Biology subjects

Seeley, W. W.

Publications and source records attributed to Seeley, W. W..

36 records · Page 2Linked to original sources

bioRxiv2024

Alterations in Lysosomal, Glial and Neurodegenerative Biomarkers in Patients with Sporadic and Genetic Forms of Frontotemporal Dementia

BackgroundFrontotemporal dementia (FTD) is the most common cause of early-onset dementia with 10-20% of cases caused by mutations in one of three genes: GRN, C9orf72, or MAPT. To effectively develop therapeutics for FTD, the identification and characterization of biomarkers to understand disease pathogenesis and evaluate the impact of specific therapeutic strategies on the target biology as well as the underlying disease pathology are essential. Moreover, tracking the longitudinal changes of these biomarkers throughout disease progression is crucial to discern their correlation with clinical manifestations for potential prognostic usage. MethodsWe conducted a comprehensive investigation of biomarkers indicative of lysosomal biology, glial cell activation, synaptic and neuronal health in cerebrospinal fluid (CSF) and plasma from non-carrier controls, sporadic FTD (symptomatic non-carriers) and symptomatic carriers of mutations in GRN, C9orf72, or MAPT, as well as asymptomatic GRN mutation carriers. We also assessed the longitudinal changes of biomarkers in GRN mutation carriers. Furthermore, we examined biomarker levels in disease impacted brain regions including middle temporal gyrus (MTG) and superior frontal gyrus (SFG) and disease-unaffected inferior occipital gyrus (IOG) from sporadic FTD and symptomatic GRN carriers. ResultsWe confirmed glucosylsphingosine (GlcSph), a lysosomal biomarker regulated by progranulin, was elevated in the plasma from GRN mutation carriers, both symptomatic and asymptomatic. GlcSph and other lysosomal biomarkers such as ganglioside GM2 and globoside GB3 were increased in the disease affected SFG and MTG regions from sporadic FTD and symptomatic GRN mutation carriers, but not in the IOG, compared to the same brain regions from controls. The glial biomarkers GFAP in plasma and YKL40 in CSF were elevated in asymptomatic GRN carriers, and all symptomatic groups, except the symptomatic C9orf72 mutation group. YKL40 was also increased in SFG and MTG regions from sporadic FTD and symptomatic GRN mutation carriers. Neuronal injury and degeneration biomarkers NfL in CSF and plasma, and UCHL1 in CSF were elevated in patients with all forms of FTD. Synaptic biomarkers NPTXR, NPTX1/2, and VGF were reduced in CSF from patients with all forms of FTD, with the most pronounced reductions observed in symptomatic MAPT mutation carriers. Furthermore, we demonstrated plasma NfL was significantly positively correlated with disease severity as measured by CDR+NACC FTLD{square}SB in genetic forms of FTD and CSF NPTXR was significantly negatively correlated with CDR+NACC FTLD{square}SB in symptomatic GRN and MAPT mutation carriers. ConclusionsIn conclusion, our comprehensive investigation replicated alterations in biofluid biomarkers indicative of lysosomal function, glial activation, synaptic and neuronal health across sporadic and genetic forms of FTD and unveiled novel insights into the dysregulation of these biomarkers within brain tissues from patients with GRN mutations. The observed correlations between biomarkers and disease severity open promising avenues for prognostic applications and for indicators of drug efficacy in clinical trials. Our data also implicated a complicated relationship between biofluid and tissue biomarker changes and future investigations should delve into the mechanistic underpinnings of these biomarkers, which will serve as a foundation for the development of targeted therapeutics for FTD.

neuroscience↗

bioRxiv2023

Atrophy-driven functional network collapse in neurodegenerative disease

Cognitive and behavioral deficits in Alzheimers disease (AD) and frontotemporal dementia (FTD) result from brain atrophy and altered functional connectivity. However, it is unclear how atrophy relates to functional connectivity disruptions across dementia subtypes and stages. We addressed this question using structural and functional MRI from 221 patients with AD (n=82), behavioral variant FTD (n=41), corticobasal syndrome (n=27), nonfluent (n=34) and semantic (n=37) variant primary progressive aphasia, and 100 cognitively normal individuals. Using partial least squares regression, we identified three principal structure-function components. The first component showed overall atrophy correlating with primary cortical hypo-connectivity and subcortical/association cortical hyper-connectivity. Components two and three linked focal syndrome-specific atrophy to peri-lesional hypo-connectivity and distal hyper-connectivity. Structural and functional component scores predicted global and domain-specific cognitive deficits. Anatomically, functional connectivity changes reflected alterations in specific brain activity gradients. Eigenmode analysis identified temporal phase and amplitude collapse as an explanation for atrophy-driven functional connectivity changes.

neuroscience↗

bioRxiv2023

KIBRA repairs synaptic plasticity and promotes resilience to tauopathy-related memory loss

Synaptic plasticity is obstructed by pathogenic tau in the brain, representing a key mechanism that underlies memory loss in Alzheimers disease (AD) and related tauopathies. Here, we define a mechanism for plasticity repair in vulnerable neurons using the C-terminus of the KIdney/BRAin (KIBRA) protein (CT-KIBRA). We show that CT-KIBRA restores plasticity and memory in transgenic mice expressing pathogenic human tau; however, CT-KIBRA did not alter tau levels or prevent tau-induced synapse loss. Instead, we find that CT-KIBRA binds to and stabilizes protein kinase M{zeta} (PKM{zeta}) to maintain synaptic plasticity and memory despite tau mediated pathogenesis. In humans we find that reduced KIBRA in brain and increased KIBRA in cerebrospinal fluid are associated with cognitive impairment and pathological tau levels in disease. Thus, our results distinguish KIBRA both as a novel biomarker of synapse dysfunction in AD and as the foundation for a synapse repair mechanism to reverse cognitive impairment in tauopathy.

neuroscience↗

bioRxiv2023

Progranulin inhibits phospholipase sPLA2-IIA to control neuroinflammation

Withdrawal StatementThe authors have withdrawn this manuscript because more work is needed to fully define the role of sPLA2-IIA. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author.

neuroscience↗

bioRxiv2022

Single-cell RNA-seq reveals alterations in peripheral CX3CR1 and nonclassical monocytes in familial tauopathy

BackgroundEmerging evidence from mouse models is beginning to elucidate the brains immune response to tau pathology, but little is known about the nature of this response in humans. In addition, it remains unclear to what extent tau pathology and the local inflammatory response within the brain influence the broader immune system. MethodsTo address these questions, we performed single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs) from carriers of pathogenic variants in MAPT, the gene encoding tau. ResultsAnalysis of [~]181,000 individual PBMC transcriptomes from MAPT pathogenic variant carriers (n = 8) and healthy non-carrier controls (n = 8) demonstrated striking differential expression in monocytes and natural killer (NK) cells. We observed a marked reduction in the expression of CX3CR1 - the gene encoding the fractalkine receptor that is known to modulate tau pathology in mouse models - in monocytes and NK cells. We also observed a significant reduction in the abundance of nonclassical monocytes and dysregulated expression of nonclassical monocyte marker genes, including FCGR3A. Finally, we identified reductions in TMEM176A and TMEM176B, genes thought to be involved in the inflammatory response in human microglia. We confirmed differential expression of select biologically relevant genes dysregulated in our scRNA-seq data using droplet digital PCR as an orthogonal technique for quantitative validation. ConclusionsOur results suggest that human peripheral immune cell expression and abundance are modulated by tau-associated pathophysiologic changes. CX3CR1 and nonclassical monocytes in particular will be a focus of future work exploring the role of these peripheral signals in additional tau-associated neurodegenerative diseases.

neuroscience↗

bioRxiv2022

Radiogenomics of C9orf72 expansion carriers reveals global transposable element de-repression and enables prediction of thalamic atrophy and clinical impairment

Hexanucleotide repeat expansion (HRE) within C9orf72 is the most common genetic cause of frontotemporal dementia (FTD). Thalamic atrophy occurs in both sporadic and familial FTD but is thought to distinctly affect HRE carriers. Separately, emerging evidence suggests widespread de-repression of transposable elements (TEs) in the brain in several neurodegenerative diseases, including C9orf72 HRE-mediated FTD (C9-FTD). Whether TE activation can be measured in peripheral blood and how the reduction in peripheral C9orf72 expression observed in HRE carriers relates to atrophy and clinical impairment remain unknown. We used the FreeSurfer pipeline and its extensions to assess the effects of C9orf72 HRE and clinical diagnosis (n = 78) on atrophy of thalamic nuclei. We also generated a novel, whole-blood RNA-seq dataset to determine the relationships between peripheral C9orf72 expression, TE activation, thalamic atrophy, and clinical severity (n = 114). We confirmed global thalamic atrophy and reduced C9orf72 expression in HRE carriers. Moreover, we identified disproportionate atrophy of the right mediodorsal lateral nucleus in HRE carriers and showed that C9orf72 expression associated with clinical severity, independent of thalamic atrophy. Strikingly, we found global peripheral activation of TEs, including the human endogenous LINE-1 element, L1HS. L1HS levels were associated with atrophy of multiple pulvinar nuclei, a thalamic region implicated in C9-FTD. Integration of peripheral transcriptomic and neuroimaging data from HRE carriers revealed atrophy of specific thalamic nuclei; demonstrated that C9orf72 levels relate to clinical severity; and identified marked de-repression of TEs, including L1HS, which predicted atrophy of FTD-relevant thalamic nuclei. Significance StatementPathogenic repeat expansion in C9orf72 is the most frequent genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis (C9-FTD/ALS). The clinical, neuroimaging, and pathological features of C9-FTD/ALS are well-characterized, whereas the intersections of transcriptomic dysregulation and brain structure remain largely unexplored. Herein, we utilized a novel radiogenomic approach to examine the relationship between peripheral blood transcriptomics and thalamic atrophy, a neuroimaging feature disproportionately impacted in C9-FTD/ALS. We confirmed reduction of C9orf72 in blood and found broad dysregulation of transposable elements--genetic elements typically repressed in the human genome--in symptomatic C9orf72 expansion carriers, which associated with atrophy of thalamic nuclei relevant to FTD. C9orf72 expression was also associated with clinical severity, suggesting that peripheral C9orf72 levels capture disease-relevant information.

neuroscience↗

bioRxiv2021

Progranulin deficiency results in reduced bis(monoacylglycero)phosphate (BMP) levels and gangliosidosis

Homozygous mutations of granulin precursor (GRN) lead to neuronal ceroid lipofuscinosis1, a severe neurodevelopmental disease, in humans and neuroinflammation in mice2. Haploinsufficiency of GRN almost invariably causes frontotemporal dementia (FTD)3,4. The GRN locus produces progranulin (PGRN), a lysosomal precursor protein that is cleaved to granulin peptides5,6. Despite intensive investigation, the function of granulins and the reason why their absence causes neurodegeneration remain unclear. Here, we investigated PGRN function in lipid degradation, a major function of lysosomes. We show that PGRN-knockout human cells, PGRN-deficient murine brain, and frontal lobes of human brains from patients with GRN mutation-related FTD have increased levels of gangliosides, highly abundant sialic acid-containing glycosphingolipids (GSL) that are degraded in lysosomes. Probing how PGRN deficiency causes these changes, we found normal levels and activities of enzymes that catabolize gangliosides. However, levels of bis(monoacylglycero)phosphate (BMP), a lysosomal lipid required for ganglioside catabolism7, were markedly reduced in PGRN-deficient cells and patient brain tissues. These data indicate that granulins are required to maintain BMP levels, which regulate ganglioside catabolism, and that PGRN deficiency in lysosomes leads to gangliosidosis. This aberrant accumulation of gangliosides may contribute to neuroinflammation and neurodegeneration susceptibility.

cell biology↗

bioRxiv2021

Dynamic autonomic nervous system patterns differentiate human emotions and manifest in resting physiology

Whether activity in the autonomic nervous system differs during distinct emotions remains controversial. We obtained continuous multichannel recordings of autonomic nervous system activity in healthy adults during a video-based emotional reactivity task. Dimensionality reduction revealed five principal components in the autonomic time series data, and these modes of covariation differentiated periods of baseline from those of video-viewing. Unsupervised clustering of the principal component time series data uncovered separable autonomic states that distinguished among the five emotion-inducing trials. These autonomic states were also detected in baseline physiology but were intermittent and of smaller magnitude. Our results suggest the autonomic nervous system assembles dynamic activity patterns during emotions that are similar across people and are present even during undirected moments of rest. One Sentence SummaryDynamic autonomic patterns distinguish among emotions and are evident in resting physiology.

neuroscience↗

bioRxiv2021

A systematic comparison of fibroblasts derived from postmortem human dura mater versus dermal epithelium for neurodegenerative disease modeling

Patient-derived cells hold great promise for precision medicine approaches in human health. Fibroblast cells have been a major source of human cells for reprogramming and differentiating into specific cell types for disease modeling. Such cells can be isolated at various stages during life (presymptomatic, symptomatic, and postmortem) and thus can potentially be used to model different phases of disease progression. In certain circumstances, however, tissues are not collected during life and only postmortem tissues are the only available source of fibroblasts. Fibroblasts cultured from postmortem human dura mater of individuals with neurodegenerative diseases have been suggested as a primary source of cells for in vitro modeling of neurodegenerative diseases. Although fibroblast-like cells from human and mouse dura mater have been previously described, their utility for reprogramming and direct differentiation protocols requires further characterization. In this study, cells derived from dermal biopsies performed in living subjects were compared to cells derived from postmortem dura mater. In two instances, we have isolated and compared dermal and dural cell lines from the same subject. Notably, striking differences between the dermis and dura mater-derived cell lines were found. Compared to dermal fibroblasts, postmortem dura mater-derived cells demonstrated different morphology, exhibited slower growth rates, failed to express fibroblast protein markers, and exhibited significant differences in gene expression profiles. In addition, dura mater-derived cells were found to exhibit a high rate of chromosomal abnormalities, particularly in the loss of the Y chromosome. Our study highlights potential limitations of postmortem human dura mater-derived cells for disease modeling, argues for rigorous karyotyping prior to reprograming, and brings into question the identity of dura mater-derived cells as belonging to a fibroblast lineage.

cell biology↗

bioRxiv2021

TDP-43 represses cryptic exon inclusion in FTD/ALS gene UNC13A

A hallmark pathological feature of neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is the depletion of RNA-binding protein TDP-43 from the nucleus of neurons in the brain and spinal cord. A major function of TDP-43 is as a repressor of cryptic exon inclusion during RNA splicing. Single nucleotide polymorphisms (SNPs) in UNC13A are among the strongest genome-wide association study (GWAS) hits associated with FTD/ALS in humans, but how those variants increase risk for disease is unknown. Here we show that TDP-43 represses a cryptic exon splicing event in UNC13A. Loss of TDP-43 from the nucleus in human brain, neuronal cell lines, and iPSC-derived motor neurons resulted in the inclusion of a cryptic exon in UNC13A mRNA and reduced UNC13A protein expression. Remarkably, the top variants associated with FTD/ALS risk in humans are located in the cryptic exon harboring intron itself and we show that they increase UNC13A cryptic exon splicing in the face of TDP-43 dysfunction. Together, our data provide a direct functional link between one of the strongest genetic risk factors for FTD/ALS (UNC13A genetic variants) and loss of TDP-43 function.

neuroscience↗

bioRxiv2021

Microglial NF-κB drives tau spreading and toxicity in a mouse model of tauopathy

Activation of microglia, the brains innate immune cells, is a prominent pathological feature in tauopathies, including Alzheimers disease. How microglia activation contributes to tau toxicity remains largely unknown. Here we show that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-{kappa}B) signaling, activated by tau, drives microglial-mediated tau propagation and toxicity. Constitutive activation of microglial NF-{kappa}B exacerbated, while inactivation diminished, tau seeding and spreading in PS19 mice, consistent with the observation that NF-{kappa}B activation accelerates processing of internalized tau fibrils in primary microglia. Remarkably, inhibition of microglial NF-{kappa}B specifically also rescued tau-mediated learning and memory deficits, and restored overall transcriptomic changes while increasing tau inclusions. On a single cell level, we discovered that tau-associated disease states in microglia were diminished by NF-{kappa}B inactivation and further transformed by constitutive NF-{kappa}B activation. Our study establishes a central role for microglial NF-{kappa}B signaling in mediating tau toxicity in tauopathy.

neuroscience↗

bioRxiv2020

Intrinsic brain activity gradients dynamically coordinate functional connectivity states

A central goal of systems neuroscience is to determine the functional-anatomical basis of brain-wide activity dynamics. While brain activity patterns appear to be low-dimensional and guided by spatial gradients, the set of gradients remains provisional and their mode of interaction is unclear. Here we applied deep learning-based dimensionality reduction to task-free fMRI images to derive an intrinsic latent space of human brain activity. Each dimension represented a discrete, dynamically fluctuating spatial activity gradient. The principal dimension was a novel unipolar sensory-association gradient underlying the global signal. A small set of gradients appeared to underlie key functional connectomics phenomena. Different task activation patterns were generated by gradients adopting task-specific configurations. Dynamical systems modelling revealed that gradients interact via state-specific coupling parameters, allowing accurate forecasts and simulations of task-specific brain activity. Together, these findings indicate that a small set of dynamic, interacting gradients create the repertoire of possible brain activity states.

neuroscience↗

bioRxiv2020

Molecular characterization of selectively vulnerable neurons in Alzheimer's Disease

Alzheimers disease (AD) is characterized by the selective vulnerability of specific neuronal populations, the molecular signatures of which are largely unknown. To identify and characterize selectively vulnerable neuronal populations, we used single-nucleus RNA sequencing to profile the caudal entorhinal cortex and the superior frontal gyrus - brain regions where neurofibrillary inclusions and neuronal loss occur early and late in AD, respectively - from postmortem brains spanning the progression of AD-type tau neurofibrillary pathology. We identified RORB as a marker of selectively vulnerable excitatory neurons in the entorhinal cortex, and subsequently validated their depletion and selective susceptibility to neurofibrillary inclusions during disease progression using quantitative neuropathological methods. We also discovered an astrocyte subpopulation, likely representing reactive astrocytes, characterized by decreased expression of genes involved in homeostatic functions. Our characterization of selectively vulnerable neurons in AD paves the way for future mechanistic studies of selective vulnerability and potential therapeutic strategies for enhancing neuronal resilience.

neuroscience↗

bioRxiv2019

Regional and hemispheric susceptibility of the temporal lobe to FTLD-TDP-43-C pathology

Post-mortem studies show that focal anterior temporal lobe (ATL) neurodegeneration is most often caused by frontotemporal lobar degeneration TDP-43 type C pathology. Clinically, these patients are described with different terms, such as semantic variant primary progressive aphasia (svPPA), semantic dementia (SD), or right temporal variant frontotemporal dementia (FTD) depending on whether the predominant symptoms affect language, semantic knowledge for object or people, or socio-emotional behaviors. ATL atrophy presents with various degrees of lateralization, with right-sided cases considered rarer even though estimation of their prevalence is hampered by the paucity of studies on well-characterized, pathology-proven cohorts. Moreover, it is not clear whether left and right variants show a similar distribution of atrophy within the ATL cross-sectionally and longitudinally. Here we study the largest cohort to-date of pathology-proven TDP-43-C cases diagnosed during life as svPPA, SD or right temporal variant FTD. We analyzed clinical, cognitive, and neuroimaging data from 30 cases, a subset of which was followed longitudinally. Guided by recent structural and functional parcellation studies, we constructed four bilateral ATL regions of interest (ROIs). The computation of an atrophy lateralization index allowed the comparison of atrophy patterns between the two hemispheres. This led to an automatic, imaging-based classification of the cases as left-predominant or right-predominant. We then compared the two groups in terms of regional atrophy patterns within the ATL ROIs (cross-sectionally) and atrophy progression (longitudinally). Results showed that 40% of pathology proven cases of TDP-43-C diagnosed with a temporal variant presented with right-lateralized atrophy. Moreover, the findings of our ATL ROI analysis indicated that, irrespective of atrophy lateralization, atrophy distribution within both ATLs follows a medial-to-lateral gradient. Finally, in both left and right cases, atrophy appeared to progress to the contralateral ATL, and from the anterior temporal pole to posterior temporal and orbitofrontal regions. Taken together, our findings indicate that incipient right predominant ATL atrophy is common in TDP-43-C pathology, and that distribution of damage within the ATLs appears to be the same in left- and right- sided variants. Thus, regardless of differences in clinical phenotype and atrophy lateralization, both temporal variants of FTD should be viewed as a spectrum presentation of the same disease. Highlights Anterior temporal lobe (ATL) degeneration is most often caused by FTLD-TDP type C pathology Cases can present with predominantly left (60%) or right (40%) ATL atrophy Within ATLs, medial regions are more vulnerable than lateral ones The observed spectrum of clinical phenotypes is driven by atrophy lateralization Left and right temporal variants of FTD should be considered the same disease

neuroscience↗

bioRxiv2019

State and trait characteristics of anterior insula time-varying functional connectivity

The human anterior insula (aINS) is a topographically organized brain region, in which ventral portions contribute to socio-emotional function through limbic and autonomic connections, whereas the dorsal aINS contributes to cognitive processes through frontal and parietal connections. Open questions remain, however, regarding how aINS connectivity varies over time. We implemented a novel approach combining seed-to-whole-brain sliding-window functional connectivity MRI and k-means clustering to assess time-varying functional connectivity of aINS subregions. We studied three independent large samples of healthy participants and longitudinal datasets to assess inter- and intra-subject stability, and related aINS time-varying functional connectivity profiles to dispositional empathy. We identified four robust aINS time-varying functional connectivity modes that displayed both "state" and "trait" characteristics: while modes featuring connectivity to sensory regions were modulated by eye closure, modes featuring connectivity to higher cognitive and emotional processing regions were stable over time and related to empathy measures.

neuroscience↗

bioRxiv2018

Partitioning the genetic architecture of amyotrophic lateral sclerosis

The genetic basis of sporadic amyotrophic lateral sclerosis (ALS) is not well understood. Using large genome-wide association studies and validated tools to quantify genetic overlap, we systematically identified single nucleotide polymorphisms (SNPs) associated with ALS conditional on genetic data from 65 different traits and diseases from >3 million people. We found strong genetic enrichment between ALS and a number of disparate traits including frontotemporal dementia, coronary artery disease, C-reactive protein, celiac disease and memory function. Beyond C9ORF72, we detected novel genetic signal within numerous loci including GIPC1, ELMO1 and COL16A and confirmed previously reported variants, such as ATXN2, KIF5A, UNC13A and MOBP. We found that ALS variants form a small-world co-expression network characterized by highly inter-connected hub genes. This network clustered into smaller sub-networks, each associated with a unique function. Altered gene expression of several sub-networks and hubs was over-represented in neuropathological samples from ALS patients and SOD1 G93A mice. Our collective findings indicate that the genetic architecture of ALS can be partitioned into distinct components where some genes are highly important for developing disease. These findings have implications for stratification and enrichment strategies for ALS clinical trials.

genetics↗

bioRxiv2018

C. elegans granulins promote an age-associated decline in protein homeostasis via lysosomal protease inhibition

The progressive failure of protein homeostasis is a hallmark of aging and a common feature in neurodegenerative disease. As the enzymes executing the final stages of autophagy, lysosomal proteases (or cathepsins) are key contributors to maintenance of protein homeostasis with age. Here, we identify the cysteine-rich granulin peptides as a new class of regulators of lysosomal aspartyl protease activity. Granulins are produced in an age and stress-dependent manner through cleavage of the neurodegenerative disease protein, progranulin. Once liberated, granulins selectively interact with the aspartyl protease ASP-3/cathepsin D to impair enzymatic activity. Consequently, protein homeostasis and lysosome function is disrupted, prompting cells to activate a compensatory transcriptional program. Our results support a model in which granulin production modulates a critical transition between the normal, physiological regulation of protease activity and the impairment of lysosomal function that can occur with age and disease.

neuroscience↗

bioRxiv2018

Myelinated inhibitory axons in human neocortex

Numerous myelinated axons traverse the human neocortex. In a previous paper (Micheva et al., 2016) we showed that in mouse many of these axons belong to local inhibitory neurons, the parvalbumin-positive basket cells. Here, using samples of neurosurgically-excised cortex, we confirm the presence of myelinated inhibitory axons in all layers of human neocortex. As in mouse, these axons have distinctive features, including high neurofilament content, short nodes of Ranvier, and high content of myelin basic protein in their myelin sheath. We further show that, consistent with the known high-energy demands of parvalbumin interneurons, the inhibitory myelinated axons have more mitochondria, as well more 2,3-cyclic nucleotide 3-phosphodiesterase (a protein enriched in the myelin cytoplasmic channels thought to provide access for trophic support from oligodendrocytes). The distinctive features of myelinated inhibitory axons in human cortical grey matter may have important implications for neurological disorders that involve pathologies of myelinated axons.

neuroscience↗