TY - JOUR A1 - Markert, Sebastian M. A1 - Skoruppa, Michael A1 - Yu, Bin A1 - Mulcahy, Ben A1 - Zhen, Mai A1 - Gao, Shangbang A1 - Sendtner, Michael A1 - Stigloher, Christian T1 - Overexpression of an ALS-associated FUS mutation in C. elegans disrupts NMJ morphology and leads to defective neuromuscular transmission JF - Biology Open N2 - The amyotrophic lateral sclerosis (ALS) neurodegenerative disorder has been associated with multiple genetic lesions, including mutations in the gene for fused in sarcoma (FUS), a nuclear-localized RNA/DNA-binding protein. Neuronal expression of the pathological form of FUS proteins in Caenorhabditis elegans results in mislocalization and aggregation of FUS in the cytoplasm, and leads to impairment of motility. However, the mechanisms by which the mutant FUS disrupts neuronal health and function remain unclear. Here we investigated the impact of ALS-associated FUS on motor neuron health using correlative light and electron microscopy, electron tomography, and electrophysiology. We show that ectopic expression of wild-type or ALS-associated human FUS impairs synaptic vesicle docking at neuromuscular junctions. ALS-associated FUS led to the emergence of a population of large, electron-dense, and filament-filled endosomes. Electrophysiological recording revealed reduced transmission from motor neurons to muscles. Together, these results suggest a pathological effect of ALS-causing FUS at synaptic structure and function organization. KW - C. elegans KW - fused in sarcoma KW - amyotrophic lateral sclerosis KW - uper-resolution array tomography KW - electron tomography KW - neuromuscular junction Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230662 VL - 9 ER - TY - JOUR A1 - Yadav, Preeti A1 - Selvaraj, Bhuvaneish T. A1 - Bender, Florian L. P. A1 - Behringer, Marcus A1 - Moradi, Mehri A1 - Sivadasan, Rajeeve A1 - Dombert, Benjamin A1 - Blum, Robert A1 - Asan, Esther A1 - Sauer, Markus A1 - Julien, Jean-Pierre A1 - Sendtner, Michael T1 - Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling JF - Acta Neuropathologica N2 - In neurons, microtubules form a dense array within axons, and the stability and function of this microtubule network is modulated by neurofilaments. Accumulation of neurofilaments has been observed in several forms of neurodegenerative diseases, but the mechanisms how elevated neurofilament levels destabilize axons are unknown so far. Here, we show that increased neurofilament expression in motor nerves of pmn mutant mice, a model of motoneuron disease, causes disturbed microtubule dynamics. The disease is caused by a point mutation in the tubulin-specific chaperone E (Tbce) gene, leading to an exchange of the most C-terminal amino acid tryptophan to glycine. As a consequence, the TBCE protein becomes instable which then results in destabilization of axonal microtubules and defects in axonal transport, in particular in motoneurons. Depletion of neurofilament increases the number and regrowth of microtubules in pmn mutant motoneurons and restores axon elongation. This effect is mediated by interaction of neurofilament with the stathmin complex. Accumulating neurofilaments associate with stathmin in axons of pmn mutant motoneurons. Depletion of neurofilament by Nefl knockout increases Stat3-stathmin interaction and stabilizes the microtubules in pmn mutant motoneurons. Consequently, counteracting enhanced neurofilament expression improves axonal maintenance and prolongs survival of pmn mutant mice. We propose that this mechanism could also be relevant for other neurodegenerative diseases in which neurofilament accumulation and loss of microtubules are prominent features. KW - Amyotrophic-lateral-sclerosis KW - Transgenic mice KW - Mouse model KW - Alzheimers disease KW - Neurofilament KW - Progressive motor neuronopathy KW - Axonal transport KW - Intermediate filaments KW - Motoneuron disease KW - Lacking neurofilaments KW - Missense mutation KW - Axon degeneration KW - Microtubules KW - Stathmin KW - Stat3 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-188234 VL - 132 IS - 1 ER - TY - JOUR A1 - Simon, Christian M. A1 - Rauskolb, Stefanie A1 - Gunnersen, Jennifer M. A1 - Holtmann, Bettina A1 - Drepper, Carsten A1 - Dombert, Benjamin A1 - Braga, Massimiliano A1 - Wiese, Stefan A1 - Jablonka, Sibylle A1 - Pühringer, Dirk A1 - Zielasek, Jürgen A1 - Hoeflich, Andreas A1 - Silani, Vincenzo A1 - Wolf, Eckhard A1 - Kneitz, Susanne A1 - Sommer, Claudia A1 - Toyka, Klaus V. A1 - Sendtner, Michael T1 - Dysregulated IGFBP5 expression causes axon degeneration and motoneuron loss in diabetic neuropathy JF - Acta Neuropathologica N2 - Diabetic neuropathy (DNP), afflicting sensory and motor nerve fibers, is a major complication in diabetes.The underlying cellular mechanisms of axon degeneration are poorly understood. IGFBP5, an inhibitory binding protein for insulin-like growth factor 1 (IGF1) is highly up-regulated in nerve biopsies of patients with DNP. We investigated the pathogenic relevance of this finding in transgenic mice overexpressing IGFBP5 in motor axons and sensory nerve fibers. These mice develop motor axonopathy and sensory deficits similar to those seen in DNP. Motor axon degeneration was also observed in mice in which the IGF1 receptor(IGF1R) was conditionally depleted in motoneurons, indicating that reduced activity of IGF1 on IGF1R in motoneurons is responsible for the observed effect. These data provide evidence that elevated expression of IGFBP5 in diabetic nerves reduces the availability of IGF1 for IGF1R on motor axons, thus leading to progressive neurodegeneration. Inhibition of IGFBP5 could thus offer novel treatment strategies for DNP. KW - Motor nerve biopsy KW - Diabetic polyneuropathy KW - Neuropathy KW - Neurotrophic factors KW - Axonal degeneration Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-154569 VL - 130 SP - 373 EP - 387 ER -