Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2015 Jul;130(1):77-92.
doi: 10.1007/s00401-015-1436-x. Epub 2015 May 6.

Whole-genome sequencing reveals important role for TBK1 and OPTN mutations in frontotemporal lobar degeneration without motor neuron disease

Cyril Pottier  1 , Kevin F Bieniek, NiCole Finch, Maartje van de Vorst, Matt Baker, Ralph Perkersen, Patricia Brown, Thomas Ravenscroft, Marka van Blitterswijk, Alexandra M Nicholson, Michael DeTure, David S Knopman, Keith A Josephs, Joseph E Parisi, Ronald C Petersen, Kevin B Boylan, Bradley F Boeve, Neill R Graff-Radford, Joris A Veltman, Christian Gilissen, Melissa E Murray, Dennis W Dickson, Rosa Rademakers
Affiliations

Whole-genome sequencing reveals important role for TBK1 and OPTN mutations in frontotemporal lobar degeneration without motor neuron disease

Cyril Pottier et al. Acta Neuropathol. 2015 Jul.

Abstract

Frontotemporal lobar degeneration with TAR DNA-binding protein 43 inclusions (FTLD-TDP) is the most common pathology associated with frontotemporal dementia (FTD). Repeat expansions in chromosome 9 open reading frame 72 (C9ORF72) and mutations in progranulin (GRN) are the major known genetic causes of FTLD-TDP; however, the genetic etiology in the majority of FTLD-TDP remains unexplained. In this study, we performed whole-genome sequencing in 104 pathologically confirmed FTLD-TDP patients from the Mayo Clinic brain bank negative for C9ORF72 and GRN mutations and report on the contribution of rare single nucleotide and copy number variants in 21 known neurodegenerative disease genes. Interestingly, we identified 5 patients (4.8 %) with variants in optineurin (OPTN) and TANK-binding kinase 1 (TBK1) that are predicted to be highly pathogenic, including two double mutants. Case A was a compound heterozygote for mutations in OPTN, carrying the p.Q235* nonsense and p.A481V missense mutation in trans, while case B carried a deletion of OPTN exons 13-15 (p.Gly538Glufs*27) and a loss-of-function mutation (p.Arg117*) in TBK1. Cases C-E carried heterozygous missense mutations in TBK1, including the p.Glu696Lys mutation which was previously reported in two amyotrophic lateral sclerosis (ALS) patients and is located in the OPTN binding domain. Quantitative mRNA expression and protein analysis in cerebellar tissue showed a striking reduction of OPTN and/or TBK1 expression in 4 out of 5 patients supporting pathogenicity in these specific patients and suggesting a loss-of-function disease mechanism. Importantly, neuropathologic examination showed FTLD-TDP type A in the absence of motor neuron disease in 3 pathogenic mutation carriers. In conclusion, we highlight TBK1 as an important cause of pure FTLD-TDP, identify the first OPTN mutations in FTLD-TDP, and suggest a potential oligogenic basis for at least a subset of FTLD-TDP patients. Our data further add to the growing body of evidence linking ALS and FTD and suggest a key role for the OPTN/TBK1 pathway in these diseases.

PubMed Disclaimer

Conflict of interest statement

Disclosure of potential conflicts of interest:

The authors declare that they have no conflict of interest.

Figures

Figure 1
Figure 1. OPTN and TBK1 mutations in FTLD-TDP cases
(a) Schematic representation of OPTN and TBK1 protein with their corresponding domains and the position of rare variants (red lines) identified in the study. Domain boundaries are shown with a vertical black line associated with the corresponding amino acid number. Each mutation has been found in a single patient which is indicated below. Mutations found in the same patient are indicated in a blue square. Binding sites to OPTN or TBK1 are indicated with a blue line. (b) Schematic representation of the partial deletion of exons 13 to 15 of OPTN (OPTN c.1243-740_1612+1292delins25) compared to wild-type OPTN (OPTN WT) along with the genomic DNA sequence chromatogram of the deletion observed in case B. (c) Genomic DNA (gDNA) and complementary DNA (cDNA) sequence chromatogram of exon 8 (right panel) demonstrating loss of the mutant (T) allele c.703C>T in cDNA for case A. gDNA and cDNA sequence chromatograms of exon14 (left panel) demonstrating the predominant presence of the mutant (T) allele c.1442C>T in cDNA sequence for case A. LIR: LC3-interacting region.
Figure 2
Figure 2. Loss of function variants in OPTN and TBK1 reduce mRNA and protein expression
(a) Relative OPTN mRNA expression levels normalized to RPLPO for cases A and B and 6 FTLD-TDP cases without mutations in OPTN and TBK1 are represented relatively to 4 control brains. (b) Representative western blot showing OPTN and GAPDH protein levels (left panel) in cases A and B, 4 FTLD-TDP cases without mutations in OPTN and TBK1 are 4 normal control brains. The relative quantification of OPTN protein (from 2 independent protein extractions) for cases A and B as well as FTLD-TDP cases without mutations in OPTN and TBK1 (n=6) and controls (n=6) is shown in right panel. (c) Relative TBK1 mRNA expression levels normalized to RPLPO for cases A and B and 6 FTLD-TDP cases without mutations in OPTN and TBK1 are represented relatively to 4 control brains. (d) Representative western blot showing TBK1 and GAPDH (left panel) for cases A and B, 4 FTLD-TDP cases without mutations in OPTN and TBK1 and 4 normal control brains. The relative quantification of TBK1 protein (from 2 independent protein extractions) for cases A and B as well as for 6 FTLD-TDP cases without mutations in OPTN and TBK1 (n=6) and controls (n=6) is shown in right panel. For all panels, the error bar +/− SEM is shown. n.s.: not significant after a Mann-Whitney test.
Figure 3
Figure 3. TBK1 protein expression of TBK1 missense variants
A western blot for TBK1 and GAPDH is presented (upper panel) for cases E, B, C and D as well as a representative control Control 098. Relative quantification of TBK1 protein for each case relatively to Control 098 is shown in the lower panel.
Figure 4
Figure 4. Neuropathology of OPTN and TBK1 double mutant carriers
Case B exhibited focal cortical atrophy of the frontal lobe (a), ventricular enlargement of the frontal and temporal horns (b), atrophy or ‘flattening’ of the caudate (b), and loss of pigmentation in the substantia nigra (c) consistent with frontotemporal lobar degeneration. Microscopically, case B had abundant neuronal cytoplasmic inclusions, neuronal intranuclear inclusions (red arrows), glial cytoplasmic inclusions, and dystrophic neurites immunoreactive for p62/sequestosome-1 (d and e) as well as TDP-43 (f and g). These lesions, along with neuronal loss and superficial cortical spongiosis, were found in the gray matter of the frontal cortex (layer II; d and f) and, surprisingly, the underlying white matter of the frontal cortex (e). Neuronal loss and fine TDP-43-immunoreactive neurites in the CA1 of the hippocampus was indicative of hippocampal sclerosis (g). No pathology was found in motor neurons (hypoglossal nucleus) including with immunohistochemistry for optineurin protein (h). Case A had similar pathology in the gray matter of the frontal cortex (i and k) with p62 (i) and TDP-43 (k) immunohistochemistry in addition to pronounced superficial cortical spongiosis. Only rare immunoreactive glial cytoplasmic inclusions (black arrows) were observed the cortical white matter (p62; j) and in the hippocampal CA1 (TDP-43; l). Despite the paucity of hippocampal TDP-43 pathology, case A was also consistent with hippocampal sclerosis due to the vacuolation of the neuropil and severe neuronal loss. Again, no pathology was observed in the motor neurons (optineurin immunohistochemistry of the trigeminal motor nucleus; m). [white bar = 1 cm (a–c), black bar = 25 µm (d–m)]
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Al-Sarraj S, King A, Troakes C, Smith B, Maekawa S, Bodi I, Rogelj B, Al-Chalabi A, Hortobagyi T, Shaw CE. p62 positive, TDP-43 negative, neuronal cytoplasmic and intranuclear inclusions in the cerebellum and hippocampus define the pathology of C9orf72-linked FTLD and MND/ALS. Acta Neuropathol. 2011;122:691–702. - PubMed
    1. Arai T, Hasegawa M, Akiyama H, Ikeda K, Nonaka T, Mori H, Mann D, Tsuchiya K, Yoshida M, Hashizume Y, Oda T. TDP-43 is a component of ubiquitin-positive tau-negative inclusions in frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Biochem Biophys Res Commun. 2006;351:602–611. - PubMed
    1. Arai T, Nonaka T, Hasegawa M, Akiyama H, Yoshida M, Hashizume Y, Tsuchiya K, Oda T, Ikeda K. Neuronal and glial inclusions in frontotemporal dementia with or without motor neuron disease are immunopositive for p62. Neurosci Lett. 2003;342:41–44. - PubMed
    1. Baker M, Mackenzie IR, Pickering-Brown SM, Gass J, Rademakers R, Lindholm C, Snowden J, Adamson J, Sadovnick AD, Rollinson S, Cannon A, Dwosh E, Neary D, Melquist S, Richardson A, Dickson D, Berger Z, Eriksen J, Robinson T, Zehr C, Dickey CA, Crook R, McGowan E, Mann D, Boeve B, Feldman H, Hutton M. Mutations in progranulin cause tau-negative frontotemporal dementia linked to chromosome 17. Nature. 2006;442:916–919. - PubMed
    1. Belzil VV, Daoud H, Desjarlais A, Bouchard JP, Dupre N, Camu W, Dion PA, Rouleau GA. Analysis of OPTN as a causative gene for amyotrophic lateral sclerosis. Neurobiology of aging. 2011;32:555, e513–e554. - PubMed

Publication types

MeSH terms