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Cited by 146Alzheimer's disease research and treatmentsNeuroinflammation and Neurodegeneration MechanismsDementia and Cognitive Impairment Research

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

Open access
Magno, Lorenza, Lessard, Christian B., Martins, Marta, Lang, Verena, Cruz, Pedro, Asi, Yasmine, Katan, Matilda, Bilsland, Jamie +4 more·2019·Alzheimer's Research & Therapy
DOI 10.1186/s13195-019-0469-0PMC PMC6359863

Published version of a preprint

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Abstract

BACKGROUND: Recent Genome Wide Association Studies (GWAS) have identified novel rare coding variants in immune genes associated with late onset Alzheimer's disease (LOAD). Amongst these, a polymorphism in phospholipase C-gamma 2 (PLCG2) P522R has been reported to be protective against LOAD. PLC enzymes are key elements in signal transmission networks and are potentially druggable targets. PLCG2 is highly expressed in the hematopoietic system. Hypermorphic mutations in PLCG2 in humans have been reported to cause autoinflammation and immune disorders, suggesting a key role for this enzyme in the regulation of immune cell function. METHODS: We assessed PLCG2 distribution in human and mouse brain tissue via immunohistochemistry and in situ hybridization. We transfected heterologous cell systems (COS7 and HEK293T cells) to determine the effect of the P522R AD-associated variant on enzymatic function using various orthogonal assays, including a radioactive assay, IP-One ELISA, and calcium assays. RESULTS: PLCG2 expression is restricted primarily to microglia and granule cells of the dentate gyrus. Plcg2 mRNA is maintained in plaque-associated microglia in the cerebral tissue of an AD mouse model. Functional analysis of the p.P522R variant demonstrated a small hypermorphic effect of the mutation on enzyme function. CONCLUSIONS: The PLCG2 P522R variant is protective against AD. We show that PLCG2 is expressed in brain microglia, and the p.P522R polymorphism weakly increases enzyme function. These data suggest that activation of PLCγ2 and not inhibition could be therapeutically beneficial in AD. PLCγ2 is therefore a potential target for modulating microglia function in AD, and a small molecule drug that weakly activates PLCγ2 may be one potential therapeutic approach.

AI snapshot

Written from the paper’s full text.

TL;DR

PLCG2 is expressed primarily in brain microglia and dentate gyrus granule cells, and its mRNA is maintained in plaque-associated microglia in an AD mouse model. The AD-protective PLCG2 P522R variant acts as a weak functional hypermorph in cell-based assays, suggesting that PLCγ2 activation rather than inhibition may be therapeutically beneficial.

Key findings

  • PLCG2 expression was primarily restricted to microglia and granule cells of the dentate gyrus; in cortical gray and white matter, all IBA1-immunoreactive microglia cell bodies contained Plcg2 transcripts (100%), with only occasional co-expression with astrocyte (5.8 ± 3.8%), endothelial (9.6 ± 1.44%), and oligodendrocyte-lineage (1.6 ± 2.2%) markers.
  • Plcg2 mRNA was maintained in microglia surrounding plaques in 6-month-old TgAPPswe/ind mice, similar to non-transgenic littermates, and Plcg2 co-localized with Trem2 transcripts in cortical and hippocampal microglia.
  • The AD-associated P522R variant showed a small hypermorphic effect: in a radioactive assay, PLC activity after EGF stimulation increased 1.24 ± 0.06 fold over WT, compared with 2.27 ± 0.43 fold for the Ali5 D993G mutation.
  • IP-One ELISA showed higher IP1 production for P522R than WT PLCγ2, and calcium flux assays showed a small but clear increase in intracellular Ca2+ release for P522R versus WT, with no significant difference in extracellular Ca2+ entry.

Methods

  • Human post-mortem frontal cortex and mouse brain tissue (WT C57BL6 and TgCRND8/TgAPPswe/ind mice) were assessed by immunohistochemistry and RNAScope in situ hybridization; RNAScope reactions were quantified using CellProfiler.
  • COS7 and HEK293T cells were transfected with PLCG2 constructs (common/WT, P522R, and D993G Ali5) and analyzed with orthogonal functional assays: radioactive inositol phosphate formation, IP-One ELISA, and Fura-2 calcium flux, with Western blotting for expression.
  • Statistical analysis used Prism 6, with one-way ANOVA plus Tukey’s multiple comparison test and two-way ANOVA with Bonferroni multiple comparisons.

Limitations

  • The paper states a technical limitation: mRNA and protein co-expression could not be confirmed in the same cells, and antibody technical difficulties occurred (one antibody no longer commercially available; others gave unspecific or no signal on fixed human post-mortem brain or mouse tissue).
  • The paper states that nuclear staining used to identify cell boundaries does not allow assessment of transcript quantification in processes.
  • Evident from the text: functional characterization was performed in heterologous cell systems (COS7 and HEK293T cells), not in microglia; the molecular mechanism of the P522R hypermorphic effect is unknown, and further experiments are needed to address functional consequences on immune cell phenotype.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1186/s13195-019-0469-0

Cites

52 of 52 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

27 of 41 cited sources checked · 17 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    PLCG2 variants/hypermorphic mutations cause inherited immune disorders (PLAID and APLAID) with autoinflammation and immune dysregulation.

    “Hypermorphic mutations in PLCG2 in humans have been reported to cause autoinflammation and immune disorders, suggesting a key role for this enzyme in the regulation of immune cell function.”
    • Also stated in: § Background · plain
      “PLCG2 variants cause inherited immune disorders designated as PLAID (PLCG2-associated antibody deficiency and immune dysregulation [12] and APLAID (autoinflammatory PLAID [13]).”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [12] Ombrello MJ, Remmers EF, Sun G, Freeman AF, Datta S, Torabi-Parizi P, et al. Cold Urticaria, immunodeficiency, and autoimmunity related to PLCG2 deletions. N Engl J Med. 2012;366:330–8. https://doi.org/10.1056/NEJMoa1102140 . source
    • cites [13] Zhou Q, Lee GS, Brady J, Datta S, Katan M, Sheikh A, et al. A hypermorphic missense mutation in PLCG2, encoding phospholipase Cγ2, causes a dominantly inherited autoinflammatory disease with immunodeficiency. Am J Hum Genet. 2012;91:713–20. https://doi.org/10.1016/j.ajhg.2012.08.006 . source
  • Premisecitation

    The PLCG2 P522R variant is associated with decreased risk of late-onset Alzheimer's disease (protective against LOAD).

    “Amongst these, a polymorphism in phospholipase C-gamma 2 (PLCG2) P522R has been reported to be protective against LOAD.”
    • Also stated in: § Background · plain
      “Notably, the PLCG2 missense variant Pro522Arg (P = 5.38 × 10−10, OR = 0.68) was associated with decreased risk of LOAD [6].”
    • Also stated in: § Conclusions · plain
      “The PLCG2 P522R variant is protective against AD.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [6] Sims R, Van Der Lee SJ, Naj AC, Bellenguez C, Badarinarayan N, Jakobsdottir J, et al. Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer’s disease. Nat Genet. 2017;49:1373–84. source
  • Interpretationcitation

    Apparent PLCG2 transcript upregulation in bulk cortical tissue is mostly related to microgliosis occurring as a consequence of neurodegeneration.

    “However, normalization to microglia-specific genes (e.g., Abi3) and data from single-cell profiling of brain immune cells [6, 36, 37], suggest that apparent PLCG2 transcript upregulation in bulk tissue is mostly related to microgliosis occurring as a consequence of neurodegeneration.”
    Quote in the paperSubstantial claim3 of 3 sources checked
    • cites [6] Sims R, Van Der Lee SJ, Naj AC, Bellenguez C, Badarinarayan N, Jakobsdottir J, et al. Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer’s disease. Nat Genet. 2017;49:1373–84. source

      The Gene Expression section reports that PLCG2 expression is higher in AD temporal cortex before adjustment for cell-type markers, but not after, and attributes the apparent elevation most likely to microgliosis. It does not establish that the microgliosis is a consequence of neurodegeneration; the paper separately argues that the microglial response in Alzheimer’s disease is not simply a downstream consequence of neurodegeneration. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [36] Keren-Shaul H, Spinrad A, Weiner A, Matcovitch-Natan O, Dvir-Szternfeld R, Ulland TK, et al. A unique microglia type associated with restricting development of Alzheimer’s disease. Cell. 2017;169:1276–1290.e17. https://doi.org/10.1016/j.cell.2017.05.018 . source
    • cites [37] Mathys H, Adaikkan C, Gao F, Young JZ, Manet E, Hemberg M, et al. Temporal tracking of microglia activation in neurodegeneration at single-cell resolution. Cell Rep. 2017;21:366–80. https://doi.org/10.1016/j.celrep.2017.09.039 . source

      The Results section on microglial proliferation reports increased microglial density in the hippocampus of neurodegenerating CK-p25 mice. The Discussion also says that increased immune-related transcripts in tissue could reflect either changes in microglial expression or expansion of the microglial population, and finds evidence for both. Our copy does not establish that bulk-tissue PLCG2 upregulation is mostly due to microgliosis; searches for PLCG2 and Abi3 found no passage addressing that specific inference. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
  • Premisecitation

    Other mutations in PLCG2 that lead to immune dysfunction are known to be activating.

    “Other mutations in PLCG2 that lead to immune dysfunction are known to be activating [7].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [7] Koss H, Bunney TD, Behjati S, Katan M. Dysfunction of phospholipase Cγ in immune disorders and cancer. Trends Biochem Sci. 2014;39:603–11. https://doi.org/10.1016/j.tibs.2014.09.004 . source
  • Premisecitation

    The protective variant P522R is located within a region of the enzyme that has a regulatory function.

    “The protective variant P522R is certainly located within a region of the enzyme that has a regulatory function (Fig. 4d, [7])”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [7] Koss H, Bunney TD, Behjati S, Katan M. Dysfunction of phospholipase Cγ in immune disorders and cancer. Trends Biochem Sci. 2014;39:603–11. https://doi.org/10.1016/j.tibs.2014.09.004 . source

      Box 1 (p. 17) describes the PLCγ-specific array as involved in interactions with regulatory proteins, and the Figures (p. 16) describe regulatory interactions involving its domains. Our copy does not mention P522R or locate that variant within the array, so it supports the region’s regulatory role but not the claimed location of P522R. (LLM, conf=0.78)

      Experimental — accuracy not yet measured
  • Classified as probably not a substantial claim. 25
  • May combine two claims. 9

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    PLCG2 mRNA upregulation has been reported in cortical tissue of LOAD patients (FC 1.35; p = 0.0028).

    “PLCG2 mRNA upregulation has been reported in cortical tissue of LOAD patients (FC, 1.35; p = 0.0028, [33])”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [33] Allen M, Carrasquillo MM, Funk C, Heavner BD, Zou F, Younkin CS, et al. Human whole genome genotype and transcriptome data for Alzheimer’s and other neurodegenerative diseases. Sci Data. 2016;3:160089. https://doi.org/10.1038/sdata.2016.89 . source

      The Methods (Study Populations and Molecular Data; page unavailable) describe transcriptome measurements from temporal cortex samples of AD and non-AD subjects. Searches for PLCG2, the reported fold change of 1.35, and p = 0.0028 found no passage reporting the claimed upregulation in our copy. (LLM, conf=0.74)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim.

    Premisecitation

    In osteoclasts, activation downstream of Trem2 initiates a cascade including phosphorylation and activation of PLCγ2.

    “In osteoclasts, activation downstream Trem2 initiates a cascade of events, including phosphorylation and activation of PLCγ2, amongst other proteins [17].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [17] Peng Q, Malhotra S, Torchia JA, Kerr WG, Coggeshall KM, Humphrey MB. TREM2- and DAP12-dependent activation of PI3K requires DAP10 and is inhibited by SHIP1. Sci Signal. 2010;3:1–16. source

  • May combine two claims.

    Premisecitation

    PLCγ2 belongs to the same interaction network as TREM2 and may be directly involved in TREM2 signaling.

    “PLCγ2 belongs to the same interaction network as TREM2 [6] and may be directly involved in its signaling pathway [15, 16].”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites [6] Sims R, Van Der Lee SJ, Naj AC, Bellenguez C, Badarinarayan N, Jakobsdottir J, et al. Rare coding variants in PLCG2, ABI3, and TREM2 implicate microglial-mediated innate immunity in Alzheimer’s disease. Nat Genet. 2017;49:1373–84. source
    • cites [15] Ford JW, McVicar DW. TREM and TREM-like receptors in inflammation and disease. Curr Opin Immunol. 2009;21:38–46. source

      The citation to this paper is attached to the suggestion that PLCγ2 may be involved in TREM2 signaling; the interaction-network statement has a separate citation. The TREM Signaling section describes TREM2 signaling through DAP12 and NTAL/LAB, but does not mention PLCγ2. Searches for “PLCγ2” and “phospholipase C gamma 2” found no passage connecting it to TREM2. (LLM, conf=0.73)

      Experimental — accuracy not yet measured
    • cites [16] Xing J, Titus AR, Humphrey MB. The TREM2-DAP12 signaling pathway in Nasu–Hakola disease: a molecular genetics perspective. Res Rep Biochem. 2015;5:89–100.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Recent findings point to microglia heterogeneity in neurodegeneration.

    “Recent findings point to microglia heterogeneity in neurodegeneration [36, 38].”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [36] Keren-Shaul H, Spinrad A, Weiner A, Matcovitch-Natan O, Dvir-Szternfeld R, Ulland TK, et al. A unique microglia type associated with restricting development of Alzheimer’s disease. Cell. 2017;169:1276–1290.e17. https://doi.org/10.1016/j.cell.2017.05.018 . source
    • cites [38] Krasemann S, Madore C, Cialic R, Baufeld C, Calcagno N, El Fatimy R, et al. The TREM2-APOE pathway drives the transcriptional phenotype of dysfunctional microglia in neurodegenerative diseases. Immunity. 2017;47:566–581.e9. https://doi.org/10.1016/j.immuni.2017.08.008 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    PLCγ2 is predominantly expressed in the hematopoietic system, including bone marrow and lymphoid organs.

    “PLCG2 is highly expressed in the hematopoietic system.”
    • Also stated in: § Background · plain
      “PLCγ2 is predominantly expressed in the bone marrow and lymphoid organs (Human Protein Atlas available from www.proteinatlas.org [11])”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [11] Mao D, Epple H, Uthgenannt B, Novack DV, Faccio R. PLCγ2 regulates osteoclastogenesis via its interaction with ITAM proteins and GAB2. J Clin Invest. 2006;116:2869–79. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    PLCγ2 shares high structural and mechanistic overlap with PLCγ1.

    “PLCγ2 shares high structural and mechanistic overlap with the other member of the PLCγ family, PLCγ1 [7].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [7] Koss H, Bunney TD, Behjati S, Katan M. Dysfunction of phospholipase Cγ in immune disorders and cancer. Trends Biochem Sci. 2014;39:603–11. https://doi.org/10.1016/j.tibs.2014.09.004 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    TREM2 is a transmembrane receptor expressed on myeloid cells and an important susceptibility gene for AD.

    “TREM2 is a transmembrane receptor expressed on the membrane of myeloid cells and an important susceptibility gene for AD [5].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [5] Guerreiro R, Wojtas A, Bras J, Carrasquillo M, Rogaeva E, Majounie E, et al. TREM2 variants in Alzheimer’s disease. N Engl J Med. 2013;368:117–27. https://doi.org/10.1056/NEJMoa1211851 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    PLCG2 mRNA upregulation has been reported in transgenic mice carrying early-AD mutations or overexpressing human tau.

    “and in transgenic mice carrying mutations associated with early AD (APP KM670/671 NL, PNSEN1 M146V) or overexpressing the human tau-4R/2N isoform (P301L) [34, 35].”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites [34] Castillo E, Leon J, Mazzei G, Abolhassani N, Haruyama N, Saito T, et al. Comparative profiling of cortical gene expression in Alzheimer’s disease patients and mouse models demonstrates a link between amyloidosis and neuroinflammation. Sci Rep. 2017;7:17762. https://doi.org/10.1038/s41598-017-17999-3 . source

      The Results report significantly increased Plcg2 expression in the cortex of App NL-G-F/NL-G-F mice carrying pathogenic App mutations. But this is an App knock-in model, not the APP/PSEN1/MAPT transgenic model described in the citing sentence. For that 3xTg-AD-H model, the Results report only Trem2—not Plcg2—as significantly increased. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [35] Matarin M, Salih DA, Yasvoina M, Cummings DM, Guelfi S, Liu W, et al. A genome-wide gene-expression analysis and database in transgenic mice during development of amyloid or tau pathology. Cell Rep. 2015;10:633–45. https://doi.org/10.1016/j.celrep.2014.12.041 . source

      The Introduction (p. 2) identifies the APP, PSEN1, and tau P301L mouse lines, and the Genome-wide Expression Analysis (p. 3) reports gene-expression changes in these models. However, searches for PLCG2 upregulation and phospholipase C gamma 2 found no passage in our copy reporting that gene's expression, so the specific claim cannot be verified. (LLM, conf=0.72)

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationcitation

    Microglia activation of Plcg2 might regulate intracellular calcium release, as shown for B cells, and contribute to modulation of specific immune responses such as phagocytosis, migration, proliferation, and survival.

    “In the brain, microglia activation of Plcg2 might regulate intracellular calcium release, as shown for B cells [12, 45], and contribute to the modulation of specific immune responses such as phagocytosis, migration, proliferation, and survival.”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites [12] Ombrello MJ, Remmers EF, Sun G, Freeman AF, Datta S, Torabi-Parizi P, et al. Cold Urticaria, immunodeficiency, and autoimmunity related to PLCG2 deletions. N Engl J Med. 2012;366:330–8. https://doi.org/10.1056/NEJMoa1102140 . source
    • cites [45] Hashimoto A, Takeda K, Inaba M, Sekimata M, Kaisho T, Ikehara S, et al. Cutting edge: essential role of phospholipase C-2 in B cell development and function. J Immunol. 2000;165:1738–42. https://doi.org/10.4049/jimmunol.165.4.1738 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Human induced pluripotent stem cell microglia-like cells harboring mutations in TREM2 show distinct defects in phagocytosis.

    “Indeed, human induced pluripotent stem cell microglia-like cells harboring mutations in TREM2 show distinct defects in phagocytosis [47].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [47] Garcia-Reitboeck P, Phillips A, Piers TM, Villegas-Llerena C, Butler M, Mallach A, et al. Human induced pluripotent stem cell-derived microglia-like cells harboring TREM2 missense mutations show specific deficits in phagocytosis. Cell Rep. 2018;24:2300–11. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    Trem2 might be one receptor acting upstream of Plcg2 and evoking such responses in innate immune cells.

    “One receptor acting upstream of Plcg2 and evoking such responses in innate immune cells might be Trem2 [17, 46].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [17] Peng Q, Malhotra S, Torchia JA, Kerr WG, Coggeshall KM, Humphrey MB. TREM2- and DAP12-dependent activation of PI3K requires DAP10 and is inhibited by SHIP1. Sci Signal. 2010;3:1–16. source
    • cites [46] Ulland TK, Colonna M. TREM2—a key player in microglial biology and Alzheimer disease. Nat Rev Neurol. 2018;14:667–75. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    Plcg2 in granule cells may be relevant for synaptic transmission and plasticity via induction of hippocampal long-term potentiation (LTP).

    “By analogy with Plcg1 function in neurons, Plcg2 in granule cells may be relevant for synaptic transmission and plasticity via induction of hippocampal long-term potentiation LTP [10, 44].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [10] Yang YR, Jung JH, Kim S-J, Hamada K, Suzuki A, Kim HJ, et al. Forebrain-specific ablation of phospholipase Cγ1 causes manic-like behavior. Mol Psychiatry. 2017;22:1473–82. https://doi.org/10.1038/mp.2016.261 . source
    • cites [44] Horn KE, Glasgow SD, Gobert D, Bull SJ, Luk T, Girgis J, et al. DCC expression by neurons regulates synaptic plasticity in the adult brain. Cell Rep. 2013;3:173–85. source

      The section “DCC Regulates Src, Phospholipase C γ, and Phosphorylated Src Family Kinase Expression” (p. 7) reports reduced PLCγ1 activation in DCC-deficient hippocampi, and “Src Is Essential for LTP Induction” (p. 10) links PLC signaling to LTP. These passages support the Plcg1 analogy, but the paper does not establish a role for Plcg2 in granule cells or show that it induces LTP. (LLM, conf=0.83)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Increased levels of Trem2 have been detected in disease-associated microglia compared to microglia in a homeostatic state.

    “Moreover, increased levels of Trem2 have been detected in disease-associated microglia compared to microglia in a homeostatic state (37).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [37] Mathys H, Adaikkan C, Gao F, Young JZ, Manet E, Hemberg M, et al. Temporal tracking of microglia activation in neurodegeneration at single-cell resolution. Cell Rep. 2017;21:366–80. https://doi.org/10.1016/j.celrep.2017.09.039 . source

      The Discussion section, “Two Distinct Reactive Microglia Phenotypes in Neurodegeneration” (page unavailable), describes a Trem2-dependent transition to a disease-associated microglia stage and lists genes upregulated in those cells, but does not list Trem2 among them. A search for Trem2 found no passage comparing its levels in disease-associated and homeostatic microglia. (LLM, conf=0.76)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Mutations in TREM2 have been associated with increased risk of AD.

    “Mutations in TREM2 have been associated with increased risk of AD [5, 18].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [5] Guerreiro R, Wojtas A, Bras J, Carrasquillo M, Rogaeva E, Majounie E, et al. TREM2 variants in Alzheimer’s disease. N Engl J Med. 2013;368:117–27. https://doi.org/10.1056/NEJMoa1211851 . source
    • cites [18] Colonna M, Wang Y. TREM2 variants: new keys to decipher Alzheimer disease pathogenesis. Nat Rev Neurosci. 2016;17:201–7. https://doi.org/10.1038/nrn.2016.7 . source

  • May combine two claims.

    Findingown data

    In mouse brain, Plcg2 transcripts are primarily restricted to microglia cells, with pronounced expression in granule cells of the hippocampal dentate gyrus.

    “PLCG2 expression is restricted primarily to microglia and granule cells of the dentate gyrus.”
    • Also stated in: § PLCG2 is expressed in microglia cells throughout the brain · plain
      “In summary, Plcg2 transcripts are primarily restricted to microglia cells across the mouse brain, with the exception of the pronounced expression seen in granule cells in the dentate gyrus.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Plcg2 was detected in the granule cell layer of the dentate gyrus.

    “Another interesting finding is the detection of Plcg2 in the granule cell layer of the dentate gyrus.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    TREM2 pathways are potentially involved in neurodegenerative processes.

    “In microglia, these pathways promote several cellular responses including survival, proliferation, phagocytosis, enhanced secretion of cytokines, and chemokines [18] and are potentially involved in neurodegenerative processes.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18] Colonna M, Wang Y. TREM2 variants: new keys to decipher Alzheimer disease pathogenesis. Nat Rev Neurosci. 2016;17:201–7. https://doi.org/10.1038/nrn.2016.7 . source

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    A small molecule drug that weakly activates PLCγ2 may be one potential therapeutic approach.

    “a small molecule drug that weakly activates PLCγ2 may be one potential therapeutic approach.”
    • Also stated in: § Background · hedged
      “a small molecule drug that activates PLCγ2 may be one potential therapeutic approach.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In microglia, TREM2 pathways promote survival, proliferation, phagocytosis, and enhanced secretion of cytokines and chemokines.

    “In microglia, these pathways promote several cellular responses including survival, proliferation, phagocytosis, enhanced secretion of cytokines, and chemokines [18] and are potentially involved in neurodegenerative processes.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [18] Colonna M, Wang Y. TREM2 variants: new keys to decipher Alzheimer disease pathogenesis. Nat Rev Neurosci. 2016;17:201–7. https://doi.org/10.1038/nrn.2016.7 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In peripheral immune cells, PLCγ2 is implicated in signaling downstream of the B cell receptor and is thought to modulate macrophages, platelets, mast cells, neutrophils, and NK cells through the Fc receptor.

    “In peripheral immune cells, PLCγ2 has been implicated in signaling pathways downstream of the B cell receptor, and it is thought to modulate the functions of macrophages, platelets, mast cells, neutrophils, and NK cells through the Fc receptor [14].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Wang D, Feng J, Wen R, Marine J-C, Sangster MY, Parganas E, et al. Phospholipase Cγ2 is essential in the functions of B cell and several Fc receptors. Immunity. 2000;13:25–35. https://doi.org/10.1016/S1074-7613(00)00005-4 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    PLCG1 is ubiquitously distributed, and its mutations are associated with some cancers and neuropsychiatric disorders.

    “PLCG1 is ubiquitously distributed, and mutations are associated with some forms of cancers, such as cutaneous T cell lymphoma [8, 9], but also neuropsychiatric disorders [10].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [8] Bunney TD, Katan M. Phosphoinositide signalling in cancer: beyond PI3K and PTEN. Nat Rev Cancer. 2010;10:342–52. https://doi.org/10.1038/nrc2842 . source
    • cites [9] Vaqué JP, Gómez-López G, Monsálvez V, Varela I, Martínez N, Pérez C, et al. PLCG1 mutations in cutaneous T-cell lymphomas. Blood. 2014;123:2034–43. https://doi.org/10.1182/blood-2013-05-504308 . source
    • cites [10] Yang YR, Jung JH, Kim S-J, Hamada K, Suzuki A, Kim HJ, et al. Forebrain-specific ablation of phospholipase Cγ1 causes manic-like behavior. Mol Psychiatry. 2017;22:1473–82. https://doi.org/10.1038/mp.2016.261 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    Plcg2 expression might be important for mnemonic functions.

    “Given the involvement of the dentate gyrus in pattern separation—distinction of closely related memories—Plcg2 expression might be important for mnemonic functions.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationown data

    Apparent co-localization of Plcg2 and Trem2 transcripts in microglia processes suggests a possible requirement of local translation for quick responses to environmental changes, and a mechanism to detect neural tissue damage.

    “We found apparent co-localization of Plcg2 and Trem2 transcripts in microglia processes, which suggests a possible requirement of local translation for quick responses to environmental changes, and a mechanism to detect neural tissue damage.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The data are representative for 3 independent experiments.

    “The data are representative for 3 independent experiments.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    Expression of WT, p.P522R variant, and EGFR was confirmed.

    “We confirmed expression of the WT, the p.P522R variant, and EGFR (Fig. 4b, Additional file 3).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Plcg2 is expressed in certain subtypes of endothelial cells, although at lower level than in microglia.

    “According to a transcriptomic analysis of cells in the vasculature, Plcg2 seems to be expressed in certain subtypes of endothelial cells, although at lower level than compared to microglia (http://betsholtzlab.org/VascularSingleCells/database.html [43]).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [43] Vanlandewijck M, He L, Mäe MA, Andrae J, Ando K, Del Gaudio F, et al. A molecular atlas of cell types and zonation in the brain vasculature. Nature. 2018;554:475–80. https://doi.org/10.1038/nature25739 . source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The study could not confirm mRNA and protein co-expression in the same cells.

    “One technical limitation of this study is that we could not confirm mRNA and protein co-expression in the same cells.”
    Quote in the paperNot a substantial claim
27 of 27

  • The paper relies on this without support.

    The effect of the P522R polymorphism on PLCγ2 enzyme function is unknown.

    “The P522R polymorphism lies within the regulatory domain of PLCγ2, but its effect on enzyme function is unknown.”

  • The paper relies on this without support.

    PLCγ2 spatial expression in resident brain immune cells and in AD is unexplored.

    “PLCγ2 spatial expression in resident brain immune cells and in AD is unexplored.”

  • The paper relies on this without support.

    Single-cell transcriptomics of human and mouse cortex suggest enrichment of PLCG2 transcripts in the microglia population.

    “Although single-cell transcriptomics of the human and mouse cortex suggest enrichment of PLCG2 transcripts in the microglia population”

  • The paper relies on this without support.

    No spatial analysis of PLCG2 in human and mouse tissue has been described so far.

    “no spatial analysis has been described for human and mouse tissue so far.”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The P522R variant moderately increases store-operated calcium entry (SOCE) in HEK293T cells.

    “In addition, depletion of intracellular calcium stores activates a calcium flux across the plasma membrane, referred to as store‐operated calcium entry (SOCE), which is also moderately increased by the P522R variant in HEK293T cells. 10”

    From The P522R protective variant of PLCG2 promotes the expression of antigen presentation genes by human microglia in an Alzheimer's disease mouse model (2022) · cites this paper as [10]

    The Results section distinguishes a small increase in intracellular Ca2+ release from store-operated Ca2+ entry. It reports no significant difference in extracellular Ca2+ entry between HEK293T cells expressing wild-type PLCγ2 and those expressing P522R. Page numbers are not provided in our copy. (LLM, conf=0.93)

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured

  • PLCG2 is exclusively expressed in microglia within the central nervous system.

    “PLCG2 is exclusively expressed in microglia within the central nervous system”

    From Heterozygous expression of the Alzheimer’s disease-protective PLCγ2 P522R variant enhances Aβ clearance while preserving synapses (2022) · cites this paper as [11]

    The Results section ('PLCG2 is expressed in microglia cells throughout the brain'; page not provided) says Plcg2 transcripts are primarily, not exclusively, restricted to microglia in the mouse brain. It reports pronounced expression in dentate gyrus granule cells and occasional co-expression with other cell markers. (LLM, conf=0.90)

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured

  • PLCG2P522R modulates phagocytosis, inflammatory responses, lipid profiles, and mitochondrial function in myeloid cells.

    “Several studies have examined the role of PLCG2P522R in myeloid cells and reported that this variant modulates phagocytosis, inflammatory responses, lipid profiles, and mitochondrial function. 11 , 19 , 24 , 25 , 26 , 27 , 28 , 29 , 30”

    From Alzheimer's disease–associated PLCG2 variants alter microglial state and function in human induced pluripotent stem cell–derived microglia‐like cells (2025) · cites this paper as [11]

    The Results show that P522R weakly increases PLCγ2 enzyme activity, and the Discussion proposes that PLCγ2 activity in microglia might influence phagocytosis and immune responses. The paper does not establish that P522R modulates those myeloid-cell responses, and it does not report effects on lipid profiles or mitochondrial function. Page numbers are unavailable in our copy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • In vitro studies have demonstrated that the P522R variant induces a slight increase in cytosolic calcium, both basally and upon stimulation, indicating mild hypermorphic activity.

    “In vitro studies have demonstrated that the P522R variant induces a slight increase in cytosolic calcium, both basally and upon stimulation, indicating mild hypermorphic activity. 10 , 11 , 12”

    From The P522R protective variant of PLCG2 promotes the expression of antigen presentation genes by human microglia in an Alzheimer's disease mouse model (2022) · cites this paper as [10]

    The Results section reports a small increase in intracellular Ca2+ release for P522R versus wild-type PLCγ2 after EGF stimulation, and the Discussion describes a small hypermorphic effect. Figure 4’s caption mentions basal and stimulated PLC activity, but our copy does not report an increase in basal cytosolic calcium. (LLM, conf=0.86)

    Experimental — accuracy not yet measured

  • The P522R mutation is hypermorphic, indicating an enhancement of immune cell functions.

    “The P522R mutation has been shown to be hypermorphic, indicating an enhancement of immune cell functions [12].”

    From Alzheimer’s disease-associated protective variant Plcg2-P522R modulates peripheral macrophage function in a sex-dimorphic manner (2024) · cites this paper as [12]

    The Results report that P522R modestly increases PLCγ2 enzyme activity, supporting its description as hypermorphic. The Conclusion says further experiments are needed to determine its effects on immune cell phenotype, so enhanced immune cell functions have not been established. (LLM, conf=0.90)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • COS7 assay names conflicting PLCG2 constructs

    Minor

    The results describe the COS7 radioactive assay as using pTriEx4-PLCG2, but the caption for that assay says the cells received pEGFPC1-PLCG2 constructs.

  • Regulatory-domain claim cites the wrong Figure 4 panel

    Minor

    The discussion cites Figure 4d for P522R's location in a regulatory region, but the caption identifies panel d as a calcium assay and panel e as the domain diagram showing mutation locations.

  • Figure 4 caption names a different protective variant

    Minor

    The Figure 4 heading calls the protective variant p.P552R, whereas the figure's own panel descriptions and the results identify it as P522R.

3 of 3

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Authors
Magno, L., Lessard, C. B., Martins, M., Lang, V., Cruz, P., Asi, Y., Katan, M., Bilsland, J., Lashley, T., Chakrabarty, P., Golde, T. E., & Whiting, P. J.
Affiliations
  • Alzheimer’s Research UK (GB)
  • University of Florida Health (US)
  • Instituto de Medicina Molecular João Lobo Antunes
  • National Hospital for Neurology and Neurosurgery (GB)
  • University College London (GB)
Corresponding author
  • Magno, Lorenza
  • Whiting, Paul J.
ORCID
Venue
Alzheimer's Research & Therapy
Publisher
Springer Science and Business Media LLC
Published
2019-02-02
Volume
11
Issue
1
Pages
16-16
ISSN
1758-9193 (ISSN-L)
DOI
10.1186/s13195-019-0469-0
PMC
PMC6359863
OpenAlex
W2892300592
Semantic Scholar
e664a981934b5b9e7429e48c2bc75211c87a6a26
Cited by
143
References
52
Citations by year
2026: 10 · 2025: 14 · 2024: 13 · 2023: 14 · 2022: 33 · 2021: 21 · 2020: 29 · 2019: 7 · 2018: 2
FWCI
12.96
Type
journal article
Language
en
Open access
Licence
Locations
  • Alzheimer s Research & Therapy (publishedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (submittedVersion, other-oa)
  • PubMed Central (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • UCL Discovery (University College London) (submittedVersion)
  • Portuguese National Funding Agency for Science, Research and Technology (RCAAP Project by FCT) (submittedVersion, other-oa)
Funders
  • National Institutes of Health (U01 AG046139, R01 AG018454, P50 AG047266)
  • Florida Department of Health (8AZ16)
  • Alzheimer's Research UK
Topics
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
Keywords
Alzheimer's disease, PLCγ2, late-onset Alzheimer's disease, microglia, granule cells, dentate gyrus, enzyme activation, rare coding variants, autoinflammation, therapeutic target, AD mouse model
MeSH terms
Alzheimer Disease, Animals, Female, Frontal Lobe, Humans, Male, Mice, Inbred C3H, Mice, Inbred C57BL, Mice, Transgenic, Genetic Variation, Mice, Phospholipase C gamma, HEK293 Cells

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-18.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-18.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

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