Overview

Pathogenicity: Alzheimer's Disease : Pathogenic
ACMG/AMP Pathogenicity Criteria: PS1, PS2, PS3, PM1, PM2, PP3
Clinical Phenotype: Alzheimer's Disease
Reference Assembly: GRCh37/hg19
Position: Chr14:73673092 A>G
dbSNP ID: NA
Coding/Non-Coding: Both
DNA Change: Substitution
Expected RNA Consequence: Splicing Alteration
Expected Protein Consequence: Deletion-Insertion
Genomic Region: Intron 8, Exon 9

Findings

This point mutation in intron 8 of PSEN1 is one of several mutations in this region that affect splicing. It occurs in a splice acceptor site, which results in the exclusion of exon 9 from transcripts, and is thus referred to as ΔE9 or Δ9. Due to the exclusion of exon 9, the predicted presenilin-1 protein lacks a stretch of about 30 amino acids.

The mutation was originally identified in a French patient with Alzheimer’s disease. The mutation is thought to have occurred de novo, as it was not present in the DNA of either parent (Rovelet-Lecrux et al., 2015).

The mutation was also identified in a German individual of European descent who presented with progressive aphasia, memory decline, and changes in interests and behavior at the age of 48 (Blauwendraat et al., 2016, Blauwendraat et al., 2017). The collection of symptoms was consistent with frontal-variant AD, and closely resembled behavioral variant frontotemporal dementia. Although segregation with disease could not be determined, this individual did have a positive family history, including a mother and sister with unspecified dementia, beginning at age 80 and 47, respectively.

This variant was absent from the gnomAD variant database (gnomAD v2.1.1, July 2021).

Neuropathology

Neuropathological data are unavailable, but MRI of the German patient showed supratentorial atrophy, particularly of parietal and occipital cortex (Blauwendraat et al., 2015). In addition, the levels of Aβ42 in cerebrospinal fluid were reduced.

Biological Effect

This point mutation abrogates a splice acceptor site in PSEN1, such that exon 9, which encodes residues 290-319, is excluded from mature transcripts. The skipping of exon 9 occurs in-frame, but introduces a missense mutation at the splice junction of exon 8 and exon 10, S290C. In silico, Mutation Taster, CADD, and DANN predict the point mutation to be disease-causing (Rovelet-Lecrux et al., 2015, Blauwendraat et al., 2017, Xiao et al., 2021).

The following summary refers to studies of PSEN1 mutants that result in the exclusion of exon 9 (denoted here as PSEN1ΔE9). PSEN1ΔE9 mutants appear to fail to undergo endoproteolytic processing in brains of transgenic mice (Lee et al., 1997), consistent with results in cultured mammalian cells (Thinakaran et al., 1996). Moreover, several cell-based studies indicate processing of APP is impaired. While some have reported decreased Aβ40 levels and increased Aβ42 levels (Dumanchin et al., 2006; Kumar-Singh et al., 2006), others have found no change in Aβ40 levels but increased Aβ42 levels (Steiner et al., 1999), or a decrease in both Aβ species (Bentahir et al., 2006). In an early study, the Aβ42(43):Aβ40 ratio was reported to be elevated in cell media, as well as in the brains of young transgenic animals co-expressing the mutant and APPswe (Borchelt et al., 1996).

Consistent with these findings, neurons derived from human iPSC lines carrying at least one copy of a PSEN1ΔE9 mutation produced less Aβ40 and had a greater Aβ42/Aβ40 ratio than controls expressing only wildtype PSEN1 (Woodruff et al., 2013). Moreover, mutant-carrying cells had significantly increased levels of the γ-secretase substrates APP α- and β-CTFs, suggesting impaired γ-secretase activity.

In vitro studies with isolated proteins also indicate an increase in the Aβ42/Aβ40 ratio, and decreases in Aβ40 and Aβ42 production (Cacquevel et al., 2012; Sun et al., 2017). A study monitoring the production of an array of Aβ peptides in mouse embryonic fibroblasts expressing a PSEN1ΔE9 mutant indicated that total secreted Aβ peptides, including Aβ38, Aβ40, Aβ42, and Aβ43, were substantially reduced compared with those of cells expressing wild-type PSEN1 (Chávez-Gutiérrez et al., 2012). Also, sizeable reductions in the Aβ38/Aβ42 and Aβ40/Aβ43 ratios were observed, both in cells and in vitro. Interestingly, the levels of the shorter peptides, Aβ40 and Aβ38, were particularly decreased, while those of longer peptides, greater than Aβ42, were increased. Other studies examining the levels of multiple Aβ peptides have reported similar findings (Svedružić et al., 2012; Kakuda et al., 2021). Chávez-Gutiérrez and colleagues proposed the mutant impairs the fourth γ-secretase cleavage in the two Aβ production lines that sequentially digest Aβ49 and Aβ48 into shorter peptides (Chávez-Gutiérrez et al., 2012).

Exon 9 deletion mutations may also affect PSEN1 transcription. In a bacterial artificial chromosome (BAC)-based expression model, PSEN1ΔE9-expressing cells exhibited reduced PSEN1 gene expression and partial loss of function relative to cells expressing wild-type PSEN1 (Ahmadi et al., 2014).

The absence of exon 9 may impair Notch processing as well. Although one study found no effect of the mutation on this substrate (Chávez-Gutiérrez et al., 2012), others have reported impaired Notch S3 cleavage and corresponding alterations in the differentiation and self-renewal of neural progenitor cells in the adult mouse brain (Bentahir et al., 2006; Veeraraghavalu et al., 2010; May 2010 news).

PSEN1ΔE9 mutations have also been implicated in the disruption of several intracellular functions. For example, by lowering PIP2 levels, PSEN1ΔE9 appears to block a cation channel that mediates capacitive calcium entry (Landman et al., 2006; Dec 2006 news). In addition, impairments in endocytosis, cholesterol homeostasis, autophagy, astrocytic response to inflammatory stimulation, mitochondrial function, calcium homeostasis, and APP intracellular localization have been reported (Woodruff et al., 2016; Oct 2016 news; Cho et al., 2019; Oh and Chung, 2017; Oksanen et al., 2019; Rojas-Charry et al., 2020). Also, alterations in tight and adherens junction protein expression, as well as in efflux properties, were found in iPSC-derived brain endothelial cells, a model of blood-brain barrier function (Oikari et al., 2020). 

Interestingly, PSEN1 was reported to play a key role in ApoE secretion and cytoplasmic localization. In experiments with PSEN-deficient fibroblasts, PSEN1ΔE9 transfection was less able to rescue these functions compared with transfection of wildtype PSEN1 (Islam et al., 2022).

Pathogenicity

Alzheimer's Disease : Pathogenic

This variant fulfilled the following criteria based on the ACMG/AMP guidelines. See a full list of the criteria in the Methods page.

Research Models

Multiple mouse models that express PSEN1 lacking exon 9 have been developed. One line, referred to as S-9 (Lee et al., 1997), was subsequently bred to an APP transgenic mouse to generate a double transgenic (APPSwe/PSEN1dE9), which has a more severe phenotype than either of the parental lines. Another double-transgenic model was made by co-injecting vectors expressing PSEN1ΔE9 and APP with the Swedish mutation (APPswe/PSEN1dE9). Although cotton-wool plaques are sometimes prominent in the brains of AD patients with ΔE9 mutations, this pathology has not been observed in ΔE9 mouse models. In addition, induced pluripotent stem cell lines derived from patients have been used to generate neurons (Woodruff et al., 2013), astrocytes (Oksanen et al., 2017), and brain endothelial cells (Oikari et al., 2020) which display several features of AD pathology.

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References

News Citations

1. Notch Your Average Joe—Grounds for PS1 Neurogenesis Inhibition? 21 May 2010
2. Beyond γ-Secretase: FAD Mutations Affect Calcium Channel via Lipid Messenger 8 Dec 2006
3. Cholesterol Trafficking Takes a Hit in Alzheimer’s Neurons 28 Oct 2016

Paper Citations

1. Lee MK, Borchelt DR, Kim G, Thinakaran G, Slunt HH, Ratovitski T, Martin LJ, Kittur A, Gandy S, Levey AI, Jenkins N, Copeland N, Price DL, Sisodia SS. Hyperaccumulation of FAD-linked presenilin 1 variants in vivo. Nat Med. 1997 Jul;3(7):756-60. PubMed.
2. Woodruff G, Reyna SM, Dunlap M, Van Der Kant R, Callender JA, Young JE, Roberts EA, Goldstein LS. Defective Transcytosis of APP and Lipoproteins in Human iPSC-Derived Neurons with Familial Alzheimer's Disease Mutations. Cell Rep. 2016 Oct 11;17(3):759-773. PubMed.
3. Oksanen M, Petersen AJ, Naumenko N, Puttonen K, Lehtonen Š, Gubert Olivé M, Shakirzyanova A, Leskelä S, Sarajärvi T, Viitanen M, Rinne JO, Hiltunen M, Haapasalo A, Giniatullin R, Tavi P, Zhang SC, Kanninen KM, Hämäläinen RH, Koistinaho J. PSEN1 Mutant iPSC-Derived Model Reveals Severe Astrocyte Pathology in Alzheimer's Disease. Stem Cell Reports. 2017 Dec 12;9(6):1885-1897. Epub 2017 Nov 16 PubMed.
4. Oikari LE, Pandit R, Stewart R, Cuní-López C, Quek H, Sutharsan R, Rantanen LM, Oksanen M, Lehtonen S, de Boer CM, Polo JM, Götz J, Koistinaho J, White AR. Altered Brain Endothelial Cell Phenotype from a Familial Alzheimer Mutation and Its Potential Implications for Amyloid Clearance and Drug Delivery. Stem Cell Reports. 2020 May 12;14(5):924-939. Epub 2020 Apr 9 PubMed.
5. Rovelet-Lecrux A, Charbonnier C, Wallon D, Nicolas G, Seaman MN, Pottier C, Breusegem SY, Mathur PP, Jenardhanan P, Le Guennec K, Mukadam AS, Quenez O, Coutant S, Rousseau S, Richard AC, Boland A, Deleuze JF, Frebourg T, Hannequin D, Campion D, CNR-MAJ collaborators. De novo deleterious genetic variations target a biological network centered on Aβ peptide in early-onset Alzheimer disease. Mol Psychiatry. 2015 Sep;20(9):1046-56. Epub 2015 Jul 21 PubMed.
6. Blauwendraat C, Wilke C, Jansen IE, Schulte C, Simón-Sánchez J, Metzger FG, Bender B, Gasser T, Maetzler W, Rizzu P, Heutink P, Synofzik M. Pilot whole-exome sequencing of a German early-onset Alzheimer's disease cohort reveals a substantial frequency of PSEN2 variants. Neurobiol Aging. 2016 Jan;37:208.e11-7. Epub 2015 Sep 30 PubMed.
7. Blauwendraat C, Wilke C, Simón-Sánchez J, Jansen IE, Reifschneider A, Capell A, Haass C, Castillo-Lizardo M, Biskup S, Maetzler W, Rizzu P, Heutink P, Synofzik M. The wide genetic landscape of clinical frontotemporal dementia: systematic combined sequencing of 121 consecutive subjects. Genet Med. 2017 Jul 27; PubMed.
8. Xiao X, Liu H, Liu X, Zhang W, Zhang S, Jiao B. APP, PSEN1, and PSEN2 Variants in Alzheimer's Disease: Systematic Re-evaluation According to ACMG Guidelines. Front Aging Neurosci. 2021;13:695808. Epub 2021 Jun 18 PubMed.
9. Thinakaran G, Borchelt DR, Lee MK, Slunt HH, Spitzer L, Kim G, Ratovitsky T, Davenport F, Nordstedt C, Seeger M, Hardy J, Levey AI, Gandy SE, Jenkins NA, Copeland NG, Price DL, Sisodia SS. Endoproteolysis of presenilin 1 and accumulation of processed derivatives in vivo. Neuron. 1996 Jul;17(1):181-90. PubMed.
10. Dumanchin C, Tournier I, Martin C, Didic M, Belliard S, Carlander B, Rouhart F, Duyckaerts C, Pellissier JF, Latouche JB, Hannequin D, Frebourg T, Tosi M, Campion D. Biological effects of four PSEN1 gene mutations causing Alzheimer disease with spastic paraparesis and cotton wool plaques. Hum Mutat. 2006 Oct;27(10):1063. PubMed.
11. Kumar-Singh S, Theuns J, Van Broeck B, Pirici D, Vennekens K, Corsmit E, Cruts M, Dermaut B, Wang R, Van Broeckhoven C. Mean age-of-onset of familial alzheimer disease caused by presenilin mutations correlates with both increased Abeta42 and decreased Abeta40. Hum Mutat. 2006 Jul;27(7):686-95. PubMed.
12. Steiner H, Romig H, Grim MG, Philipp U, Pesold B, Citron M, Baumeister R, Haass C. The biological and pathological function of the presenilin-1 Deltaexon 9 mutation is independent of its defect to undergo proteolytic processing. J Biol Chem. 1999 Mar 19;274(12):7615-8. PubMed.
13. Bentahir M, Nyabi O, Verhamme J, Tolia A, Horré K, Wiltfang J, Esselmann H, De Strooper B. Presenilin clinical mutations can affect gamma-secretase activity by different mechanisms. J Neurochem. 2006 Feb;96(3):732-42. PubMed.
14. Borchelt DR, Thinakaran G, Eckman CB, Lee MK, Davenport F, Ratovitsky T, Prada CM, Kim G, Seekins S, Yager D, Slunt HH, Wang R, Seeger M, Levey AI, Gandy SE, Copeland NG, Jenkins NA, Price DL, Younkin SG, Sisodia SS. Familial Alzheimer's disease-linked presenilin 1 variants elevate Abeta1-42/1-40 ratio in vitro and in vivo. Neuron. 1996 Nov;17(5):1005-13. PubMed.
15. Woodruff G, Young JE, Martinez FJ, Buen F, Gore A, Kinaga J, Li Z, Yuan SH, Zhang K, Goldstein LS. The presenilin-1 ΔE9 mutation results in reduced γ-secretase activity, but not total loss of PS1 function, in isogenic human stem cells. Cell Rep. 2013 Nov 27;5(4):974-85. Epub 2013 Nov 14 PubMed.
16. Cacquevel M, Aeschbach L, Houacine J, Fraering PC. Alzheimer's disease-linked mutations in presenilin-1 result in a drastic loss of activity in purified γ-secretase complexes. PLoS One. 2012;7(4):e35133. PubMed.
17. Sun L, Zhou R, Yang G, Shi Y. Analysis of 138 pathogenic mutations in presenilin-1 on the in vitro production of Aβ42 and Aβ40 peptides by γ-secretase. Proc Natl Acad Sci U S A. 2017 Jan 24;114(4):E476-E485. Epub 2016 Dec 5 PubMed.
18. Chávez-Gutiérrez L, Bammens L, Benilova I, Vandersteen A, Benurwar M, Borgers M, Lismont S, Zhou L, Van Cleynenbreugel S, Esselmann H, Wiltfang J, Serneels L, Karran E, Gijsen H, Schymkowitz J, Rousseau F, Broersen K, De Strooper B. The mechanism of γ-Secretase dysfunction in familial Alzheimer disease. EMBO J. 2012 May 16;31(10):2261-74. Epub 2012 Apr 13 PubMed.
19. Svedružić ZM, Popović K, Smoljan I, Sendula-Jengić V. Modulation of γ-secretase activity by multiple enzyme-substrate interactions: implications in pathogenesis of Alzheimer's disease. PLoS One. 2012;7(3):e32293. PubMed.
20. Kakuda N, Takami M, Okochi M, Kasuga K, Ihara Y, Ikeuchi T. Switched Aβ43 generation in familial Alzheimer's disease with presenilin 1 mutation. Transl Psychiatry. 2021 Nov 3;11(1):558. PubMed.
21. Ahmadi S, Wade-Martins R. Familial Alzheimer's disease coding mutations reduce Presenilin-1 expression in a novel genomic locus reporter model. Neurobiol Aging. 2014 Feb;35(2):443.e5-443.e16. PubMed.
22. Veeraraghavalu K, Choi SH, Zhang X, Sisodia SS. Presenilin 1 mutants impair the self-renewal and differentiation of adult murine subventricular zone-neuronal progenitors via cell-autonomous mechanisms involving notch signaling. J Neurosci. 2010 May 19;30(20):6903-15. PubMed.
23. Landman N, Jeong SY, Shin SY, Voronov SV, Serban G, Kang MS, Park MK, Di Paolo G, Chung S, Kim TW. Presenilin mutations linked to familial Alzheimer's disease cause an imbalance in phosphatidylinositol 4,5-bisphosphate metabolism. Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19524-9. PubMed.
24. Cho YY, Kwon OH, Park MK, Kim TW, Chung S. Elevated cellular cholesterol in Familial Alzheimer's presenilin 1 mutation is associated with lipid raft localization of β-amyloid precursor protein. PLoS One. 2019;14(1):e0210535. Epub 2019 Jan 25 PubMed.
25. Oh HG, Chung S. Activation of transient receptor potential melastatin 7 (TRPM7) channel increases basal autophagy and reduces amyloid β-peptide. Biochem Biophys Res Commun. 2017 Nov 4;493(1):494-499. Epub 2017 Sep 1 PubMed.
26. Oksanen M, Hyötyläinen I, Trontti K, Rolova T, Wojciechowski S, Koskuvi M, Viitanen M, Levonen AL, Hovatta I, Roybon L, Lehtonen Š, Kanninen KM, Hämäläinen RH, Koistinaho J. NF-E2-related factor 2 activation boosts antioxidant defenses and ameliorates inflammatory and amyloid properties in human Presenilin-1 mutated Alzheimer's disease astrocytes. Glia. 2020 Mar;68(3):589-599. Epub 2019 Oct 31 PubMed.
27. Rojas-Charry L, Calero-Martinez S, Morganti C, Morciano G, Park K, Hagel C, Marciniak SJ, Glatzel M, Pinton P, Sepulveda-Falla D. Susceptibility to cellular stress in PS1 mutant N2a cells is associated with mitochondrial defects and altered calcium homeostasis. Sci Rep. 2020 Apr 15;10(1):6455. PubMed.
28. Islam S, Sun Y, Gao Y, Nakamura T, Noorani AA, Li T, Wong PC, Kimura N, Matsubara E, Kasuga K, Ikeuchi T, Tomita T, Zou K, Michikawa M. Presenilin Is Essential for ApoE Secretion, a Novel Role of Presenilin Involved in Alzheimer's Disease Pathogenesis. J Neurosci. 2022 Feb 23;42(8):1574-1586. Epub 2022 Jan 5 PubMed.

Other Citations

1. APPSwe/PSEN1dE9

External Citations

1. gnomAD v2.1.1

Further Reading

No Available Further Reading