ACS Chemical Neuroscience最新文献

Hemorrhagic stroke triggers secondary brain injury through the red blood cell toxins hemoglobin (Hb) and heme, which fuel iron-driven lipid peroxidation and neuronal injury. We sought to use organotypic brain-slice cultures to dissect how the high-affinity scavenger proteins haptoglobin (Hp) and hemopexin (Hpx) modulate this cascade. By day 7 of culture, slices remained structurally intact, metabolically active, and responsive to oxidative stress, enabling precise toxin exposure studies. Isotopic ⁵⁸Fe tracing revealed that upon cell-free Hb and heme exposures, heme-iron accumulated in brain slices and heightened lipid peroxidation. In contrast, Hpx neutralized heme, nearly abolishing iron deposition, while Hp partially reduced Hb-driven iron accumulation. Both scavengers attenuated lipid peroxidation and reduced neuronal cell death. Transcriptomic profiling revealed that free toxins increased oxidative stress and neuroinflammatory activation markers, whereas Hpx suppressed the expression of heme-induced genes. Remarkably, HbHp complexes triggered a strong Nrf2-centered adaptive program that enhanced iron metabolism and glutathione synthesis. Integrating five readouts─iron accumulation, lipid peroxidation, neuronal cell death, heme-stress transcripts, and Nrf2/metabolic transcripts─via bootstrap-based principal component analysis yielded two orthogonal axes. An oxidative toxicity axis (PC1) captured iron-driven reactive oxygen species and cell death, while a metabolic adaptation axis (PC2) reflected Nrf2-mediated reprogramming. Free toxins clustered at the toxic extreme on PC1, and heme–Hpx aligned near baseline. HbHp shifted slices upward on PC2, reducing neuronal loss through safe adaptation. These findings establish that Hpx neutralizes free heme, whereas Hp stabilizes Hb and elicits cytoprotective gene expression, offering a rational, dual-scavenger strategy to mitigate secondary brain injury in hemorrhagic stroke.

Parkinson’s disease (PD) is a debilitating neurological disorder characterized by the buildup of abnormal protein clumps, primarily composed of a protein called Alpha-Synuclein (α-Syn). Under physiological conditions, α-Syn exists as a dynamic, intrinsically disordered protein that resists aggregation through transient intramolecular interactions. However, under pathological conditions, this protein can misfold and stack into rigid, fibrous structures known as amyloid fibrils. These fibrillar deposits accumulate within neurons and are central to PD pathogenesis. This review focuses on understanding what keeps monomeric α-Syn in its innocuous form and what causes it to shift into a disease-associated state. In particular, we explore the role of subtle, often-overlooked intramolecular forces, like cation−π, π–π, and CH−π interactions, that may help stabilize the protein and prevent aggregation. We also examine how genetic mutations linked to familial forms of PD influence these internal interactions and drive the formation of partially folded intermediate forms that can trigger fibril growth. Some familial mutations accelerate α-Syn aggregation, while others slow it down, but the reasons behind these different outcomes are not fully understood. By analyzing how these mutations alter the protein’s early structure and behavior, this review aims to shed light on the first steps of α-Syn misfolding. A deeper understanding of these mechanisms could support the development of new therapies designed to stabilize the soluble form of monomeric α-Syn and slow or prevent disease progression.

The primo vascular system (PVS) is a fine-scale circulatory network composed of nanoscale tissues that are closely associated with biological signal transmission pathways, such as the gut–brain axis, and that harbor immune and regenerative cells. Mast cells (MCs), critical mediators of gut–brain axis communication, have been implicated in the pathogenesis of Alzheimer’s disease (AD). Characterized by a high MC density, the PVS is increasingly recognized as a potential modulator of immune responses and tissue regeneration. However, its pathological alterations in neurodegenerative conditions remain poorly understood. This study aimed to investigate the nanoscale structural and immunological characteristics of the organ surface and meningeal PVS (OS-PVS and M-PVS) in APP/PS2 transgenic mice, a well-established model of AD. Behavioral testing in APP/PS2 mice confirmed cognitive impairments characteristic of AD. Atomic force microscopy revealed irregular alignment of primo subvessels and interstitial spaces, along with increased surface roughness and loss of spatial periodicity. Scanning electron microscopy showed a significant increase in the density and diameter of primo pores, as well as reduced fiber structure diameter, suggesting ultrastructural remodeling. Toluidine blue and immunofluorescence staining demonstrated elevated MC density and degranulation ratio within the PVS. These findings suggest that the OS-PVS and M-PVS undergo coordinated nanoscale structural and immunological remodeling in AD, reflecting shared pathological features within the PVS. MC activity within the PVS may contribute to the neuroimmune dysregulation underlying disease progression, supporting its role as an anatomical conduit for immune communication along the gut–brain axis.

The escalating global burden of Alzheimer’s disease (AD), projected to reach $16.9 trillion by 2050 with disproportionate impacts on low- and middle-income countries and racial minorities, underscores an urgent need for accessible early detection tools. Current therapies offer limited symptomatic relief but fail to halt neurodegeneration. Serum exosomal lipids, which reflect brain pathophysiology through blood–brain barrier crossing vesicles, present promising minimally invasive biomarkers. However, a standardized framework for their systematic development is lacking. We propose a structured three-phase approach comprising discovery, analytical validation, and clinical utility assessment. The discovery phase employs nontargeted lipidomics of serum exosomes from AD patients and controls integrated with machine learning to identify dysregulated pathways and prioritize candidate biomarkers. Analytical validation involves targeted quantification using UPLC-MS/MS to optimize sensitivity and specificity within complex matrices, with rigorous performance evaluation via receiver operating characteristic (ROC) curve analysis and area under the curve (AUC) analysis in independent case-control cohorts establishing preliminary diagnostic cut-offs. Clinical utility assessment requires longitudinal evaluation in treated AD cohorts to correlate biomarker dynamics with disease progression or therapeutic response, refine diagnostic thresholds, and explore presymptomatic risk prediction. Implementing this framework demands multidisciplinary collaboration and strict ethical adherence. This strategy paves the way for clinically validated serum exosomal lipid biomarkers to enable presymptomatic detection and personalized risk stratification, ultimately mitigating AD’s devastating socioeconomic impact.

Drimane sesquiterpenoids are biologically active compounds found in plants, fungi, and marine organisms. Three isodrimenine derivatives, 5,6-dehydro-7-keto-isodrimenine (DH7KID), 7-keto-isodrimenine (7KID), and 7-acetoxy-isodrimenine (7AID), belonging to the drimane-type sesquiterpene family were synthesized and evaluated for activity at various human nicotinic acetylcholine receptor (nAChR) subtypes using two-electrode voltage-clamp electrophysiology. All three compounds exhibited comparable inhibitory potency across nAChR subtypes but showed greater selectively for α7-containing receptors. For DH7KID, the selectivity order was α7β2 ≅ α7 > α4β4 > α6*β2β3 (*α6-α3 chimera) > α4β2 ≅ α6*β4 > α3β4 ≅ α3β2 > α9α10. Inhibition of α7 and α4β4 nAChRs by DH7KID and 7KID, respectively, was independent of acetylcholine concentration, indicating a noncompetitive mechanism and suggesting that these compounds do not act at the orthosteric site. Furthermore, inhibition was voltage-independent, consistent with binding to a nonluminal allosteric site. The deactivation time constants of currents mediated by α7- and α4-containing nAChRs were unaffected by isodrimenine. In silico structural analyses further supported the interaction of DH7KID with nonluminal allosteric sites on the α7 nAChR. Collectively, these findings demonstrate that isodrimenine derivatives function as negative allosteric modulators of α7-containing nAChRs. Given the biological significance of α7 nAChRs, isodrimenine-induced inhibition may have therapeutic relevance for neuropsychiatric disorders.

Spinal cord injury (SCI) disrupts motor, sensory, and autonomic functions, profoundly impairing quality of life. Here, we investigate the role of the proton-activated chloride (PAC) channel, encoded by Pacc1, in motor function recovery following SCI. We found that PAC is expressed in the spinal cord, predominantly in microglia, and its expression markedly increases after injury. In Pacc1 knockout mice, motor recovery was significantly improved, accompanied by reduced microgliosis. Moreover, microglia-specific deletion of Pacc1 decreased lesion volume and further enhanced motor recovery, as demonstrated by behavioral assessments. Mechanistically, loss of Pacc1 in microglia suppressed excessive microglial activation and the release of pro-inflammatory cytokines after injury. Together, these findings identify the PAC channel as an injury-induced regulator that aggravates inflammation and impairs motor recovery. Targeting PAC may thus represent a promising therapeutic strategy to mitigate inflammation and promote spinal cord repair after SCI.

The GluN2B subunit of N-methyl-d-aspartate receptors (NMDARs) plays a key role in regulating excitatory neurotransmission and synaptic plasticity. Aberrant GluN2B signaling contributes to glutamate-mediated excitotoxicity and has been implicated in neurodegenerative and neuropsychiatric disorders, making it a crucial target for therapeutic development and in vivo imaging. In this study, we systematically evaluated the pharmacokinetics and imaging characteristics of both (R)- and (S)-enantiomers of [¹⁸F]PF-NB1 PET tracers in nonhuman primates to determine their suitability for clinical translation. Dynamic PET scans, arterial input functions, kinetic modeling, and blocking studies were performed to assess brain uptake, regional distribution consistent with GluN2B expression, binding specificity, and metabolite profiles. In addition to direct comparison of the two enantiomers, we benchmarked their in vivo performance against analogous ¹⁸F-labeled GluN2B tracers, including OF-Me-NB1 and OF-NB1. This cross-evaluation revealed differences in brain uptake, regional distribution matching GluN2B expression, binding specificity, and metabolic stability. Regional time-activity curves were fitted with the one-tissue compartment (1TC) model to derive regional volume of distribution (V_T) values, which were higher for (R)-[¹⁸F]PF-NB1(61.5–169.4 mL/cm³) than (S)-[¹⁸F]PF-NB1 (48.6–88.9 mL/cm³) in the same monkey. A GluN2B selective antagonist, Co-101,244, substantially reduced the uptake and V_T values of both (R)- and (S)-[¹⁸F]PF-NB1 across brain regions, with calculated target occupancy of 96% and 90%, and nondisplaceable volume of distribution (V_ND, mL/cm³) values of 10.01 and 11.45, respectively. In the same monkey, regional nondisplaceable binding potential (BP_ND) values ranged from 3.24 to 6.76 for (S)-[¹⁸F]PF-NB1, and from 5.12 to 15.92 for (R)-[¹⁸F]PF-NB1.

Neuronal plasticity in response to external stimuli underlies learning and memory, and RNA methylation has emerged as a critical regulator of this process. Yet how different modifications contribute to activity-dependent regulation remains unclear. N¹-Methyladenosine (m¹A) and N⁶-methyladenosine (m⁶A) are methylation both occurred at adenosine, but at different positions. To compare m¹A and m⁶A dynamics in primary cortical neurons during neuronal activation mimicked by KCl depolarization, we performed single-nucleotide resolution GLORI-seq and m¹A MAP-seq while overall m⁶A levels were markedly reduced, m¹A levels remained stable. m⁶A sites exhibited a shift from the canonical DRACH motif to AA-rich contexts, whereas m¹A motifs were unchanged. Structure modeling revealed preferential localization of m¹A to low-minimum free energy (MFE), loop-enriched regions, in contrast to a broader distribution of m⁶A across flexible structures. Integration with RNA-seq data further showed that transcripts harboring upregulated m¹A sites displayed elevated expressions, particularly when these sites were embedded in loop-like RNA structures, suggesting a structural basis for m¹A-mediated transcript enhancement. In contrast, m⁶A site changes were not associated with transcriptional differences, but their neighboring sequences were enriched for translation-related RNA-binding proteins. Together, these findings define a division of labor between adenosine methylations: m¹A enhances a RNA output via structural encoding, while m⁶A modulates translation through dynamic RNA-binding protein interactions, offering a mechanistic framework for epitranscriptomic coordination during activity-dependent neuronal plasticity.

Alzheimer’s disease (AD) is a prevalent neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques, tau neurofibrillary tangles, and progressive neuronal loss leading to cognitive decline. With millions affected worldwide, there remains an urgent need for innovative treatment strategies to combat this disease. Genome-wide association studies (GWAS) have identified genes expressed in microglia, the resident immune cells of the brain, as key mediators of AD susceptibility. Among microglial risk genes, CD33 and TREM2 stand out for their contrasting roles in AD risk. Accumulating evidence indicates that these receptors converge on overlapping signaling pathways to regulate microglial activation and Aβ clearance. Here, we review the current understanding of CD33 and TREM2 biology in AD, with a focus on their potential crosstalk and functional antagonism. We propose potential mechanistic models by which human CD33 isoforms regulate TREM2 activity in either the absence or presence of Aβ pathology and discuss therapeutic strategies targeting this axis. Together, these insights suggest new avenues for microglia-targeted interventions in AD.

Understanding how drug exposure alters synaptic proteins is essential for uncovering the molecular mechanisms underlying addiction and identifying new therapeutic targets. Synaptoneurosomes (SNs), subcellular fractions enriched in pre- and postsynaptic components, provide a powerful resource for studying synaptic adaptations in the brain. Here, we applied a deep, discovery-based proteomic strategy to profile SNs isolated from the dorsal striatum (DS) of rats 1 h after acute methamphetamine (Meth) administration. To maximize proteome coverage, we combined tandem mass tag (TMT) labeling, offline high-pH fractionation, and low-pH nanoflow liquid chromatography coupled to high-resolution (orbitrap) mass spectrometry (HRMS). This approach enabled identification of ∼6100 cytosolic and membrane proteins from ∼500 ng of SN proteome digest─representing the most comprehensive DS SN proteome reported to date. A comparative analysis between Meth-treated and saline control animals revealed 147 differentially abundant proteins (81 with increased abundance; 66 with decreased abundance) enriched in pathways related to dopamine biosynthesis, synaptic vesicle cycling, mitochondrial energy metabolism, and proteasomal degradation. These findings highlight coordinated molecular remodeling of striatal synapses in response to Meth and demonstrate the utility of deep SN proteomics in addiction research. Deep, low-input SN proteomics nominates vesicle acidification, mitochondrial ATP supply, and proteasome function as testable pathway-level targets in addiction.