Six generations of CHMP2B-mediated Frontotemporal Dementia: Clinical features, predictive testing, progression, and survival

Clinical characterization of CCT2 and its role in autophagy regulation during age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of vision loss in the elderly, and the role of chaperonin containing TCP1 subunit 2 (CCT2) remains unclear. This study aims to elucidate the mechanistic link between CCT2 and AMD, contributing to improved understanding and potential therapeutic strategies. Retinal and RPE-Choroid transcriptome array data from 130 AMD patients and 121 normal donors (GSE29801 dataset) were reanalyzed to assess CCT2 expression across different AMD subtypes, age groups, and genders. Single-sample gene set enrichment analysis was performed to explore correlations with autophagy-related genes and other established AMD causes. Additionally, CCT2 expression was validated in sodium iodate (NaIO₃)-induced 661 W cells (photoreceptor-like cells) using quantitative real-time PCR (qRT-PCR). CCT2 was significantly enriched in advanced AMD retinas compared to intermediate stages in retina (both macular and extramacular) and early stages in extramacular retina (p < 0.05). NaIO3-treated 661 W cells exhibited a similar expression trend, confirming transcriptomic findings. CCT2 is significantly upregulated in advanced AMD and may contribute to drusen degradation. It shows potential as both a biomarker and an independent diagnostic indicator, particularly for advanced-stage AMD.

A novel splice-site mutation in CHMP2B associated with frontotemporal dementia: The first report from China and literature review

BACKGROUND

Frontotemporal dementia (FTD) has genetic heterogeneity, and the endosomal ESCRTIII-complex subunit CHMP2B variant is a rare cause of FTD. The mutations in CHMP2B were first identified in a large Danish pedigree with autosomal dominant FTD, and have also been found in several individuals from Belgium, France, the United States, and Türkiye. In the Chinese population, cases of CHMP2B variant-associated FTD have never been reported.

METHODS

The spectrum of clinical symptoms and the genetic analysis of the presented patient were identified and investigated. Besides this case, we assessed previously reported cases with CHMP2B gene mutations.

RESULTS

This study presents a Chinese patient harboring a novel heterozygous A-to-T variant (NM_014043:c.532-2A>T) in CHMP2B with a phenotype compatible with FTD. Although previous reports suggested cases of CHMP2B variant-associated FTD initially presented with personality changes and stereotypical movements at the age of 50, this case was characterized by psychosis involving delusion of persecution, auditory hallucination, and suspiciousness at the earlier onset age of 44. Minigene splicing assay revealed that the splice-site variant could result in the retention of intron 5.

CONCLUSION

This is the first case of CHMP2B variant-associated FTD reported in the Chinese population. The novel c.532-2A>T variant in the acceptor splice site of exon 6 retaining intron 5 was predicted to cause truncated protein and protein conformation changes. This discovery may expand the genetic and phenotypic spectrum of CHMP2B variant-associated FTD.

Endo-lysosomal protein concentrations in CSF from patients with frontotemporal dementia caused by CHMP2B mutation

Introduction

Increasing evidence implicates proteostatic dysfunction as an early event in the development of frontotemporal dementia (FTD). This study aimed to explore potential cerebrospinal fluid (CSF) biomarkers associated with the proteolytic systems in genetic FTD caused by CHMP2B mutation.

Methods

Combining solid-phase extraction and parallel reaction monitoring mass spectrometry, a panel of 47 peptides derived from 20 proteins was analyzed in CSF from 31 members of the Danish CHMP2B-FTD family.

Results

Compared with family controls, mutation carriers had significantly higher levels of complement C9, lysozyme and transcobalamin II, and lower levels of ubiquitin, cathepsin B, and amyloid precursor protein.

Discussion

Lower CSF ubiquitin concentrations in CHMP2B mutation carriers indicate that ubiquitin levels relate to the specific disease pathology, rather than all-cause neurodegeneration. Increased lysozyme and complement proteins may indicate innate immune activation. Altered levels of amyloid precursor protein and cathepsins have previously been associated with impaired lysosomal proteolysis in FTD.

Highlights

CSF markers of proteostasis were explored in CHMP2B-mediated frontotemporal dementia (FTD).31 members of the Danish CHMP2B-FTD family were included.We used solid-phase extraction and parallel reaction monitoring mass spectrometry.Six protein levels were significantly altered in CHMP2B-FTD compared with controls.Lower CSF ubiquitin levels in patients suggest association with disease mechanisms.

TDP-43 Proteinopathy and Tauopathy: Do They Have Pathomechanistic Links?

Transactivation response DNA binding protein 43 kDa (TDP-43) and tau are major pathological proteins of neurodegenerative disorders, of which neuronal and glial aggregates are pathological hallmarks. Interestingly, accumulating evidence from neuropathological studies has shown that comorbid TDP-43 pathology is observed in a subset of patients with tauopathies, and vice versa. The concomitant pathology often spreads in a disease-specific manner and has morphological characteristics in each primary disorder. The findings from translational studies have suggested that comorbid TDP-43 or tau pathology has clinical impacts and that the comorbid pathology is not a bystander, but a part of the disease process. Shared genetic risk factors or molecular abnormalities between TDP-43 proteinopathies and tauopathies, and direct interactions between TDP-43 and tau aggregates, have been reported. Further investigations to clarify the pathogenetic factors that are shared by a broad spectrum of neurodegenerative disorders will establish key therapeutic targets.

The Role of Vti1a in Biological Functions and Its Possible Role in Nervous System Disorders

Vesicle transport through interaction with t-SNAREs 1A (Vti1a), a member of the N-ethylmaleimide-sensitive factor attachment protein receptor protein family, is involved in cell signaling as a vesicular protein and mediates vesicle trafficking. Vti1a appears to have specific roles in neurons, primarily by regulating upstream neurosecretory events that mediate exocytotic proteins and the availability of secretory organelles, as well as regulating spontaneous synaptic transmission and postsynaptic efficacy to control neurosecretion. Vti1a also has essential roles in neural development, autophagy, and unconventional extracellular transport of neurons. Studies have shown that Vti1a dysfunction plays critical roles in pathological mechanisms of Hepatic encephalopathy by influencing spontaneous neurotransmission. It also may have an unknown role in amyotrophic lateral sclerosis. A VTI1A variant is associated with the risk of glioma, and the fusion product of the VTI1A gene and the adjacent TCF7L2 gene is involved in glioma development. This review summarizes Vti1a functions in neurons and highlights the role of Vti1a in the several nervous system disorders.