TY - JOUR A1 - Lichter, Katharina A1 - Paul, Mila Marie A1 - Pauli, Martin A1 - Schoch, Susanne A1 - Kollmannsberger, Philip A1 - Stigloher, Christian A1 - Heckmann, Manfred A1 - Sirén, Anna-Leena T1 - Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse JF - Cell Reports N2 - Rab3A-interacting molecule (RIM) is crucial for fast Ca\(^{2+}\)-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α\(^{−/−}\) and wild-type mice. In RIM1α\(^{−/−}\), AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0–2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α\(^{−/−}\) is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs. KW - active zone KW - acute brain slices KW - CA3 KW - electron tomography KW - high-pressure freezing KW - hippocampal mossy fiber bouton KW - RIM1α KW - SV pool KW - synaptic ultrastructure KW - presynaptic Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300913 VL - 40 IS - 12 ER - 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 - Frank, Benjamin A1 - Marcu, Ana A1 - de Oliveira Almeida Petersen, Antonio Luis A1 - Weber, Heike A1 - Stigloher, Christian A1 - Mottram, Jeremy C. A1 - Scholz, Claus Jürgen A1 - Schurigt, Uta T1 - Autophagic digestion of Leishmania major by host macrophages is associated with differential expression of BNIP3, CTSE, and the miRNAs miR-101c, miR-129, and miR-210 JF - Parasites & Vectors N2 - Background Autophagy participates in innate immunity by eliminating intracellular pathogens. Consequently, numerous microorganisms have developed strategies to impair the autophagic machinery in phagocytes. In the current study, interactions between Leishmania major (L. m.) and the autophagic machinery of bone marrow-derived macrophages (BMDM) were analyzed. Methods BMDM were generated from BALB/c mice, and the cells were infected with L. m. promastigotes. Transmission electron microscopy (TEM) and electron tomography were used to investigate the ultrastructure of BMDM and the intracellular parasites. Affymetrix® chip analyses were conducted to identify autophagy-related messenger RNAs (mRNAs) and microRNAs (miRNAs). The protein expression levels of autophagy related 5 (ATG5), BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3), cathepsin E (CTSE), mechanistic target of rapamycin (MTOR), microtubule-associated proteins 1A/1B light chain 3B (LC3B), and ubiquitin (UB) were investigated through western blot analyses. BMDM were transfected with specific small interfering RNAs (siRNAs) against autophagy-related genes and with mimics or inhibitors of autophagy-associated miRNAs. The infection rates of BMDM were determined by light microscopy after a parasite-specific staining. Results The experiments demonstrated autophagy induction in BMDM after in vitro infection with L. m.. The results suggested a putative MTOR phosphorylation-dependent counteracting mechanism in the early infection phase and indicated that intracellular amastigotes were cleared by autophagy in BMDM in the late infection phase. Transcriptomic analyses and specific downregulation of protein expression with siRNAs suggested there is an association between the infection-specific over expression of BNIP3, as well as CTSE, and the autophagic activity of BMDM. Transfection with mimics of mmu-miR-101c and mmu-miR-129-5p, as well as with an inhibitor of mmu-miR-210-5p, demonstrated direct effects of the respective miRNAs on parasite clearance in L. m.-infected BMDM. Furthermore, Affymetrix® chip analyses revealed a complex autophagy-related RNA network consisting of differentially expressed mRNAs and miRNAs in BMDM, which indicates high glycolytic and inflammatory activity in the host macrophages. Conclusions Autophagy in L. m.-infected host macrophages is a highly regulated cellular process at both the RNA level and the protein level. Autophagy has the potential to clear parasites from the host. The results obtained from experiments with murine host macrophages could be translated in the future to develop innovative and therapeutic antileishmanial strategies for human patients. KW - autophagy KW - BNIP3 KW - CTSE KW - electron tomography KW - leishmania major KW - macrophages KW - miRNAs KW - MTOR KW - siRNAs KW - transmission electron microscopy Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-124997 VL - 8 IS - 404 ER -