Publications

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4 Publications visible to you, out of a total of 4

Abstract (Expand)

Heterozygous mutations in the TBK1 gene can cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The majority of TBK1-ALS/FTD patients carry deleterious loss-of-expression mutations, and it is still unclear which TBK1 function leads to neurodegeneration. We investigated the impact of the pathogenic TBK1 missense variant p.E696K, which does not abolish protein expression, but leads to a selective loss of TBK1 binding to the autophagy adaptor protein and TBK1 substrate optineurin. Using organelle-specific proteomics, we found that in a knock-in mouse model and human iPSC-derived motor neurons, the p.E696K mutation causes presymptomatic onset of autophagolysosomal dysfunction in neurons precipitating the accumulation of damaged lysosomes. This is followed by a progressive, age-dependent motor neuron disease. Contrary to the phenotype of mice with full Tbk1 knock-out, RIPK/TNF-alpha-dependent hepatic, neuronal necroptosis, and overt autoinflammation were not detected. Our in vivo results indicate autophagolysosomal dysfunction as a trigger for neurodegeneration and a promising therapeutic target in TBK1-ALS/FTD.

Authors: D. Brenner, K. Sieverding, J. Srinidhi, S. Zellner, C. Secker, R. Yilmaz, J. Dyckow, S. Amr, A. Ponomarenko, E. Tunaboylu, Y. Douahem, J. S. Schlag, L. Rodriguez Martinez, G. Kislinger, C. Niemann, K. Nalbach, W. P. Ruf, J. Uhl, J. Hollenbeck, L. Schirmer, A. Catanese, C. S. Lobsiger, K. M. Danzer, D. Yilmazer-Hanke, C. Munch, P. Koch, A. Freischmidt, M. Fetting, C. Behrends, R. Parlato, J. H. Weishaupt

Date Published: 6th May 2024

Publication Type: Journal

Abstract (Expand)

Aging results in gray and white matter degeneration, but the specific microglial responses are unknown. Using single-cell RNA sequencing from white and gray matter separately, we identified white matter-associated microglia (WAMs), which share parts of the disease-associated microglia (DAM) gene signature and are characterized by activation of genes implicated in phagocytic activity and lipid metabolism. WAMs depend on triggering receptor expressed on myeloid cells 2 (TREM2) signaling and are aging dependent. In the aged brain, WAMs form independent of apolipoprotein E (APOE), in contrast to mouse models of Alzheimer's disease, in which microglia with the WAM gene signature are generated prematurely and in an APOE-dependent pathway similar to DAMs. Within the white matter, microglia frequently cluster in nodules, where they are engaged in clearing degenerated myelin. Thus, WAMs may represent a potentially protective response required to clear degenerated myelin accumulating during white matter aging and disease.

Authors: S. Safaiyan, S. Besson-Girard, T. Kaya, L. Cantuti-Castelvetri, L. Liu, H. Ji, M. Schifferer, G. Gouna, F. Usifo, N. Kannaiyan, D. Fitzner, X. Xiang, M. J. Rossner, M. Brendel, O. Gokce, M. Simons

Date Published: 7th Apr 2021

Publication Type: Journal

Abstract (Expand)

Niemann-Pick type C disease is a rare neurodegenerative disorder mainly caused by mutations in NPC1, resulting in abnormal late endosomal/lysosomal lipid storage. Although microgliosis is a prominent pathological feature, direct consequences of NPC1 loss on microglial function remain not fully characterized. We discovered pathological proteomic signatures and phenotypes in NPC1-deficient murine models and demonstrate a cell autonomous function of NPC1 in microglia. Loss of NPC1 triggers enhanced phagocytic uptake and impaired myelin turnover in microglia that precede neuronal death. Npc1(-/-) microglia feature a striking accumulation of multivesicular bodies and impaired trafficking of lipids to lysosomes while lysosomal degradation function remains preserved. Molecular and functional defects were also detected in blood-derived macrophages of NPC patients that provide a potential tool for monitoring disease. Our study underscores an essential cell autonomous role for NPC1 in immune cells and implies microglial therapeutic potential.

Authors: A. Colombo, L. Dinkel, S. A. Muller, L. Sebastian Monasor, M. Schifferer, L. Cantuti-Castelvetri, J. Konig, L. Vidatic, T. Bremova-Ertl, A. P. Lieberman, S. Hecimovic, M. Simons, S. F. Lichtenthaler, M. Strupp, S. A. Schneider, S. Tahirovic

Date Published: 24th Feb 2021

Publication Type: Journal

Abstract (Expand)

Remyelination requires innate immune system function, but how exactly microglia and macrophages clear myelin debris after injury and tailor a specific regenerative response is unclear. Here, we asked whether pro-inflammatory microglial/macrophage activation is required for this process. We established a novel toxin-based spinal cord model of de- and remyelination in zebrafish and showed that pro-inflammatory NF-kappaB-dependent activation in phagocytes occurs rapidly after myelin injury. We found that the pro-inflammatory response depends on myeloid differentiation primary response 88 (MyD88). MyD88-deficient mice and zebrafish were not only impaired in the degradation of myelin debris, but also in initiating the generation of new oligodendrocytes for myelin repair. We identified reduced generation of TNF-alpha in lesions of MyD88-deficient animals, a pro-inflammatory molecule that was able to induce the generation of new premyelinating oligodendrocytes. Our study shows that pro-inflammatory phagocytic signaling is required for myelin debris degradation, for inflammation resolution, and for initiating the generation of new oligodendrocytes.

Authors: M. I. Cunha, M. Su, L. Cantuti-Castelvetri, S. A. Muller, M. Schifferer, M. Djannatian, I. Alexopoulos, F. van der Meer, A. Winkler, T. J. van Ham, B. Schmid, S. F. Lichtenthaler, C. Stadelmann, M. Simons

Date Published: 4th May 2020

Publication Type: Journal

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