KO zebrafish line as a pertinent experimental model of WS and confirmed the therapeutic potential of NCS1. The wfs1ab ^KO line therefore appeared as an efficient model to identify novel therapeutic strategies, such as gene or pharmacological therapies targeting NCS1 that will correct or block WS symptoms.

Dysregulated Ca2+ Homeostasis as a Central Theme in Neurodegeneration: Lessons from Alzheimer's Disease and Wolfram Syndrome

Calcium ions (Ca²⁺) operate as important messengers in the cell, indispensable for signaling the underlying numerous cellular processes in all of the cell types in the human body. In neurons, Ca²⁺ signaling is crucial for regulating synaptic transmission and for the processes of learning and memory formation. Hence, the dysregulation of intracellular Ca²⁺ homeostasis results in a broad range of disorders, including cancer and neurodegeneration. A major source for intracellular Ca²⁺ is the endoplasmic reticulum (ER), which has close contacts with other organelles, including mitochondria. In this review, we focus on the emerging role of Ca²⁺ signaling at the ER–mitochondrial interface in two different neurodegenerative diseases, namely Alzheimer’s disease and Wolfram syndrome. Both of these diseases share some common hallmarks in the early stages, including alterations in the ER and mitochondrial Ca²⁺ handling, mitochondrial dysfunction and increased Reactive oxygen species (ROS) production. This indicates that similar mechanisms may underly these two disease pathologies and suggests that both research topics might benefit from complementary research.