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  1. Article ; Online: Impaired protein degradation in FTLD and related disorders.

    Götzl, Julia K / Lang, Christina M / Haass, Christian / Capell, Anja

    Ageing research reviews

    2016  Volume 32, Page(s) 122–139

    Abstract: Impaired protein degradation has been discussed as a cause or consequence of various neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's disease. More recently, evidence accumulated that dysfunctional protein degradation may ... ...

    Abstract Impaired protein degradation has been discussed as a cause or consequence of various neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's disease. More recently, evidence accumulated that dysfunctional protein degradation may play a role in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Since in almost all neurodegenerative diseases, protein aggregates are disease-defining hallmarks, it is most likely that impaired protein degradation contributes to disease onset and progression. In the majority of FTD cases, the pathological protein aggregates contain either microtubuleassociated protein tau or TAR DNA-binding protein (TDP)-43. Aggregates are also positive for ubiquitin and p62/sequestosome 1 (SQSTM1) indicating that these aggregates are targeted for degradation. FTD-linked mutations in genes encoding three autophagy adaptor proteins, p62/SQSTM1, ubiquilin 2 and optineurin, indicate that impaired autophagy might cause FTD. Furthermore, the strongest evidence for lysosomal impairment in FTD is provided by the progranulin (GRN) gene, which is linked to FTD and neuronal ceroid lipofuscinosis. In this review, we summarize the observations that have been made during the last years linking the accumulation of disease-associated proteins in FTD to impaired protein degradation pathways. In addition, we take resent findings for nucleocytoplasmic transport defects of TDP-43, as discussed for hexanucleotide repeat expansions in C9orf72 into account and provide a hypothesis how the interplay of altered nuclear transport and protein degradation leads to the accumulation of protein deposits.
    MeSH term(s) Active Transport, Cell Nucleus/physiology ; Autophagy/physiology ; Cell Cycle Proteins/genetics ; DNA-Binding Proteins/metabolism ; Frontotemporal Dementia/metabolism ; Humans ; Lysosomes/metabolism ; Mutation ; Nerve Degeneration/metabolism ; Neuronal Ceroid-Lipofuscinoses/metabolism ; Proteolysis ; Sequestosome-1 Protein/genetics ; Transcription Factor TFIIIA/genetics ; Ubiquitins/genetics
    Chemical Substances Cell Cycle Proteins ; DNA-Binding Proteins ; OPTN protein, human ; SQSTM1 protein, human ; Sequestosome-1 Protein ; Transcription Factor TFIIIA ; UBQLN2 protein, human ; Ubiquitins
    Language English
    Publishing date 2016-05-07
    Publishing country England
    Document type Journal Article ; Review ; Research Support, Non-U.S. Gov't
    ZDB-ID 2075672-0
    ISSN 1872-9649 ; 1568-1637
    ISSN (online) 1872-9649
    ISSN 1568-1637
    DOI 10.1016/j.arr.2016.04.008
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Membrane orientation and subcellular localization of transmembrane protein 106B (TMEM106B), a major risk factor for frontotemporal lobar degeneration.

    Lang, Christina M / Fellerer, Katrin / Schwenk, Benjamin M / Kuhn, Peer-Hendrik / Kremmer, Elisabeth / Edbauer, Dieter / Capell, Anja / Haass, Christian

    The Journal of biological chemistry

    2012  Volume 287, Issue 23, Page(s) 19355–19365

    Abstract: TMEM106B was identified as a major risk factor in a genome-wide association study for frontotemporal lobar degeneration (FTLD) with TAR DNA-binding protein (TDP)-43 pathology. The most significant association of TMEM106B single nucleotide polymorphisms ... ...

    Abstract TMEM106B was identified as a major risk factor in a genome-wide association study for frontotemporal lobar degeneration (FTLD) with TAR DNA-binding protein (TDP)-43 pathology. The most significant association of TMEM106B single nucleotide polymorphisms with risk of FTLD-TDP was observed in patients with progranulin (GRN) mutations. Subsequent studies suggested an inverse correlation between TMEM106B expression and GRN levels in patient serum. However, in this study, this was not confirmed as we failed to detect a significant alteration of GRN levels upon knockdown or exogenous expression of TMEM106B in heterologous cells. To provide a basis for understanding TMEM106B function in health and disease, we investigated the membrane orientation and subcellular localization of this completely uncharacterized protein. By differential membrane extraction and sequential mutagenesis of potential N-glycosylation sites, we identified TMEM106B as a type 2 integral membrane protein with a highly glycosylated luminal domain. Glycosylation is partially required for the transport of TMEM106B beyond the endoplasmic reticulum to late cellular compartments. Endogenous as well as overexpressed TMEM106B localizes to late endosomes and lysosomes. Interestingly, the inhibition of vacuolar H(+)-ATPases significantly increased the levels of TMEM106B, a finding that may provide an unexpected biochemical link to GRN, because this protein is also strongly increased under the same conditions. Our findings provide a biochemical and cell biological basis for the understanding of the pathological role of TMEM106B in FTLD, an incurable neurodegenerative disorder.
    MeSH term(s) Cell Membrane/genetics ; Cell Membrane/metabolism ; Cell Membrane/pathology ; Endosomes/genetics ; Endosomes/metabolism ; Endosomes/pathology ; Frontotemporal Lobar Degeneration/genetics ; Frontotemporal Lobar Degeneration/metabolism ; Frontotemporal Lobar Degeneration/pathology ; Genome-Wide Association Study ; Glycosylation ; HEK293 Cells ; HeLa Cells ; Humans ; Lysosomes/genetics ; Lysosomes/metabolism ; Lysosomes/pathology ; Membrane Proteins/genetics ; Membrane Proteins/metabolism ; Nerve Tissue Proteins/genetics ; Nerve Tissue Proteins/metabolism ; Polymorphism, Single Nucleotide ; Protein Transport/genetics ; Risk Factors ; Vacuolar Proton-Translocating ATPases/genetics ; Vacuolar Proton-Translocating ATPases/metabolism
    Chemical Substances Membrane Proteins ; Nerve Tissue Proteins ; TMEM106B protein, human ; Vacuolar Proton-Translocating ATPases (EC 3.6.1.-)
    Language English
    Publishing date 2012-04-17
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.M112.365098
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: The FTLD risk factor TMEM106B and MAP6 control dendritic trafficking of lysosomes.

    Schwenk, Benjamin M / Lang, Christina M / Hogl, Sebastian / Tahirovic, Sabina / Orozco, Denise / Rentzsch, Kristin / Lichtenthaler, Stefan F / Hoogenraad, Casper C / Capell, Anja / Haass, Christian / Edbauer, Dieter

    The EMBO journal

    2013  Volume 33, Issue 5, Page(s) 450–467

    Abstract: TMEM106B is a major risk factor for frontotemporal lobar degeneration with TDP-43 pathology. TMEM106B localizes to lysosomes, but its function remains unclear. We show that TMEM106B knockdown in primary neurons affects lysosomal trafficking and blunts ... ...

    Abstract TMEM106B is a major risk factor for frontotemporal lobar degeneration with TDP-43 pathology. TMEM106B localizes to lysosomes, but its function remains unclear. We show that TMEM106B knockdown in primary neurons affects lysosomal trafficking and blunts dendritic arborization. We identify microtubule-associated protein 6 (MAP6) as novel interacting protein for TMEM106B. MAP6 over-expression inhibits dendritic branching similar to TMEM106B knockdown. MAP6 knockdown fully rescues the dendritic phenotype of TMEM106B knockdown, supporting a functional interaction between TMEM106B and MAP6. Live imaging reveals that TMEM106B knockdown and MAP6 overexpression strongly increase retrograde transport of lysosomes in dendrites. Downregulation of MAP6 in TMEM106B knockdown neurons restores the balance of anterograde and retrograde lysosomal transport and thereby prevents loss of dendrites. To strengthen the link, we enhanced anterograde lysosomal transport by expressing dominant-negative Rab7-interacting lysosomal protein (RILP), which also rescues the dendrite loss in TMEM106B knockdown neurons. Thus, TMEM106B/MAP6 interaction is crucial for controlling dendritic trafficking of lysosomes, presumably by acting as a molecular brake for retrograde transport. Lysosomal misrouting may promote neurodegeneration in patients with TMEM106B risk variants.
    MeSH term(s) Animals ; Cell Line ; Dendrites/metabolism ; Gene Expression ; Gene Knockdown Techniques ; Humans ; Lysosomes/metabolism ; Membrane Proteins/metabolism ; Microtubule-Associated Proteins/metabolism ; Nerve Tissue Proteins/metabolism ; Protein Interaction Mapping ; Rats
    Chemical Substances MAP6 protein, human ; Membrane Proteins ; Microtubule-Associated Proteins ; Nerve Tissue Proteins ; TMEM106B protein, human
    Language English
    Publishing date 2013-12-19
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 586044-1
    ISSN 1460-2075 ; 0261-4189
    ISSN (online) 1460-2075
    ISSN 0261-4189
    DOI 10.1002/embj.201385857
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Common pathobiochemical hallmarks of progranulin-associated frontotemporal lobar degeneration and neuronal ceroid lipofuscinosis.

    Götzl, Julia K / Mori, Kohji / Damme, Markus / Fellerer, Katrin / Tahirovic, Sabina / Kleinberger, Gernot / Janssens, Jonathan / van der Zee, Julie / Lang, Christina M / Kremmer, Elisabeth / Martin, Jean-Jacques / Engelborghs, Sebastiaan / Kretzschmar, Hans A / Arzberger, Thomas / Van Broeckhoven, Christine / Haass, Christian / Capell, Anja

    Acta neuropathologica

    2014  Volume 127, Issue 6, Page(s) 845–860

    Abstract: Heterozygous loss-of-function mutations in the progranulin (GRN) gene and the resulting reduction of GRN levels is a common genetic cause for frontotemporal lobar degeneration (FTLD) with accumulation of TAR DNA-binding protein (TDP)-43. Recently, it has ...

    Abstract Heterozygous loss-of-function mutations in the progranulin (GRN) gene and the resulting reduction of GRN levels is a common genetic cause for frontotemporal lobar degeneration (FTLD) with accumulation of TAR DNA-binding protein (TDP)-43. Recently, it has been shown that a complete GRN deficiency due to a homozygous GRN loss-of-function mutation causes neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disorder. These findings suggest that lysosomal dysfunction may also contribute to some extent to FTLD. Indeed, Grn(-/-) mice recapitulate not only pathobiochemical features of GRN-associated FTLD-TDP (FTLD-TDP/GRN), but also those which are characteristic for NCL and lysosomal impairment. In Grn(-/-) mice the lysosomal proteins cathepsin D (CTSD), LAMP (lysosomal-associated membrane protein) 1 and the NCL storage components saposin D and subunit c of mitochondrial ATP synthase (SCMAS) were all found to be elevated. Moreover, these mice display increased levels of transmembrane protein (TMEM) 106B, a lysosomal protein known as a risk factor for FTLD-TDP pathology. In line with a potential pathological overlap of FTLD and NCL, Ctsd(-/-) mice, a model for NCL, show elevated levels of the FTLD-associated proteins GRN and TMEM106B. In addition, pathologically phosphorylated TDP-43 occurs in Ctsd(-/-) mice to a similar extent as in Grn(-/-) mice. Consistent with these findings, some NCL patients accumulate pathologically phosphorylated TDP-43 within their brains. Based on these observations, we searched for pathological marker proteins, which are characteristic for NCL or lysosomal impairment in brains of FTLD-TDP/GRN patients. Strikingly, saposin D, SCMAS as well as the lysosomal proteins CTSD and LAMP1/2 are all elevated in patients with FTLD-TDP/GRN. Thus, our findings suggest that lysosomal storage disorders and GRN-associated FTLD may share common features.
    MeSH term(s) Animals ; Brain/metabolism ; Brain/pathology ; Cathepsin D/genetics ; Cathepsin D/metabolism ; DNA-Binding Proteins/metabolism ; Disease Models, Animal ; Frontotemporal Lobar Degeneration/metabolism ; Frontotemporal Lobar Degeneration/pathology ; Granulins ; Humans ; Immunoblotting ; Immunohistochemistry ; Intercellular Signaling Peptides and Proteins/deficiency ; Intercellular Signaling Peptides and Proteins/genetics ; Intercellular Signaling Peptides and Proteins/metabolism ; Mice, Knockout ; Neuronal Ceroid-Lipofuscinoses/metabolism ; Neuronal Ceroid-Lipofuscinoses/pathology ; Phosphorylation ; Progranulins
    Chemical Substances DNA-Binding Proteins ; GRN protein, human ; Granulins ; Grn protein, mouse ; Intercellular Signaling Peptides and Proteins ; Progranulins ; TARDBP protein, human ; TDP-43 protein, mouse ; Cathepsin D (EC 3.4.23.5) ; Ctsd protein, mouse (EC 3.4.23.5)
    Language English
    Publishing date 2014-03-12
    Publishing country Germany
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1079-0
    ISSN 1432-0533 ; 0001-6322
    ISSN (online) 1432-0533
    ISSN 0001-6322
    DOI 10.1007/s00401-014-1262-6
    Database MEDical Literature Analysis and Retrieval System OnLINE

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