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Bhattarai P, Gunasekaran TI, Belloy ME, Reyes-Dumeyer D, Jülich D, Tayran H, Yilmaz E, Flaherty D, Turgutalp B, Sukumar G, Alba C, McGrath EM, Hupalo DN, Bacikova D, Le Guen Y, Lantigua R, Medrano M, Rivera D, Recio P, Nuriel T, Ertekin-Taner N, Teich AF, Dickson DW, Holley S, Greicius M, Dalgard CL, Zody M, Mayeux R, Kizil C, Vardarajan BN. Rare genetic variation in fibronectin 1 (FN1) protects against APOEε4 in Alzheimer's disease. Acta Neuropathol 2024; 147:70. [PMID: 38598053 PMCID: PMC11006751 DOI: 10.1007/s00401-024-02721-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/28/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024]
Abstract
The risk of developing Alzheimer's disease (AD) significantly increases in individuals carrying the APOEε4 allele. Elderly cognitively healthy individuals with APOEε4 also exist, suggesting the presence of cellular mechanisms that counteract the pathological effects of APOEε4; however, these mechanisms are unknown. We hypothesized that APOEε4 carriers without dementia might carry genetic variations that could protect them from developing APOEε4-mediated AD pathology. To test this, we leveraged whole-genome sequencing (WGS) data in the National Institute on Aging Alzheimer's Disease Family Based Study (NIA-AD FBS), Washington Heights/Inwood Columbia Aging Project (WHICAP), and Estudio Familiar de Influencia Genetica en Alzheimer (EFIGA) cohorts and identified potentially protective variants segregating exclusively among unaffected APOEε4 carriers. In homozygous unaffected carriers above 70 years old, we identified 510 rare coding variants. Pathway analysis of the genes harboring these variants showed significant enrichment in extracellular matrix (ECM)-related processes, suggesting protective effects of functional modifications in ECM proteins. We prioritized two genes that were highly represented in the ECM-related gene ontology terms, (FN1) and collagen type VI alpha 2 chain (COL6A2) and are known to be expressed at the blood-brain barrier (BBB), for postmortem validation and in vivo functional studies. An independent analysis in a large cohort of 7185 APOEε4 homozygous carriers found that rs140926439 variant in FN1 was protective of AD (OR = 0.29; 95% CI [0.11, 0.78], P = 0.014) and delayed age at onset of disease by 3.37 years (95% CI [0.42, 6.32], P = 0.025). The FN1 and COL6A2 protein levels were increased at the BBB in APOEε4 carriers with AD. Brain expression of cognitively unaffected homozygous APOEε4 carriers had significantly lower FN1 deposition and less reactive gliosis compared to homozygous APOEε4 carriers with AD, suggesting that FN1 might be a downstream driver of APOEε4-mediated AD-related pathology and cognitive decline. To validate our findings, we used zebrafish models with loss-of-function (LOF) mutations in fn1b-the ortholog for human FN1. We found that fibronectin LOF reduced gliosis, enhanced gliovascular remodeling, and potentiated the microglial response, suggesting that pathological accumulation of FN1 could impair toxic protein clearance, which is ameliorated with FN1 LOF. Our study suggests that vascular deposition of FN1 is related to the pathogenicity of APOEε4, and LOF variants in FN1 may reduce APOEε4-related AD risk, providing novel clues to potential therapeutic interventions targeting the ECM to mitigate AD risk.
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Affiliation(s)
- Prabesh Bhattarai
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
| | - Tamil Iniyan Gunasekaran
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Michael E Belloy
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- NeuroGenomics and Informatics Center, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Dolly Reyes-Dumeyer
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Dörthe Jülich
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, 06520, USA
| | - Hüseyin Tayran
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
| | - Elanur Yilmaz
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
| | - Delaney Flaherty
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Bengisu Turgutalp
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
| | - Gauthaman Sukumar
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, 20817, USA
| | - Camille Alba
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, 20817, USA
| | - Elisa Martinez McGrath
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, 20817, USA
| | - Daniel N Hupalo
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, 20817, USA
| | - Dagmar Bacikova
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, 20817, USA
| | - Yann Le Guen
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
- Quantitative Sciences Unit, Department of Medicine, Stanford University, Stanford, CA, USA
| | - Rafael Lantigua
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
- Department of Medicine, College of Physicians and Surgeons, Columbia University New York, New York, USA
| | - Martin Medrano
- School of Medicine, Pontificia Universidad Catolica Madre y Maestra, Santiago, Dominican Republic
| | - Diones Rivera
- Department of Neurology, CEDIMAT, Plaza de la Salud, Santo Domingo, Dominican Republic
- School of Medicine, Universidad Pedro Henriquez Urena (UNPHU), Santo Domingo, Dominican Republic
| | - Patricia Recio
- Department of Neurology, CEDIMAT, Plaza de la Salud, Santo Domingo, Dominican Republic
| | - Tal Nuriel
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Nilüfer Ertekin-Taner
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
- Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Andrew F Teich
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA
| | - Scott Holley
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, 06520, USA
| | - Michael Greicius
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | - Clifton L Dalgard
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
- The American Genome Center, Center for Military Precision Health, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Michael Zody
- New York Genome Center, New York, NY, 10013, USA
| | - Richard Mayeux
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA
- Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY, 10032, USA
- Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 W 168th St., New York, NY, 10032, USA
| | - Caghan Kizil
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA.
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA.
- Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Badri N Vardarajan
- Department of Neurology, Columbia University Irving Medical Center, Columbia University New York, New York, NY, USA.
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Irving Medical Center, Columbia University, New York, NY, USA.
- Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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Han G, Gupta SD, Gable K, Bacikova D, Sengupta N, Somashekarappa N, Proia RL, Harmon JM, Dunn TM. The ORMs interact with transmembrane domain 1 of Lcb1 and regulate serine palmitoyltransferase oligomerization, activity and localization. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:245-259. [PMID: 30529276 DOI: 10.1016/j.bbalip.2018.11.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/30/2018] [Accepted: 11/24/2018] [Indexed: 10/27/2022]
Abstract
Serine palmitoyltransferase (SPT), an endoplasmic reticulum-localized membrane enzymecomposed of acatalytic LCB1/LCB2 heterodimer and a small activating subunit (Tsc3 in yeast; ssSPTs in mammals), is negatively regulated by the evolutionarily conserved family of proteins known as the ORMs. In yeast, SPT, the ORMs, and the PI4P phosphatase Sac1, copurify in the "SPOTs" complex. However, neither the mechanism of ORM inhibition of SPT nor details of the interactions of the ORMs and Sac1 with SPT are known. Here we report that the first transmembrane domain (TMD1) of Lcb1 is required for ORM binding to SPT. Loss of binding is not due to altered membrane topology of Lcb1 since replacing TMD1 with a heterologous TMD restores membrane topology but not ORM binding. TMD1 deletion also eliminates ORM-dependent formation of SPT oligomers as assessed by co-immunoprecipitation assays and in vivo imaging. Expression of ORMs lacking derepressive phosphorylation sites results in constitutive SPT oligomerization, while phosphomimetic ORMs fail to induce oligomerization under any conditions. Significantly, when LCB1-RFP and LCB1ΔTMD1-GFP were coexpressed, more LCB1ΔTMD1-GFP was in the peripheral ER, suggesting ORM regulation is partially accomplished by SPT redistribution. Tsc3 deletion does not abolish ORM inhibition of SPT, indicating the ORMs do not simply prevent activation by Tsc3. Binding of Sac1 to SPT requires Tsc3, but not the ORMs, and Sac1 does not influence ORM-mediated oligomerization of SPT. Finally, yeast mutants lacking ORM regulation of SPT require the LCB-P lyase Dpl1 to maintain long-chain bases at sublethal levels.
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Affiliation(s)
- Gongshe Han
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Sita D Gupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Kenneth Gable
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Dagmar Bacikova
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Nivedita Sengupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Niranjanakumari Somashekarappa
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Richard L Proia
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, United States of America
| | - Jeffrey M Harmon
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America
| | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799, United States of America.
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Harmon JM, Bacikova D, Gable K, Gupta SD, Han G, Sengupta N, Somashekarappa N, Dunn TM. Topological and functional characterization of the ssSPTs, small activating subunits of serine palmitoyltransferase. J Biol Chem 2013; 288:10144-10153. [PMID: 23426370 DOI: 10.1074/jbc.m113.451526] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The topological and functional organization of the two isoforms of the small subunits of human serine palmitoyltransferase (hssSPTs) that activate the catalytic hLCB1/hLCB2 heterodimer was investigated. A variety of experimental approaches placed the N termini of the ssSPTs in the cytosol, their C termini in the lumen, and showed that they contain a single transmembrane domain. Deletion analysis revealed that the ability to activate the heterodimer is contained in a conserved 33-amino acid core domain that has the same membrane topology as the full-length protein. In combination with analysis of isoform chimera and site-directed mutagenesis, a single amino acid residue in this core (Met(25) in ssSPTa and Val(25) in ssSPTb) was identified which confers specificity for palmitoyl- or stearoyl-CoA, respectively, in both yeast and mammalian cells. This same residue also determines which isoform is a better activator of a mutant heterodimer, hLCB1(S331F)/hLCB2a, which has increased basal SPT activity and decreased amino acid substrate selectivity. This suggests that the role of the ssSPTs is to increase SPT activity without compromising substrate specificity. In addition, the observation that the C-terminal domains of ssSPTa and ssSPTb, which are highly conserved within each subfamily but are the most divergent regions between isoform subfamilies, are not required for activation of the heterodimer or for acyl-CoA selectivity suggests that the ssSPTs have additional roles that remain to be discovered.
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Affiliation(s)
- Jeffrey M Harmon
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Dagmar Bacikova
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Kenneth Gable
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Sita D Gupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Gongshe Han
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | - Nivedita Sengupta
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
| | | | - Teresa M Dunn
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.
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