Biology of oligodendrocyte and myelin in the mammalian central nervous system

Multi-functional memantine nitrate attenuated cognitive impairment in models of vascular dementia and Alzheimer's disease through neuroprotection and increased cerebral blood flow

Alzheimer's disease (AD) and vascular dementia (VaD) are two prevalent forms of dementia. VaD is linked to cerebrovascular lesions, such as those from white matter ischemia and chronic cerebral hypoperfusion, which can also occur in AD. Nitric oxide (NO) regulates cerebral blood flow (CBF) in the central nervous system. Memantine is an NMDA receptor antagonist approved for AD treatment. This study investigated the efficacy and molecular mechanism of MN-08, a novel memantine nitrate, in one VaD model (2VO) and two AD models (APP/PS1 mice and Aβ1-42-induced mice). MN-08 increased CBF, ameliorated cognitive and memory functions in VaD and AD, and was more effective than memantine. MN-08 increased the survival rate of CA1 neurons and mitigated white matter lesions and axonal damage. Moreover, MN-08 protected neurons from OGD-induced loss and promoted axonal outgrowth in the hippocampus by upregulating phosphorylated Akt (p-Akt), glycogen synthase kinase-3β (p-GSK3β), and high-molecular-weight neurofilaments (p-NFH). The beneficial effects of MN-08 were attenuated by carboxy-PTIO, a potent NO scavenger, suggesting that MN-08-derived NO may alleviate cognitive impairment from cerebral hypoperfusion. Taken together, our studies demonstrate that MN-08 is a promising therapeutic agent for the treatment of dementia including VaD and AD.

Exploring synergistic effects: Atorvastatin and electrical stimulation in spinal cord injury therapy

Spinal cord trauma represents a significant clinical challenge, and improving patient outcomes is a main priority for many scientific teams globally. Despite advances in the understanding its pathogenesis, the overall mechanisms occurring in the spinal cord after traumatic injury remain unclear. This study explores the possible synergistic effects of a regenerative therapy that combines electrical stimulation with the anti-inflammatory drug Atorvastatin (ATR) after spinal cord injury (SCI). SCI was induced at the T9 segment under isoflurane anesthesia and applying a compression force of 40 g for 15 minutes. An oscillating field stimulator (OFS) was implanted subcutaneously, delivering a weak electric current (50 µA) that changed polarity every 15 minutes for six weeks to promote axonal growth at the injury site. Female Wistar albino rats were divided into four groups: SCI with non-functional stimulator (SCI + nOFS), SCI with functional stimulator (SCI+OFS), and two groups that received ATR together with stimulator for 7 days after injury (SCI+OFS+ATR, SCI+nOFS+ATR). Behavioral tests (hot-plate test and BBB scale) showed improvement in sensory and motor performance in animals treated with the combination therapy. The protein levels of astrocytes (GFAP), neurofilaments (NF-L), newly sprouting axons (GAP-43), and oligodendrocytes (PLP -1, CNPase) were analysed by Western blot. The results showed increased neurofilaments, newly sprouting axons and oligodendrocytes in groups receiving both individual and combination therapies, with a decrease in their concentrations in the following order: SCI+OFS+ATR, SCI+nOFS+ATR, SCI+OFS, SCI+nOFS. In addition, astrocyte protein levels were lower in the SCI+OFS+ATR group compared with others. Histological analysis showed a significant reduction in white and gray matter after SCI, but less white and gray matter volume loss was found in the groups receiving therapies (SCI+OFS+ATR, SCI+nOFS+ATR, SCI+OFS). These results suggest that the combination of Atorvastatin with OFS stimulation promotes neural recovery after SCI, highlighting the potential of combination therapies in enhancing regenerative outcomes.

Excitotoxic lesion in the corpus callosum of neonatal rats: A model for encephalopathy of prematurity

Encephalopathy of prematurity (EP) can develop in preterm infants exposed to risk factors like extreme prematurity, low birth weight, hypoxia, infections, and inflammation. These factors can induce excitotoxicity in the brain's gray and white matter, leading to the death of neurons and oligodendrocyte progenitors. Understanding the brain mechanisms of EP requires animal models. In this study, we generated an EP model by injecting N-methyl-D-aspartic acid (NMDA) into the corpus callosum (CC) of neonatal male rats on postnatal day (PND) 5. Rats were divided into five groups: Intact, Vehicle, and three doses of NMDA (3, 4, or 5 μg). On PND 20, we measured the volumes of the CC, motor cortex (MC), and lateral ventricles. The 5 µg NMDA dose caused the largest lesion. We later assessed these structures on PNDs 6, 10, 20, and 30 to monitor lesion progression. We also analyzed myelin basic protein (MBP) expression and counted NeuN-positive cells using immunofluorescent markers. NMDA groups showed reduced MBP expression and fewer NeuN-positive cells in the MC. Additionally, NMDA-treated rats exhibited increased motor activity in the open field and reduced fall latencies in the rotarod task compared to controls. In conclusion, our perinatal excitotoxic lesion model in rats demonstrates structural abnormalities, including decreased MBP and loss of NeuN-positive cells, alongside motor and habituation impairments, resembling those seen in human EP.

Imaging the structural connectome with hybrid MRI-microscopy tractography

Mapping how neurons are structurally wired into whole-brain networks can be challenging, particularly in larger brains where 3D microscopy is not available. Multi-modal datasets combining MRI and microscopy provide a solution, where high resolution but 2D microscopy can be complemented by whole-brain but lowresolution MRI. However, there lacks unified approaches to integrate and jointly analyse these multi-modal data in an insightful way. To address this gap, we introduce a data-fusion method for hybrid MRI-microscopy fibre orientation and connectome reconstruction. Specifically, we complement precise "in-plane" orientations from microscopy with "through-plane" information from MRI to construct 3D hybrid fibre orientations at resolutions far exceeding that of MRI whilst preserving microscopy's myelin specificity, resulting in superior fibre tracking. Our method is openly available, can be deployed on standard 2D microscopy, including different microscopy contrasts, and is species agnostic, facilitating neuroanatomical investigation in both animal models and human brains.

Subcortical plaques and inflammation reflect cortical and meningeal pathologies in progressive multiple sclerosis

It remains elusive whether lesions and inflammation in the sub/juxtacortical white matter reflect cortical and/or meningeal pathologies. Elucidating this could have implications for MRI monitoring as sub/juxtacortical lesions are detectable by routine MRI, while cortical lesions and meningeal inflammation are not. By large-area microscopy, we quantified total and mixed active plaque loads along with densities and sizes of perivascular mononuclear infiltrates (infiltrates) in the sub/juxtacortical white matter ≤2 mm from the cortex, intra-cortically and in the meninges. Data were related to ante-mortem clinical parameters in a false discovery rate-corrected analysis. We compared 12 patients with primary progressive multiple sclerosis (PPMS) and 15 with secondary progressive MS to 22 controls. Fifteen patients and 11 controls contributed with hemispheric sections. Sections were stained with haematoxylin-eosin, for myelin and for microglia/macrophages. B cells and T cells were confirmed in a subset. Immunoglobulin G depositions in selected cortical plaques resembled depositions described before in "slowly expanding" plaques in the white matter. We quantified plaque activity by measuring microglia-dominated and macrophage-dominated areas. Sub/juxtacortical plaques (load and activity) reflected plaque activity in the cerebral cortex. Plaque activity and infiltrates were more pronounced in the sub/juxtacortical white matter than in the cerebral cortex while conversely, the total plaque load was highest in the cortex. Infiltrates correlated trans-cortically and sub/juxtacortical plaque activity reflected cortical and meningeal infiltrates. Sub/juxtacortical infiltrate sizes correlated with shorter survival after progression onset. Two patients with PPMS and putatively fatal brain stem lesions argue against incidental findings. Trans-cortical inflammatory flares and plaque activity may be pathogenic in progressive MS. We suggest emphasis on sub/juxtacortical MRI lesions as plausible surrogates for cortical and meningeal pathologies and, when present, as indicators for cognitive testing.

Dysregulation of Myelination in Focal Cortical Dysplasia Type II of the Human Frontal Lobe

Focal cortical dysplasias (FCDs) are local malformations of the human neocortex and a leading cause of intractable epilepsy. FCDs are classified into different subtypes including FCD IIa and IIb, characterized by a blurred gray-white matter boundary or a transmantle sign indicating abnormal white matter myelination. Recently, we have shown that myelination is also compromised in the gray matter of FCD IIa of the temporal lobe. Since myelination is key for brain function, which is imbalanced in epilepsy, in the current study, we investigated myelination in the gray matter of FCD IIa and IIb from the frontal lobe on the morphological, ultrastructural, and transcriptional level. We found that FCD IIa presents with an ordinary radial myelin fiber pattern, but with a reduced thickness of myelin sheaths of 500-1000 nm thick axons in comparison to FCD IIb and with an attenuation of the myelin synthesis machinery. In contrast, FCD IIb showed an irregular and disorganized myelination pattern covering an enlarged area in comparison to FCD IIa and controls and with increased numbers of myelinating oligodendrocytes (OLs). FCD IIb had significantly thicker myelin sheaths of large caliber axons (above 1000 nm) when compared to FCD IIa. Accordingly, FCD IIb showed a significant up-regulation of myelin-associated mRNAs in comparison to FCD IIa and enhanced binding capacities of the transcription factor MYRF to target sites in myelin-associated genes. These data indicate that FCD IIa and IIb are characterized by a differential dysregulation of myelination in the gray matter of the frontal lobe.

Small brains but big challenges: white matter tractography in early life samples

In the human brain, white matter development is a complex and long-lasting process involving intermingling micro- and macrostructural mechanisms, such as fiber growth, pruning and myelination. Did you know that all these neurodevelopmental changes strongly affect MRI signals, with consequences on tractography performances and reliability? This communication aims to elaborate on these aspects, highlighting the importance of tracking and studying the developing connections with dedicated approaches.

Effect of Cytoskeletal Linker Protein GAS2L1 on Oligodendrocyte and Myelin Development

Oligodendrocytes (OLs), the myelin-forming cells of the central nervous system (CNS), develop from OL precursor cells (OPCs) through a complex process involving significant morphological changes that are critically dependent on the dynamic interactions between cytoskeletal networks. Growth arrest-specific 2-like protein 1 (GAS2L1) is a cytoskeletal linker protein that mediates the cross-talk between actin filaments and microtubules. However, its role in OL and myelin development remains unknown. Here, we report that GAS2L1 is expressed in both OPCs and mature OLs, and that overexpression or knockdown of Gas2l1 in cultured OPCs in vitro impaired or enhanced their differentiation, respectively, while both inhibited their proliferation. We generated a Gas2l1 fl/fl mouse line and found that mice with conditional knockout of Gas2l1 in OL lineage cells (Olig1-Cre;Gas2l1 fl/fl , cKO) showed an increased number of mature OLs and enhanced myelination, as well as a reduction in the branching complexity of OPCs. In addition, an alternative mouse line with postnatally induced Gas2l1 ablation specifically in OPCs (Pdfgra-CreER T2 ;Gas2l1 fl/fl , iKO) recapitulated the acceleration of OL and myelin development as well as the inhibition of OPC process branching. Furthermore, EdU tracking in Gas2l1 iKO mice in vivo and in their OPC cultures in vitro showed both a reduction in OPC proliferation and an increase in OL maturation. Finally, cultured OPCs from iKO mice showed an increase in filopodia extension. Taken together, our results demonstrate an effect of GAS2L1 on the regulation of OL/myelin development and may provide a novel potential therapeutic target for various diseases involving OL/myelin pathology.

The α- to γ-enolase switch: The role and regulation of γ-enolase during oligodendrocyte differentiation

The glycolytic enzyme γ-enolase is a highly specific neuronal marker that is known to replace ubiquitously expressed α-enolase in the brain. Moreover, γ-enolase has been shown to exert neurotrophic activity, which is regulated by cathepsin X, a lysosomal peptidase. This study investigates the role of γ-enolase and its regulation by cathepsin X during the differentiation of oligodendrocytes, which are essential for normal brain function. We established a differentiation protocol for the human oligodendroglioma (HOG) cell line and demonstrated for the first time that an α- to γ-enolase switch occurs during HOG cell differentiation. This switch was confirmed by the expression of specific markers underscoring the role of γ-enolase in oligodendrocyte differentiation. Moreover, γ-enolase overexpression enhanced oligodendrocyte differentiation, while silencing of γ-enolase by siRNA significantly decreased maturation marker. Further, the regulatory role of cysteine peptidase cathepsin X on γ-enolase function was found. Silencing cathepsin X significantly changed cell morphology, enhanced oligodendrocyte differentiation, altered the expression of oligodendrocyte markers, and increased levels of the active form of γ-enolase. Inhibiting cathepsin X similarly changed cell morphology and enhanced oligodendrocyte differentiation. These findings suggest that cathepsin X modulates γ-enolase activity and thereby influences oligodendrocyte differentiation and thus neuronal function.

Oligodendrocyte arrangement, identification and morphology in the developing superior olivary complex

Oligodendrocytes provide myelination, metabolic and developmental support for neurons and circuits. Within the auditory superior olivary complex (SOC), relevant for sound localization and spectro-temporal integration, oligodendrocytes are fundamental for fast neuronal communication and accurate timing of sound signals. Despite their important role in function and development, an assessment of their developmental arrangement and morphology is missing for the SOC. Here, immunofluorescence labeling and single cell electroporation was used to quantify their distribution, identification and morphology between postnatal day (P) 5 and ~ P54 in the SOC of Mongolian gerbils (Meriones unguiculatus). Oligodendrocytes show developmental, region-specific accumulations, redistributions and density profiles. Their identification by Olig2 and SOX10 appears age specific, while myelinating oligodendrocytes are detected by co-labeling with S100 irrespective of age. Comparison of oligodendrocyte density and identification between mature gerbil and Etruscan shrew (Suncus etruscus), revealed species-specific differences. Morphologically, the number of myelinating processes decreased, while process length, diameter and coverage area of oligodendrocytes increased during development. Together, oligodendrocyte developmental alterations occur at moments of SOC circuit refinement supporting functions beyond myelination.

Impact of Microglia-Derived Extracellular Vesicles on Resident Central Nervous System Cell Populations After Acute Brain Injury Under Various External Stimuli Conditions

Acute brain injuries (ABI) caused by various emergencies can lead to structural and functional damage to brain tissue. Common causes include traumatic brain injury, cerebral hemorrhage, ischemic stroke, and heat stroke. Globally, ABI represent a significant portion of neurosurgical cases. Previous studies have emphasized the significant therapeutic potential of stem cell-derived extracellular vesicles (EVs). Recent research indicates that EVs extracted from resident cells in the central nervous system (CNS) also show therapeutic potential following brain injury. Microglia, as innate immune cells of the CNS, respond to changes in the internal environment by altering their phenotype and secreting EVs that impact various CNS cells, including neurons, astrocytes, oligodendrocytes, endothelial cells, neural stem cells (NSCs), and microglia themselves. Notably, under different external stimuli, microglia can either promote neuronal survival, angiogenesis, and myelin regeneration while reducing glial scarring and inflammation, or they can exert opposite effects. This review summarizes and evaluates the current research findings on how microglia-derived EVs influence various CNS cells after ABI under different external stimuli. It analyzes the interaction mechanisms between EVs and resident CNS cells and discusses potential future research directions and clinical applications.

Claudin-11, a hypomyelinating leukodystrophy 22 (HLD22)-responsible protein, uniquely interacts with shroom-2 to change cell phenotypes

Oligodendroglial cells are a type of glial cell in the central nervous system (CNS) that wrap neuronal axons with differentiated plasma membranes known as myelin sheaths. While the physiological functions of oligodendrocytes, such as generating saltatory conduction and protecting neuronal axons, are well understood, the physiological and/or pathophysiological molecular mechanisms governing their differentiation before myelination remain unclear. In this study, we describe for the first time that claudin-11, a protein associated with hypomyelinating leukodystrophy 22 (HLD22), interacts with shroom-2, a presumable adaptor protein containing the PSD95, DLG1, and ZO-1 (PDZ) domain. Knockdown of claudin-11 using specific siRNA resulted in a decrease in morphological changes and marker proteins in the FBD-102b oligodendroglial model undergoing differentiation. Transfection of the C-terminal PDZ ligand sequence of claudin-11, which was found to interact with the PDZ domain of shroom-2, also reduced these phenotypic changes. The HLD22-associated mutated sequence in claudin-11 failed to interact with the PDZ domain of shroom-2. Furthermore, knockdown of shroom-2 or transfection of the PDZ domain of shroom-2, which is involved in the interaction with claudin-11, resulted in decreased morphological changes and marker protein expression. These changes were linked to the phosphorylation states of Akt kinase, a key signaling molecule in oligodendroglial cell differentiation and myelination. These results suggest that the interaction between claudin-11 and shroom-2 plays a key role in shaping cell morphology, providing insights into the molecular mechanisms underlying oligodendroglial differentiation before myelination, as well as potential pathological mechanisms associated with HLD22 at the molecular and cellular levels.

The crosstalk between CNS resident glial cells and peripheral immune cells is critical for age-dependent demyelination and subsequent remyelination

White-matter diseases like multiple sclerosis begin in young adulthood. Aging, being a risk factor, contributes to the progression of these diseases and makes neurological disabilities worsen. Aging causes white matter alteration due to myelin loss, axonal degeneration, and hyperintensities, resulting in cognitive impairment and neurological disorders. Aging also negatively affects central nervous system resident glial cells and peripheral immune cells, contributing to myelin degeneration and diminished myelin renewal process. Restoration of myelin failure with aging accelerates the progression of cognitive decline. This review will mainly focus on how age-related altered functions of glial and peripheral cells will affect myelin sheath alteration and myelin restoration. This understanding can give us insights into the underlying mechanisms of demyelination and failure of remyelination with aging concerning altered glial and peripheral immune cell function and their crosstalk. Also, we will explain the therapeutic strategies to enhance the remyelination process of an aging brain to improve the cognitive health of an aging person.

Amyloid-β Dysregulates Oligodendroglial Lineage Cell Dynamics and Myelination via PKC in the Zebrafish Spinal Cord

Soluble forms of amyloid-β (Aβ) peptide have been proposed as candidates to induce oligodendrocyte (OL) and myelin dysfunctions in the early stages of Alzheimer's disease (AD) pathology. Nevertheless, little is known about how Aβ affects OL differentiation and myelination in vivo, and the underlying molecular mechanisms. In this study, we explored the effects of a brain intraventricular injection of Aβ on OLs and myelin in the developing spinal cord of zebrafish larvae. Using quantitative fluorescent in situ RNA hybridization assays, we demonstrated that Aβ altered myrf and mbp mRNA levels and the regional distribution of mbp during larval development, suggesting an early differentiation of OLs. Through live imaging of Tg(myrf:mScarlet) and Tg(mbpa:tagRFP) zebrafish lines, both crossed with Tg(olig2:EGFP), we found that Aβ increased the number of myrf+ and mbp+ OLs in the dorsal spinal cord at 72 hpf and 5 dpf, respectively, without affecting total cell numbers. Furthermore, Aβ also increased the number of Sox10+cells, myelin sheaths per OL, and the number of myelinated axons in the dorsal spinal cord at 8 dpf compared to vehicle-injected control animals. Interestingly, the treatment of Aβ-injected zebrafish with the pan-PKC inhibitor Gö6983 restored the aforementioned alterations in OLs and myelin to control levels. Altogether, not only do we demonstrate that Aβ induces a precocious oligodendroglial differentiation leading to dysregulated myelination, but we also identified PKC as a key player in Aβ-induced pathology.

Del Río Hortega's insights into oligodendrocytes: recent advances in subtype characterization and functional roles in axonal support and disease

Pío Del Río Hortega (1882-1945) was a giant of modern neuroscience and perhaps the most impactful member of Cajal's School. His contributions to clarifying the structure of the nervous system were key to understanding the brain beyond neurons. He uncovered microglia and oligodendrocytes, the latter until then named mesoglia. Most importantly, the characterization of oligodendroglia subtypes he made has stood the omics revolution that added molecular details relevant to comprehend their biological properties. Astounding as it may seem on today's eyes, he postulated a century ago that oligodendrocytes provide trophic support to axons, an idea that is now beyond doubt and under scrutiny as dysfunction at the axon-myelin unit is key to neurodegeneration. Here, we revised recent key advancements in oligodendrocyte biology that shed light on Hortega's ideas a century ago.

Thinning of originally-existing, mature myelin represents a nondestructive form of myelin loss in the adult CNS

The main function of oligodendrocytes is to assemble and maintain myelin that wraps and insulates axons in the central nervous system (CNS). Traditionally, myelin structure, particularly its thickness, was believed to remain remarkably stable in adulthood (including early and middle adulthood, but not late adulthood or aging). However, emerging evidence reveals that the thickness of originally-existing, mature myelin (OEM) can undergo dynamic changes in the adult CNS. This overview highlights recent findings on the alteration of OEM thickness in the adult CNS, explores the underlying mechanisms, and proposes that progressive thinning of OEM represents a novel, nondestructive form of myelin loss in myelin disorders of the CNS.

Paranodal instability driven by axonal mitochondrial accumulation in ischemic demyelination and cognitive decline

BACKGROUND

Subcortical ischemic demyelination is the primary cause of vascular cognitive impairment in the elderly. However, its underlying mechanisms remain elusive.

METHODS

Using a bilateral common carotid artery stenosis (BACS) mouse model and an in vitro cerebellar slice model treated with low glucose-low oxygen (LGLO), we investigated a novel mechanism of vascular demyelination.

RESULTS

This work identified syntaphilin-mediated docking of mitochondria as the initial event preceding ischemic demyelination. This axonal insult drives paranodal retraction, myelin instability, and subsequent cognitive impairment through excessive oxidation of protein 4.1B by mitochondrial ROS. Syntaphilin knockdown reestablished the balance of mitochondrial axoplasmic transport, reduced axonal ROS burden, and consequently decreased the abnormal oxidation of protein 4.1B, an essential component that secures the Caspr1/contactin-1/NF155 complex tethered to the axonal cytoskeleton βII-Spectrin within paranodes. This ultimately protected the paranodal structure and myelin and improved cognitive function.

CONCLUSIONS

Our findings reveal a distinct pathological characteristic of ischemic demyelination and highlight the therapeutic potential of modulating axonal mitochondrial mobility to stabilize myelin structures and improve vascular cognitive impairment.

Bisphenol A exposure during gestation and lactation in mice: Sex-specific consequences on oligodendrocytes and myelination

Bisphenol A (BPA), a ubiquitous environmental endocrine disruptor, is suspected of disturbing brain development through largely unknown cellular and molecular mechanisms. In the central nervous system, oligodendrocytes are responsible for forming myelin sheaths, which enhance the propagation of action potentials along axons. Disruption of axon myelination can have lifelong consequences, making oligodendrocyte differentiation and myelination critical stages of brain development. In the present study, mice were exposed to BPA during gestation and lactation through drinking water at concentrations of 25 and 250 μg.L-1. These doses, corresponding to estimated exposures of 4 μg.kg-1.d-1 and 40 μg.kg-1.d-1, respectively, led to disturbances in lipid remodeling associated with myelination in the offspring. Importantly, changes in myelin lipid composition were selectively observed in female mice and were transient, being visible only at post-natal day P15 but not at later stages (P30 and P60). In females exposed to BPA, myelin exhibited a lower proportion of phosphatidylcholines and higher proportions of other glycerophospholipid subclasses, thus resembling more mature myelin. Conversely, male myelin was not affected, likely due to its already more mature lipid composition. Additionally, transcriptomic analysis of female oligodendrocytes at P15 did not reveal any transcriptional changes in genes related to lipid metabolism, further suggesting post-transcriptional effects of BPA via chaperone-mediated protein folding and RNA splicing. In males, the altered genes were mainly associated with synaptic transmission. Finally, alterations in chromatin accessibility were also largely sex dependent and did not correlate with transcription, with the exception of the Cwc22. At this locus, BPA exposure increased chromatin accessibility in half of mice of both sexes, leading to an "unchanged/open" bimodal profile correlated with "unchanged/upregulated" gene expression. Together, these results open new insights into the sex-dependent mechanisms of BPA's effects on brain development.

Fine particulate matter from burning oil and gas and associated neurological symptoms among Deepwater Horizon oil spill cleanup workers

Burning and flaring of oil and gas following the 2010 Deepwater Horizon (DWH) oil spill generated high airborne concentrations of fine particulate matter (PM2.5). Neurological effects of PM2.5 have been previously reported, but this relationship has received limited attention in the context of oil spills. We evaluated associations between burning-related PM2.5 and prevalence of self-reported neurological symptoms during, and 1-3 years after, the DWH disaster cleanup. For 9914 DWH disaster responders in the Gulf Long-term Follow-up Study who worked on the water, we examined aggregate outcomes (central nervous system [CNS; dizziness, sweating, palpitations, nausea, or migraine/severe headache] and peripheral nervous system [PNS; tingling/numbness in extremities, blurred vision, or stumbling] symptoms) and individual symptoms (CNS and PNS symptoms, plus insomnia, vomiting, seizures, and fatigue). We estimated PM2.5 concentrations via Gaussian plume dispersion models and linked these to detailed DWH cleanup work histories. We used log-binomial regression to estimate adjusted prevalence ratios (PR) and 95% confidence intervals, accounting for age, race, ethnicity, and sex, and DWH disaster-related co-exposures to benzene, toluene, ethylbenzene, xylene, and n-hexane (BTEX-H). We examined effect measure modification by age, race, smoking, and BTEX-H exposure. During the disaster, 34% of participants experienced at least one symptom (23% CNS, 12% PNS); 1-3 years later, 30% did (19% CNS, 17% PNS). Evidence of associations with PM2.5 was most consistent for CNS symptoms (PR range: 1.17 to 1.51), although we did not observe exposure-response trends. For PNS, PR ranged from 0.96 to 1.84. Associations with PM were more apparent among those with lower BTEX-H exposure and among older workers. We found some evidence of an association between burning-related PM2.5 and prevalence of neurologic symptoms during the DWH disaster response and 1-3 years later. Understanding these relationships can inform responses to future disasters to better protect human health.

GCN2-Mediated eIF2α Phosphorylation Is Required for Central Nervous System Remyelination

Under conditions of amino acid deficiency, mammalian cells activate a nutrient-sensing kinase known as general control nonderepressible 2 (GCN2). The activation of GCN2 results in the phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF2α), which can be phosphorylated by three other three integrated stress response (ISR) kinases, reducing overall protein synthesis. GCN2 activation also promotes the translation of specific mRNAs, some of which encode transcription factors that enhance the transcription of genes involved in the synthesis, transport, and metabolism of amino acids to restore cellular homeostasis. The phosphorylation of eIF2α has been shown to protect oligodendrocytes, the cells responsible for producing myelin in the central nervous system during remyelination. Here, we explore the potential role of the kinase GCN2 in the myelination process. We challenged mice deficient in the GCN2-encoding gene with a pharmacological demyelinating stimulus (cuprizone) and evaluated the recovery of myelin as well as ISR activation through the levels of eIF2α phosphorylation. Our findings indicate that GCN2 controls the establishment of myelin by fine-tuning its abundance and morphology in the central nervous system. We also found that GCN2 is essential for remyelination. Surprisingly, we discovered that GCN2 is necessary to maintain eIF2α levels during remyelination.

RhoA regulates oligodendrocyte differentiation and myelination by orchestrating cortical and membrane tension

Timely differentiation and myelin formation by oligodendrocytes are essential for the physiological functioning of the central nervous system (CNS). While the Rho GTPase RhoA has been hinted as a negative regulator of myelin sheath formation, the precise in vivo mechanisms have remained elusive. Here we show that RhoA controls the timing and progression of myelination by oligodendrocytes through a fine-tuned balance between cortical tension, membrane tension and cell shape. Using a conditional mouse model, we observe that Rhoa ablation results in the acceleration of myelination driven by hastened differentiation and facilitated through membrane expansion induced by changes in MLCII activity and in F-actin redistribution and turnover within the cell. These findings reveal RhoA as a central molecular integrator of alterations in actin cytoskeleton, actomyosin contractility and membrane tension underlying precise morphogenesis of oligodendrocytes and normal myelination of the CNS.

Diverse functions of DEAD-box proteins in oligodendrocyte development, differentiation, and homeostasis

Oligodendrocytes, a type of glial cell in the central nervous system, have a critical role in the formation of myelin around axons, facilitating saltatory conduction, and maintaining the integrity of nerve axons. The dysregulation of oligodendrocyte differentiation and homeostasis have been implicated in a wide range of neurological diseases, including dysmyelinating disorders (e.g., Pelizaeus-Merzbacher disease), demyelinating diseases (e.g., multiple sclerosis), Alzheimer's disease, and psychiatric disorders. Therefore, unraveling the mechanisms of oligodendrocyte development, differentiation, and homeostasis is essential for understanding the pathogenesis of these diseases and the development of therapeutic interventions. Numerous studies have identified and analyzed the functions of transcription factors, RNA metabolic factors, translation control factors, and intracellular and extracellular signals involved in the series of processes from oligodendrocyte fate determination to terminal differentiation. DEAD-box proteins, multifunctional RNA helicases that regulate various intracellular processes, including transcription, RNA processing, and translation, are increasingly recognized for their diverse roles in various aspects of oligodendrocyte development, differentiation, and maintenance of homeostasis. This review introduces the latest insights into the regulatory networks of oligodendrocyte biology mediated by DEAD-box proteins.

Targeting Oligodendrocyte Dynamics and Remyelination: Emerging Therapies and Personalized Approaches in Multiple Sclerosis Management

Multiple sclerosis (MS) is a progressive autoimmune condition that primarily affects young people and is characterized by demyelination and neurodegeneration of the central nervous system (CNS). This in-depth review explores the complex involvement of oligodendrocytes, the primary myelin- producing cells in the CNS, in the pathophysiology of MS. It discusses the biochemical processes and signalling pathways required for oligodendrocytes to function and remain alive, as well as how they might fail and cause demyelination to occur. We investigate developing therapeutic options that target remyelination, a fundamental component of MS treatment. Remyelination approaches promote the survival and differentiation of oligodendrocyte precursor cells (OPCs), restoring myelin sheaths. This improves nerve fibre function and may prevent MS from worsening. We examine crucial parameters influencing remyelination success, such as OPC density, ageing, and signalling pathway regulation (e.g., Retinoid X receptor, LINGO-1, Notch). The review also examines existing neuroprotective and antiinflammatory medications being studied to see if they can assist oligodendrocytes in surviving and reducing the severity of MS symptoms. The review focuses on medicines that target the myelin metabolism in oligodendrocytes. Altering oligodendrocyte metabolism has been linked to reversing demyelination and improving MS patient outcomes through various mechanisms. We also explore potential breakthroughs, including innovative antisense technologies, deep brain stimulation, and the impact of gut health and exercise on MS development. The article discusses the possibility of personalized medicine in MS therapy, emphasizing the importance of specific medicines based on individual molecular profiles. The study emphasizes the need for reliable biomarkers and improved imaging tools for monitoring disease progression and therapy response. Finally, this review focuses on the importance of oligodendrocytes in MS and the potential for remyelination therapy. It also underlines the importance of continued research to develop more effective treatment regimens, taking into account the complexities of MS pathology and the different factors that influence disease progression and treatment.

Neuroprotective Effects of Functionalized Hydrophilic Carbon Clusters: Targeted Therapy of Traumatic Brain Injury in an Open Blast Rat Model

Traumatic brain injury (TBI) causes multiple cerebrovascular disruptions and oxidative stress. These pathological mechanisms are often accompanied by serious impairment of cerebral blood flow autoregulation and neuronal and glial degeneration.

BACKGROUND/OBJECTIVES

Multiple biochemical cascades are triggered by brain damage, resulting in reactive oxygen species production alongside blood loss and hypoxia. However, most currently available early antioxidant therapies lack capacity and hence sufficient efficacy against TBI. The aim of this study was to test a novel catalytic antioxidant nanoparticle to alleviate the damage occurring in blast TBI.

METHODS

TBI was elicited in an open blast rat model, in which the rats were exposed to the effects of an explosive blast. Key events of the post-traumatic chain in the brain parenchyma were studied using immunohistochemistry. The application of a newly developed biologically compatible catalytic superoxide dismutase mimetic carbon-based nanocluster, a poly-ethylene-glycol-functionalized hydrophilic carbon cluster (PEG-HCC), was tested post-blast to modulate the components of the TBI process.

RESULTS

The PEG-HCC was shown to significantly ameliorate neuronal loss in the brain cortex, the dentate gyrus, and hippocampus when administered shortly after the blast. There was also a significant increase in endothelial activity to repair blood-brain barrier damage as well as the modulation of microglial and astrocyte activity and an increase in inducible NO synthase in the cortex.

CONCLUSIONS

We have demonstrated qualitatively and quantitatively that the previously demonstrated antioxidant properties of PEG-HCCs have a neuroprotective effect after traumatic brain injury following an explosive blast, acting at multiple levels of the pathological chain of events elicited by TBI.

Ancestral Genomic Functional Differences in Oligodendroglia: Implications for Alzheimer's Disease

Background

This study aims to elucidate ancestry-specific changes to the genomic regulatory architecture in induced pluripotent stem cell (iPSC)-derived oligodendroglia, focusing on their implications for Alzheimer's disease (AD). This work addresses the lack of diversity in previous iPSC studies by including ancestries that contribute to African American (European/African) and Hispanic/Latino populations (Amerindian/African/European).

Methods

We generated 12 iPSC lines-four African, four Amerindian, and four European- from both AD patients and non-cognitively impaired individuals, with varying APOE genotypes (APOE3/3 and APOE4/4). These lines were differentiated into neural spheroids containing oligodendrocyte lineage cells. Single-nuclei RNA sequencing and ATAC sequencing were employed to analyze transcriptional and chromatin accessibility profiles, respectively. Differential gene expression, chromatin accessibility, and Hi-C analyses were conducted, followed by pathway analysis to interpret the results.

Results

We identified ancestry-specific differences in gene expression and chromatin accessibility. Notably, numerous AD GWAS-associated genes were differentially expressed across ancestries. The largest number of differentially expressed genes (DEGs) were found in European vs. Amerindian and African vs. Amerindian iPSC-derived oligodendrocyte progenitor cells (OPCs). Pathway analysis of APOE4/4 carriers vs APOE3/3 carriers exhibited upregulation of a large number of disease and metabolic pathways in APOE4/4 individuals of all ancestries. Of particular interest was that APOE4/4 carriers had significantly upregulated cholesterol biosynthesis genes relative to APOE3/3 individuals across all ancestries, strongest in iOPCs. Comparison of iOPC and iOL transcriptome data with corresponding human frontal cortex data demonstrated a high correlation (R2 > 0.85).

Conclusions

This research emphasizes the importance of including diverse ancestries in AD research to uncover critical gene expression differences between populations and ancestries that may influence disease susceptibility and therapeutic interventions. The upregulation of cholesterol biosynthesis genes in APOE4/4 carriers of all three ancestries supports the concept that APOE4 may produce disease effects early in life, which could have therapeutic implications as we move forward towards specific therapy for APOE4 carriers. These findings and the high correlation between brain and iPSC-derived OPC and OL transcriptomes support the relevance of this approach as a model for disease study.

Establishing validated RT-qPCR workflow for the analysis of oligodendrocyte gene expression in the developing murine brain

Myelination is essential for the proper conduction of impulses across neuronal networks. Mature, myelinating glia differentiate from progenitor cells through distinct stages that correspond to oligodendrocyte-specific gene expression markers. Reverse transcription quantiatative PCR (RT-qPCR) is a common technique used to quantify gene expression across cell development; however, a lack of standardization and transparency in methodology may lead to irreproducible data. Here, we have designed and validated RT-qPCR assays for oligodendrocyte genes and reference genes in the developing C57BL6/J mouse brain that align with the MIQE guidelines, including quality controls for primer specificity, temperature dependence, and efficiency. A panel of eight commonly used reference genes was ranked using a series of reference gene stability methods that consistently identified Gapdh, Sdha, Hmbs, Hprt1, and Pgk1 as the top candidates for normalization across brain regions. In the cerebrum, myelin genes peaked in expression at postnatal day 21, which corresponds to the peak of developmental myelination. The gene expression patterns from the brain homogenate were in agreement with previously reported RNA-seq and microarray profiles from oligodendrocyte lineage cells. The validated RT-qPCR assays begin to build a framework for future investigation into the molecular mechanisms that regulate myelination in mouse models of brain development, aging, and disease.

Single-point macromolecular proton fraction mapping using a 0.3 T permanent magnet MRI system: phantom and healthy volunteer study

In a 0.3 T permanent-magnet magnetic resonance imaging (MRI) system, quantifying myelin content is challenging owing to long imaging times and low signal-to-noise ratio. macromolecular proton fraction (MPF) offers a quantitative assessment of myelin in the nervous system. We aimed to demonstrate the practical feasibility of MPF mapping in the brain using a 0.3 T MRI. Both 0.3 T and 3.0 T MRI systems were used. The MPF-mapping protocol used a standard 3D fast spoiled gradient-echo sequence based on the single-point reference method. Proton density, T1, and magnetization transfer-weighted images were obtained from a protein phantom at 0.3 T and 3.0 T to calculate MPF maps. MPF was measured in all phantom sections to assess its relationship to protein concentration. We acquired MPF maps for 16 and 8 healthy individuals at 0.3 T and 3.0 T, respectively, measuring MPF in nine brain tissues. Differences in MPF between 0.3 T and 3.0 T, and between 0.3 T and previously reported MPF at 0.5 T, were investigated. Pearson's correlation coefficient between protein concentration and MPF at 0.3 T and 3.0 T was 0.92 and 0.90, respectively. The 0.3 T MPF of brain tissue strongly correlated with 3.0 T MPF and literature values measured at 0.5 T. The absolute mean differences in MPF between 0.3 T and 0.5 T were 0.42% and 1.70% in white and gray matter, respectively. Single-point MPF mapping using 0.3 T permanent-magnet MRI can effectively assess myelin content in neural tissue.

Mechanism and prospects of mitochondrial transplantation for spinal cord injury treatment

Spinal cord injury (SCI) involves a continuous and dynamic cascade of complex reactions, with mitochondrial damage and dysfunction-induced energy metabolism disorders playing a central role throughout the process. These disorders not only determine the severity of secondary injuries but also influence the potential for axonal regeneration. Given the critical role of energy metabolism disturbances in the pathology of SCI, strategies such as enhancing mitochondrial transport within axons to alleviate local energy deficits, or transplanting autologous or allogeneic mitochondria to restore energy supply to damaged tissues, have emerged as potential approaches for SCI repair. These strategies also aim to modulate local inflammatory responses and apoptosis. Preclinical studies have initially demonstrated that mitochondrial transplantation (MT) significantly reduces neuronal death and promotes axonal regeneration following spinal cord injury. MT achieves this by regulating signaling pathways such as MAPK/ERK and PI3K/Akt, promoting the expression of growth-associated protein-43 (GAP-43) in neurons, and inhibiting the expression of apoptosis-related proteins like Grp78, Chop, and P-Akt, thereby enhancing the survival and regeneration of damaged neurons. Additionally, MT plays a role in promoting the expression of vascular endothelial growth factor, facilitating tissue repair, and reducing the secretion of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6. Furthermore, MT modulates neuronal apoptosis and inflammatory responses by decreasing the expression of p-JNK, a member of the MAPK family. In summary, by reviewing the detailed mechanisms underlying the cascade of pathological processes in SCI, we emphasize the changes in endogenous mitochondria post-SCI and the potential of exogenous MT in SCI repair. This review aims to provide insights and a basis for developing more effective clinical treatments for SCI.

Contribution of amyloid deposition from oligodendrocytes in a mouse model of Alzheimer's disease

BACKGROUND

The accumulation of β-amyloid (Aβ) peptides into insoluble plaques is an early pathological feature of Alzheimer's disease (AD). BACE1 is the sole β-secretase for Aβ generation, making it an attractive therapeutic target for AD therapy. While BACE1 inhibitors have been shown to reduce Aβ levels in people with AD, clinical trials targeting BACE1 have failed due to unwanted synaptic deficits. Understanding the physiological role of BACE1 in individual cell types is essential for developing effective BACE inhibitors for the treatment of AD. Recent single-cell RNA transcriptomic assays revealed that oligodendrocytes are enriched with genes required for generating Aβ. However, the contribution of oligodendrocytes to amyloid plaque burden in AD and the side effects of oligodendrocyte-specific Bace1 deletion remain to be explored.

METHODS

We generated an oligodendrocyte-specific Bace1 knockout model (Bace1fl/fl;Olig2-Cre) to monitor potential disruptions in myelination using standard electron microscopy. Long-term potentiation (LTP) was monitored to measure synaptic integrity. We crossed the Bace1fl/fl;Olig2-Cre model with heterozygous AppNL-G-F/wt knock-in AD mice to generate AD mice lacking oligodendrocyte Bace1 (Bace1fl/fl;Olig2-Cre; AppNL-G-F/wt) and examined amyloid plaque number and insoluble Aβ levels and gliosis in these animals. Single nuclei RNA sequencing experiments were conducted to examine molecular changes in response to Bace1 deficiency in oligodendrocytes in the wild type or APP knock-in background.

RESULTS

Bace1 deletion in oligodendrocytes caused no change in myelin thickness in the corpus callosum but a marginal reduction in myelin sheath thickness of the optic nerve. Synaptic strength measured by LTP was not different between Bace1fl/fl;Olig2-Cre and age-matched Bace1fl/fl control animals, suggesting no major effect on synaptic plasticity. Intriguingly, deletion of Bace1 in 12-month-old heterozygous AD knock-in mice (Bace1fl/fl;Olig2-Cre; AppNL-G-F/wt mice) caused a significant reduction of amyloid plaques by ~ 33% in the hippocampus and ~ 29% in the cortex compared to age-matched AD mice (Bace1fl/fl;AppNL-G-F/wt). Insoluble Aβ1-40 and Aβ1-42 levels were reduced comparably while more astrocytes and microglia were observed in surrounding amyloid plaques. Unbiased single-nuclei RNA sequencing results revealed that deletion of oligodendrocyte Bace1 in APPNL-G-F/wt knock-in mice increased expression of genes associated with Aβ generation and clearance such as ADAM10, Ano4, ApoE, Il33, and Sort1.

CONCLUSION

Our results provide compelling evidence that the amyloidogenic pathway in oligodendrocytes contributes to Aβ plaque formation in the AD brain. While specifically targeting BACE1 inhibition in oligodendrocytes for reducing Aβ pathology in AD is likely challenging, this is a potentially explorable strategy in future studies.

The physiological role of the unfolded protein response in the nervous system

The unfolded protein response (UPR) is a cellular stress response pathway activated when the endoplasmic reticulum, a crucial organelle for protein folding and modification, encounters an accumulation of unfolded or misfolded proteins. The UPR aims to restore endoplasmic reticulum homeostasis by enhancing protein folding capacity, reducing protein biosynthesis, and promoting protein degradation. It also plays a pivotal role in coordinating signaling cascades to determine cell fate and function in response to endoplasmic reticulum stress. Recent research has highlighted the significance of the UPR not only in maintaining endoplasmic reticulum homeostasis but also in influencing various physiological processes in the nervous system. Here, we provide an overview of recent findings that underscore the UPR's involvement in preserving the function and viability of neuronal and myelinating cells under physiological conditions, and highlight the critical role of the UPR in brain development, memory storage, retinal cone development, myelination, and maintenance of myelin thickness.

Bisphenol-F and Bisphenol-S (BPF and BPS) Impair the Stemness of Neural Stem Cells and Neuronal Fate Decision in the Hippocampus Leading to Cognitive Dysfunctions

Neurogenesis occurs throughout life in the hippocampus of the brain, and many environmental toxicants inhibit neural stem cell (NSC) function and neuronal generation. Bisphenol-A (BPA), an endocrine disrupter used for surface coating of plastic products causes injury in the developing and adult brain; thus, many countries have banned its usage in plastic consumer products. BPA analogs/alternatives such as bisphenol-F (BPF) and bisphenol-S (BPS) may also cause neurotoxicity; however, their effects on neurogenesis are still not known. We studied the effects of BPF and BPS exposure from gestational day 6 to postnatal day 21 on neurogenesis. We found that exposure to non-cytotoxic concentrations of BPF and BPS significantly decreased the number/size of neurospheres, BrdU+ (proliferating NSC marker) and MAP-2+ (neuronal marker) cells and GFAP+ astrocytes in the hippocampus NSC culture, suggesting reduced NSC stemness and self-renewal and neuronal differentiation and increased gliogenesis. These analogs also reduced the number of BrdU/Sox-2+, BrdU/Dcx+, and BrdU/NeuN+ co-labeled cells in the hippocampus of the rat brain, suggesting decreased NSC proliferation and impaired maturation of newborn neurons. BPF and BPS treatment increases BrdU/cleaved caspase-3+ cells and Bax-2 and cleaved caspase protein levels, leading to increased apoptosis in hippocampal NSCs. Transmission electron microscopy studies suggest that BPF and BPS also caused degeneration of neuronal myelin sheath, altered mitochondrial morphology, and reduced number of synapses in the hippocampus leading to altered cognitive functions. These results suggest that BPF and BPS exposure decreased the NSC pool, inhibited neurogenesis, induced apoptosis of NSCs, caused myelin degeneration/synapse degeneration, and impaired learning and memory in rats.

Stress-induced c-fos expression in the medial prefrontal cortex differentially affects the main residing cell phenotypes

Stress poses a challenge to the body's equilibrium and triggers a series of responses that enable organisms to adapt to stressful stimuli. The medial prefrontal cortex (mPFC), particularly in acute stress conditions, undergoes significant physiological changes to cope with the demands associated with cellular activation. The proto-oncogene c-fos and its protein product c-Fos have long been utilized to investigate the effects of external factors on the central nervous system (CNS). While c-Fos expression has traditionally been attributed to neurons, emerging evidence suggests its potential expression in glial cells. In this study, our main objective was to explore the expression of c-Fos in glial cells and examine how acute stress influences these activity patterns. We conducted our experiments on male Wistar rats, subjecting them to acute stress and sacrificing them 2 h after the stressor initiation. Using double-labelling fluorescent immunohistochemistry targeting c-Fos, along with markers such as GFAP, Iba-1, Olig2, NG2, and NeuN, we analyzed 35 μm brain slices obtained from the mPFC. Our findings compellingly demonstrate that c-Fos expression extends beyond neurons and is present in astrocytes, oligodendrocytes, microglia, and NG2 cells-the diverse population of glial cells. Moreover, we observed distinct regulation of c-Fos expression in response to stress across different subregions of the mPFC. These results emphasize the importance of considering glial cells and their perspective in studies investigating brain activity, highlighting c-Fos as a response marker in glial cells. By shedding light on the differential regulation of c-Fos expression in response to stress, our study contributes to the understanding of glial cell involvement in stress-related processes. This underscores the significance of including glial cells in investigations of brain activity and expands our knowledge of c-Fos as a potential marker for glial cell responses.

Astrocytic Ephrin-B1 Regulates Oligodendrocyte Development and Myelination

Astrocytes have been implicated in oligodendrocyte development and myelination, however, the mechanisms by which astrocytes regulate oligodendrocytes remain unclear. Our findings suggest a new mechanism that regulates astrocyte-mediated oligodendrocyte development through ephrin-B1 signaling in astrocytes. Using a mouse model, we examined the role of astrocytic ephrin-B1 signaling in oligodendrocyte development by deleting ephrin-B1 specifically in astrocytes during the postnatal days (P)14-P28 period and used mRNA analysis, immunohistochemistry, and mouse behaviors to study its effects on oligodendrocytes and myelination. We found that deletion of astrocytic ephrin-B1 downregulated many genes associated with oligodendrocyte development, myelination, and lipid metabolism in the hippocampus and the corpus callosum. Additionally, we observed a reduced number of oligodendrocytes and impaired myelination in the corpus callosum of astrocyte-specific ephrin-B1 KO mice. Finally, our data show reduced motor strength in these mice exhibiting clasping phenotype and impaired performance in the rotarod test most likely due to impaired myelination. Our studies provide new evidence that astrocytic ephrin-B1 positively regulates oligodendrocyte development and myelination, potentially through astrocyte-oligodendrocyte interactions.

Progesterone alleviates esketamine-induced hypomyelination via PI3K/Akt signaling pathway in the developing rat brain

The neurodevelopmental toxicity of anesthetics has been confirmed repeatedly, and esketamine is now widely used in pediatric surgeries. Oligodendrocyte precursor cells (OPCs) evolved into mature oligodendrocytes (OLs) and formed myeline sheath during the early brain development. In this study, we investigated whether esketamine exposure interrupted development of OPCs and induced hypomyelination in rats. Further we explored the roles of PI3K/Akt phosphorylation in OPCs development and myelination. Sprague Dawley rats with different ages (postnatal day (P) 1, 3, 7 and 12) were exposed to 40mg/kg esketamine. Progesterone treatment was given (16 mg/kg per day for 3 days) 24 h after esketamine exposure via the intraperitoneal route. Corpus callosum tissues were collected at P8 or P14 for western blot and immunofluorescence analyses. Esketamine exposure at P7 and P12 significantly reduced myelin basic protein (MBP) expression and CC1+ OLs number in corpus callosum. Esketamine exposure at P7 not only aggravated the mature OLs apoptosis, also decreased the OPCs proliferation and differentiation, which was related with dephosphorylation of PI3K/Akt. Progesterone was able to promote OPCs differentiation and ameliorate esketamine-induced hypomyelination by enhancing PI3K/Akt phosphorylation. Stage-dependent abnormality of OPCs/OLs after esketamine leads to the esketamine-induced hypomyelination. Esketamine interrupted OPCs evolution via PI3K/Akt signaling pathway, which can be ameliorated by progesterone.

A rapidly progressive multiple system atrophy-cerebellar variant model presenting marked glial reactions with inflammation and spreading of α-synuclein oligomers and phosphorylated α-synuclein aggregates

Multiple system atrophy (MSA) is a severe α-synucleinopathy facilitated by glial reactions; the cerebellar variant (MSA-C) preferentially involves olivopontocerebellar fibres with conspicuous demyelination. A lack of aggressive models that preferentially involve olivopontocerebellar tracts in adulthood has hindered our understanding of the mechanisms of demyelination and neuroaxonal loss, and thus the development of effective treatments for MSA. We therefore aimed to develop a rapidly progressive mouse model that recaptures MSA-C pathology. We crossed Plp1-tTA and tetO-SNCA*A53T mice to generate Plp1-tTA::tetO-SNCA*A53T bi-transgenic mice, in which human A53T α-synuclein-a mutant protein with enhanced aggregability-was specifically produced in the oligodendrocytes of adult mice using Tet-Off regulation. These bi-transgenic mice expressed mutant α-synuclein from 8 weeks of age, when doxycycline was removed from the diet. All bi-transgenic mice presented rapidly progressive motor deterioration, with wide-based ataxic gait around 22 weeks of age and death around 30 weeks of age. They also had prominent demyelination in the brainstem/cerebellum. Double immunostaining demonstrated that myelin basic protein was markedly decreased in areas in which SM132, an axonal marker, was relatively preserved. Demyelinating lesions exhibited marked ionised calcium-binding adaptor molecule 1-, arginase-1-, and toll-like receptor 2-positive microglial reactivity and glial fibrillary acidic protein-positive astrocytic reactivity. Microarray analysis revealed a strong inflammatory response and cytokine/chemokine production in bi-transgenic mice. Neuronal nuclei-positive neuronal loss and patchy microtubule-associated protein 2-positive dendritic loss became prominent at 30 weeks of age. However, a perceived decrease in tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta in bi-transgenic mice compared with wild-type mice was not significant, even at 30 weeks of age. Wild-type, Plp1-tTA, and tetO-SNCA*A53T mice developed neither motor deficits nor demyelination. In bi-transgenic mice, double immunostaining revealed human α-synuclein accumulation in neurite outgrowth inhibitor A (Nogo-A)-positive oligodendrocytes beginning at 9 weeks of age; its expression was further increased at 10 to 12 weeks, and these increased levels were maintained at 12, 24, and 30 weeks. In an α-synuclein-proximity ligation assay, α-synuclein oligomers first appeared in brainstem oligodendrocytes as early as 9 weeks of age; they then spread to astrocytes, neuropil, and neurons at 12 and 16 weeks of age. α-Synuclein oligomers in the brainstem neuropil were most abundant at 16 weeks of age and decreased thereafter; however, those in Purkinje cells successively increased until 30 weeks of age. Double immunostaining revealed the presence of phosphorylated α-synuclein in Nogo-A-positive oligodendrocytes in the brainstem/cerebellum as early as 9 weeks of age. In quantitative assessments, phosphorylated α-synuclein gradually and successively accumulated at 12, 24, and 30 weeks in bi-transgenic mice. By contrast, no phosphorylated α-synuclein was detected in wild-type, tetO-SNCA*A53T, or Plp1-tTA mice at any age examined. Pronounced demyelination and tubulin polymerisation, promoting protein-positive oligodendrocytic loss, was closely associated with phosphorylated α-synuclein aggregates at 24 and 30 weeks of age. Early inhibition of mutant α-synuclein expression by doxycycline diet at 23 weeks led to fully recovered demyelination; inhibition at 27 weeks led to persistent demyelination with glial reactions, despite resolving phosphorylated α-synuclein aggregates. In conclusion, our bi-transgenic mice exhibited progressively increasing demyelination and neuroaxonal loss in the brainstem/cerebellum, with rapidly progressive motor deterioration in adulthood. These mice showed marked microglial and astrocytic reactions with inflammation that was closely associated with phosphorylated α-synuclein aggregates. These features closely mimic human MSA-C pathology. Notably, our model is the first to suggest that α-synuclein oligomers may spread from oligodendrocytes to neurons in transgenic mice with human α-synuclein expression in oligodendrocytes. This model of MSA is therefore particularly useful for elucidating the in vivo mechanisms of α-synuclein spreading from glia to neurons, and for developing therapies that target glial reactions and/or α-synuclein oligomer spreading and aggregate formation in MSA.

CRISPR/CasRx-Mediated Knockdown of Rab7B Restores Incomplete Cell Shape Induced by Pelizaeus-Merzbacher Disease-Associated PLP1 p.Ala243Val

Pelizaeus-Merzbacher disease (PMD, currently known as hypomyelinating leukodystrophy type 1 [HLD1]) is a hereditary hypomyelinating and/or demyelinating disease associated with the proteolipid protein 1 (plp1) gene in the central nervous system (CNS). One of the major causes of this condition is incomplete or defective oligodendroglial cell myelin sheath formation triggered by endoplasmic reticulum (ER) stress and subsequent unfolded protein response (UPR). The HLD1-associated Ala-243-to-Val mutation (p.Ala243Val) of PLP1 is widely recognized to trigger defective oligodendroglial cell morphological differentiation, primarily due to ER stress. We have previously reported that knockdown of Rab7B (also known as Rab42), a small GTP/GDP-binding protein involved in intracellular vesicle trafficking around the lysosome, can recover chemical ER stress-induced incomplete cell shapes in the FBD-102b cell line, a model of oligodendroglial cell morphological differentiation. Here, we present findings indicating that incomplete cell shapes induced by PLP1 p.Ala243Val can be restored by knockdown of Rab7B using the clustered regularly interspaced short palindromic repeats (CRISPR) and CasRx (also known as Cas13d) system. Also, the knockdown promoted the trafficking of PLP1 p.Ala243Val to lysosome-associated membrane protein 1 (LAMP1)-positive organelles. These results highlight the unique role of Rab7B knockdown in modulating oligodendroglial cell morphological changes and potentially facilitating the transport of mutated PLP1 to LAMP1-positive organelles, suggesting its potential as a therapeutic target for alleviating HLD1 phenotypes, at least in part, at the molecular and cellular levels.

In silico modelling of neuron signal impact of cytokine storm-induced demyelination

In this study, we develop an in silico model of a neuron's behaviour under demyelination caused by a cytokine storm to investigate the effects of viral infections in the brain. We use a comprehensive model to measure how cytokine-induced demyelination affects the propagation of action potential (AP) signals within a neuron. We analysed the effects of neuron-neuron communications by applying information and communication theory at different levels of demyelination. Our simulations demonstrate that virus-induced degeneration can play a role in the signal power and spiking rate, which compromise the propagation and processing of information between neurons. We propose a transfer function to model the weakening effects on the AP. Our results show that demyelination induced by a cytokine storm not only degrades the signal but also impairs its propagation within the axon. Our proposed in silico model can analyse virus-induced neurodegeneration and enhance our understanding of virus-induced demyelination.

Macrophage GIT1 promotes oligodendrocyte precursor cell differentiation and remyelination after spinal cord injury

Spinal cord injury (SCI) can result in severe motor and sensory deficits, for which currently no effective cure exists. The pathological process underlying this injury is extremely complex and involves many cell types in the central nervous system. In this study, we have uncovered a novel function for macrophage G protein-coupled receptor kinase-interactor 1 (GIT1) in promoting remyelination and functional repair after SCI. Using GIT1flox/flox Lyz2-Cre (GIT1 CKO) mice, we identified that GIT1 deficiency in macrophages led to an increased generation of tumor necrosis factor-alpha (TNFα), reduced proportion of mature oligodendrocytes (mOLs), impaired remyelination, and compromised functional recovery in vivo. These effects in GIT1 CKO mice were reversed with the administration of soluble TNF inhibitor. Moreover, bone marrow transplantation from GIT1 CWT mice reversed adverse outcomes in GIT1 CKO mice, further indicating the role of macrophage GIT1 in modulating spinal cord injury repair. Our in vitro experiments showed that macrophage GIT1 plays a critical role in secreting TNFα and influences the differentiation of oligodendrocyte precursor cells (OPCs) after stimulation with myelin debris. Collectively, our data uncovered a new role of macrophage GIT1 in regulating the transformation of OPCs into mOLs, essential for functional remyelination after SCI, suggesting that macrophage GIT1 could be a promising treatment target of SCI.

Longitudinal Imaging of Injured Spinal Cord Myelin and White Matter with 3D Ultrashort Echo Time Magnetization Transfer (UTE-MT) and Diffusion MRI

Quantitative MRI techniques could be helpful to noninvasively and longitudinally monitor dynamic changes in spinal cord white matter following injury, but imaging and postprocessing techniques in small animals remain lacking. Unilateral C5 hemisection lesions were created in a rat model, and ultrashort echo time magnetization transfer (UTE-MT) and diffusion-weighted sequences were used for imaging following injury. Magnetization transfer ratio (MTR) measurements and preferential diffusion along the longitudinal axis of the spinal cord were calculated as fractional anisotropy or an apparent diffusion coefficient ratio over transverse directions. The area of myelinated white matter was obtained by thresholding the spinal cord using mean MTR or diffusion ratio values from the contralesional side of the spinal cord. A decrease in white matter areas was observed on the ipsilesional side caudal to the lesions, which is consistent with known myelin and axonal changes following spinal cord injury. The myelinated white matter area obtained through the UTE-MT technique and the white matter area obtained through diffusion imaging techniques showed better performance to distinguish evolution after injury (AUCs > 0.94, p < 0.001) than the mean MTR (AUC = 0.74, p = 0.01) or ADC ratio (AUC = 0.68, p = 0.05) values themselves. Immunostaining for myelin basic protein (MBP) and neurofilament protein NF200 (NF200) showed atrophy and axonal degeneration, confirming the MRI results. These compositional and microstructural MRI techniques may be used to detect demyelination or remyelination in the spinal cord after spinal cord injury.

Knockdown of Rab9 Recovers Defective Morphological Differentiation Induced by Chemical ER Stress Inducer or PMD-Associated PLP1 Mutant Protein in FBD-102b Cells

Small GTP-binding proteins of the Rab family regulate intracellular vesicle trafficking across many aspects of the transport system. Among these, Rab9 is recognized for its role in controlling the transport system not only around the trans-Golgi network but also around the late endosome. However, the specific functions across different cell types and tissues remain unclear. Here, for the first time, we report that Rab9 negatively regulates morphological changes in the FBD-102b cell line, an oligodendroglial precursor cell line undergoing morphological differentiation. The knockdown of Rab9 led to an increase in cell shape alterations characterized by widespread membrane extensions. These changes were accompanied by increased expression levels of oligodendroglial cell differentiation and myelination marker proteins. Notably, the knockdown of Rab9 was capable of recovering defective cell morphological changes induced by tunicamycin, an inducer of endoplasmic reticulum (ER) stress, which is one of the major causes of oligodendroglial cell diseases such as Pelizaeus-Merzbacher disease (PMD, currently known as hypomyelinating leukodystrophy type 1 [HLD1]). In addition, Rab9 knockdown recovered levels of ER stress marker proteins and differentiation markers. Similar results were obtained in the cases of dithiothreitol (DTT), another chemical ER stress inducer, as well as HLD1-associated proteolipid protein 1 (PLP1) mutant protein. These results indicate a unique role for Rab9 in oligodendroglial cell morphological changes, suggesting its potential as a therapeutic target for mitigating diseases such as HLD1 at the molecular and cellular levels.

Lipids and α-Synuclein: adding further variables to the equation

Aggregation of alpha-Synuclein (αSyn) has been connected to several neurodegenerative diseases, such as Parkinson's disease (PD), dementia with Lewy Bodies (DLB), and multiple system atrophy (MSA), that are collected under the umbrella term synucleinopathies. The membrane binding abilities of αSyn to negatively charged phospholipids have been well described and are connected to putative physiological functions of αSyn. Consequently, αSyn-related neurodegeneration has been increasingly connected to changes in lipid metabolism and membrane lipid composition. Indeed, αSyn aggregation has been shown to be triggered by the presence of membranes in vitro, and some genetic risk factors for PD and DLB are associated with genes coding for proteins directly involved in lipid metabolism. At the same time, αSyn aggregation itself can cause alterations of cellular lipid composition and brain samples of patients also show altered lipid compositions. Thus, it is likely that there is a reciprocal influence between cellular lipid composition and αSyn aggregation, which can be further affected by environmental or genetic factors and ageing. Little is known about lipid changes during physiological ageing and regional differences of the lipid composition of the aged brain. In this review, we aim to summarise our current understanding of lipid changes in connection to αSyn and discuss open questions that need to be answered to further our knowledge of αSyn related neurodegeneration.

Aqueous Ionic Liquid Mixtures as Minimal Models of Lipid Bilayer Membranes

We introduce aqueous ionic liquid (IL) mixtures, specifically mixtures of 1-butyl-3-imidazoliumtetrafluoroborate (BMImBF4), with water as a minimal model of lipid bilayer membranes. Imidazolium-based ILs are known to form clustered nanoscale structures in which local inhomogeneities, micellar or lamellar structures, are formed to shield hydrophobic parts of the cation from the polar cosolvent (water). To investigate these nanostructures, dynamic light scattering (DLS) on samples with different mixing ratios of water and BMImBF4 was performed. At mixing ratios of 50% and 45% (v/v), small and homogeneous nanostructures can indeed be detected. To test whether, in particular, these stable nanostructures in aqueous mixtures may mimic the effects of phospholipid bilayer membranes, we further investigated their interaction with myelin basic protein (MBP), a peripheral, intrinsically disordered membrane protein of the myelin sheath. Using dynamic light scattering (DLS), continuous wave (CW) and pulse electron paramagnetic resonance (EPR), and small-angle X-ray scattering (SAXS) on recombinantly produced, "healthy" charge variants rmC1WT and double cysteine variant C1S17CH85C, we find that the size and the shape of the determined nanostructures in an optimum mixture offer model membranes in which the protein exhibits native behavior. SAXS measurements illuminate the size and shape of the nanostructures and indicate IL-rich "beads" clipped together by functional MBP, one of the in vivo roles of the protein in the myelin sheath. All the gathered data combined indicate that the 50% and 45% aqueous IL mixtures can be described as offering minimal models of a lipid mono- or bilayer that allow native processing and potential study of at least peripheral membrane proteins like MBP.

GPR56: A potential therapeutic target for neurological and psychiatric disorders

GPR56, also known as GPR56/ADGRG1, is a member of the ADGRG subgroup belonging to adhesion G protein-coupled receptors (aGPCRs). aGPCRs are the second largest subfamily of the GPCR superfamily, which is the largest family of membrane protein receptors in the human genome. Studies in recent years have demonstrated that GPR56 is integral to the normal development of the brain and functions as an important player in cortical development, suggesting that GPR56 is involved in many physiological processes. Indeed, aberrant expression of GPR56 has been implicated in multiple neurological and psychiatric disorders, including bilateral frontoparietal polymicrogyria (BFPP), depression and epilepsy. In a recent study, it was found that upregulated expression of GPR56 reduced depressive-like behaviours in an animal model of depression, indicating that GPR56 plays an important role in the antidepressant response. Given the link of GPR56 with the antidepressant response, the function of GPR56 has become a focus of research. Although GPR56 may be a potential target for the development of antidepressants, the underlying molecular mechanisms remain largely unknown. Therefore, in this review, we will summarize the latest findings of GPR56 function in neurological and psychiatric disorders (depression, epilepsy, autism, and BFPP) and emphasize the mechanisms of GPR56 in activation and signalling in those conditions. After reviewing several studies, attributing to its significant biological functions and exceptionally long extracellular N-terminus that interacts with multiple ligands, we draw a conclusion that GPR56 may serve as an important drug target for neuropsychological diseases.

Exploring Intrinsic Disorder in Human Synucleins and Associated Proteins

In this work, we explored the intrinsic disorder status of the three members of the synuclein family of proteins-α-, β-, and γ-synucleins-and showed that although all three human synucleins are highly disordered, the highest levels of disorder are observed in γ-synuclein. Our analysis of the peculiarities of the amino acid sequences and modeled 3D structures of the human synuclein family members revealed that the pathological mutations A30P, E46K, H50Q, A53T, and A53E associated with the early onset of Parkinson's disease caused some increase in the local disorder propensity of human α-synuclein. A comparative sequence-based analysis of the synuclein proteins from various evolutionary distant species and evaluation of their levels of intrinsic disorder using a set of commonly used bioinformatics tools revealed that, irrespective of their origin, all members of the synuclein family analyzed in this study were predicted to be highly disordered proteins, indicating that their intrinsically disordered nature represents an evolutionary conserved and therefore functionally important feature. A detailed functional disorder analysis of the proteins in the interactomes of the human synuclein family members utilizing a set of commonly used disorder analysis tools showed that the human α-synuclein interactome has relatively higher levels of intrinsic disorder as compared with the interactomes of human β- and γ- synucleins and revealed that, relative to the β- and γ-synuclein interactomes, α-synuclein interactors are involved in a much broader spectrum of highly diversified functional pathways. Although proteins interacting with three human synucleins were characterized by highly diversified functionalities, this analysis also revealed that the interactors of three human synucleins were involved in three common functional pathways, such as the synaptic vesicle cycle, serotonergic synapse, and retrograde endocannabinoid signaling. Taken together, these observations highlight the critical importance of the intrinsic disorder of human synucleins and their interactors in various neuronal processes.

Stabilizing axin leads to optic nerve hypoplasia in a mouse model of autism

Autism spectrum disorder (ASD) is a group of neurodevelopment disorders characterized by deficits in social interaction and communication, and repetitive or stereotyped behavior. Autistic children are more likely to have vision problems, and ASD is unusually common among blind people. However, the mechanisms behind the vision disorders in autism are unclear. Stabilizing WNT-targeted scaffold protein Axin2 by XAV939 during embryonic development causes overproduction of cortical neurons and leads to autistic-like behaviors in mice. In this study, we investigated the relationship between vision abnormality and autism using an XAV939-induced mouse model of autism. We found that the mice receiving XAV939 had decreased amplitude of bright light-adaptive ERG. The amplitudes and latency of flash visual evoked potential recorded from XAV939-treated mice were lower and longer, respectively than in the control mice, suggesting that XAV939 inhibits visual signal processing and conductance. Anatomically, the diameters of RGC axons were reduced when Axin2 was stabilized during the development, and the optic fibers had defective myelin sheaths and reduced oligodendrocytes. The results suggest that the WNT signaling pathway is crucial for optic nerve development. This study provides experimental evidence that conditions interfering with brain development may also lead to visual problems, which in turn might exaggerate the autistic features in humans.

Hypomyelination Leukodystrophy 16 (HLD16)-Associated Mutation p.Asp252Asn of TMEM106B Blunts Cell Morphological Differentiation

Transmembrane protein 106B (TMEM106B), which is a type II transmembrane protein, is believed to be involved in intracellular dynamics and morphogenesis in the lysosome. TMEM106B is known to be a risk factor for frontotemporal lobar degeneration and has been recently identified as the receptor needed for the entry of SARS-CoV-2, independently of angiotensin-converting enzyme 2 (ACE2). A missense mutation, p.Asp252Asn, of TMEM106B is associated with hypomyelinating leukodystrophy 16 (HLD16), which is an oligodendroglial cell-related white matter disorder causing thin myelin sheaths or myelin deficiency in the central nervous system (CNS). However, it remains to be elucidated how the mutated TMEM106B affects oligodendroglial cells. Here, we show that the TMEM106B mutant protein fails to exhibit lysosome distribution in the FBD-102b cell line, an oligodendroglial precursor cell line undergoing differentiation. In contrast, wild-type TMEM106B was indeed localized in the lysosome. Cells harboring wild-type TMEM106B differentiated into ones with widespread membranes, whereas cells harboring mutated TMEM106B failed to differentiate. It is of note that the output of signaling through the lysosome-resident mechanistic target of rapamycin (mTOR) was greatly decreased in cells harboring mutated TMEM106B. Furthermore, treatment with hesperetin, a citrus flavonoid known as an activator of mTOR signaling, restored the molecular and cellular phenotypes induced by the TMEM106B mutant protein. These findings suggest the potential pathological mechanisms underlying HLD16 and their amelioration.

Reflective imaging of myelin integrity in the human and mouse central nervous systems

The structural integrity of myelin sheaths in the central nervous system (CNS) is crucial for the maintenance of its function. Electron microscopy (EM) is the gold standard for visualizing individual myelin sheaths. However, the tissue processing involved can induce artifacts such as shearing of myelin, which can be difficult to distinguish from true myelin abnormalities. Spectral confocal reflectance (SCoRe) microscopy is an imaging technique that leverages the differential refractive indices of compacted CNS myelin in comparison to surrounding parenchyma to detect individual compact myelin internodes with reflected light, positioning SCoRe as a possible complementary method to EM to assess myelin integrity. Whether SCoRe is sensitive enough to detect losses in myelin compaction when myelin quantity is otherwise unaffected has not yet been directly tested. Here, we assess the capacity of SCoRe to detect differences in myelin compaction in two mouse models that exhibit a loss of myelin compaction without demyelination: microglia-deficient mice (Csf1r-FIRE Δ/Δ) and wild-type mice fed with the CSF1R inhibitor PLX5622. In addition, we compare the ability to detect compact myelin sheaths using SCoRe in fixed-frozen versus paraffin-embedded mouse tissue. Finally, we show that SCoRe can successfully detect individual sheaths in aged human paraffin-embedded samples of deep white matter regions. As such, we find SCoRe to be an attractive technique to investigate myelin integrity, with sufficient sensitivity to detect myelin ultrastructural abnormalities and the ability to perform equally well in tissue preserved using different methods.

Cerebral White Matter Alterations Associated With Oligodendrocyte Vulnerability in Organic Acidurias: Insights in Glutaric Aciduria Type I

The white matter is an important constituent of the central nervous system, containing axons, oligodendrocytes, and its progenitor cells, astrocytes, and microglial cells. Oligodendrocytes are central for myelin synthesis, the insulating envelope that protects axons and allows normal neural conduction. Both, oligodendrocytes and myelin, are highly vulnerable to toxic factors in many neurodevelopmental and neurodegenerative disorders associated with disturbances of myelination. Here we review the main alterations in oligodendrocytes and myelin observed in some organic acidurias/acidemias, which correspond to inherited neurometabolic disorders biochemically characterized by accumulation of potentially neurotoxic organic acids and their derivatives. The yet incompletely understood mechanisms underlying the high vulnerability of OLs and/or myelin in glutaric acidemia type I, the most prototypical cerebral organic aciduria, are particularly discussed.

Combined Central and Peripheral Demyelination (CCPD) Associated with MOG Antibodies: Report of Four New Cases and Narrative Review of the Literature

Background/Objectives: Myelin oligodendrocyte glycoprotein (MOG) is exclusively expressed in the central nervous system (CNS) and is found on the outer surface of oligodendrocytes. Antibodies to MOG are associated with CNS demyelination, whereas peripheral nervous system (PNS) demyelination is seldom reported to be related to MOG-IgG. Methods: The database of patients seen in our neurological academic center was searched for MOG-IgG seropositivity and concomitant demyelinating polyneuropathy. For the purpose of the review, in March 2024, we searched for case reports and case series in the following databases: PubMed, Scopus, Cochrane, and ScienceDirect. Inclusion criteria were MOG-IgG seropositivity and demyelinating polyneuropathy. Exclusion criteria were type of publication other than case reports and case series, unconfirmed diagnosis of demyelinating polyneuropathy, and other diseases causing demyelination in either the CNS or PNS. Critical appraisal of the selected case reports and case series was realized by JBI. Results: Four new cases were identified with MOG-IgG and confirmed demyelinating polyneuropathy. This review identified 22 cases that have been published since 2018. Clinical, imaging, neurophysiological, and immunological characteristics, as well as treatment options and outcomes are presented and compared to those of other cases with combined central and peripheral demyelination (CCPD). Conclusions: The pathogenetic mechanism is unclear; thus, different hypotheses are discussed. New case reporting and large cohort studies will help further the exploration of the underlying mechanism and guide more effective therapeutic interventions.

Quantitative susceptibility mapping in the brain reflects spatial expression of genes involved in iron homeostasis and myelination

Quantitative susceptibility mapping (QSM) is an MRI modality used to non-invasively measure iron content in the brain. Iron exhibits a specific anatomically varying pattern of accumulation in the brain across individuals. The highest regions of accumulation are the deep grey nuclei, where iron is stored in paramagnetic molecule ferritin. This form of iron is considered to be what largely contributes to the signal measured by QSM in the deep grey nuclei. It is also known that QSM is affected by diamagnetic myelin contents. Here, we investigate spatial gene expression of iron and myelin related genes, as measured by the Allen Human Brain Atlas, in relation to QSM images of age-matched subjects. We performed multiple linear regressions between gene expression and the average QSM signal within 34 distinct deep grey nuclei regions. Our results show a positive correlation (p < .05, corrected) between expression of ferritin and the QSM signal in deep grey nuclei regions. We repeated the analysis for other genes that encode proteins thought to be involved in the transport and storage of iron in the brain, as well as myelination. In addition to ferritin, our findings demonstrate a positive correlation (p < .05, corrected) between the expression of ferroportin, transferrin, divalent metal transporter 1, several gene markers of myelinating oligodendrocytes, and the QSM signal in deep grey nuclei regions. Our results suggest that the QSM signal reflects both the storage and active transport of iron in the deep grey nuclei regions of the brain.