Hypomyelinating leukodystrophy associated with a deleterious mutation in the ATRN gene

The proteomic signature of circulating extracellular vesicles following intracerebral hemorrhage: Novel insights into mechanisms underlying recovery

Circulating extracellular vesicles (EVs) can participate in innate repair processes triggered after intracerebral hemorrhage (ICH). We aimed to describe changes in the proteomic profile of circulating EVs between the acute and subacute phases of ICH and to compare the findings depending on outcomes, as an approach to unraveling such repair mechanisms. This was a prospective observational study including patients with non-traumatic supratentorial ICH. Exclusion criteria were previous disability, signs of herniation on baseline computed tomography, or limited life expectancy. EVs were isolated from blood samples at 24 h and 7 days after symptom onset. After 6-months' follow-up, patients were dichotomized into poor and good outcomes, defining good as an improvement of >10 points or > 50 % on the National Institutes of Health Stroke Scale and a modified Rankin Scale of 0-2. The protein cargo was analyzed by quantitative mass spectrometry and compared according to outcomes. Forty-four patients completed follow-up, 16 (35.5 %) having good outcomes. We identified 1321 proteins in EVs, 37 with differential abundance. In patients with good outcomes, proteins related to stress response (DERA, VNN2, TOMM34) and angiogenesis (RHG01) had increased abundance at 7 days. EVs from patients with poor outcomes showed higher levels of acute-phase reactants (CRP, SAA2) at 7 days compared with 24 h. In conclusion, the protein content of circulating EVs in patients with ICH changes over time, the changes varying depending on the clinical outcome, with greater abundance of proteins potentially involved in the repair processes of patients with good outcomes.

MOLECULAR MIMICRY OF SARS-COV-2 SPIKE PROTEIN IN THE NERVOUS SYSTEM: A BIOINFORMATICS APPROACH

Introduction

The development of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in record time to cope with the ongoing coronavirus disease 2019 (COVID-19) pandemic has led to uncertainty about their use and the appearance of adverse neurological reactions. The SARS-CoV-2 spike protein (SP) is used to produce neutralizing antibodies and stimulate innate immunity. However, considering the alterations in the nervous system (NS) caused by COVID- 19, cross-reactions are plausible.

Objective

To identify peptides in Homo sapiens SP-like proteins involved in myelin and axon homeostasis that may be affected due to molecular mimicry by antibodies and T cells induced by interaction with SP.

Materials and methods

A bioinformatics approach was used. To select the H. sapiens proteins to be studied, related biological processes categorized based on gene ontology were extracted through the construction of a protein–protein interaction network. Peripheral myelin protein 22, a major component of myelin in the peripheral nervous system, was used as the query protein. The extracellular domains and regions susceptible to recognition by antibodies were extracted from UniProt. In the study of T cells, linear sequence similarity between H. sapiens proteins and SP was assessed using BLASTp. This study considered the similarity in terms of biochemical groups per residue and affinity to the human major histocompatibility complex (human leukocyte antigen I), which were evaluated using Needle and NetMHCpan 4.1, respectively.

Results

A large number of shared pentapeptides between SP and H. sapiens proteins were identified. However, only a small group of 39 proteins was linked to axon and myelin homeostasis. In particular, some proteins, such as phosphacan, attractin, and teneurin-4, were susceptible targets of B and T cells. Other proteins closely related to myelin components in the NS, such as myelin-associated glycoprotein, were found to share at least one pentamer with SP in extracellular domains.

Conclusion

Proteins involved in the maintenance of nerve conduction in the central and peripheral NS were identified in H. sapiens. Based on these findings, re-evaluation of the vaccine composition is recommended to prevent possible neurological side effects.

Attractin Participates in Schizophrenia by Affecting Testosterone Levels

Attractin (ATRN) is a widely expressed glycoprotein that is involved in energy homeostasis, neurodevelopment, and immune response. It is encoded by a gene spanning 180 kb on chromosome 20p13, a region previously implicated in schizophrenia by linkage studies. To address a possible role of ATRN in disorders of the central nervous system, we created an atrn knockout zebrafish line and performed behavioral tests. Adult atrn^–/– zebrafish exhibited more pronounced attack behavior relative to wild-type control zebrafish in a tracking analysis. Biochemical analysis revealed elevated testosterone levels in atrn^–/– zebrafish. At the gene expression level, we noted an upregulation of cyp51 and hsd17b7, key proteins in testosterone synthesis in the brains of both adult and larvae of atrn^–/– zebrafish. In order to further elucidate the relationship between testosterone and behavioral syndromes, we then compared testosterone levels of 9,008 psychiatric patients and 247 healthy controls from the same catchment area. Of all subjects examined, male subjects with schizophrenia exhibited lower testosterone levels compared with controls. In contrast, female subjects with a diagnosis of schizophrenia or bipolar disorder featured higher testosterone levels than did same sex controls. Purposeful sampling of extreme groups showed reduced ATRN expression in a subset of these subjects. Finally, we identified 14 subjects with ATRN mutations. All of whom displayed abnormal testosterone levels. In summary, the interplay of ATRN and testosterone may help to explain sexual dimorphisms in selected behavioral phenotypes.

Attractin Gene Deficiency in Rats Leads to Impairments in Both Activity and Spatial Learning and Memory

Attractin (ATRN), an autosomal recessive gene that is widely distributed in the brain, is involved in the execution of a variety of brain functions and associated with certain neuropsychiatric disorders. Here, we introduce a novel rat strain harboring a mutation in ATRN that was generated by knocking in ATRN-G505C via the CRISPR/Cas9 system. We assessed the behavioral performance of these mutant ATRN knock-in rats. The G505C mutation was introduced into exon 9, and a synthetic primer was inserted into introns 8-9 for genotyping. The 505th amino acid, a Gly (G) residue, was mutated to a Cys (C) residue, i.e., GGC was mutated to TGC. Behavioral experiments showed that homozygous ATRN rats spent significantly more time searching for the escape platform in the acquisition trial and significantly less time in the target area in the probe trial in the Morris water maze (MWM) test and traveled a significantly shorter distance in the open field test (OFT) than wild-type rats. In addition, Western blot analysis and immunohistochemistry showed that rats with the mutant ATRN gene exhibited significantly reduced expression of brain-derived neurotrophic factor (BDNF). In summary, our results indicate that mutations in the ATRN gene directly lead to learning and memory impairments and slight motor deficits. These findings provide new clues for the mechanism by which mutant ATRN induces neurodegenerative changes.

C-type lectins in immunity and homeostasis

The C-type lectins are a superfamily of proteins that recognize a broad repertoire of ligands and that regulate a diverse range of physiological functions. Most research attention has focused on the ability of C-type lectins to function in innate and adaptive antimicrobial immune responses, but these proteins are increasingly being recognized to have a major role in autoimmune diseases and to contribute to many other aspects of multicellular existence. Defects in these molecules lead to developmental and physiological abnormalities, as well as altered susceptibility to infectious and non-infectious diseases. In this Review, we present an overview of the roles of C-type lectins in immunity and homeostasis, with an emphasis on the most exciting recent discoveries.