Biology subjects

Grenier-Boley, B.

Publications and source records attributed to Grenier-Boley, B..

7 recordsLinked to original sources

bioRxiv2026

The Alzheimer's disease-associated rs28834970 variant in PTK2B impairs electrical activity and regulates Tau phosphorylation and APP processing in human neuronal cultures

Background: Genome-wide association studies have identified the PTK2B gene, which encodes Proline-rich tyrosine kinase 2 (PYK2), as a genetic risk factor for Alzheimer's disease (AD). However, its role in AD aetiology remains to be understood, as a complex contribution to amyloid {beta} (A{beta}) toxicity, tauopathy and neuronal dysfunction is suggested by contradictory evidence. Determining how the causal variant among AD-associated PTK2B variants impairs PYK2 function to trigger AD hallmarks could bring clarification. Methods: We combined in silico prediction tools with luciferase reporter assays in neuroblastoma cells to prioritize potential AD-associated PTK2B functional variants. We generated isogenic KOLF2.1J induced pluripotent stem cells (iPSCs) carrying the most relevant functional variant using CRISPR-Cas9 and differentiated them into human neuronal cultures (hNCs). We assessed PYK2 expression via immunoblotting, performed transcriptomic profiling using RNA-sequencing, analyzed neuronal network activity via multielectrode array (MEA) recordings, quantified synaptic density through immunocytochemistry in microfluidic devices, and assessed Tau phosphorylation and amyloid-precursor protein (APP) metabolism. Results: The rs28834970 regulatory variant was identified as the most functionally relevant in our model, with the C risk allele promoting transcription factor C/EBP{beta} binding within a cis-regulatory element. In hNCs, the homozygous rs28834970 CC genotype reduced total PYK2 levels by more than 80%, while increasing the proportion of phosphorylated (activated) PYK2. Transcriptomic analysis revealed 724 downregulated and 113 upregulated gene sets, with altered expression of genes involved in extracellular matrix organization, cytoplasmic translation and neurotransmitter secretion. MEA recordings showed reduced network recruitment and altered burst organization. Immunocytochemistry in microfluidic devices consistently revealed that rs28834970 impacts dendritic development and postsynaptic maturation. The risk genotype significantly elevated Tau phosphorylation at pathological sites (Thr181, Thr217, Thr231, Ser202-Thr205, Ser396-Ser404), and enhanced APP processing, resulting in decreased levels of APP and CTF but increased levels of sAPP, sAPP{beta} and A{beta}. Conclusion: The rs28834970 C risk allele mechanistically links AD susceptibility to downregulation of PTK2B/PYK2 expression and to the increase in Tau pathology and A{beta} levels while compromising synaptic structure and function.

genetics↗

bioRxiv2024

Neuronal downregulation of PLCG2 impairs synaptic function and elicits Alzheimer disease hallmarks

We developed a high content screening to investigate how Alzheimer disease (AD) genetic risk factors may affect synaptic mechanisms in rat primary neuronal cultures. Out of the target genes identified, we found that Plcg2 downregulation in mouse dentate gyrus neurons consistently disrupted dendritic morphology and synaptic function. In human neuronal cultures (hNCs), PLCG2 downregulation also impaired synaptic function and increased A{beta} levels and Tau phosphorylation. Very rare PLCG2 loss-of-function (LoF) variants were associated with a 10-fold increased AD risk. PLCG2 LoF carriers exhibit low mRNA/protein PLCG2/PLC{gamma}2 levels and the R953* LoF mutation compromised synaptic function and increased AD hallmarks in hNCs. Single nuclei RNAseq analyses confirmed that the downregulation of PLCG2 impacted pathways related to synaptic and neuronal functions, potentially through neurexin in neurons. In conclusion, PLC{gamma}2 downregulation could increase AD risk by impairing synaptic functions and increasing the A{beta} levels and Tau phosphorylation in neurons.

neuroscience↗

bioRxiv2021

Primary brain cell infection by Toxoplasma gondii reveals the extent and dynamics of parasite differentiation and impact on neuron biology.

Toxoplasma gondii is a eukaryotic parasite that forms latent cysts in the brain of immunocompetent individuals. The latent parasite infection of the immune-privileged central nervous system is linked to most complications. With no drug currently available to eliminate the latent cysts in the brain of infected hosts, the consequences of neurons long-term infection are unknown. It has long been known that T. gondii specifically differentiates into a latent form (bradyzoite) in neurons, but how the infected neuron responds to the infection remains to be elucidated. We have established a new in vitro model resulting in the production of mature bradyzoite cysts in brain cells. Using dual, host and parasite RNA-seq, we characterized the dynamics of differentiation of the parasite, revealing the involvement of key pathways in this process. Moreover, we identified how the infected brain cells responded to the parasite infection revealing the drastic changes that take place. We showed that neuronal-specific pathways are strongly affected, with synapse signaling being particularly affected, especially glutamatergic synapse signaling. The establishment of this new in vitro model allows investigating both the dynamics of parasite differentiation and the specific response of neurons to the long-term infection by this parasite.

microbiology↗

bioRxiv2019

Alzheimer’s genetic risk factor FERMT2 (Kindlin-2) is regulated by risk allele-binding of miR-4504 and leads to synaptic dysfunction in an APP-dependent manner

Although APP metabolism is being intensively investigated, a large fraction of its modulators are yet to be characterized. In this context, we combined two genome-wide high-content screenings to assess the functional impact of miRNAs and genes on APP metabolism and the signaling pathways involved. This approach highlighted the involvement of FERMT2 (or Kindlin-2), a genetic risk factor of Alzheimers disease (AD), as a potential key modulator of axon guidance; a neuronal process that depends on the regulation of APP metabolism. We found that FERMT2 directly interacts with APP to modulate its metabolism and that FERMT2 under-expression impacts axonal growth, synaptic connectivity and long-term potentiation in an APP-dependent manner. Lastly, the rs7143400-T allele, which is associated with an increased AD risk and localized within the 3UTR of FERMT2, induced a down-regulation of FERMT2 expression through binding of miR-4504 among others. This miRNA is mainly expressed in neurons and significantly overexpressed in AD brains compared to controls. Altogether, our data provide strong evidence for a detrimental effect of FERMT2 under-expression in neurons and insight on how this may influence AD pathogenesis.

pathology↗

bioRxiv2018

Meta-analysis of genetic association with diagnosed Alzheimer’s disease identifies novel risk loci and implicates Abeta, Tau, immunity and lipid processing

Late-onset Alzheimers disease (LOAD, onset age > 60 years) is the most prevalent dementia in the elderly1, and risk is partially driven by genetics2. Many of the loci responsible for this genetic risk were identified by genome-wide association studies (GWAS)3-8. To identify additional LOAD risk loci, the we performed the largest GWAS to date (89,769 individuals), analyzing both common and rare variants. We confirm 20 previous LOAD risk loci and identify four new genome-wide loci (IQCK, ACE, ADAM10, and ADAMTS1). Pathway analysis of these data implicates the immune system and lipid metabolism, and for the first time tau binding proteins and APP metabolism. These findings show that genetic variants affecting APP and A{beta} processing are not only associated with early-onset autosomal dominant AD but also with LOAD. Analysis of AD risk genes and pathways show enrichment for rare variants (P = 1.32 x 10-7) indicating that additional rare variants remain to be identified.

genetics↗

bioRxiv2017

Genome-wide Association Study Links APOEϵ4 and BACE1 Variants with Plasma Amyloid β Levels

INTRODUCTIONThere is increasing interest in plasma A{beta} as an endophenotype and biomarker of Alzheimers disease (AD). Identifying the genetic determinants of plasma A{beta} levels may elucidate important processes that determine plasma A{beta} measures. METHODSWe included 12,369 non-demented participants derived from eight population-based studies. Imputed genetic data and plasma A{beta}1-40, A{beta}1-42 levels and A{beta}1-42/A{beta}1-40 ratio were used to perform genome-wide association studies, gene-based and pathway analyses. Significant variants and genes were followed-up for the association with PET A{beta} deposition and AD risk. RESULTSSingle-variant analysis identified associations across APOE for A{beta}1-42 and A{beta}1-42/A{beta}1-40 ratio, and BACE1 for A{beta}1-40. Gene-based analysis of A{beta}1-40 additionally identified associations for APP, PSEN2, CCK and ZNF397. There was suggestive interaction between a BACE1 variant and APOE{varepsilon}4 on brain A{beta} deposition. DISCUSSIONIdentification of variants near/in known major A{beta}-processing genes strengthens the relevance of plasma-A{beta} levels both as an endophenotype and a biomarker of AD.

genetics↗

bioRxiv2017

A common haplotype lowers SPI1 (PU.1) expression in myeloid cells and delays age at onset for Alzheimer’s disease

In this study we used age at onset of Alzheimers disease (AD), cerebrospinal fluid (CSF) biomarkers, and cis-expression quantitative trait loci (cis-eQTL) datasets to identify candidate causal genes and mechanisms underlying AD GWAS loci. In a genome-wide survival analysis of 40,255 samples, eight of the previously reported AD risk loci are significantly (P < 5x10-8) or suggestively (P < 1x10-5) associated with age at onset-defined survival (AAOS) and a further fourteen novel loci reached suggestive significance. Using stratified LD score regression we demonstrated a significant enrichment of AD heritability in hematopoietic cells of the myeloid and B-lymphoid lineage. We then investigated the impact of these 22 AAOS-associated variants on CSF biomarkers and gene expression in cells of the myeloid lineage. In particular, the minor allele of rs1057233 (G), within the previously reported CELF1 AD risk locus, shows association with higher age at onset of AD (P=8.40x10-6), higher CSF levels of A{beta}42 (P=1.2x10-4), and lower expression of SPI1 in monocytes (P=1.50x10-105) and macrophages (P=6.41x10-87). SPI1 encodes PU.1, a transcription factor critical for myeloid cell development and function. AD heritability is enriched within the SPI1 cistromes of monocytes and macrophages, implicating a myeloid PU.1 target gene network in the etiology of AD. Finally, experimentally altered PU.1 levels are correlated with phagocytic activity of BV2 mouse microglial cells and specific changes in the expression of multiple myeloid-expressed genes, including the mouse orthologs of AD-associated genes, APOE, CLU/APOJ, CD33, MS4A4A/MS4A6A, and TYROBP. Our results collectively suggest that lower SPI1 expression reduces AD risk by modulating myeloid cell gene expression and function.

neuroscience↗