Publications by authors named "Yalda Baradaran-Heravi"

5 Publications

  • Page 1 of 1

Family-based exome sequencing identifies RBM45 as a possible candidate gene for frontotemporal dementia and amyotrophic lateral sclerosis.

Neurobiol Dis 2021 Aug 9;156:105421. Epub 2021 Jun 9.

Neurodegenerative Brain Diseases, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium; Institute Born-Bunge, Antwerp, Belgium. Electronic address:

Neurodegenerative disorders like frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are pathologically characterized by toxic protein deposition in the cytoplasm or nucleus of affected neurons and glial cells. Many of these aggregated proteins belong to the class of RNA binding proteins (RBP), and, when mutated, account for a significant subset of familial ALS and FTD cases. Here, we present first genetic evidence for the RBP gene RBM45 in the FTD-ALS spectrum. RBM45 shows many parallels with other FTD-ALS associated genes and proteins. Multiple lines of evidence have demonstrated that RBM45 is an RBP that, upon mutation, redistributes to the cytoplasm where it co-aggregates with other RBPs into cytoplasmic stress granules (SG), evolving to persistent toxic TDP-43 immunoreactive inclusions. Exome sequencing in two affected first cousins of a heavily affected early-onset dementia family listed a number of candidate genes. The gene with the highest pathogenicity score was the RBP gene RBM45. In the family, the RBM45 Arg183* nonsense mutation co-segregated in both affected cousins. Validation in an unrelated patient (n = 548) / control (n = 734) cohort identified an additional RBM45 Arg183* carrier with bvFTD on a shared 4 Mb haplotype. Transcript and protein expression analysis demonstrated loss of nuclear RBM45, suggestive of a loss-of-function disease mechanism. Further, two more ultra-rare VUS, one in the nuclear localization signal (NLS, p.Lys456Arg) in an ALS patient and one in the intrinsically disordered homo-oligomer assembly (HOA) domain (p.Arg314Gln) in a patient with nfvPPA were detected. Our findings suggest that the pathomechanisms linking RBM45 with FTD and ALS may be related to its loss of nuclear function as a mediator of mRNA splicing, cytoplasmic retention or its inability to form homo-oligomers, leading to aggregate formation with trapping of other RBPs including TDP-43, which may accumulate into persisted TDP-43 inclusions.
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http://dx.doi.org/10.1016/j.nbd.2021.105421DOI Listing
August 2021

Stress granule mediated protein aggregation and underlying gene defects in the FTD-ALS spectrum.

Neurobiol Dis 2020 02 15;134:104639. Epub 2019 Oct 15.

Neurodegenerative Brain Diseases group, Center for Molecular Neurology, VIB, Antwerp, Belgium; Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium. Electronic address:

Stress granules (SGs) are dynamic membraneless compartments composed out of RNA-binding proteins (RBPs) and RNA molecules that assemble temporarily to allow the cell to cope with cellular stress by stalling mRNA translation and moving synthesis towards cytoprotective proteins. Aberrant SGs have become prime suspects in the nucleation of toxic protein aggregation in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Perturbed SG dynamics appears to be mediated by alterations in RNA binding proteins (RBP). Indeed, a growing number of FTD and/or ALS related RBPs coding genes (TDP43, FUS, EWSR1, TAF15, hnRNPA1, hnRNPA2B1, ATXN2, TIA1) have been identified to interfere with SG formation through mutation of their low-complexity domain (LCD), and thereby cause or influence disease. Interestingly, disease pathways associated to the C9orf72 repeat expansion, the leading genetic cause of the FTD-ALS spectrum, intersect with SG-mediated protein aggregate formation. In this review, we provide a comprehensive overview of known SG proteins and their genetic contribution to the FTD-ALS spectrum. Importantly, multiple LCD-baring RBPs have already been identified in FTD-ALS that have not yet been genetically linked to disease. These should be considered candidate genes and offer opportunities for gene prioritization when mining sequencing data of unresolved FTD and ALS. Further, we zoom into the current understanding of the molecular processes of perturbed RBP function leading to disturbed SG dynamics, RNA metabolism, and pathological inclusions. Finally, we indicate how these gained insights open new avenues for therapeutic strategies targeting phase separation and SG dynamics to reverse pathological protein aggregation and protect against toxicity.
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http://dx.doi.org/10.1016/j.nbd.2019.104639DOI Listing
February 2020

Presence of tau astrogliopathy in frontotemporal dementia caused by a novel Grn nonsense (Trp2*) mutation.

Neurobiol Aging 2019 04 20;76:214.e11-214.e15. Epub 2018 Nov 20.

Brain Tissue Bank, Fundación CIEN, Instituto de Salud Carlos III, Madrid, Spain.

Frontotemporal lobar degeneration caused by GRN mutations is mainly associated with a TDP-43 type A proteinopathy. We present a family with autosomal dominant frontotemporal lobar degeneration caused by a novel GRN nonsense mutation (c.5G>A: p.Trp2*) in which the proband's brain also showed prominent glial tauopathy consistent with an aging-related tau astrogliopathy. Astrocytic tauopathy, 4R(+) and 3R(-) immunoreactive, was characterized by thorn-shaped astrocytes present in subpial, subependymal, and perivascular areas, and in gray matter; plus granular or fuzzy tau immunoreactivity in astrocytic processes in gray matter, either solitary or clustered in different regions. Some neurofibrillary tangles and pretangles, both 3R and 4R(+), were present in the medial temporal lobe but did not exhibit the characteristic distribution of Alzheimer's type pathology. This 4R-tau aging-related tau astrogliopathy is likely a co-occurring pathology, although an interaction between progranulin and tau proteins within the neurodegenerative process should not be ruled out.
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http://dx.doi.org/10.1016/j.neurobiolaging.2018.11.010DOI Listing
April 2019

No supportive evidence for TIA1 gene mutations in a European cohort of ALS-FTD spectrum patients.

Neurobiol Aging 2018 09 23;69:293.e9-293.e11. Epub 2018 May 23.

Alzheimer's Disease and Other Cognitive Disorders Unit, Neurology Department, Hospital Clínic, Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.

We evaluated the genetic contribution of the T cell-restricted intracellular antigen-1 gene (TIA1) in a European cohort of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) patients. Exonic resequencing of TIA1 in 1120 patients (693 FTD, 341 ALS, 86 FTD-ALS) and 1039 controls identified in total 5 rare heterozygous missense variants, affecting the TIA1 low-complexity domain (LCD). Only 1 missense variant, p.Met290Thr, identified in a familial FTD patient with disease onset at 64 years, was absent from controls yet received a combined annotation-dependent depletion score of 11.42. By contrast, 3 of the 4 variants also detected in unaffected controls, p.Val294Glu, p.Gln318Arg, and p.Ala381Thr, had combined annotation-dependent depletion scores greater than 20. Our findings in a large European patient-control series indicate that variants in TIA1 are not a common cause of ALS and FTD. The observation of recurring TIA1 missense variants in unaffected individuals lead us to conclude that the exact genetic contribution of TIA1 to ALS and FTD pathogenesis remains to be further elucidated.
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http://dx.doi.org/10.1016/j.neurobiolaging.2018.05.005DOI Listing
September 2018

Deleterious ABCA7 mutations and transcript rescue mechanisms in early onset Alzheimer's disease.

Acta Neuropathol 2017 Sep 27;134(3):475-487. Epub 2017 Apr 27.

Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.

Premature termination codon (PTC) mutations in the ATP-Binding Cassette, Sub-Family A, Member 7 gene (ABCA7) have recently been identified as intermediate-to-high penetrant risk factor for late-onset Alzheimer's disease (LOAD). High variability, however, is observed in downstream ABCA7 mRNA and protein expression, disease penetrance, and onset age, indicative of unknown modifying factors. Here, we investigated the prevalence and disease penetrance of ABCA7 PTC mutations in a large early onset AD (EOAD)-control cohort, and examined the effect on transcript level with comprehensive third-generation long-read sequencing. We characterized the ABCA7 coding sequence with next-generation sequencing in 928 EOAD patients and 980 matched control individuals. With MetaSKAT rare variant association analysis, we observed a fivefold enrichment (p = 0.0004) of PTC mutations in EOAD patients (3%) versus controls (0.6%). Ten novel PTC mutations were only observed in patients, and PTC mutation carriers in general had an increased familial AD load. In addition, we observed nominal risk reducing trends for three common coding variants. Seven PTC mutations were further analyzed using targeted long-read cDNA sequencing on an Oxford Nanopore MinION platform. PTC-containing transcripts for each investigated PTC mutation were observed at varying proportion (5-41% of the total read count), implying incomplete nonsense-mediated mRNA decay (NMD). Furthermore, we distinguished and phased several previously unknown alternative splicing events (up to 30% of transcripts). In conjunction with PTC mutations, several of these novel ABCA7 isoforms have the potential to rescue deleterious PTC effects. In conclusion, ABCA7 PTC mutations play a substantial role in EOAD, warranting genetic screening of ABCA7 in genetically unexplained patients. Long-read cDNA sequencing revealed both varying degrees of NMD and transcript-modifying events, which may influence ABCA7 dosage, disease severity, and may create opportunities for therapeutic interventions in AD.
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http://dx.doi.org/10.1007/s00401-017-1714-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5563332PMC
September 2017
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