Data integration for functional annotation of regulatory single nucleotide polymorphisms associated with Alzheimer's disease susceptibility

Polymorphisms of nicotinic acetylcholine receptors in Alzheimer’s disease: a systematic review and data analysis

Objective

This study was conducted to accomplish a better insight into the impact of single nucleotide polymorphisms (SNPs) of nicotinic acetylcholine receptors (nAChR) at the risk of Alzheimer’s disease (AD) and their possible pathogenicity.

Methods

We carried out a systemic review of accessible studies. The case–control studies were assessed by an electronic search of international and local databases to identify relevant studies on SNPs relating to nAChR genes in AD. Two reviewers evaluated the inclusion/exclusion criteria, summarized, and analyzed the extracted data. We used odds ratios (ORs) with 95% confidence intervals (CIs) for reporting our data. Online databases were checked for possible pathogenicity of statistically significant SNPs. Also, online databases, including NCBI, NIH, ClinVar, RegulomeDB, and Ensemble, were used to analyze and identify structure and function, DNA features, and flank sequencing in SNPs.

Results

Among all collected SNPs, rs4779978 and rs1827294 on CHRNA7, rs1044394 on CHRNA4, and rs1127314 on CHRNB2 showed statistically significant between AD cases and controls.

Conclusions

Some SNPs from the reviewed reports show evidence supporting their possible involvement in AD pathology. However, more comprehensive studies are necessary to identify the exact correlation and their role on the pathogenicity of disease.

TREM2 Mediates Microglial Anti-Inflammatory Activations in Alzheimer's Disease: Lessons Learned from Transcriptomics

Alzheimer’s disease (AD) is a lethal neurodegenerative disorder primarily affecting the aged population. The etiopathogenesis of AD, especially that of the sporadic type, remains elusive. The triggering receptor expressed on myeloid cells 2 (TREM2), a member of TREM immunoglobulin superfamily, plays a critical role in microglial physiology. Missense mutations in human TREM2 are determined as genetic risk factors associated with the development of sporadic AD. However, the roles of TREM2 in the pathogenesis of AD are still to be established. In this review, we outlined the influence of Trem2 on balance of pro- and anti-inflammatory microglial activations from a perspective of AD mouse model transcriptomics. On this basis, we further speculated the roles of TREM2 in different stages of AD, which may shed light to the development of TREM2-targeted strategy for the prevention and treatment of this neurodegenerative disorder.

Identification of hub ubiquitin ligase genes affecting Alzheimer's disease by analyzing transcriptome data from multiple brain regions

The ubiquitin-proteasome system (UPS) plays crucial roles in numerous cellular functions. Dysfunction of the UPS shows certain correlations with the pathological changes in Alzheimer's disease (AD). This study aimed to explore the different impairments of the UPS in multiple brain regions and identify hub ubiquitin ligase (E3) genes in AD. The brain transcriptome, blood transcriptome and proteome data of AD were downloaded from a public database. The UPS genes were collected from the Ubiquitin and Ubiquitin-like Conjugation Database. The hub E3 genes were defined as the differentially expressed E3 genes shared by more than three brain regions. E3Miner and UbiBrowser were used to predict the substrate of hub E3. This study shows varied impairment of the UPS in different brain regions in AD. Furthermore, we identify seven hub E3 genes (CUL1, CUL3, EIF3I, NSMCE1, PAFAH1B1, RNF175, and UCHL1) that are downregulated in more than three brain regions. Three of these genes (CUL1, EIF3I, and NSMCE1) showed consistent low expression in blood. Most of these genes have been reported to promote AD, whereas the impact of RNF175 on AD is not yet reported. Further analysis revealed a potential regulatory mechanism by which hub E3 and its substrate genes may affect transcription functions and then exacerbate AD. This study identified seven hub E3 genes and their substrate genes affect transcription functions and then exacerbate AD. These findings may be helpful for the development of diagnostic biomarkers and therapeutic targets for AD.