High-throughput morphometric and transcriptomic profiling uncovers composition of naïve and sensory-deprived cortical cholinergic VIP/CHAT neurons.

Cortical neuronal networks control cognitive output, but their composition and modulation remain elusive. Here, we studied the morphological and transcriptional diversity of cortical cholinergic VIP/ChAT interneurons (VChIs), a sparse population with a largely unknown function. We focused on VChIs from the whole barrel cortex and developed a high-throughput automated reconstruction framework, termed PopRec, to characterize hundreds of VChIs from each mouse in an unbiased manner, while preserving 3D cortical coordinates in multiple cleared mouse brains, accumulating thousands of cells. We identified two fundamentally distinct morphological types of VChIs, bipolar and multipolar that differ in their cortical distribution and general morphological features. Following mild unilateral whisker deprivation on postnatal day seven, we found after three weeks both ipsi- and contralateral dendritic arborization differences and modified cortical depth and distribution patterns in the barrel fields alone. To seek the transcriptomic drivers, we developed NuNeX, a method for isolating nuclei from fixed tissues, to explore sorted VChIs. This highlighted differentially expressed neuronal structural transcripts, altered exitatory innervation pathways and established Elmo1 as a key regulator of morphology following deprivation.

Ribosomal protein L24 mediates mammalian microRNA processing in an evolutionarily conserved manner.

To investigate the mechanism(s) underlying the expression of primate-specific microRNAs (miRs), we sought DNA regulatory elements and proteins mediating expression of the primate-specific hsa-miR-608 (miR-608), which is located in the SEMA4G gene and facilitates the cholinergic blockade of inflammation by targeting acetylcholinesterase mRNA. 'Humanized' mice carrying pre-miR-608 flanked by 250 bases of endogenous sequences inserted into the murine Sema4g gene successfully expressed miR-608. Moreover, by flanking miR-608 by shortened fragments of its human genome region we identified an active independent promoter within the 150 nucleotides 5' to pre-miR-608, which elevated mature miR-608 levels by 100-fold in transfected mouse- and human-originated cells. This highlighted a regulatory role of the 5' flank as enabling miR-608 expression. Moreover, pull-down of the 150-base 5' sequence revealed its interaction with ribosomal protein L24 (RPL24), implicating an additional mechanism controlling miR-608 levels. Furthermore, RPL24 knockdown altered the expression of multiple miRs, and RPL24 immunoprecipitation indicated that up- or down-regulation of the mature miRs depended on whether their precursors bind RPL24 directly. Finally, further tests showed that RPL24 interacts directly with DDX5, a component of the large microprocessor complex, to inhibit miR processing. Our findings reveal that RPL24, which has previously been shown to play a role in miR processing in Arabidopsis thaliana, has a similar evolutionarily conserved function in miR biogenesis in mammals. We thus characterize a novel extra-ribosomal role of RPL24 in primate miR regulation.

Novel single-nucleus transcriptomics unravels developmental and functionally controlled principles of mammalian neuromuscular junctions.

Prof Ohno's team (Ohkawara et al. 2023, current issue) underscored the dynamic and functional features that co-shape the embryonic and early post-natal development of mammalian neuromuscular junctions (NMJs) using single-nucleus transcriptomics which provides specific insights into the activities of individually studied nuclei and their functional characteristics. Unlike other single-nucleus transcriptomics studies, which tend to be limited to single developmental time points, this article provides novel views of the complex developmental and regulatory dynamics and embryonic cell type origins underscoring the formation of functioning mammalian NMJs by combining this transcriptomic approach with interference tests in cultured C2C12 myotubes. This reveals intriguing novel links between the particular nicotinic acetylcholine receptor genes (nAChR) and regulator transcripts thereof and enables outlining the sequential development of functioning NMJs along embryogenesis and soon after delivery. Specifically, the timewise and cell type origins of the studied nuclei emerged as essential for NMJ neurogenesis and inter-cellular transfer of specific regulators has been indicated. Breaking the barriers between distinct research subdisciplines, this study opens new neurochemistry research directions that recombine developmental, regulatory, and functional transcriptomics in NMJ-including tissues. Moreover, these findings may facilitate tests of diverse pharmaceutical and therapeutic modulators of neuromuscular functioning in health and disease, assisting the translational research progress in treating devastating neuromuscular states such as in amyotrophic lateral sclerosis, myasthenia gravis or individuals poisoned occupationally or otherwise with anticholinesterase inhibitors.

Recent advances in cholinergic mechanisms: A preface for the ISCM2022 special issue.

This preface introduces the Journal of Neurochemistry special issue on Cholinergic Mechanisms that highlights the progress in the molecular, structural, neurochemical, pharmacological, toxicological, and clinical studies of the cholinergic system which underline its complexity and impact on health and disease. This issue comprises of (systematic) reviews and original articles, the majority of which have been presented at the 17th International Symposium on Cholinergic Mechanisms (ISCM2022) held in Dubrovnik, Croatia in May 2022. The symposium brought together leading "Cholinergikers" to shed new light on cholinergic transmission, ranging from the molecular to the clinical and cognitive mechanisms.

EDITOR SPOTLIGHT: Interview with Cholinergic Mechanisms Special Issue Guest Editor Hermona Soreq.

Hermona Soreq holds a Hebrew University Slesinger Chair in Molecular Neuroscience and is among the founding members of the Edmond and Lily Safra Center of Brain Sciences (ELSC). Soreq's research (H-impact: 98) focuses on acetylcholine (ACh)-related pathways and combines RNA-sequencing technologies, transgenic engineering, and molecular biology tests with in-depth analysis approaches. Her work addresses microRNAs (miRs) and transfer RNA fragments (tRFs) which have rapidly acquired wide recognition as global controllers of regulatory processes in healthy and diseased brain and body, including anxiety, inflammation, and cognition. Altogether, Soreq's work leads to molecular neuroscience-driven prevention and/or intervention with diseases involving impaired ACh signaling, including schizophrenia, bipolar disorder, Alzheimer's disease, and stress. Hermona led this Special Issue based on the 17th Symposium on Cholinergic Mechanisms (ISCM2022). We interviewed her on the progress in the field, what she wants to achieve as Senior Editor for the Gene Regulation and Genetics category at the Journal of Neurochemistry, key moments, and future directions.

Recent advances in cholinergic mechanisms as reactions to toxicity, stress, and neuroimmune insults.

This review presents recent studies of the chemical and molecular regulators of acetylcholine (ACh) signaling and the complexity of the small molecule and RNA regulators of those mechanisms that control cholinergic functioning in health and disease. The underlying structural, neurochemical, and transcriptomic concepts, including basic and translational research and clinical studies, shed new light on how these processes inter-change under acute states, age, sex, and COVID-19 infection; all of which modulate ACh-mediated processes and inflammation in women and men and under diverse stresses. The aspect of organophosphorus (OP) compound toxicity is discussed based on the view that despite numerous studies, acetylcholinesterase (AChE) is still a vulnerable target in OP poisoning because of a lack of efficient treatment and the limitations of oxime-assisted reactivation of inhibited AChE. The over-arching purpose of this review is thus to discuss mechanisms of cholinergic signaling dysfunction caused by OP pesticides, OP nerve agents, and anti-cholinergic medications; and to highlight new therapeutic strategies to combat both the acute and chronic effects of these chemicals on the cholinergic and neuroimmune systems. Furthermore, OP toxicity was examined in view of cholinesterase inhibition and beyond in order to highlight improved small molecules and RNA therapeutic strategies and assess their predicted pitfalls to reverse the acute toxicity and long-term deleterious effects of OPs.

Cerebrospinal fluid and blood profiles of transfer RNA fragments show age, sex, and Parkinson's disease-related changes.

Transfer RNA fragments (tRFs) have recently been shown to be an important family of small regulatory RNAs with diverse functions. Recent reports have revealed modified tRF blood levels in a number of nervous system conditions including epilepsy, ischemic stroke, and neurodegenerative diseases, but little is known about tRF levels in the cerebrospinal fluid (CSF). To address this issue, we studied age, sex, and Parkinson's disease (PD) effects on the distributions of tRFs in the CSF and blood data of healthy controls and PD patients from the NIH and the Parkinson's Progression Markers Initiative (PPMI) small RNA-seq datasets. We discovered that long tRFs are expressed in higher levels in the CSF than in the blood. Furthermore, the CSF showed a pronounced age-associated decline in the level of tRFs cleaved from the 3'-end and anti-codon loop of the parental tRNA (3'-tRFs, i-tRFs), and more pronounced profile differences than the blood profiles between the sexes. In comparison, we observed moderate age-related elevation of blood 3'-tRF levels. In addition, distinct sets of tRFs in the CSF and in the blood segregated PD patients from controls. Finally, we found enrichment of tRFs predicted to target cholinergic mRNAs (Cholino-tRFs) among mitochondrial-originated tRFs, raising the possibility that the neurodegeneration-related mitochondrial impairment in PD patients may lead to deregulation of their cholinergic tone. Our findings demonstrate that the CSF and blood tRF profiles are distinct and that the CSF tRF profiles are modified in a sex-, age-, and disease-related manner, suggesting that they reflect the inter-individual cerebral differences and calling for incorporating this important subset of small RNA regulators into future studies.

Systemic inflammation impairs microglial Aß clearance through NLRP3 inflammasome.

Alzheimer's disease is the most prevalent type of dementia and is caused by the deposition of extracellular amyloid-beta and abnormal tau phosphorylation. Neuroinflammation has emerged as an additional pathological component. Microglia, representing the brain's major innate immune cells, play an important role during Alzheimer's. Once activated, microglia show changes in their morphology, characterized by a retraction of cell processes. Systemic inflammation is known to increase the risk for cognitive decline in human neurogenerative diseases including Alzheimer's. Here, we assess for the first time microglial changes upon a peripheral immune challenge in the context of aging and Alzheimer's in vivo, using 2-photon laser scanning microscopy. Microglia were monitored at 2 and 10 days post-challenge by lipopolysaccharide. Microglia exhibited a reduction in the number of branches and the area covered at 2 days, a phenomenon that resolved at 10 days. Systemic inflammation reduced microglial clearance of amyloid-beta in APP/PS1 mice. NLRP3 inflammasome knockout blocked many of the observed microglial changes upon lipopolysaccharide, including alterations in microglial morphology and amyloid pathology. NLRP3 inhibition may thus represent a novel therapeutic target that may protect the brain from toxic peripheral inflammation during systemic infection.

Defining the Riddle in Order to Solve It: There Is More Than One "Parkinson's Disease".

BACKGROUND: More than 200 years after James Parkinsondescribed a clinical syndrome based on his astute observations, Parkinson's disease (PD) has evolved into a complex entity, akin to the heterogeneity of other complex human syndromes of the central nervous system such as dementia, motor neuron disease, multiple sclerosis, and epilepsy. Clinicians, pathologists, and basic science researchers evolved arrange of concepts andcriteria for the clinical, genetic, mechanistic, and neuropathological characterization of what, in their best judgment, constitutes PD. However, these specialists have generated and used criteria that are not necessarily aligned between their different operational definitions, which may hinder progress in solving the riddle of the distinct forms of PD and ultimately how to treat them. OBJECTIVE: This task force has identified current in consistencies between the definitions of PD and its diverse variants in different domains: clinical criteria, neuropathological classification, genetic subtyping, biomarker signatures, and mechanisms of disease. This initial effort for "defining the riddle" will lay the foundation for future attempts to better define the range of PD and its variants, as has been done and implemented for other heterogeneous neurological syndromes, such as stroke and peripheral neuropathy. We strongly advocate for a more systematic and evidence-based integration of our diverse disciplines by looking at well-defined variants of the syndrome of PD. CONCLUSION: Accuracy in defining endophenotypes of "typical PD" across these different but interrelated disciplines will enable better definition of variants and their stratification in therapeutic trials, a prerequisite for breakthroughs in the era of precision medicine. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Barrel cortex VIP/ChAT interneurons suppress sensory responses in vivo.

Cortical interneurons expressing vasoactive intestinal polypeptide (VIP) and choline acetyltransferase (ChAT) are sparsely distributed throughout the neocortex, constituting only 0.5% of its neuronal population. The co-expression of VIP and ChAT suggests that these VIP/ChAT interneurons (VChIs) can release both γ-aminobutyric acid (GABA) and acetylcholine (ACh). In vitro physiological studies quantified the response properties and local connectivity patterns of the VChIs; however, the function of VChIs has not been explored in vivo. To study the role of VChIs in cortical network dynamics and their long-range connectivity pattern, we used in vivo electrophysiology and rabies virus tracing in the barrel cortex of mice. We found that VChIs have a low spontaneous spiking rate (approximately 1 spike/s) in the barrel cortex of anesthetized mice; nevertheless, they responded with higher fidelity to whisker stimulation than the neighboring layer 2/3 pyramidal neurons (Pyrs). Analysis of long-range inputs to VChIs with monosynaptic rabies virus tracing revealed that direct thalamic projections are a significant input source to these cells. Optogenetic activation of VChIs in the barrel cortex of awake mice suppresses the sensory responses of excitatory neurons in intermediate amplitudes of whisker deflections while increasing the evoked spike latency. The effect of VChI activation on the response was similar for both high-whisking (HW) and low-whisking (LW) conditions. Our findings demonstrate that, despite their sparsity, VChIs can effectively modulate sensory processing in the cortical microcircuit.

Ageing-associated small RNA cargo of extracellular vesicles.

Previous work on murine models and humans demonstrated global as well as tissue-specific molecular ageing trajectories of RNAs. Extracellular vesicles (EVs) are membrane vesicles mediating the horizontal transfer of genetic information between different tissues. We sequenced small regulatory RNAs (sncRNAs) in two mouse plasma fractions at five time points across the lifespan from 2-18 months: (1) sncRNAs that are free-circulating (fc-RNA) and (2) sncRNAs bound outside or inside EVs (EV-RNA). Different sncRNA classes exhibit unique ageing patterns that vary between the fcRNA and EV-RNA fractions. While tRNAs showed the highest correlation with ageing in both fractions, rRNAs exhibited inverse correlation trajectories between the EV- and fc-fractions. For miRNAs, the EV-RNA fraction was exceptionally strongly associated with ageing, especially the miR-29 family in adipose tissues. Sequencing of sncRNAs and coding genes in fat tissue of an independent cohort of aged mice up to 27 months highlighted the pivotal role of miR-29a-3p and miR-29b-3p in ageing-related gene regulation that we validated in a third cohort by RT-qPCR.

Transfer RNA fragments replace microRNA regulators of the cholinergic poststroke immune blockade.

Stroke is a leading cause of death and disability. Recovery depends on a delicate balance between inflammatory responses and immune suppression, tipping the scale between brain protection and susceptibility to infection. Peripheral cholinergic blockade of immune reactions fine-tunes this immune response, but its molecular regulators are unknown. Here, we report a regulatory shift in small RNA types in patient blood sequenced 2 d after ischemic stroke, comprising massive decreases of microRNA levels and concomitant increases of transfer RNA fragments (tRFs) targeting cholinergic transcripts. Electrophoresis-based size-selection followed by qRT-PCR validated the top six up-regulated tRFs in a separate cohort of stroke patients, and independent datasets of small and long RNA sequencing pinpointed immune cell subsets pivotal to these responses, implicating CD14+ monocytes in the cholinergic inflammatory reflex. In-depth small RNA targeting analyses revealed the most-perturbed pathways following stroke and implied a structural dichotomy between microRNA and tRF target sets. Furthermore, lipopolysaccharide stimulation of murine RAW 264.7 cells and human CD14+ monocytes up-regulated the top six stroke-perturbed tRFs, and overexpression of stroke-inducible tRF-22-WE8SPOX52 using a single-stranded RNA mimic induced down-regulation of immune regulator Z-DNA binding protein 1. In summary, we identified a "changing of the guards" between small RNA types that may systemically affect homeostasis in poststroke immune responses, and pinpointed multiple affected pathways, which opens new venues for establishing therapeutics and biomarkers at the protein and RNA level.

Sex-specific declines in cholinergic-targeting tRNA fragments in the nucleus accumbens in Alzheimer's disease.

INTRODUCTION: Females with Alzheimer's disease (AD) suffer accelerated dementia and loss of cholinergic neurons compared to males, but the underlying mechanisms are unknown. Seeking causal contributors to both these phenomena, we pursued changes in transfer RNS (tRNA) fragments (tRFs) targeting cholinergic transcripts (CholinotRFs). METHODS: We analyzed small RNA-sequencing (RNA-Seq) data from the nucleus accumbens (NAc) brain region which is enriched in cholinergic neurons, compared to hypothalamic or cortical tissues from AD brains; and explored small RNA expression in neuronal cell lines undergoing cholinergic differentiation. RESULTS: NAc CholinotRFs of mitochondrial genome origin showed reduced levels that correlated with elevations in their predicted cholinergic-associated mRNA targets. Single-cell RNA seq from AD temporal cortices showed altered sex-specific levels of cholinergic transcripts in diverse cell types; inversely, human-originated neuroblastoma cells under cholinergic differentiation presented sex-specific CholinotRF elevations. DISCUSSION: Our findings support CholinotRFs contributions to cholinergic regulation, predicting their involvement in AD sex-specific cholinergic loss and dementia.

Stress-inducible phosphoprotein 1 (HOP/STI1/STIP1) regulates the accumulation and toxicity of α-synuclein in vivo.

The predominantly pre-synaptic intrinsically disordered protein α-synuclein is prone to misfolding and aggregation in synucleinopathies, such as Parkinson's disease (PD) and Dementia with Lewy bodies (DLB). Molecular chaperones play important roles in protein misfolding diseases and members of the chaperone machinery are often deposited in Lewy bodies. Here, we show that the Hsp90 co-chaperone STI1 co-immunoprecipitated α-synuclein, and co-deposited with Hsp90 and Hsp70 in insoluble protein fractions in two mouse models of α-synuclein misfolding. STI1 and Hsp90 also co-localized extensively with filamentous S129 phosphorylated α-synuclein in ubiquitin-positive inclusions. In PD human brains, STI1 transcripts were increased, and in neurologically healthy brains, STI1 and α-synuclein transcripts correlated. Nuclear Magnetic Resonance (NMR) analyses revealed direct interaction of α-synuclein with STI1 and indicated that the STI1 TPR2A, but not TPR1 or TPR2B domains, interacted with the C-terminal domain of α-synuclein. In vitro, the STI1 TPR2A domain facilitated S129 phosphorylation by Polo-like kinase 3. Moreover, mice over-expressing STI1 and Hsp90ß presented elevated α-synuclein S129 phosphorylation accompanied by inclusions when injected with α-synuclein pre-formed fibrils. In contrast, reduced STI1 function decreased protein inclusion formation, S129 α-synuclein phosphorylation, while mitigating motor and cognitive deficits as well as mesoscopic brain atrophy in α-synuclein-over-expressing mice. Our findings reveal a vicious cycle in which STI1 facilitates the generation and accumulation of toxic α-synuclein conformers, while α-synuclein-induced proteostatic stress increased insoluble STI1 and Hsp90.

Longitudinal Basal Forebrain Degeneration Interacts with TREM2/C3 Biomarkers of Inflammation in Presymptomatic Alzheimer's Disease.

Cholinergic inputs originating from the peripheral nervous system regulate the inflammatory immune responses of macrophages during clearance of blood-based pathogens. Because microglia are involved in clearing amyloid and tau pathology from the central nervous system, we hypothesized that cholinergic input originating from the basal forebrain might similarly regulate inflammatory immune responses to these pathologies in the aging brain. To explore this hypothesis, we leveraged the Alzheimer's Disease Neuroimaging Initiative dataset. Cognitively normal older male and female human adults were differentiated according to the relative concentration of phosphorylated tau and amyloid in their cerebrospinal fluid, yielding neurotypical and preclinical, cognitively healthy, subgroups. We then tracked these two groups longitudinally with structural MRI and biomarkers of inflammation, including soluble sTREM2 levels in the CSF and complement C3 expression in the blood transcriptome. Longitudinal loss of basal forebrain volume was larger in the preclinical compared with the neurotypical subgroup. Across preclinical adults, loss of basal forebrain volume was associated with greater longitudinal accumulation of sTREM2 and higher peripheral blood C3 expression. None of these relationships were attributable to degeneration in the whole-brain gray matter volume. Preclinical APOE e4 carriers exhibited the largest loss of basal forebrain volume and highest C3 expression. Consistent with the known anti-inflammatory influence of the peripheral cholinergic pathways on macrophages, our findings indicate that a loss of central cholinergic input originating from the basal forebrain might remove a key check on microglial inflammation induced by amyloid and tau accumulation.SIGNIFICANCE STATEMENT In the peripheral nervous system, cholinergic modulation holds the reactivity of macrophages to blood-based pathogens in check, promoting clearance while preventing runaway inflammation and immune-triggered cell death. Microglia are the brain's resident macrophages and play an important role in clearing accumulated amyloid and tau from neurons. Here, we demonstrate that a loss of cholinergic integrity in the CNS, indexed by longitudinal decreases of basal forebrain volume, interacts with multiple biomarkers of inflammation in cognitively normal older adults with abnormal amyloid and tau pathology. These interactions were not detected in cognitively normal older adults with "neurotypical" levels of amyloid and tau. An age-related loss of cholinergic neuromodulation may remove key checks on microglial reactivity to amyloid and tau.

Preface: Cholinergic mechanisms: This is the Preface for the special issue "Cholinergic Mechanisms".

This special issue of the Journal of Neurochemistry, entitled "Cholinergic Mechanisms," presents 15 reviews and two original papers, which have been selected to cover the broad spectrum of topics and disciplines presented at the XVIth International Symposium on Cholinergic Mechanisms (ISCM-XVI), ranging from the molecular and the cellular to the clinical and the cognitive mechanisms of cholinergic transmission. The authors discuss recent developments in the field, for instance, the association of cholinergic transmission with a number of important neurological and neuromuscular diseases in the central and peripheral nervous systems.

Regulators of cholinergic signaling in disorders of the central nervous system.

Cholinergic signaling is crucial in cognitive processes, and degenerating cholinergic projections are a pathological hallmark in dementia. Use of cholinesterase inhibitors is currently the main treatment option to alleviate symptoms of Alzheimer's disease and has been postulated as a therapeutic strategy in acute brain damage (stroke and traumatic brain injury). However, the benefits of this treatment are still not clear. Importantly, cholinergic receptors are expressed both by neurons and by astrocytes and microglia, and binding of acetylcholine to the α7 nicotinic receptor in glial cells results in anti-inflammatory response. Similarly, the brain fine-tunes the peripheral immune response over the cholinergic anti-inflammatory axis. All of these processes are of importance for the outcome of acute and chronic neurological disease. Here, we summarize the main findings about the role of cholinergic signaling in brain disorders and provide insights into the complexity of molecular regulators of cholinergic responses, such as microRNAs and transfer RNA fragments, both of which may fine-tune the orchestra of cholinergic mRNAs. The available data suggest that these small noncoding RNA regulators may include promising biomarkers for predicting disease course and assessing treatment responses and might also serve as drug targets to attenuate signaling cascades during overwhelming inflammation and to ameliorate regenerative capacities of neuroinflammation.

Cortical VIP+ /ChAT+ interneurons: From genetics to function.

One of the urgent tasks of neuroscience is to understand how neuronal circuits operate, what makes them fail, and how to repair them when needed. Achieving this goal requires identifying the principal circuitry elements and their interactions with one another. However, what constitutes 'an atom' of a neuronal circuit, a neuronal type, is a complex question. In this review we focus on a class of cortical neurons that are exclusively identified by the expression of vasoactive intestinal polypeptide (VIP) and choline acetyltransferase (ChAT). The genetic profile of these VIP+ /ChAT+ interneurons suggests that they can release both γ-aminobutyric acid (GABA) and acetylcholine (ACh). This hints to a specific potential role in the cortical circuitry. Yet the VIP+ /ChAT+ interneurons are sparse (a mere 0.5% of the cortical neurons), which raises questions about their potential to significantly affect the circuit function. In view of recent developments in genetic techniques that allow for direct manipulation of these neurons, we provide a thorough and updated picture of the properties of the VIP+ /ChAT+ interneurons. We discuss their genetic profile, their physiological and structural properties, and their input-output mapping in sensory cortices and the medial prefrontal cortex (mPFC). Then, we examine possible amplification mechanisms for mediating their function in the cortical microcircuit. Finally, we discuss directions for further exploration of the VIP+ /ChAT+ population, focusing on its function during behavioral tasks as compared to the VIP+ /ChAT- population.

Modulation of hippocampal neuronal resilience during aging by the Hsp70/Hsp90 co-chaperone STI1.

Chaperone networks are dysregulated with aging, but whether compromised Hsp70/Hsp90 chaperone function disturbs neuronal resilience is unknown. Stress-inducible phosphoprotein 1 (STI1; STIP1; HOP) is a co-chaperone that simultaneously interacts with Hsp70 and Hsp90, but whose function in vivo remains poorly understood. We combined in-depth analysis of chaperone genes in human datasets, analysis of a neuronal cell line lacking STI1 and of a mouse line with a hypomorphic Stip1 allele to investigate the requirement for STI1 in aging. Our experiments revealed that dysfunctional STI1 activity compromised Hsp70/Hsp90 chaperone network and neuronal resilience. The levels of a set of Hsp90 co-chaperones and client proteins were selectively affected by reduced levels of STI1, suggesting that their stability depends on functional Hsp70/Hsp90 machinery. Analysis of human databases revealed a subset of co-chaperones, including STI1, whose loss of function is incompatible with life in mammals, albeit they are not essential in yeast. Importantly, mice expressing a hypomorphic STI1 allele presented spontaneous age-dependent hippocampal neurodegeneration and reduced hippocampal volume, with consequent spatial memory deficit. We suggest that impaired STI1 function compromises Hsp70/Hsp90 chaperone activity in mammals and can by itself cause age-dependent hippocampal neurodegeneration in mice. Cover Image for this issue: doi: 10.1111/jnc.14749.

NEAT1 is overexpressed in Parkinson's disease substantia nigra and confers drug-inducible neuroprotection from oxidative stress.

Recent reports attribute numerous regulatory functions to the nuclear paraspeckle-forming long noncoding RNA, nuclear enriched assembly transcript 1 (NEAT1), but the implications of its involvement in Parkinson's disease (PD) remain controversial. To address this issue, we assessed NEAT1 expression levels and cell type patterns in the substantia nigra (SN) from 53 donors with and without PD, as well as in interference tissue culture tests followed by multiple in-house and web-available models of PD. PCR quantification identified elevated levels of NEAT1 expression in the PD SN compared with control brains, an elevation that was reproducible across a multitude of disease models. In situ RNA hybridization supported neuron-specific formation of NEAT1-based paraspeckles at the SN and demonstrated coincreases of NEAT1 and paraspeckles in cultured cells under paraquat (PQ)-induced oxidative stress. Furthermore, neuroprotective agents, including fenofibrate and simvastatin, induced NEAT1 up-regulation, whereas RNA interference-mediated depletion of NEAT1 exacerbated death of PQ-exposed cells in a leucine-rich repeat kinase 2-mediated manner. Our findings highlight a novel protective role for NEAT1 in PD and suggest a previously unknown mechanism for the neuroprotective traits of widely used preventive therapeutics.-Simchovitz, A., Hanan, M., Niederhoffer, N., Madrer, N., Yayon, N., Bennett, E. R., Greenberg, D. S., Kadener, S., Soreq, H. NEAT1 is overexpressed in Parkinson's disease substantia nigra and confers drug-inducible neuroprotection from oxidative stress.