Searching the whole genome for variants that associate with soluble TREM2 in human cerebrospinal fluid, researchers have turned up single-nucleotide polymorphisms near genes for the membrane-spanning 4-domains subfamily A, which had been linked previously to late-onset AD.
Two common SNPs in the MS4A gene cluster stood out. An intergenic variant that lowers AD risk and delays symptom onset promotes expression of MS4A4A and MS4A6A. This variant associates with higher CSF sTREM2. In keeping with the theme, a missense mutation in the MS4A4A gene seems to do the opposite. It increases disease risk and accelerates onset, while reducing sTREM2. Detailed in a paper posted on June 20 to the bioRχiv preprint server, the analysis suggests that MS4A family members regulate processing of the microglial receptor.
“These findings also provide a mechanistic explanation of the original GWAS signal in the MS4A locus for AD risk and indicate that TREM2 is involved in sporadic AD risk in general, not only in TREM2 risk-variant carriers,” wrote the scientists, who were led by Celeste Karch, Laura Piccio, and Carlos Cruchaga, all from Washington University, St. Louis.
Prior GWAS indicated that variants in MS4A4E and MS4A6A increased and decreased, respectively, AD risk by about 10 percent (Hollingworth et al., 2011; Naj et al., 2011). The roughly 16 members of the MS4A transmembrane family are thought to have a function in lipid sensing on membranes and to regulate protein trafficking in microglia; however, a mechanistic explanation for their AD association had not been established.
Joint first authors Yuetiva Deming, Fabia Filipello, and Francesca Cignarella set out to identify genetic modifiers of CSF sTREM2, which ticks higher in early AD and correlates with CSF tau and phospho-tau (Mar 2016 news). Researchers believe levels of this soluble fragment of the microglial receptor reflect activation of the cells.
Deming and colleagues ran a genome-wide association analysis of sTREM2 levels among 813 people in the Alzheimer’s Disease Neuroimaging Initiative. People with TREM2 variants that predispose to AD were excluded. From more than 7.3 million common SNPs, a positive signal shot up in chromosome 11q12, the site of the MS4A cluster. Lying near MS4A4A, the intergenic SNP rs1582763 emerged as most significant. It associated with higher sTREM2, accounting for more than 6 percent of the sTREM2 variance. The association held among 606 AD cases and 207 normal controls. Previous GWAS had indicated this SNP reduced AD risk and delayed disease onset (Lambert et al., 2013; Huang et al., 2017).
Controlling for this association, Deming and colleagues reanalyzed the data to discover that another polymorphism, rs659156, independently associated with sTREM2, but this time with lower levels of the fragment. This SNP switches a valine for a methionine at position 159 of the MS4A4A protein and associates with increased risk for AD and with accelerated onset. The authors replicated both associations with an additional 580 CSF samples from six different sources: the Knight ADRC center at WashU; the DIAN cohort; two studies from the University of Gothenburg; one from Saint Pau Hospital, Barcelona; and one at the Clinic Institute of Neurosciences, Hospital Clinic of Barcelona.
Together, the findings suggest these SNPs modulate expression of MS4A family members and, by extension, processing of TREM2. In line with this, Deming and colleagues found that rs1582763 correlated with expression of MS4A6A in the blood, and to a lesser extent expression of MS4A4A and MS4A2. The rs659156 missense variant correlated with MS4A4A and MS4A6A in the blood. Further, in 103 brain samples from the Knight ADRC center and 19 samples from DIAN, expression of the MS4A family members 6A, 4A, and 7 correlated with expression of TREM2. In autopsy-confirmed late-onset AD samples and controls, the correlation between TREM2 expression and MS4A4A/MS4A6A was particularly strong.
Drilling deeper, the authors found that MS4A4A co-localized with TREM2 in the cytoplasm of human macrophages, mainly near the nucleus and less so on the plasma membrane. Two antibodies against MS4A4A suppressed interleukin-4-induced release of sTREM2 into the cell medium, supporting the idea that MS4A4A, a transmembrane protein, promotes TREM2 processing. One antibody to MS4A6A had no effect in this assay, but the authors noted that they can’t yet rule out the possibility that it may also be involved.
The authors believe MS4A4A could eventually become a therapeutic target, but caution that more work will be needed to understand how this protein affects sTREM2. Little is known about MSA4A proteins in the brain. A previous study by Robert Datta at Harvard Medical School on the MS4A protein family in the mammalian olfactory system identified them as seven-transmembrane G-protein-coupled receptors (GPCRs) that responded to fatty acid ligands (Greer et al., 2016).
As of July 6, the manuscript pdf has been viewed on bioRχiv 109 times, the abstract 444 times.—Tom Fagan
- Hollingworth P, Harold D, Sims R, Gerrish A, Lambert JC, Carrasquillo MM, Abraham R, Hamshere ML, Pahwa JS, Moskvina V, Dowzell K, Jones N, Stretton A, Thomas C, Richards A, Ivanov D, Widdowson C, Chapman J, Lovestone S, Powell J, Proitsi P, Lupton MK, Brayne C, Rubinsztein DC, Gill M, Lawlor B, Lynch A, Brown KS, Passmore PA, Craig D, McGuinness B, Todd S, Holmes C, Mann D, Smith AD, Beaumont H, Warden D, Wilcock G, Love S, Kehoe PG, Hooper NM, Vardy ER, Hardy J, Mead S, Fox NC, Rossor M, Collinge J, Maier W, Jessen F, Rüther E, Schürmann B, Heun R, Kölsch H, van den Bussche H, Heuser I, Kornhuber J, Wiltfang J, Dichgans M, Frölich L, Hampel H, Gallacher J, Hüll M, Rujescu D, Giegling I, Goate AM, Kauwe JS, Cruchaga C, Nowotny P, Morris JC, Mayo K, Sleegers K, Bettens K, Engelborghs S, De Deyn PP, Van Broeckhoven C, Livingston G, Bass NJ, Gurling H, McQuillin A, Gwilliam R, Deloukas P, Al-Chalabi A, Shaw CE, Tsolaki M, Singleton AB, Guerreiro R, Mühleisen TW, Nöthen MM, Moebus S, Jöckel KH, Klopp N, Wichmann HE, Pankratz VS, Sando SB, Aasly JO, Barcikowska M, Wszolek ZK, Dickson DW, Graff-Radford NR, Petersen RC, , van Duijn CM, Breteler MM, Ikram MA, DeStefano AL, Fitzpatrick AL, Lopez O, Launer LJ, Seshadri S, Berr C, Campion D, Epelbaum J, Dartigues JF, Tzourio C, Alpérovitch A, Lathrop M, Feulner TM, Friedrich P, Riehle C, Krawczak M, Schreiber S, Mayhaus M, Nicolhaus S, Wagenpfeil S, Steinberg S, Stefansson H, Stefansson K, Snædal J, Björnsson S, Jonsson PV, Chouraki V, Genier-Boley B, Hiltunen M, Soininen H, Combarros O, Zelenika D, Delepine M, Bullido MJ, Pasquier F, Mateo I, Frank-Garcia A, Porcellini E, Hanon O, Coto E, Alvarez V, Bosco P, Siciliano G, Mancuso M, Panza F, Solfrizzi V, Nacmias B, Sorbi S, Bossù P, Piccardi P, Arosio B, Annoni G, Seripa D, Pilotto A, Scarpini E, Galimberti D, Brice A, Hannequin D, Licastro F, Jones L, Holmans PA, Jonsson T, Riemenschneider M, Morgan K, Younkin SG, Owen MJ, O'Donovan M, Amouyel P, Williams J. Common variants at ABCA7, MS4A6A/MS4A4E, EPHA1, CD33 and CD2AP are associated with Alzheimer's disease. Nat Genet. 2011 May;43(5):429-35. PubMed.
- Naj AC, Jun G, Beecham GW, Wang LS, Vardarajan BN, Buros J, Gallins PJ, Buxbaum JD, Jarvik GP, Crane PK, Larson EB, Bird TD, Boeve BF, Graff-Radford NR, De Jager PL, Evans D, Schneider JA, Carrasquillo MM, Ertekin-Taner N, Younkin SG, Cruchaga C, Kauwe JS, Nowotny P, Kramer P, Hardy J, Huentelman MJ, Myers AJ, Barmada MM, Demirci FY, Baldwin CT, Green RC, Rogaeva E, St George-Hyslop P, Arnold SE, Barber R, Beach T, Bigio EH, Bowen JD, Boxer A, Burke JR, Cairns NJ, Carlson CS, Carney RM, Carroll SL, Chui HC, Clark DG, Corneveaux J, Cotman CW, Cummings JL, DeCarli C, DeKosky ST, Diaz-Arrastia R, Dick M, Dickson DW, Ellis WG, Faber KM, Fallon KB, Farlow MR, Ferris S, Frosch MP, Galasko DR, Ganguli M, Gearing M, Geschwind DH, Ghetti B, Gilbert JR, Gilman S, Giordani B, Glass JD, Growdon JH, Hamilton RL, Harrell LE, Head E, Honig LS, Hulette CM, Hyman BT, Jicha GA, Jin LW, Johnson N, Karlawish J, Karydas A, Kaye JA, Kim R, Koo EH, Kowall NW, Lah JJ, Levey AI, Lieberman AP, Lopez OL, Mack WJ, Marson DC, Martiniuk F, Mash DC, Masliah E, McCormick WC, McCurry SM, McDavid AN, McKee AC, Mesulam M, Miller BL, Miller CA, Miller JW, Parisi JE, Perl DP, Peskind E, Petersen RC, Poon WW, Quinn JF, Rajbhandary RA, Raskind M, Reisberg B, Ringman JM, Roberson ED, Rosenberg RN, Sano M, Schneider LS, Seeley W, Shelanski ML, Slifer MA, Smith CD, Sonnen JA, Spina S, Stern RA, Tanzi RE, Trojanowski JQ, Troncoso JC, Van Deerlin VM, Vinters HV, Vonsattel JP, Weintraub S, Welsh-Bohmer KA, Williamson J, Woltjer RL, Cantwell LB, Dombroski BA, Beekly D, Lunetta KL, Martin ER, Kamboh MI, Saykin AJ, Reiman EM, Bennett DA, Morris JC, Montine TJ, Goate AM, Blacker D, Tsuang DW, Hakonarson H, Kukull WA, Foroud TM, Haines JL, Mayeux R, Pericak-Vance MA, Farrer LA, Schellenberg GD. Common variants at MS4A4/MS4A6E, CD2AP, CD33 and EPHA1 are associated with late-onset Alzheimer's disease. Nat Genet. 2011 May;43(5):436-41. Epub 2011 Apr 3 PubMed.
- Lambert JC, Ibrahim-Verbaas CA, Harold D, Naj AC, Sims R, Bellenguez C, DeStafano AL, Bis JC, Beecham GW, Grenier-Boley B, Russo G, Thorton-Wells TA, Jones N, Smith AV, Chouraki V, Thomas C, Ikram MA, Zelenika D, Vardarajan BN, Kamatani Y, Lin CF, Gerrish A, Schmidt H, Kunkle B, Dunstan ML, Ruiz A, Bihoreau MT, Choi SH, Reitz C, Pasquier F, Cruchaga C, Craig D, Amin N, Berr C, Lopez OL, De Jager PL, Deramecourt V, Johnston JA, Evans D, Lovestone S, Letenneur L, Morón FJ, Rubinsztein DC, Eiriksdottir G, Sleegers K, Goate AM, Fiévet N, Huentelman MW, Gill M, Brown K, Kamboh MI, Keller L, Barberger-Gateau P, McGuiness B, Larson EB, Green R, Myers AJ, Dufouil C, Todd S, Wallon D, Love S, Rogaeva E, Gallacher J, St George-Hyslop P, Clarimon J, Lleo A, Bayer A, Tsuang DW, Yu L, Tsolaki M, Bossù P, Spalletta G, Proitsi P, Collinge J, Sorbi S, Sanchez-Garcia F, Fox NC, Hardy J, Deniz Naranjo MC, Bosco P, Clarke R, Brayne C, Galimberti D, Mancuso M, Matthews F, European Alzheimer's Disease Initiative (EADI), Genetic and Environmental Risk in Alzheimer's Disease, Alzheimer's Disease Genetic Consortium, Cohorts for Heart and Aging Research in Genomic Epidemiology, Moebus S, Mecocci P, Del Zompo M, Maier W, Hampel H, Pilotto A, Bullido M, Panza F, Caffarra P, Nacmias B, Gilbert JR, Mayhaus M, Lannefelt L, Hakonarson H, Pichler S, Carrasquillo MM, Ingelsson M, Beekly D, Alvarez V, Zou F, Valladares O, Younkin SG, Coto E, Hamilton-Nelson KL, Gu W, Razquin C, Pastor P, Mateo I, Owen MJ, Faber KM, Jonsson PV, Combarros O, O'Donovan MC, Cantwell LB, Soininen H, Blacker D, Mead S, Mosley TH Jr, Bennett DA, Harris TB, Fratiglioni L, Holmes C, de Bruijn RF, Passmore P, Montine TJ, Bettens K, Rotter JI, Brice A, Morgan K, Foroud TM, Kukull WA, Hannequin D, Powell JF, Nalls MA, Ritchie K, Lunetta KL, Kauwe JS, Boerwinkle E, Riemenschneider M, Boada M, Hiltuenen M, Martin ER, Schmidt R, Rujescu D, Wang LS, Dartigues JF, Mayeux R, Tzourio C, Hofman A, Nöthen MM, Graff C, Psaty BM, Jones L, Haines JL, Holmans PA, Lathrop M, Pericak-Vance MA, Launer LJ, Farrer LA, van Duijn CM, Van Broeckhoven C, Moskvina V, Seshadri S, Williams J, Schellenberg GD, Amouyel P, Wang J, Uitterlinden AG, Rivadeneira F, Koudstgaal PJ, Longstreth WT Jr, Becker JT, Kuller LH, Lumley T, Rice K, Garcia M, Aspelund T, Marksteiner JJ, Dal-Bianco P, Töglhofer AM, Freudenberger P, Ransmayr G, Benke T, Toeglhofer AM, Bressler J, Breteler MM, Fornage M, Hernández I, Rosende Roca M, Ana Mauleón M, Alegrat M, Ramírez-Lorca R, González-Perez A, Chapman J, Stretton A, Morgan A, Kehoe PG, Medway C, Lord J, Turton J, Hooper NM, Vardy E, Warren JD, Schott JM, Uphill J, Ryan N, Rossor M, Ben-Shlomo Y, Makrina D, Gkatzima O, Lupton M, Koutroumani M, Avramidou D, Germanou A, Jessen F, Riedel-Heller S, Dichgans M, Heun R, Kölsch H, Schürmann B, Herold C, Lacour A, Drichel D, Hoffman P, Kornhuber J, Gu W, Feulner T, van den Bussche H, Lawlor B, Lynch A, Mann D, Smith AD, Warden D, Wilcock G, Heuser I, Wiltgang J, Frölich L, Hüll M, Mayo K, Livingston G, Bass NJ, Gurling H, McQuillin A, Gwilliam R, Deloukas P, Al-Chalabi A, Shaw CE, Singleton AB, Guerreiro R, Jöckel KH, Klopp N, Wichmann HE, Dickson DW, Graff-Radford NR, Ma L, Bisceglio G, Fisher E, Warner N, Pickering-Brown S. Meta-analysis of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease. Nat Genet. 2013 Dec;45(12):1452-8. Epub 2013 Oct 27 PubMed.
- Huang KL, Marcora E, Pimenova AA, Di Narzo AF, Kapoor M, Jin SC, Harari O, Bertelsen S, Fairfax BP, Czajkowski J, Chouraki V, Grenier-Boley B, Bellenguez C, Deming Y, McKenzie A, Raj T, Renton AE, Budde J, Smith A, Fitzpatrick A, Bis JC, DeStefano A, Adams HH, Ikram MA, van der Lee S, Del-Aguila JL, Fernandez MV, Ibañez L, International Genomics of Alzheimer's Project, Alzheimer's Disease Neuroimaging Initiative, Sims R, Escott-Price V, Mayeux R, Haines JL, Farrer LA, Pericak-Vance MA, Lambert JC, van Duijn C, Launer L, Seshadri S, Williams J, Amouyel P, Schellenberg GD, Zhang B, Borecki I, Kauwe JS, Cruchaga C, Hao K, Goate AM. A common haplotype lowers PU.1 expression in myeloid cells and delays onset of Alzheimer's disease. Nat Neurosci. 2017 Aug;20(8):1052-1061. Epub 2017 Jun 19 PubMed.
- Greer PL, Bear DM, Lassance JM, Bloom ML, Tsukahara T, Pashkovski SL, Masuda FK, Nowlan AC, Kirchner R, Hoekstra HE, Datta SR. A Family of non-GPCR Chemosensors Defines an Alternative Logic for Mammalian Olfaction. Cell. 2016 Jun 16;165(7):1734-1748. Epub 2016 May 26 PubMed.
No Available Further Reading
- Deming Y, Filipello F, Cignarella F, Cantoni C, Hsu S, Mikesell R, Li Z, Del-Aguila JL, Dube U, Fabiana Geraldo Farias FG, Bradley J, Benitez B, Budde J, Ibanez L, Fernandez MV, Alzheimer’s Disease Neuroimaging Initiative (ADNI), Dominantly Inherited Alzheimer Network (DIAN), Blennow K, Zetterberg H, Heslegrave A, Johansson PM, Svensson J, Nellgård B, Lleo A, Alcolea D, Clarimon J, Rami L, Molinuevo JL, Suarez-Calvet M, Morenas-Rodríguez E, Kleinberger G, Ewers M, Harari O, Christian Haass C, Brett TJ, Karch CM, Piccio L, Cruchaga C. The MS4A gene cluster is a key regulator of soluble TREM2 and Alzheimer disease risk. bioRχiv. June 20, 2018