Acta Neuropathologica Communications最新文献

Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease leading to motor neuron loss. Currently mutations in > 40 genes have been linked to ALS, but the contribution of many genes and genetic mutations to the ALS pathogenic process remains poorly understood. Therefore, we first performed comparative interactome analyses of five recently discovered ALS-associated proteins (C21ORF2, KIF5A, NEK1, TBK1, and TUBA4A) which highlighted many novel binding partners, and both unique and shared interactors. The analysis further identified C21ORF2 as a strongly connected protein. The role of C21ORF2 in neurons and in the nervous system, and of ALS-associated C21ORF2 variants is largely unknown. Therefore, we combined human iPSC-derived motor neurons with other models and different molecular cell biological approaches to characterize the potential pathogenic effects of C21ORF2 mutations in ALS. First, our data show C21ORF2 expression in ALS-relevant mouse and human neurons, such as spinal and cortical motor neurons. Further, the prominent ALS-associated variant C21ORF2-V58L caused increased apoptosis in mouse neurons and movement defects in zebrafish embryos. iPSC-derived motor neurons from C21ORF2-V58L-ALS patients, but not isogenic controls, show increased apoptosis, and changes in DNA damage response, mitochondria and neuronal excitability. In addition, C21ORF2-V58L induced post-transcriptional downregulation of NEK1, an ALS-associated protein implicated in apoptosis and DDR. In all, our study defines the pathogenic molecular and cellular effects of ALS-associated C21ORF2 mutations and implicates impaired post-transcriptional regulation of NEK1 downstream of mutant C21ORF72 in ALS.

Neuroepithelial tumors with fusion of PLAGL1 or amplification of PLAGL1/PLAGL2 have recently been described often with ependymoma-like or embryonal histology respectively. To further evaluate emerging entities with PLAG-family genetic alterations, the histologic, molecular, clinical, and imaging features are described for 8 clinical cases encountered at St. Jude (EWSR1-PLAGL1 fusion n = 6; PLAGL1 amplification n = 1; PLAGL2 amplification n = 1). A histologic feature observed on initial resection in a subset (4/6) of supratentorial neuroepithelial tumors with EWSR1-PLAGL1 rearrangement was the presence of concurrent ependymal and ganglionic differentiation. This ranged from prominent clusters of ganglion cells within ependymoma/subependymoma-like areas, to interspersed ganglion cells of low to moderate frequency among otherwise ependymal-like histology, or focal areas with a ganglion cell component. When present, the combination of ependymal-like and ganglionic features within a supratentorial neuroepithelial tumor may raise consideration for an EWSR1-PLAGL1 fusion, and prompt initiation of appropriate molecular testing such as RNA sequencing and methylation profiling. One of the EWSR1-PLAGL1 fusion cases showed subclonal INI1 loss in a region containing small clusters of rhabdoid/embryonal cells, and developed a prominent ganglion cell component on recurrence. As such, EWSR1-PLAGL1 neuroepithelial tumors are a tumor type in which acquired inactivation of SMARCB1 and development of AT/RT features may occur and lead to clinical progression. In contrast, the PLAGL2 and PLAGL1 amplified cases showed either embryonal histology or contained an embryonal component with a significant degree of desmin staining, which could also serve to raise consideration for a PLAG entity when present. Continued compilation of associated clinical data and histopathologic findings will be critical for understanding emerging entities with PLAG-family genetic alterations.

Pituitary neuroendocrine tumors (PitNET) represent the vast majority of sellar masses. Some behave aggressively, growing rapidly and invading surrounding tissues, with high rates of recurrence and resistance to therapy. Our aim was to establish patterns of genomic, transcriptomic and methylomic evolution throughout time in primary and recurrent tumors from the same patient. Therefore, we performed transcriptome- and exome-sequencing and methylome microarrays of aggressive, primary, and recurrent PitNET from the same patient. Primary and recurrent tumors showed a similar exome profile, potentially indicating a stable genome over time. In contrast, the transcriptome of primary and recurrent PitNET was dissimilar. Gonadotroph, silent corticotroph, as well as metastatic corticotroph and a somatotroph PitNET expressed genes related to fatty acid biosynthesis and metabolism, phosphatidylinositol signaling, glycerophospholipid and phospholipase D signaling, respectively. Diacylglycerol kinase gamma (DGKG), a key enzyme in glycerophospholipid metabolism and phosphatidylinositol signaling pathways, was differentially expressed between primary and recurrent PitNET. These alterations did not seem to be regulated by DNA methylation, but rather by several transcription factors. Molecular docking showed that dasatinib, a small molecule tyrosine kinase inhibitor used in the treatment of chronic lymphocytic and acute lymphoblastic leukemia, could target DGKG. Dasatinib induced apoptosis and decreased proliferation in GH3 cells. Our data indicate that pituitary tumorigenesis could be driven by transcriptomically heterogeneous clones, and we describe alternative pharmacological therapies for aggressive and recurrent PitNET.

Research in the field of traumatic brain injury has until now heavily relied on the use of animal models to identify potential therapeutic approaches. However, a long series of failed clinical trials has brought many scientists to question the translational reliability of pre-clinical results obtained in animals. The search for an alternative to conventional models that better replicate human pathology in traumatic brain injury is thus of the utmost importance for the field. Recently, orthotopic xenotransplantation of human brain organoids into living animal models has been achieved. This review summarizes the existing literature on this new method, focusing on its potential applications in preclinical research, both in the context of cell replacement therapy and disease modelling. Given the obvious advantages of this approach to study human pathologies in an in vivo context, we here critically review its current limitations while considering its possible applications in traumatic brain injury research.

CSF1R-related disorder (CSF1R-RD) is a neurodegenerative condition that predominantly affects white matter due to genetic alterations in the CSF1R gene, which is expressed by microglia. We studied an elderly man with a hereditary, progressive dementing disorder of unclear etiology. Standard genetic testing for leukodystrophy and other neurodegenerative conditions was negative. Brain autopsy revealed classic features of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), including confluent white matter degeneration with axonal spheroids and pigmented glial cells in the affected white matter, consistent with CSF1R-RD. Subsequent long-read sequencing identified a novel deletion in CSF1R that was not detectable with short-read exome sequencing. To gain insight into potential mechanisms underlying white matter degeneration in CSF1R-RD, we studied multiple brain regions exhibiting varying degrees of white matter pathology. We found decreased CSF1R transcript and protein across brain regions, including intact white matter. Single nuclear RNA sequencing (snRNAseq) identified two disease-associated microglial cell states: lipid-laden microglia (expressing GPNMB, ATG7, LGALS1, LGALS3) and inflammatory microglia (expressing IL2RA, ATP2C1, FCGBP, VSIR, SESN3), along with a small population of CD44⁺ peripheral monocyte-derived macrophages exhibiting migratory and phagocytic signatures. GPNMB⁺ lipid-laden microglia with ameboid morphology represented the end-stage disease microglia state. Disease-associated oligodendrocytes exhibited cell stress signatures and dysregulated apoptosis-related genes. Disease-associated oligodendrocyte precursor cells (OPCs) displayed a failure in their differentiation into mature myelin-forming oligodendrocytes, as evidenced by upregulated LRP1, PDGFRA, SOX5, NFIA, and downregulated NKX2-2, NKX6.2, SOX4, SOX8, TCF7L2, YY1, ZNF488. Overall, our findings highlight microglia-oligodendroglia crosstalk in demyelination, with CSF1R dysfunction promoting phagocytic and inflammatory microglia states, an arrest in OPC differentiation, and oligodendrocyte depletion.

Medulloblastoma, the most common malignant pediatric brain tumor, is classified into four main molecular subgroups, but group 3 and group 4 tumors are difficult to subclassify and have a poor prognosis. Rapid point-of-care diagnostic and prognostic assays are needed to improve medulloblastoma risk stratification and management. N6-methyladenosine (m6A) is a common RNA modification and long non-coding RNAs (lncRNAs) play a central role in tumor progression, but their impact on gene expression and associated clinical outcomes in medulloblastoma are unknown. Here we analyzed 469 medulloblastoma tumor transcriptomes to identify lncRNAs co-expressed with m6A regulators. Using LASSO-Cox analysis, we identified a five-gene m6A-associated lncRNA signature (M6LSig) significantly associated with overall survival, which was combined in a prognostic clinical nomogram. Using expression of the 67 m6A-associated lncRNAs, a subgroup classification model was generated using the XGBoost machine learning algorithm, which had a classification accuracy > 90%, including for group 3 and 4 samples. All M6LSig genes were significantly correlated with at least one immune cell type abundance in the tumor microenvironment, and the risk score was positively correlated with CD4⁺ naïve T cell abundance and negatively correlated with follicular helper T cells and eosinophils. Knockdown of key m6A writer genes METTL3 and METTL14 in a group 3 medulloblastoma cell line (D425-Med) decreased cell proliferation and upregulated many M6LSig genes identified in our in silico analysis, suggesting that the signature genes are functional in medulloblastoma. This study highlights a crucial role for m6A-dependent lncRNAs in medulloblastoma prognosis and immune responses and provides the foundation for practical clinical tools that can be rapidly deployed in clinical settings.

Wolfram syndrome (WS) is a rare childhood disease characterized by diabetes mellitus, diabetes insipidus, blindness, deafness, neurodegeneration and eventually early death, due to autosomal recessive mutations in the WFS1 (and WFS2) gene. While it is categorized as a neurodegenerative disease, it is increasingly becoming clear that other cell types besides neurons may be affected and contribute to the pathogenesis. MRI studies in patients and phenotyping studies in WS rodent models indicate white matter/myelin loss, implicating a role for oligodendroglia in WS-associated neurodegeneration. In this study, we sought to determine if oligodendroglia are affected in WS and whether their dysfunction may be the primary cause of the observed optic neuropathy and brain neurodegeneration. We demonstrate that 7.5-month-old Wfs1^∆exon8 mice display signs of abnormal myelination and a reduced number of oligodendrocyte precursor cells (OPCs) as well as abnormal axonal conduction in the optic nerve. An MRI study of the brain furthermore revealed grey and white matter loss in the cerebellum, brainstem, and superior colliculus, as is seen in WS patients. To further dissect the role of oligodendroglia in WS, we performed a transcriptomics study of WS patient iPSC-derived OPCs and pre-myelinating oligodendrocytes. Transcriptional changes compared to isogenic control cells were found for genes with a role in ER function. However, a deep phenotyping study of these WS patient iPSC-derived oligodendroglia unveiled normal differentiation, mitochondria-associated endoplasmic reticulum (ER) membrane interactions and mitochondrial function, and no overt signs of ER stress. Overall, the current study indicates that oligodendroglia functions are largely preserved in the WS mouse and patient iPSC-derived models used in this study. These findings do not support a major defect in oligodendroglia function as the primary cause of WS, and warrant further investigation of neurons and neuron-oligodendroglia interactions as a target for future neuroprotective or -restorative treatments for WS.

Primary familial brain calcification (PFBC) is a genetic neurological disorder characterized by symmetric brain calcifications that manifest with variable neurological symptoms. This study aimed to explore the genetic basis of PFBC and elucidate the underlying pathophysiological mechanisms. Six patients from four pedigrees with brain calcification were enrolled. Whole-exome sequencing identified two novel homozygous variants, c.488G > T (p.W163L) and c.2135G > A (p.W712*), within the myogenesis regulating glycosidase (MYORG) gene. Cerebellar ataxia (n = 5) and pyramidal signs (n = 4) were predominant symptoms, with significant clinical heterogeneity noted even within the same family. An autopsy of one patient revealed extensive brainstem calcifications, sparing the cerebral cortex, and marked by calcifications predominantly in capillaries and arterioles. The pathological study suggested morphological alterations characterized by shortened foot processes within astrocytes in regions with pronounced calcification and decreased immunoreactivity of AQP4. The morphology of astrocytes in regions without calcification remains preserved. Neuronal loss and gliosis were observed in the basal ganglia, thalamus, brainstem, cerebellum, and dentate nucleus. Notably, olivary hypertrophy, a previously undescribed feature in MYORG-PFBC, was discovered. Neuroimaging showed reduced blood flow in the cerebellum, highlighting the extent of cerebellar involvement. Among perivascular cells constituting the blood-brain barrier (BBB) and neurovascular unit, MYORG is most highly expressed in astrocytes. Astrocytes are integral components of the BBB, and their dysfunction can precipitate BBB disruption, potentially leading to brain calcification and subsequent neuronal loss. This study presents two novel homozygous variants in the MYORG gene and highlights the pivotal role of astrocytes in the development of brain calcifications, providing insights into the pathophysiological mechanisms underlying PFBC associated with MYORG variants.