Biology subjects

Buhidma, Y.

Publications and source records attributed to Buhidma, Y..

3 recordsLinked to original sources

bioRxiv2025

Transcriptomic and pathological analysis of the hnRNP network reveals glial involvement in FTLD pathological subtypes

Frontotemporal dementia (FTD) is a neurodegenerative disorder with a strong heritable component. Frontotemporal lobar degeneration (FTLD) refers to the pathological changes seen in FTD, characterised by atrophy of the frontal and temporal lobes and the presence of abnormal protein inclusions. In the case of FTLD with hyperphosphorylated TDP-43 positive inclusions (FTLD-TDP), five pathological subtypes (A, B, C, D, and E) are observed based on the types and distribution of inclusions found in the brain. In all subtypes, there tends to be a large variability in the number of pathological inclusions observed between cases, with limited correlation to clinical manifestations. TDP-43 is an RNA binding protein belonging to the heterogeneous nuclear ribonucleoprotein (hnRNP) family which along with other hnRNPs modulates multiple aspects of RNA processing. HnRNPs other than TDP-43 have been implicated in several neurological diseases, including ALS, FTLD-TDP, FTLD-FUS and Alzheimers disease. Multiple hnRNPs have been found in pathological inclusions in specific subtypes of FTLD-TDP, suggesting potential roles in the disease process. The role of the hnRNP network in FTLD disease pathogenesis, however, has not yet been investigated. This study aimed to comprehensively evaluate the presence and expression of hnRNP proteins in two pathological subtypes of sporadic FTLD-TDP (A and C) as well as the genetic form FTLD-TDP A C9orf72 using immunohistochemistry and gene expression analysis by single-nuclei RNA-sequencing. We found that there was great variability in frequency of TDP-43 pathology across and within FTLD-TDP pathological subtypes. Finally, our findings suggest that distinct global transcriptomic profiles may underlie the different pathological subtypes of FTLD-TDP. The most prominent transcriptomic changes were observed in oligodendrocytes and astrocytes, involving multiple hnRNPs across FTLD subtypes compared to controls. Transcriptomic co-expression analysis further revealed that glial clusters were more strongly associated with RNA processing dysfunction and contribute to disease classification. Together, these findings highlight the involvement of the hnRNP network and glial-specific RNA processing alterations in FTLD-TDP pathophysiology, offering new insight into the molecular distinctions between pathological subtypes and potential targets for future investigation.

neuroscience↗

bioRxiv2025

Apolipoprotein E abundance is elevated in the brains of individuals with Down syndrome-Alzheimer's disease

Trisomy of chromosome 21, the cause of Down syndrome (DS), is the most commonly occurring genetic cause of Alzheimers disease (AD). Here, we compare the frontal cortex proteome of people with Down syndrome-Alzheimers disease (DSAD) to demographically matched cases of early-onset AD and healthy ageing controls. We find wide dysregulation of the proteome, beyond proteins encoded by chromosome 21, including an increase in the abundance of the key AD-associated protein, APOE, in people with DSAD compared to matched cases of AD. To understand the cell types that may contribute to changes in protein abundance, we undertook a matched single-nuclei RNA-sequencing study, which demonstrated that APOE expression was elevated in subtypes of astrocytes, endothelial cells and pericytes in DSAD. We further investigate how trisomy 21 may cause increased APOE. Increased abundance of APOE may impact the development of, or response to, AD pathology in the brain of people with DSAD, altering disease mechanisms with clinical implications. Overall, these data highlight that trisomy 21 alters both the transcriptome and proteome of people with DS in the context of AD, and that these differences should be considered when selecting therapeutic strategies for this vulnerable group of individuals who have high-risk of early-onset dementia.

neuroscience↗

bioRxiv2023

Differential neuronal vulnerability to C9orf72 repeat expansion driven by Xbp1 transcription signature

A G4C2 repeat expansion in the gene C9orf72 (C9) is the most common genetic cause of sporadic and familial frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). What determines why cell death is triggered only in specific neuronal populations, while others remain protected or are less susceptible to disease is still an open question. In particular, whether it is the transcriptional response to the accumulation of toxic insults or the initial cellular state that determines their vulnerability is still unknown. We have carried out a large-scale profiling of single cell transcriptional signatures throughout disease development in a Drosophila model of C9 repeat toxicity. This enabled us to monitor transcriptional shifts and track changes in cell populations during disease progression. We have identified neuronal populations which are depleted in response to C9 repeat expression, and therefore vulnerable to toxicity. On the other hand, other neuron types are resistant to toxicity, and maintain their cell number during disease progression. Our findings suggest that a major determinant of vulnerability is the transcriptional state of the cell before it is exposed to C9 repeat expression. We have identified a conserved transcriptional profile that is associated with resistance to C9 repeat toxicity. Neurons resistant to disease display a higher expression of genes involved in protein homeostasis, with Xbp1 identified as a crucial transcription factor determining neuronal vulnerability.

neuroscience↗