Alzheimer’s disease Phospholipase C-gamma-2 (PLCG2) protective variant is a functional hypermorph

Magno, Lorenza; Lessard, Christian; Martins, Marta; Cruz, Pedro; Katan, Matilda; Bilsland, Jamie; Chakrabaty, Paramita; Golde, Todd E.; Whiting, Paul

doi:10.1101/409706

Cited by 37 publications

(59 citation statements)

References 41 publications

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“…This altered signalling likely directly contributes to protection against AD as it acts downstream of receptors, such as TREM2 and CSF1R, implicated in AD. An earlier study had indicated that the R522 variant may be hyperfunctional in COS7 and HEK293T expression systems (Magno et al , 2019). Importantly, our studies show that PLCγ2 with the R522 variant exhibits increased function in both human and mouse disease-relevant microglia when expressed at physiological normal levels, in the context of other PLC enzymes.…”

Section: Discussionsupporting

confidence: 59%

The Alzheimer’s disease protective P522R variant ofPLCG2, consistently enhances stimulus-dependent PLCγ2 activation, depleting substrate and altering cell function

Maguire

Menzies

Phillips

et al. 2020

Preprint

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Recent genome-wide association studies of Alzheimer's disease (AD) have identified variants implicating immune pathways in disease development. A rare coding variant of PLCG2, which encodes PLCγ2, shows a significant protective effect for AD (rs72824905, P522R, P=5.38x10 -10 , Odds Ratio = 0.68). Molecular dynamic modelling of the PLCγ2-R522 variant, situated within the auto-inhibitory domain of PLCγ2, suggests a structural change to the protein. Through CRISPR-engineering we have generated novel PLCG2-R522 harbouring human induced pluripotent cell lines (hiPSC) and a mouse knockin model, neither of which exhibits alterations in endogenous PLCG2 expression. Mouse microglia and macrophages and hiPSC-derived microglia-like cells with the R522 mutation, all demonstrate a consistent non-redundant hyperfunctionality in the context of normal expression of other PLC isoforms. This signalling alteration manifests as enhanced cellular Ca 2+ store release (~20-40% increase) in response to physiologically-relevant stimuli (e.g. Fc receptor ligation and Aβ oligomers). This hyperfunctionality resulted in increased PIP2 depletion in the cells with the PLCγ2-R522 variant after exposure to stimuli and reduced basal detection of PIP2 levels in vivo. These PLCγ2-R522 associated abnormalities resulted in impairments to phagocytosis (fungal and bacterial particles) and enhanced endocytosis (Aβ oligomers and dextran). PLCγ2 sits downstream of disease relevant pathways, such as TREM2 and CSF1R and alterations in its activity, direct impacts cell function, which in the context of the inherent drugability of enzymes such as PLCγ2, raise the prospect of manipulation of PLCγ2 as a therapeutic target in Alzheimer's Disease.

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Section: Discussionsupporting

confidence: 59%

The Alzheimer’s disease protective P522R variant ofPLCG2, consistently enhances stimulus-dependent PLCγ2 activation, depleting substrate and altering cell function

Maguire

Menzies

Phillips

et al. 2020

Preprint

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“…Bone marrow-derived macrophage (BMDM) cultures were established from femur and tibia bones of six-month-old Plcγ2-P522R KI mice and their wild type (WT) littermates [10-12]. The P522R variant has previously been shown to increase the production of inositol phosphate (Ip1, a surrogate of Ip3) and intracellular calcium release in transiently transfected HEK293 and COS cells [13]. To assess Plcγ2 enzyme activity in KI myeloid cells, Ip1 formation was measured from BMDM lysates as previously described [6, 13].…”

Section: Resultsmentioning

confidence: 99%

“…The P522R variant has previously been shown to increase the production of inositol phosphate (Ip1, a surrogate of Ip3) and intracellular calcium release in transiently transfected HEK293 and COS cells [13]. To assess Plcγ2 enzyme activity in KI myeloid cells, Ip1 formation was measured from BMDM lysates as previously described [6, 13]. A significantly higher basal Ip1 levels was detected in cultured KI BMDMs as compared to WT cells, and treatment with the phospholipase C agonist m-3M3FBS [7] further increased the levels of Ip1 in both, KI and WT cells ( Fig.…”

Section: Resultsmentioning

confidence: 99%

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The Alzheimer’s disease-associated protectivePlcγ2-P522R variant promotes beneficial microglial functions

Takalo

Wittrahm

Wefers

et al. 2020

Preprint

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BackgroundMicroglia-specific genetic variants are enriched in several neurodegenerative diseases, including Alzheimer’s disease (AD), implicating a central role for alterations of the innate immune system in the disease etiology. A rare coding variant in the PLCG2 gene (rs72824905, p.P522R) selectively expressed in microglia and macrophages was recently identified and shown to reduce the risk for AD.MethodsTo assess the role of this variant in the context of immune cell functions, we generated a Plcγ2-P522R knock-in (KI) mouse model using CRISPR/Cas9 gene editing.ResultsFunctional analyses of macrophages derived from homozygous KI mice and wild type (WT) littermates revealed that the P522R variant potentiates the primary function of Plcγ2 as a Pip2-metabolizing enzyme. This was associated with improved survival, enhanced phagocytic activity, and increased acute inflammatory response of the KI cells. Enhanced phagocytosis was also observed in mouse BV2 microglia-like cells overexpressing human PLCγ2-P522R, but not in PLCγ2-WT expressing cells. Furthermore, the brain mRNA signature together with microglia-specific PET imaging indicated microglia activation in Plcγ2-P522R KI mice.ConclusionThus, we have delineated cellular mechanisms of the protective Plcγ2-P522R variant, which provide further support for the emerging idea that activated microglia exert protective functions in AD.

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“…The dissection of the molecular mechanism behind these potential regulatory variants might help to elucidate the gain or loss of the function mechanism of the PLCG2 gene. This information could be critical for drug-targeting purposes 56 .…”

Section: Discussionmentioning

confidence: 99%

Common variants in Alzheimer’s disease: Novel association of six genetic variants with AD and risk stratification by polygenic risk scores

Rojas

Moreno‐Grau

Tesi

et al. 2019

Preprint

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BACKGROUND:Disentangling the genetic constellation underlying Alzheimer's disease (AD) is important. Doing so allows us to identify biological pathways underlying AD, point towards novel drug targets and use the variants for individualised risk predictions in disease modifying or prevention trials. In the present work we report on the largest genome-wide association study (GWAS) for AD risk to date and show the combined utility of proven AD loci for precision medicine using polygenic risk scores (PRS). METHODS:Three sets of summary statistics were included in our meta-GWAS of AD: an Spanish casecontrol study (GR@ACE/DEGESCO study, n = 12,386), the case-control study of International Genomics of Alzheimer project (IGAP, n = 82,771) and the UK Biobank (UKB) AD-by-proxy case-control study (n=314,278). Using these resources, we performed a fixed-effects inversevariance-weighted meta-analysis. Detected loci were confirmed in a replication study of 19,089 AD cases and 39,101 controls from 16 European-ancestry cohorts not previously used. We constructed a weighted PRS based on the 39 AD variants. PRS were generated by multiplying the genotype dosage of each risk allele for each variant by its respective weight, and then summing across all variants. We first validated it for AD in independent data (assessing effects of subthreshold signal, diagnostic certainty, age at onset and sex) and tested its effect on risk (odds for disease) and age at onset in the GR@ACE/DEGESCO study. FINDINGS:Using our meta-GWAS approach and follow-up analysis, we identified novel genome-wide significant associations of six genetic variants with AD risk (rs72835061-CHRNE, rs2154481-APP, rs876461-PRKD3/NDUFAF7, rs3935877-PLCG2 and two missense variants: rs34173062/rs34674752 in SHARPIN gene) and confirmed a stop codon mutation in the IL34 gene increasing the risk of AD (IL34-Tyr213Ter), and two other variants in PLCG2 and HS3ST1 regions. This brings the total number of genetic variants associated with AD to 39 (excluding APOE). The PRS based on these variants was associated with AD in an independent clinical ADcase control dataset (OR=1.30, per 1-SD increase in the PRS, 95%CI 1.18-1.44, p = 1.1×10 -7 ), a similar effect to that in the GR@ACE/DEGESCO (OR=1.27, 95%CI 1.23-1.32, p = 7.4×10 -39 ). We then explored the combined effects of these 39 variants in a PRS for AD risk and age-at-onset stratification in GR@ACE/DEGESCO. Excluding APOE, we observed a gradual risk increase over the 2% tiles; when comparing the extremes, those with the 2% highest risk had a 2.98-fold (95% CI 2.12-4.18, p = 3.2×10 -10 ) increased risk compared to those with the 2% lowest risk (p = 5.9×10 -10 ). Using the PRS we identified APOE ɛ33 carriers with a similar risk as APOE ɛ4 heterozygotes carriers, as well as APOE ɛ4 heterozygote carriers with a similar risk as APOE ɛ4 homozygote. Considering age at onset; there was a 9-year difference between median onset of AD the lowest risk group and the highest risk group (82 vs 73 years; p = 1.6×10 -6 ); a 4-year median onset diff...

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Alzheimer’s disease Phospholipase C-gamma-2 (PLCG2) protective variant is a functional hypermorph

Cited by 37 publications

References 41 publications

The Alzheimer’s disease protective P522R variant ofPLCG2, consistently enhances stimulus-dependent PLCγ2 activation, depleting substrate and altering cell function

The Alzheimer’s disease protective P522R variant ofPLCG2, consistently enhances stimulus-dependent PLCγ2 activation, depleting substrate and altering cell function

The Alzheimer’s disease-associated protectivePlcγ2-P522R variant promotes beneficial microglial functions

Common variants in Alzheimer’s disease: Novel association of six genetic variants with AD and risk stratification by polygenic risk scores

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