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• W2912165492 abstract "•Genetic manipulation of the spliceosome enhances Tau neurotoxicity in flies•Mutation of the core spliceosome factor, SmB, causes progressive neurodegeneration•The Tau and SmB transcriptomes share similar profiles of RNA-splicing errors•Alzheimer’s disease Tau pathology associates with cryptic splicing errors in human brains In Alzheimer’s disease (AD), spliceosomal proteins with critical roles in RNA processing aberrantly aggregate and mislocalize to Tau neurofibrillary tangles. We test the hypothesis that Tau-spliceosome interactions disrupt pre-mRNA splicing in AD. In human postmortem brain with AD pathology, Tau coimmunoprecipitates with spliceosomal components. In Drosophila, pan-neuronal Tau expression triggers reductions in multiple core and U1-specific spliceosomal proteins, and genetic disruption of these factors, including SmB, U1-70K, and U1A, enhances Tau-mediated neurodegeneration. We further show that loss of function in SmB, encoding a core spliceosomal protein, causes decreased survival, progressive locomotor impairment, and neuronal loss, independent of Tau toxicity. Lastly, RNA sequencing reveals a similar profile of mRNA splicing errors in SmB mutant and Tau transgenic flies, including intron retention and non-annotated cryptic splice junctions. In human brains, we confirm cryptic splicing errors in association with neurofibrillary tangle burden. Our results implicate spliceosome disruption and the resulting transcriptome perturbation in Tau-mediated neurodegeneration in AD. In Alzheimer’s disease (AD), spliceosomal proteins with critical roles in RNA processing aberrantly aggregate and mislocalize to Tau neurofibrillary tangles. We test the hypothesis that Tau-spliceosome interactions disrupt pre-mRNA splicing in AD. In human postmortem brain with AD pathology, Tau coimmunoprecipitates with spliceosomal components. In Drosophila, pan-neuronal Tau expression triggers reductions in multiple core and U1-specific spliceosomal proteins, and genetic disruption of these factors, including SmB, U1-70K, and U1A, enhances Tau-mediated neurodegeneration. We further show that loss of function in SmB, encoding a core spliceosomal protein, causes decreased survival, progressive locomotor impairment, and neuronal loss, independent of Tau toxicity. Lastly, RNA sequencing reveals a similar profile of mRNA splicing errors in SmB mutant and Tau transgenic flies, including intron retention and non-annotated cryptic splice junctions. In human brains, we confirm cryptic splicing errors in association with neurofibrillary tangle burden. Our results implicate spliceosome disruption and the resulting transcriptome perturbation in Tau-mediated neurodegeneration in AD. In eukaryotes, precursor mRNA (pre-mRNA) splicing removes introns and generates mature mRNA transcripts, subserving a critical role in the regulation of gene expression. Splicing contributes to neuronal transcriptional diversity and function, and disruption of splicing mechanisms causes neurologic disease (Cooper et al., 2009Cooper T.A. Wan L. Dreyfuss G. RNA and disease.Cell. 2009; 136: 777-793Abstract Full Text Full Text PDF PubMed Scopus (775) Google Scholar, Tollervey et al., 2011Tollervey J.R. Wang Z. Hortobágyi T. Witten J.T. Zarnack K. Kayikci M. Clark T.A. Schweitzer A.C. Rot G. Curk T. et al.Analysis of alternative splicing associated with aging and neurodegeneration in the human brain.Genome Res. 2011; 21: 1572-1582Crossref PubMed Scopus (125) Google Scholar). For example, spinal muscular atrophy is caused by mutations in the survival motor neuron (SMN) gene, which initiates assembly of the spliceosome, the molecular machine responsible for pre-mRNA splicing (Lefebvre et al., 1995Lefebvre S. Bürglen L. Reboullet S. Clermont O. Burlet P. Viollet L. Benichou B. Cruaud C. Millasseau P. Zeviani M. et al.Identification and characterization of a spinal muscular atrophy-determining gene.Cell. 1995; 80: 155-165Abstract Full Text PDF PubMed Google Scholar, Lorson et al., 1999Lorson C.L. Hahnen E. Androphy E.J. Wirth B. A single nucleotide in the SMN gene regulates splicing and is responsible for spinal muscular atrophy.Proc. Natl. Acad. Sci. USA. 1999; 96: 6307-6311Crossref PubMed Scopus (989) Google Scholar). Mutation of other RNA-binding proteins implicated in splicing, including the TAR DNA-binding protein 43 (TDP-43) and fused in sarcoma (FUS), are associated with frontotemporal dementia and amyotrophic lateral sclerosis (FTD-ALS) (Neumann et al., 2006Neumann M. Sampathu D.M. Kwong L.K. Truax A.C. Micsenyi M.C. Chou T.T. Bruce J. Schuck T. Grossman M. Clark C.M. et al.Ubiquitinated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis.Science. 2006; 314: 130-133Crossref PubMed Scopus (3686) Google Scholar, Sreedharan et al., 2008Sreedharan J. Blair I.P. Tripathi V.B. Hu X. Vance C. Rogelj B. Ackerley S. Durnall J.C. Williams K.L. Buratti E. et al.TDP-43 mutations in familial and sporadic amyotrophic lateral sclerosis.Science. 2008; 319: 1668-1672Crossref PubMed Scopus (1688) Google Scholar, Vance et al., 2009Vance C. Rogelj B. Hortobágyi T. De Vos K.J. Nishimura A.L. Sreedharan J. Hu X. Smith B. Ruddy D. Wright P. et al.Mutations in FUS, an RNA processing protein, cause familial amyotrophic lateral sclerosis type 6.Science. 2009; 323: 1208-1211Crossref PubMed Scopus (1662) Google Scholar). In experimental mouse models, loss of function in spliceosomal components is also associated with neurodegenerative phenotypes (Jia et al., 2012Jia Y. Mu J.C. Ackerman S.L. Mutation of a U2 snRNA gene causes global disruption of alternative splicing and neurodegeneration.Cell. 2012; 148: 296-308Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar, Ling et al., 2015Ling J.P. Pletnikova O. Troncoso J.C. Wong P.C. TDP-43 repression of nonconserved cryptic exons is compromised in ALS-FTD.Science. 2015; 349: 650-655Crossref PubMed Scopus (152) Google Scholar, Polymenidou et al., 2011Polymenidou M. Lagier-Tourenne C. Hutt K.R. Huelga S.C. Moran J. Liang T.Y. Ling S.-C. Sun E. Wancewicz E. Mazur C. et al.Long pre-mRNA depletion and RNA missplicing contribute to neuronal vulnerability from loss of TDP-43.Nat. Neurosci. 2011; 14: 459-468Crossref PubMed Scopus (683) Google Scholar, Tan et al., 2016Tan Q. Yalamanchili H.K. Park J. De Maio A. Lu H.-C. Wan Y.-W. White J.J. Bondar V.V. Sayegh L.S. Liu X. et al.Extensive cryptic splicing upon loss of RBM17 and TDP43 in neurodegeneration models.Hum. Mol. Genet. 2016; 25: 5083-5093PubMed Google Scholar, Zhang et al., 2008Zhang Z. Lotti F. Dittmar K. Younis I. Wan L. Kasim M. Dreyfuss G. SMN deficiency causes tissue-specific perturbations in the repertoire of snRNAs and widespread defects in splicing.Cell. 2008; 133: 585-600Abstract Full Text Full Text PDF PubMed Scopus (422) Google Scholar). The major spliceosome is composed of five small nuclear ribonucleoprotein particle (snRNP) complexes (U1, U2, U4, U5, and U6), each including a small nuclear RNA (snRNA), seven Sm proteins (or Lsm proteins in U6), and specific factors, such as U1-70K, U1A, and U1C for the U1 snRNP (Will and Lührmann, 2011Will C.L. Lührmann R. Spliceosome structure and function.Cold Spring Harb. Perspect. Biol. 2011; 3: a003707Crossref PubMed Scopus (725) Google Scholar). Assembly begins with the formation of the core snRNA-Sm protein complex in the cytoplasm, followed by nuclear import and subsequent incorporation of specific proteins to generate the mature snRNP. Pre-mRNA splicing is initiated by recognition of 5′ splice sites by the U1 snRNP, followed by dynamic interactions with other snRNP complexes. Disruption of spliceosomal factors, either in cell culture or mouse genetic models, induces widespread mRNA splicing errors, including intron retention and cryptic junctions—consisting of non-conserved, non-annotated splice junctions (Humphrey et al., 2017Humphrey J. Emmett W. Fratta P. Isaacs A.M. Plagnol V. Quantitative analysis of cryptic splicing associated with TDP-43 depletion.BMC Med. Genomics. 2017; 10: 38Crossref PubMed Scopus (15) Google Scholar, Jia et al., 2012Jia Y. Mu J.C. Ackerman S.L. Mutation of a U2 snRNA gene causes global disruption of alternative splicing and neurodegeneration.Cell. 2012; 148: 296-308Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar, Kaida et al., 2010Kaida D. Berg M.G. Younis I. Kasim M. Singh L.N. Wan L. Dreyfuss G. U1 snRNP protects pre-mRNAs from premature cleavage and polyadenylation.Nature. 2010; 468: 664-668Crossref PubMed Scopus (354) Google Scholar, Ling et al., 2015Ling J.P. Pletnikova O. Troncoso J.C. Wong P.C. TDP-43 repression of nonconserved cryptic exons is compromised in ALS-FTD.Science. 2015; 349: 650-655Crossref PubMed Scopus (152) Google Scholar, Polymenidou et al., 2011Polymenidou M. Lagier-Tourenne C. Hutt K.R. Huelga S.C. Moran J. Liang T.Y. Ling S.-C. Sun E. Wancewicz E. Mazur C. et al.Long pre-mRNA depletion and RNA missplicing contribute to neuronal vulnerability from loss of TDP-43.Nat. Neurosci. 2011; 14: 459-468Crossref PubMed Scopus (683) Google Scholar, Tan et al., 2016Tan Q. Yalamanchili H.K. Park J. De Maio A. Lu H.-C. Wan Y.-W. White J.J. Bondar V.V. Sayegh L.S. Liu X. et al.Extensive cryptic splicing upon loss of RBM17 and TDP43 in neurodegeneration models.Hum. Mol. Genet. 2016; 25: 5083-5093PubMed Google Scholar, Zhang et al., 2008Zhang Z. Lotti F. Dittmar K. Younis I. Wan L. Kasim M. Dreyfuss G. SMN deficiency causes tissue-specific perturbations in the repertoire of snRNAs and widespread defects in splicing.Cell. 2008; 133: 585-600Abstract Full Text Full Text PDF PubMed Scopus (422) Google Scholar). Cryptic splicing has also been documented in human postmortem brain from individuals with TDP-43 mutations (Ling et al., 2015Ling J.P. Pletnikova O. Troncoso J.C. Wong P.C. TDP-43 repression of nonconserved cryptic exons is compromised in ALS-FTD.Science. 2015; 349: 650-655Crossref PubMed Scopus (152) Google Scholar). Emerging evidence suggests that disrupted assembly of RNA-binding protein complexes, such as the spliceosome, may promote FTD-ALS pathogenesis (Ito et al., 2017Ito D. Hatano M. Suzuki N. RNA binding proteins and the pathological cascade in ALS/FTD neurodegeneration.Sci. Transl. Med. 2017; 9: eaah5436Crossref PubMed Scopus (14) Google Scholar, Lee et al., 2016aLee K.-H. Zhang P. Kim H.J. Mitrea D.M. Sarkar M. Freibaum B.D. Cika J. Coughlin M. Messing J. Molliex A. et al.C9orf72 Dipeptide Repeats Impair the Assembly, Dynamics, and Function of Membrane-Less Organelles.Cell. 2016; 167: 774-788.e17Abstract Full Text Full Text PDF PubMed Scopus (273) Google Scholar, Yin et al., 2017Yin S. Lopez-Gonzalez R. Kunz R.C. Gangopadhyay J. Borufka C. Gygi S.P. Gao F.-B. Reed R. Evidence that C9ORF72 Dipeptide Repeat Proteins Associate with U2 snRNP to Cause Mis-splicing in ALS/FTD Patients.Cell Rep. 2017; 19: 2244-2256Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar). Tau protein, encoded by the microtubule associated protein tau (MAPT) gene, aggregates to form neurofibrillary tangles, characteristic of Alzheimer’s disease (AD) and other tauopathies. Neurofibrillary tangle pathologic burden is strongly correlated with cognitive decline in AD (Arriagada et al., 1992Arriagada P.V. Growdon J.H. Hedley-Whyte E.T. Hyman B.T. Neurofibrillary tangles but not senile plaques parallel duration and severity of Alzheimer’s disease.Neurology. 1992; 42: 631-639Crossref PubMed Google Scholar, Braak and Braak, 1991Braak H. Braak E. Neuropathological stageing of Alzheimer-related changes.Acta Neuropathol. 1991; 82: 239-259Crossref PubMed Google Scholar, Gómez-Isla et al., 1997Gómez-Isla T. Hollister R. West H. Mui S. Growdon J.H. Petersen R.C. Parisi J.E. Hyman B.T. Neuronal loss correlates with but exceeds neurofibrillary tangles in Alzheimer’s disease.Ann. Neurol. 1997; 41: 17-24Crossref PubMed Scopus (993) Google Scholar), and soluble, oligomeric forms of Tau are also implicated in synaptic dysfunction and neuronal death (Cowan and Mudher, 2013Cowan C.M. Mudher A. Are tau aggregates toxic or protective in tauopathies?.Front. Neurol. 2013; 4: 114Crossref PubMed Scopus (89) Google Scholar, Spires-Jones and Hyman, 2014Spires-Jones T.L. Hyman B.T. The intersection of amyloid beta and tau at synapses in Alzheimer’s disease.Neuron. 2014; 82: 756-771Abstract Full Text Full Text PDF PubMed Scopus (433) Google Scholar). In human AD postmortem brain tissue, multiple core and specific components of the U1 snRNP co-aggregate with Tau in neurofibrillary tangles (Bai et al., 2013Bai B. Hales C.M. Chen P.-C. Gozal Y. Dammer E.B. Fritz J.J. Wang X. Xia Q. Duong D.M. Street C. et al.U1 small nuclear ribonucleoprotein complex and RNA splicing alterations in Alzheimer’s disease.Proc. Natl. Acad. Sci. USA. 2013; 110: 16562-16567Crossref PubMed Scopus (140) Google Scholar, Hales et al., 2014Hales C.M. Dammer E.B. Diner I. Yi H. Seyfried N.T. Gearing M. Glass J.D. Montine T.J. Levey A.I. Lah J.J. Aggregates of small nuclear ribonucleic acids (snRNAs) in Alzheimer’s disease.Brain Pathol. 2014; 24: 344-351Crossref PubMed Scopus (0) Google Scholar), and similar findings have been reported in MAPT transgenic mice (Maziuk et al., 2018Maziuk B.F. Apicco D.J. Cruz A.L. Jiang L. Ash P.E.A. da Rocha E.L. Zhang C. Yu W.H. Leszyk J. Abisambra J.F. et al.RNA binding proteins co-localize with small tau inclusions in tauopathy.Acta Neuropathol. Commun. 2018; 6: 71Crossref PubMed Scopus (37) Google Scholar, Vanderweyde et al., 2016Vanderweyde T. Apicco D.J. Youmans-Kidder K. Ash P.E.A. Cook C. Lummertz da Rocha E. Jansen-West K. Frame A.A. Citro A. Leszyk J.D. et al.Interaction of tau with the RNA-Binding Protein TIA1 Regulates tau Pathophysiology and Toxicity.Cell Rep. 2016; 15: 1455-1466Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar) and in vitro (Bishof et al., 2018Bishof I. Dammer E.B. Duong D.M. Kundinger S.R. Gearing M. Lah J.J. Levey A.I. Seyfried N.T. RNA-binding proteins with basic-acidic dipeptide (BAD) domains self-assemble and aggregate in Alzheimer’s disease.J. Biol. Chem. 2018; 293: 11047-11066Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar). Consistent with these observations, evidence of altered splicing in AD has also recently emerged (Bai et al., 2013Bai B. Hales C.M. Chen P.-C. Gozal Y. Dammer E.B. Fritz J.J. Wang X. Xia Q. Duong D.M. Street C. et al.U1 small nuclear ribonucleoprotein complex and RNA splicing alterations in Alzheimer’s disease.Proc. Natl. Acad. Sci. USA. 2013; 110: 16562-16567Crossref PubMed Scopus (140) Google Scholar, Raj et al., 2018Raj T. Li Y.I. Wong G. Humphrey J. Wang M. Ramdhani S. Wang Y.-C. Ng B. Gupta I. Haroutunian V. et al.Integrative transcriptome analyses of the aging brain implicate altered splicing in Alzheimer’s disease susceptibility.Nat. Genet. 2018; 50: 1584-1592Crossref PubMed Scopus (64) Google Scholar). Independently, in a screen of candidate genes from AD-associated human genomic loci, we discovered that SmB, the fly ortholog of human SNRPN (encoding SmN), modulates Tau-mediated neurotoxicity (Shulman et al., 2014Shulman J.M. Imboywa S. Giagtzoglou N. Powers M.P. Hu Y. Devenport D. Chipendo P. Chibnik L.B. Diamond A. Perrimon N. et al.Functional screening in Drosophila identifies Alzheimer’s disease susceptibility genes and implicates Tau-mediated mechanisms.Hum. Mol. Genet. 2014; 23: 870-877Crossref PubMed Scopus (83) Google Scholar). Here, we couple studies in human autopsy cohorts and Drosophila models to further investigate the hypothesis that Tau-spliceosome interactions lead to splicing errors and, ultimately, neurodegeneration in AD. We previously showed that multiple core and U1-specific components of the spliceosome are enriched in insoluble protein fractions and closely associate with neurofibrillary tangles in AD postmortem brain tissue (Bai et al., 2013Bai B. Hales C.M. Chen P.-C. Gozal Y. Dammer E.B. Fritz J.J. Wang X. Xia Q. Duong D.M. Street C. et al.U1 small nuclear ribonucleoprotein complex and RNA splicing alterations in Alzheimer’s disease.Proc. Natl. Acad. Sci. USA. 2013; 110: 16562-16567Crossref PubMed Scopus (140) Google Scholar, Bishof et al., 2018Bishof I. Dammer E.B. Duong D.M. Kundinger S.R. Gearing M. Lah J.J. Levey A.I. Seyfried N.T. RNA-binding proteins with basic-acidic dipeptide (BAD) domains self-assemble and aggregate in Alzheimer’s disease.J. Biol. Chem. 2018; 293: 11047-11066Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar, Hales et al., 2014Hales C.M. Dammer E.B. Diner I. Yi H. Seyfried N.T. Gearing M. Glass J.D. Montine T.J. Levey A.I. Lah J.J. Aggregates of small nuclear ribonucleic acids (snRNAs) in Alzheimer’s disease.Brain Pathol. 2014; 24: 344-351Crossref PubMed Scopus (0) Google Scholar). To further explore the potential for interactions with soluble, oligomeric forms of Tau that most likely mediate toxicity, we performed immunoaffinity-purification coupled to mass spectrometry. A Tau monoclonal antibody (Tau5) was used for immunoprecipitation from human brain lysate soluble fractions, prepared from either AD or non-demented control autopsy cases (n = 4 each; Table S1), and normalized for total protein levels. As a negative control, we performed immunoprecipitation with a non-specific immunoglobulin G (IgG) from pooled control and AD inputs. Tau immunoprecipitation was confirmed by western blot analysis (Figure S1A). Next, samples were on-bead digested and peptides analyzed by liquid chromatography-tandem mass spectrometry using label-free quantitation. Our analysis identified 1,065 proteins across all samples. Differential enrichment analysis of Tau-interacting partners identified 513 proteins enriched in AD versus control brains (p < 0.05, fold-change > 1.5; Data S1, tab i), highlighting proteins with significantly altered interactions in the context of AD pathology (Figure 1A). Among those proteins characterized by increased affinity for Tau in AD are numerous ribonucleoproteins (p = 7.7 × 10−5) based on Gene Ontology (GO) enrichment analysis, with roles in mRNA processing, including splicing and/or translation (Figures 1A and S1C; Data S1, tabs i and ii). Among these, nine spliceosome proteins, including SNRNP70 (U1-70K), SNRPD2 (SmD2), SNRPD3 (SmD3), SNRPN (SmN), and SNRPA (U1A), each exhibited more than 6-fold increased affinity to Tau in AD brains versus control (Figure S1B). These data suggest that, in AD, soluble forms of Tau may associate with spliceosome components, possibly preceding the formation of neurofibrillary tangles. Expression of human MAPT in Drosophila is neurotoxic, including either wild-type Tau (TauWT) or mutant forms associated with familial frontotemporal dementia. We initially selected a mutant TauV337M transgenic fly strain, which is amenable to sensitive and robust detection of genetic modifiers (Shulman and Feany, 2003Shulman J.M. Feany M.B. Genetic modifiers of tauopathy in Drosophila.Genetics. 2003; 165: 1233-1242PubMed Google Scholar, Shulman et al., 2011Shulman J.M. Chipendo P. Chibnik L.B. Aubin C. Tran D. Keenan B.T. Kramer P.L. Schneider J.A. Bennett D.A. Feany M.B. De Jager P.L. Functional screening of Alzheimer pathology genome-wide association signals in Drosophila.Am. J. Hum. Genet. 2011; 88: 232-238Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar, Shulman et al., 2014Shulman J.M. Imboywa S. Giagtzoglou N. Powers M.P. Hu Y. Devenport D. Chipendo P. Chibnik L.B. Diamond A. Perrimon N. et al.Functional screening in Drosophila identifies Alzheimer’s disease susceptibility genes and implicates Tau-mediated mechanisms.Hum. Mol. Genet. 2014; 23: 870-877Crossref PubMed Scopus (83) Google Scholar). Using the GMR-GAL4 driver, we directed expression of Tau to the Drosophila retina, along with RNAi transgenes targeting 10 distinct U1 snRNP components, including the Sm core (SmB, SmD1, SmD2, SmD3, SmE, SmF, and SmG) and U1-specific factors (U1-70K, U1C, and U1A). We required consistent interactions with at least two independent lines to minimize off-target effects and excluded RNAi strains with evidence of significant retinal toxicity in the absence of Tau (Data S1, tab iii). These experiments confirmed our prior results with SmB (Shulman et al., 2014Shulman J.M. Imboywa S. Giagtzoglou N. Powers M.P. Hu Y. Devenport D. Chipendo P. Chibnik L.B. Diamond A. Perrimon N. et al.Functional screening in Drosophila identifies Alzheimer’s disease susceptibility genes and implicates Tau-mediated mechanisms.Hum. Mol. Genet. 2014; 23: 870-877Crossref PubMed Scopus (83) Google Scholar) and additionally revealed that knockdown of fly homologs of SmD2, U1-70K, U1C, and SmE similarly enhance Tau-induced retinal degeneration, causing reduced eye size and increased, roughened appearance (all p < 0.0001; Figure 1B). We next employed a complementary assay in which Tau expression is restricted to adult photoreceptors, using the Rhodopsin 1 (Rh1)-GAL4 driver, causing an age-dependent, progressive loss of the light-induced depolarization response, but preserved retinal morphology (Chouhan et al., 2016Chouhan A.K. Guo C. Hsieh Y.-C. Ye H. Senturk M. Zuo Z. Li Y. Chatterjee S. Botas J. Jackson G.R. et al.Uncoupling neuronal death and dysfunction in Drosophila models of neurodegenerative disease.Acta Neuropathol. Commun. 2016; 4: 62Crossref PubMed Scopus (36) Google Scholar). Based on the electroretinogram (ERG), we confirmed that RNAi knockdown of U1 snRNP components showed consistent enhancement of the Rh1 > TauWT functional degenerative phenotype (Figure S2A). To further examine for dose-sensitive genetic interactions, we also tested available mutant alleles, including null alleles for fly snRNP-U1-70K and sans-fille (snf, an ortholog of U1A) (Flickinger and Salz, 1994Flickinger T.W. Salz H.K. The Drosophila sex determination gene snf encodes a nuclear protein with sequence and functional similarity to the mammalian U1A snRNP protein.Genes Dev. 1994; 8: 914-925Crossref PubMed Google Scholar, Salz et al., 2004Salz H.K. Mancebo R.S. Nagengast A.A. Speck O. Psotka M. Mount S.M. The Drosophila U1-70K protein is required for viability, but its arginine-rich domain is dispensable.Genetics. 2004; 168: 2059-2065Crossref PubMed Scopus (0) Google Scholar) or a newly generated SmB hypomorphic allele (SmBMG; see below). The Tau ERG phenotype was dominantly enhanced in either an SmBMG/+ (Figure 1C) or snf+/− heterozygous genetic background (Figure S2B) but not in snRNP-U1-70K+/− (Figure S2C), whereas control heterozygous animals had normal ERGs in the absence of Tau. Next, we expressed Tau pan-neuronally using the elav-GAL4 driver line, which causes age-dependent neuronal loss and histologic changes in the adult brain (Wittmann et al., 2001Wittmann C.W. Wszolek M.F. Shulman J.M. Salvaterra P.M. Lewis J. Hutton M. Feany M.B. Tauopathy in Drosophila: neurodegeneration without neurofibrillary tangles.Science. 2001; 293: 711-714Crossref PubMed Google Scholar). RNAi knockdown of U1 snRNP genes using elav-GAL4 resulted in embryonic lethality, so we again took advantage of the available mutant alleles to examine for dominant genetic interactions. In 10-day-old animals, elav > TauR406W causes a mild degree of neurodegenerative changes, based on the accumulation of vacuoles on hematoxylin and eosin-stained, paraffin brain sections (Figure 1D). By contrast, Tau-induced neurodegeneration was dominantly enhanced in either an SmBMG/+ (Figure 1D) or snRNP-U1-70K+/− (Figures S2D and S2E) heterozygous genetic background, but not in snf+/−. We did not detect evidence of neurodegeneration in heterozygous SmB or snRNP-U1-70K control flies independent of Tau (Figures 1D and S2E). In sum, based on multiple independent assays, our data suggest that genetic manipulation of U1 snRNP components can enhance Tau-induced neurodegenerative phenotypes in Drosophila. We previously reported that overexpression of SmB suppresses the Tau rough eye phenotype (Shulman et al., 2014Shulman J.M. Imboywa S. Giagtzoglou N. Powers M.P. Hu Y. Devenport D. Chipendo P. Chibnik L.B. Diamond A. Perrimon N. et al.Functional screening in Drosophila identifies Alzheimer’s disease susceptibility genes and implicates Tau-mediated mechanisms.Hum. Mol. Genet. 2014; 23: 870-877Crossref PubMed Scopus (83) Google Scholar). However, we were unable to confirm consistent suppression of Tau-induced vacuolar degeneration in the adult brain (Figure S2F). If Tau disrupts the function of multiple spliceosome proteins, it is possible that overexpression of one factor in isolation (e.g., SmB) is not sufficient to rescue Tau toxicity in all contexts (discussed further below). We next examined the expression of core and U1-specific spliceosomal proteins in the brains of Tau transgenic flies (elav > TauR406W). We focused on 1-day-old adults preceding the onset of significant neuronal loss (Wittmann et al., 2001Wittmann C.W. Wszolek M.F. Shulman J.M. Salvaterra P.M. Lewis J. Hutton M. Feany M.B. Tauopathy in Drosophila: neurodegeneration without neurofibrillary tangles.Science. 2001; 293: 711-714Crossref PubMed Google Scholar). Based on western blots prepared from adult head total protein homogenates, elav > TauR406W flies demonstrate an approximately 30%–50% reduction in the levels of multiple core (SmB, SmD3) and U1-specific (U1A/SNF and U1-70K) spliceosomal components when compared to elav-GAL4/+ controls, whereas SmD2 was increased (Figures 2A and 2B ). Based on quantitative real-time PCR, mRNA levels were not significantly altered for three out of five spliceosomal factors (SmB, SmD3, and snf), consistent with a post-transcriptional mechanism for the observed protein reductions (Figure 2C). In addition, immunofluorescence staining of adult brains using the anti-Sm antibody (Y12), which recognizes both SmB and SmD3 in Drosophila (Brahms et al., 2000Brahms H. Raymackers J. Union A. de Keyser F. Meheus L. Lührmann R. The C-terminal RG dipeptide repeats of the spliceosomal Sm proteins D1 and D3 contain symmetrical dimethylarginines, which form a major B-cell epitope for anti-Sm autoantibodies.J. Biol. Chem. 2000; 275: 17122-17129Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar, Gonsalvez et al., 2006Gonsalvez G.B. Rajendra T.K. Tian L. Matera A.G. The Sm-protein methyltransferase, dart5, is essential for germ-cell specification and maintenance.Curr. Biol. 2006; 16: 1077-1089Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar), or an anti-U1A antibody confirmed significantly reduced U1 snRNP levels and depletion from neuronal nuclei (Figures 2D and 2E). In human AD postmortem brain tissue, multiple spliceosomal proteins can be found mislocalized to the cytoplasm, co-aggregating with Tau in neurofibrillary tangles (Bai et al., 2013Bai B. Hales C.M. Chen P.-C. Gozal Y. Dammer E.B. Fritz J.J. Wang X. Xia Q. Duong D.M. Street C. et al.U1 small nuclear ribonucleoprotein complex and RNA splicing alterations in Alzheimer’s disease.Proc. Natl. Acad. Sci. USA. 2013; 110: 16562-16567Crossref PubMed Scopus (140) Google Scholar, Hales et al., 2014Hales C.M. Dammer E.B. Diner I. Yi H. Seyfried N.T. Gearing M. Glass J.D. Montine T.J. Levey A.I. Lah J.J. Aggregates of small nuclear ribonucleic acids (snRNAs) in Alzheimer’s disease.Brain Pathol. 2014; 24: 344-351Crossref PubMed Scopus (0) Google Scholar). In Drosophila neurons, although Tau is misfolded and hyperphosphorylated as in human AD, it remains predominantly soluble and oligomeric (Ali et al., 2012Ali Y.O. Ruan K. Zhai R.G. NMNAT suppresses tau-induced neurodegeneration by promoting clearance of hyperphosphorylated tau oligomers in a Drosophila model of tauopathy.Hum. Mol. Genet. 2012; 21: 237-250Crossref PubMed Scopus (65) Google Scholar, Cowan et al., 2010Cowan C.M. Bossing T. Page A. Shepherd D. Mudher A. Soluble hyper-phosphorylated tau causes microtubule breakdown and functionally compromises normal tau in vivo.Acta Neuropathol. 2010; 120: 593-604Crossref PubMed Scopus (68) Google Scholar, Mudher et al., 2004Mudher A. Shepherd D. Newman T.A. Mildren P. Jukes J.P. Squire A. Mears A. Drummond J.A. Berg S. MacKay D. et al.GSK-3β inhibition reverses axonal transport defects and behavioural phenotypes in Drosophila.Mol. Psychiatry. 2004; 9: 522-530Crossref PubMed Scopus (0) Google Scholar, Wittmann et al., 2001Wittmann C.W. Wszolek M.F. Shulman J.M. Salvaterra P.M. Lewis J. Hutton M. Feany M.B. Tauopathy in Drosophila: neurodegeneration without neurofibrillary tangles.Science. 2001; 293: 711-714Crossref PubMed Google Scholar). In other human tauopathies, such as corticobasal degeneration, fibrillar Tau inclusions are observed in both neurons and glia, and prior work has established that Tau aggregates more readily when expressed in Drosophila glia, forming insoluble, tangle-like, cytoplasmic inclusions (Colodner and Feany, 2010Colodner K.J. Feany M.B. Glial fibrillary tangles and JAK/STAT-mediated glial and neuronal cell death in a Drosophila model of glial tauopathy.J. Neurosci. 2010; 30: 16102-16113Crossref PubMed Scopus (43) Google Scholar). As a complementary approach, we therefore stained for Sm proteins in a Drosophila glial tauopathy model, which relies on the repo-GAL4 glial driver. Indeed, aged repo > TauWT flies manifest numerous cytoplasmic aggregates costaining for both phospho-Tau (anti-pSer214) and SmB/SmD3 (Y12) (Figure 2F). Consistent with this, on western blots, we can detect both Tau and increased SmB protein in insoluble fractions prepared from repo > TauWT heads (Figure S3B). Together, our results suggest that soluble Tau species lead to a loss of snRNP protein levels, whereas insoluble forms of Tau coaggregate with spliceosomal proteins, leading to cytoplasmic sequestration. Our data suggest that pathological forms of Tau can trigger a reduction in core and U1-specific spliceosomal components in Drosophila neurons, and that further experimental reduction of these proteins" @default.
• W2912165492 created "2019-02-21" @default.
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• W2912165492 date "2019-10-01" @default.
• W2912165492 modified "2023-10-13" @default.
• W2912165492 title "Tau-Mediated Disruption of the Spliceosome Triggers Cryptic RNA Splicing and Neurodegeneration in Alzheimer’s Disease" @default.
• W2912165492 cites W1263857580 @default.
• W2912165492 cites W1437041981 @default.
• W2912165492 cites W1488980960 @default.
• W2912165492 cites W1619082318 @default.
• W2912165492 cites W1841850981 @default.
• W2912165492 cites W1854281301 @default.
• W2912165492 cites W1904847174 @default.
• W2912165492 cites W1909655902 @default.
• W2912165492 cites W1952608303 @default.
• W2912165492 cites W1965286266 @default.
• W2912165492 cites W1965906734 @default.
• W2912165492 cites W1980477780 @default.
• W2912165492 cites W1980548655 @default.
• W2912165492 cites W1980782305 @default.
• W2912165492 cites W1981218311 @default.
• W2912165492 cites W1984652813 @default.
• W2912165492 cites W1990393476 @default.
• W2912165492 cites W1991665568 @default.
• W2912165492 cites W1997198091 @default.
• W2912165492 cites W2002439648 @default.
• W2912165492 cites W2003618511 @default.
• W2912165492 cites W2004712987 @default.
• W2912165492 cites W2011639334 @default.
• W2912165492 cites W2012418668 @default.
• W2912165492 cites W2015809578 @default.
• W2912165492 cites W2018276118 @default.
• W2912165492 cites W2020815630 @default.
• W2912165492 cites W2021280501 @default.
• W2912165492 cites W2021678907 @default.
• W2912165492 cites W2028446861 @default.
• W2912165492 cites W2034691490 @default.
• W2912165492 cites W2038120434 @default.
• W2912165492 cites W2040454459 @default.
• W2912165492 cites W2045162637 @default.
• W2912165492 cites W2052742260 @default.
• W2912165492 cites W2053116497 @default.
• W2912165492 cites W2054380003 @default.
• W2912165492 cites W2057329207 @default.
• W2912165492 cites W2060061304 @default.
• W2912165492 cites W2065356080 @default.
• W2912165492 cites W2066231767 @default.
• W2912165492 cites W2073889874 @default.
• W2912165492 cites W2074726646 @default.
• W2912165492 cites W2075426349 @default.
• W2912165492 cites W2080578111 @default.
• W2912165492 cites W2084453905 @default.
• W2912165492 cites W2085782370 @default.
• W2912165492 cites W2088860412 @default.
• W2912165492 cites W2089084448 @default.
• W2912165492 cites W2091533776 @default.
• W2912165492 cites W2101042581 @default.
• W2912165492 cites W2113525941 @default.
• W2912165492 cites W2114525505 @default.
• W2912165492 cites W2114706544 @default.
• W2912165492 cites W2122132730 @default.
• W2912165492 cites W2127863733 @default.
• W2912165492 cites W2128817844 @default.
• W2912165492 cites W2133465414 @default.
• W2912165492 cites W2137709496 @default.
• W2912165492 cites W2139066576 @default.
• W2912165492 cites W2139199979 @default.
• W2912165492 cites W2142798429 @default.
• W2912165492 cites W2145506897 @default.
• W2912165492 cites W2145631524 @default.
• W2912165492 cites W2148393113 @default.
• W2912165492 cites W2150860983 @default.
• W2912165492 cites W2153020791 @default.
• W2912165492 cites W2156220037 @default.
• W2912165492 cites W2158217645 @default.
• W2912165492 cites W2158789637 @default.
• W2912165492 cites W2161130389 @default.
• W2912165492 cites W2161586678 @default.
• W2912165492 cites W2163610234 @default.
• W2912165492 cites W2163962112 @default.
• W2912165492 cites W2168639701 @default.
• W2912165492 cites W2169456326 @default.
• W2912165492 cites W2169831780 @default.
• W2912165492 cites W2170776626 @default.
• W2912165492 cites W2171564701 @default.
• W2912165492 cites W2179438025 @default.

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