@article{SalehiZarePrezzaetal.2023, author = {Salehi, Saeede and Zare, Abdolhossein and Prezza, Gianluca and Bader, Jakob and Schneider, Cornelius and Fischer, Utz and Meissner, Felix and Mann, Matthias and Briese, Michael and Sendtner, Michael}, title = {Cytosolic Ptbp2 modulates axon growth in motoneurons through axonal localization and translation of Hnrnpr}, series = {Nature Communications}, volume = {14}, journal = {Nature Communications}, doi = {10.1038/s41467-023-39787-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357639}, year = {2023}, abstract = {The neuronal RNA-binding protein Ptbp2 regulates neuronal differentiation by modulating alternative splicing programs in the nucleus. Such programs contribute to axonogenesis by adjusting the levels of protein isoforms involved in axon growth and branching. While its functions in alternative splicing have been described in detail, cytosolic roles of Ptbp2 for axon growth have remained elusive. Here, we show that Ptbp2 is located in the cytosol including axons and growth cones of motoneurons, and that depletion of cytosolic Ptbp2 affects axon growth. We identify Ptbp2 as a major interactor of the 3' UTR of Hnrnpr mRNA encoding the RNA-binding protein hnRNP R. Axonal localization of Hnrnpr mRNA and local synthesis of hnRNP R protein are strongly reduced when Ptbp2 is depleted, leading to defective axon growth. Ptbp2 regulates hnRNP R translation by mediating the association of Hnrnpr with ribosomes in a manner dependent on the translation factor eIF5A2. Our data thus suggest a mechanism whereby cytosolic Ptbp2 modulates axon growth by fine-tuning the mRNA transport and local synthesis of an RNA-binding protein.}, language = {en} } @article{MassihVehSchenkeetal.2023, author = {Massih, Bita and Veh, Alexander and Schenke, Maren and Mungwa, Simon and Seeger, Bettina and Selvaraj, Bhuvaneish T. and Chandran, Siddharthan and Reinhardt, Peter and Sterneckert, Jared and Hermann, Andreas and Sendtner, Michael and L{\"u}ningschr{\"o}r, Patrick}, title = {A 3D cell culture system for bioengineering human neuromuscular junctions to model ALS}, series = {Frontiers in Cell and Developmental Biology}, volume = {11}, journal = {Frontiers in Cell and Developmental Biology}, issn = {2296-634X}, doi = {10.3389/fcell.2023.996952}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304161}, year = {2023}, abstract = {The signals that coordinate and control movement in vertebrates are transmitted from motoneurons (MNs) to their target muscle cells at neuromuscular junctions (NMJs). Human NMJs display unique structural and physiological features, which make them vulnerable to pathological processes. NMJs are an early target in the pathology of motoneuron diseases (MND). Synaptic dysfunction and synapse elimination precede MN loss suggesting that the NMJ is the starting point of the pathophysiological cascade leading to MN death. Therefore, the study of human MNs in health and disease requires cell culture systems that enable the connection to their target muscle cells for NMJ formation. Here, we present a human neuromuscular co-culture system consisting of induced pluripotent stem cell (iPSC)-derived MNs and 3D skeletal muscle tissue derived from myoblasts. We used self-microfabricated silicone dishes combined with Velcro hooks to support the formation of 3D muscle tissue in a defined extracellular matrix, which enhances NMJ function and maturity. Using a combination of immunohistochemistry, calcium imaging, and pharmacological stimulations, we characterized and confirmed the function of the 3D muscle tissue and the 3D neuromuscular co-cultures. Finally, we applied this system as an in vitro model to study the pathophysiology of Amyotrophic Lateral Sclerosis (ALS) and found a decrease in neuromuscular coupling and muscle contraction in co-cultures with MNs harboring ALS-linked SOD1 mutation. In summary, the human 3D neuromuscular cell culture system presented here recapitulates aspects of human physiology in a controlled in vitro setting and is suitable for modeling of MND.}, language = {en} } @article{AndreskaLueningschroerWolfetal.2023, author = {Andreska, Thomas and L{\"u}ningschr{\"o}r, Patrick and Wolf, Daniel and McFleder, Rhonda L. and Ayon-Olivas, Maurilyn and Rattka, Marta and Drechsler, Christine and Perschin, Veronika and Blum, Robert and Aufmkolk, Sarah and Granado, Noelia and Moratalla, Rosario and Sauer, Markus and Monoranu, Camelia and Volkmann, Jens and Ip, Chi Wang and Stigloher, Christian and Sendtner, Michael}, title = {DRD1 signaling modulates TrkB turnover and BDNF sensitivity in direct pathway striatal medium spiny neurons}, series = {Cell Reports}, volume = {42}, journal = {Cell Reports}, number = {6}, doi = {10.1016/j.celrep.2023.112575}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-349932}, year = {2023}, abstract = {Highlights • Dopamine receptor-1 activation induces TrkB cell-surface expression in striatal neurons • Dopaminergic deficits cause TrkB accumulation and clustering in the ER • TrkB clusters colocalize with cargo receptor SORCS-2 in direct pathway striatal neurons • Intracellular TrkB clusters fail to fuse with lysosomes after dopamine depletion Summary Disturbed motor control is a hallmark of Parkinson's disease (PD). Cortico-striatal synapses play a central role in motor learning and adaption, and brain-derived neurotrophic factor (BDNF) from cortico-striatal afferents modulates their plasticity via TrkB in striatal medium spiny projection neurons (SPNs). We studied the role of dopamine in modulating the sensitivity of direct pathway SPNs (dSPNs) to BDNF in cultures of fluorescence-activated cell sorting (FACS)-enriched D1-expressing SPNs and 6-hydroxydopamine (6-OHDA)-treated rats. DRD1 activation causes enhanced TrkB translocation to the cell surface and increased sensitivity for BDNF. In contrast, dopamine depletion in cultured dSPN neurons, 6-OHDA-treated rats, and postmortem brain of patients with PD reduces BDNF responsiveness and causes formation of intracellular TrkB clusters. These clusters associate with sortilin related VPS10 domain containing receptor 2 (SORCS-2) in multivesicular-like structures, which apparently protects them from lysosomal degradation. Thus, impaired TrkB processing might contribute to disturbed motor function in PD.}, language = {en} } @article{DengReinhardHennleinetal.2022, author = {Deng, Chunchu and Reinhard, Sebastian and Hennlein, Luisa and Eilts, Janna and Sachs, Stefan and Doose, S{\"o}ren and Jablonka, Sibylle and Sauer, Markus and Moradi, Mehri and Sendtner, Michael}, title = {Impaired dynamic interaction of axonal endoplasmic reticulum and ribosomes contributes to defective stimulus-response in spinal muscular atrophy}, series = {Translational Neurodegeneration}, volume = {11}, journal = {Translational Neurodegeneration}, number = {1}, issn = {2047-9158}, doi = {10.1186/s40035-022-00304-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300649}, year = {2022}, abstract = {Background: Axonal degeneration and defects in neuromuscular neurotransmission represent a pathological hallmark in spinal muscular atrophy (SMA) and other forms of motoneuron disease. These pathological changes do not only base on altered axonal and presynaptic architecture, but also on alterations in dynamic movements of organelles and subcellular structures that are not necessarily reflected by static histopathological changes. The dynamic interplay between the axonal endoplasmic reticulum (ER) and ribosomes is essential for stimulus-induced local translation in motor axons and presynaptic terminals. However, it remains enigmatic whether the ER and ribosome crosstalk is impaired in the presynaptic compartment of motoneurons with Smn (survival of motor neuron) deficiency that could contribute to axonopathy and presynaptic dysfunction in SMA. Methods: Using super-resolution microscopy, proximity ligation assay (PLA) and live imaging of cultured motoneurons from a mouse model of SMA, we investigated the dynamics of the axonal ER and ribosome distribution and activation. Results: We observed that the dynamic remodeling of ER was impaired in axon terminals of Smn-deficient motoneurons. In addition, in axon terminals of Smn-deficient motoneurons, ribosomes failed to respond to the brain-derived neurotrophic factor stimulation, and did not undergo rapid association with the axonal ER in response to extracellular stimuli. Conclusions: These findings implicate impaired dynamic interplay between the ribosomes and ER in axon terminals of motoneurons as a contributor to the pathophysiology of SMA and possibly also other motoneuron diseases.}, language = {en} } @article{HaberstumpfForsterLeinweberetal.2022, author = {Haberstumpf, Sophia and Forster, Andr{\´e} and Leinweber, Jonas and Rauskolb, Stefanie and Hewig, Johannes and Sendtner, Michael and Lauer, Martin and Polak, Thomas and Deckert, J{\"u}rgen and Herrmann, Martin J.}, title = {Measurement invariance testing of longitudinal neuropsychiatric test scores distinguishes pathological from normative cognitive decline and highlights its potential in early detection research}, series = {Journal of Neuropsychology}, volume = {16}, journal = {Journal of Neuropsychology}, number = {2}, doi = {10.1111/jnp.12269}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318932}, pages = {324 -- 352}, year = {2022}, abstract = {Objective Alzheimer's disease (AD) is a growing challenge worldwide, which is why the search for early-onset predictors must be focused as soon as possible. Longitudinal studies that investigate courses of neuropsychological and other variables screen for such predictors correlated to mild cognitive impairment (MCI). However, one often neglected issue in analyses of such studies is measurement invariance (MI), which is often assumed but not tested for. This study uses the absence of MI (non-MI) and latent factor scores instead of composite variables to assess properties of cognitive domains, compensation mechanisms, and their predictability to establish a method for a more comprehensive understanding of pathological cognitive decline. Methods An exploratory factor analysis (EFA) and a set of increasingly restricted confirmatory factor analyses (CFAs) were conducted to find latent factors, compared them with the composite approach, and to test for longitudinal (partial-)MI in a neuropsychiatric test battery, consisting of 14 test variables. A total of 330 elderly (mean age: 73.78 ± 1.52 years at baseline) were analyzed two times (3 years apart). Results EFA revealed a four-factor model representing declarative memory, attention, working memory, and visual-spatial processing. Based on CFA, an accurate model was estimated across both measurement timepoints. Partial non-MI was found for parameters such as loadings, test- and latent factor intercepts as well as latent factor variances. The latent factor approach was preferable to the composite approach. Conclusion The overall assessment of non-MI latent factors may pose a possible target for this field of research. Hence, the non-MI of variances indicated variables that are especially suited for the prediction of pathological cognitive decline, while non-MI of intercepts indicated general aging-related decline. As a result, the sole assessment of MI may help distinguish pathological from normative aging processes and additionally may reveal compensatory neuropsychological mechanisms.}, language = {en} } @article{FrancoEspinGatiusArmengoletal.2022, author = {Franco-Espin, Julio and Gatius, Ala{\´o} and Armengol, Jos{\´e} {\´A}ngel and Arumugam, Saravanan and Moradi, Mehri and Sendtner, Michael and Calder{\´o}, Jordi and Tabares, Lucia}, title = {SMN is physiologically downregulated at wild-type motor nerve terminals but aggregates together with neurofilaments in SMA mouse models}, series = {Biomolecules}, volume = {12}, journal = {Biomolecules}, number = {10}, issn = {2218-273X}, doi = {10.3390/biom12101524}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290263}, year = {2022}, abstract = {Survival motor neuron (SMN) is an essential and ubiquitously expressed protein that participates in several aspects of RNA metabolism. SMN deficiency causes a devastating motor neuron disease called spinal muscular atrophy (SMA). SMN forms the core of a protein complex localized at the cytoplasm and nuclear gems and that catalyzes spliceosomal snRNP particle synthesis. In cultured motor neurons, SMN is also present in dendrites and axons, and forms part of the ribonucleoprotein transport granules implicated in mRNA trafficking and local translation. Nevertheless, the distribution, regulation, and role of SMN at the axons and presynaptic motor terminals in vivo are still unclear. By using conventional confocal microscopy and STED super-resolution nanoscopy, we found that SMN appears in the form of granules distributed along motor axons at nerve terminals. Our fluorescence in situ hybridization and electron microscopy studies also confirmed the presence of β-actin mRNA, ribosomes, and polysomes in the presynaptic motor terminal, key elements of the protein synthesis machinery involved in local translation in this compartment. SMN granules co-localize with the microtubule-associated protein 1B (MAP1B) and neurofilaments, suggesting that the cytoskeleton participates in transporting and positioning the granules. We also found that, while SMN granules are physiologically downregulated at the presynaptic element during the period of postnatal maturation in wild-type (non-transgenic) mice, they accumulate in areas of neurofilament aggregation in SMA mice, suggesting that the high expression of SMN at the NMJ, together with the cytoskeletal defects, contribute to impairing the bi-directional traffic of proteins and organelles between the axon and the presynaptic terminal.}, language = {en} } @article{GhanawiHennleinZareetal.2021, author = {Ghanawi, Hanaa and Hennlein, Luisa and Zare, Abdolhossein and Bader, Jakob and Salehi, Saeede and Hornburg, Daniel and Ji, Changhe and Sivadasan, Rajeeve and Drepper, Carsten and Meissner, Felix and Mann, Matthias and Jablonka, Sibylle and Briese, Michael and Sendtner, Michael}, title = {Loss of full-length hnRNP R isoform impairs DNA damage response in motoneurons by inhibiting Yb1 recruitment to chromatin}, series = {Nucleic Acids Research}, volume = {49}, journal = {Nucleic Acids Research}, number = {21}, doi = {10.1093/nar/gkab1120}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265687}, pages = {12284-12305}, year = {2021}, abstract = {Neurons critically rely on the functions of RNA-binding proteins to maintain their polarity and resistance to neurotoxic stress. HnRNP R has a diverse range of post-transcriptional regulatory functions and is important for neuronal development by regulating axon growth. Hnrnpr pre-mRNA undergoes alternative splicing giving rise to a full-length protein and a shorter isoform lacking its N-terminal acidic domain. To investigate functions selectively associated with the full-length hnRNP R isoform, we generated a Hnrnpr knockout mouse (Hnrnpr\(^{tm1a/tm1a}\)) in which expression of full-length hnRNP R was abolished while production of the truncated hnRNP R isoform was retained. Motoneurons cultured from Hnrnpr\(^{tm1a/tm1a}\) mice did not show any axonal growth defects but exhibited enhanced accumulation of double-strand breaks and an impaired DNA damage response upon exposure to genotoxic agents. Proteomic analysis of the hnRNP R interactome revealed the multifunctional protein Yb1 as a top interactor. Yb1-depleted motoneurons were defective in DNA damage repair. We show that Yb1 is recruited to chromatin upon DNA damage where it interacts with gamma-H2AX, a mechanism that is dependent on full-length hnRNP R. Our findings thus suggest a novel role of hnRNP R in maintaining genomic integrity and highlight the function of its N-terminal acidic domain in this context.}, language = {en} } @article{JiBaderRamanathanetal.2021, author = {Ji, Changhe and Bader, Jakob and Ramanathan, Pradhipa and Hennlein, Luisa and Meissner, Felix and Jablonka, Sibylle and Mann, Matthias and Fischer, Utz and Sendtner, Michael and Briese, Michael}, title = {Interaction of 7SK with the Smn complex modulates snRNP production}, series = {Nature Communications}, volume = {12}, journal = {Nature Communications}, number = {1}, doi = {10.1038/s41467-021-21529-1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259125}, pages = {1278}, year = {2021}, abstract = {Gene expression requires tight coordination of the molecular machineries that mediate transcription and splicing. While the interplay between transcription kinetics and spliceosome fidelity has been investigated before, less is known about mechanisms regulating the assembly of the spliceosomal machinery in response to transcription changes. Here, we report an association of the Smn complex, which mediates spliceosomal snRNP biogenesis, with the 7SK complex involved in transcriptional regulation. We found that Smn interacts with the 7SK core components Larp7 and Mepce and specifically associates with 7SK subcomplexes containing hnRNP R. The association between Smn and 7SK complexes is enhanced upon transcriptional inhibition leading to reduced production of snRNPs. Taken together, our findings reveal a functional association of Smn and 7SK complexes that is governed by global changes in transcription. Thus, in addition to its canonical nuclear role in transcriptional regulation, 7SK has cytosolic functions in fine-tuning spliceosome production according to transcriptional demand.}, language = {en} } @article{BrieseSendtner2021, author = {Briese, Michael and Sendtner, Michael}, title = {Keeping the balance: the noncoding RNA 7SK as a master regulator for neuron development and function}, series = {BioEssays}, volume = {43}, journal = {BioEssays}, number = {8}, doi = {10.1002/bies.202100092}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256613}, year = {2021}, abstract = {The noncoding RNA 7SK is a critical regulator of transcription by adjusting the activity of the kinase complex P-TEFb. Release of P-TEFb from 7SK stimulates transcription at many genes by promoting productive elongation. Conversely, P-TEFb sequestration by 7SK inhibits transcription. Recent studies have shown that 7SK functions are particularly important for neuron development and maintenance and it can thus be hypothesized that 7SK is at the center of many signaling pathways contributing to neuron function. 7SK activates neuronal gene expression programs that are key for terminal differentiation of neurons. Proteomics studies revealed a complex protein interactome of 7SK that includes several RNA-binding proteins. Some of these novel 7SK subcomplexes exert non-canonical cytosolic functions in neurons by regulating axonal mRNA transport and fine-tuning spliceosome production in response to transcription alterations. Thus, a picture emerges according to which 7SK acts as a multi-functional RNA scaffold that is integral for neuron homeostasis.}, language = {en} } @article{BrieseSaalBauernschubertLueningschroeretal.2020, author = {Briese, Michael and Saal-Bauernschubert, Lena and L{\"u}ningschr{\"o}r, Patrick and Moradi, Mehri and Dombert, Benjamin and Surrey, Verena and Appenzeller, Silke and Deng, Chunchu and Jablonka, Sibylle and Sendtner, Michael}, title = {Loss of Tdp-43 disrupts the axonal transcriptome of motoneurons accompanied by impaired axonal translation and mitochondria function}, series = {Acta Neuropathologica Communications}, volume = {8}, journal = {Acta Neuropathologica Communications}, doi = {10.1186/s40478-020-00987-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230322}, year = {2020}, abstract = {Protein inclusions containing the RNA-binding protein TDP-43 are a pathological hallmark of amyotrophic lateral sclerosis and other neurodegenerative disorders. The loss of TDP-43 function that is associated with these inclusions affects post-transcriptional processing of RNAs in multiple ways including pre-mRNA splicing, nucleocytoplasmic transport, modulation of mRNA stability and translation. In contrast, less is known about the role of TDP-43 in axonal RNA metabolism in motoneurons. Here we show that depletion of Tdp-43 in primary motoneurons affects axon growth. This defect is accompanied by subcellular transcriptome alterations in the axonal and somatodendritic compartment. The axonal localization of transcripts encoding components of the cytoskeleton, the translational machinery and transcripts involved in mitochondrial energy metabolism were particularly affected by loss of Tdp-43. Accordingly, we observed reduced protein synthesis and disturbed mitochondrial functions in axons of Tdp-43-depleted motoneurons. Treatment with nicotinamide rescued the axon growth defect associated with loss of Tdp-43. These results show that Tdp-43 depletion in motoneurons affects several pathways integral to axon health indicating that loss of TDP-43 function could thus make a major contribution to axonal pathomechanisms in ALS.}, language = {en} } @article{LueningschroerSlottaHeimannetal.2020, author = {L{\"u}ningschr{\"o}r, Patrick and Slotta, Carsten and Heimann, Peter and Briese, Michael and Weikert, Ulrich M. and Massih, Bita and Appenzeller, Silke and Sendtner, Michael and Kaltschmidt, Christian and Kaltschmidt, Barbara}, title = {Absence of Plekhg5 Results in Myelin Infoldings Corresponding to an Impaired Schwann Cell Autophagy, and a Reduced T-Cell Infiltration Into Peripheral Nerves}, series = {Frontiers in Cellular Neuroscience}, volume = {14}, journal = {Frontiers in Cellular Neuroscience}, issn = {1662-5102}, doi = {10.3389/fncel.2020.00185}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207538}, year = {2020}, abstract = {Inflammation and dysregulation of the immune system are hallmarks of several neurodegenerative diseases. An activated immune response is considered to be the cause of myelin breakdown in demyelinating disorders. In the peripheral nervous system (PNS), myelin can be degraded in an autophagy-dependent manner directly by Schwann cells or by macrophages, which are modulated by T-lymphocytes. Here, we show that the NF-κB activator Pleckstrin homology containing family member 5 (Plekhg5) is involved in the regulation of both Schwann cell autophagy and recruitment of T-lymphocytes in peripheral nerves during motoneuron disease. Plekhg5-deficient mice show defective axon/Schwann cell units characterized by myelin infoldings in peripheral nerves. Even at late stages, Plekhg5-deficient mice do not show any signs of demyelination and inflammation. Using RNAseq, we identified a transcriptional signature for an impaired immune response in sciatic nerves, which manifested in a reduced number of CD4\(^+\) and CD8\(^+\) T-cells. These findings identify Plekhg5 as a promising target to impede myelin breakdown in demyelinating PNS disorders.}, language = {en} } @article{MarkertSkoruppaYuetal.2020, author = {Markert, Sebastian M. and Skoruppa, Michael and Yu, Bin and Mulcahy, Ben and Zhen, Mai and Gao, Shangbang and Sendtner, Michael and Stigloher, Christian}, title = {Overexpression of an ALS-associated FUS mutation in C. elegans disrupts NMJ morphology and leads to defective neuromuscular transmission}, series = {Biology Open}, volume = {9}, journal = {Biology Open}, doi = {10.1242/bio.055129}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230662}, year = {2020}, abstract = {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.}, language = {en} } @article{AndreskaLueningschroerSendtner2020, author = {Andreska, Thomas and L{\"u}ningschr{\"o}r, Patrick and Sendtner, Michael}, title = {Regulation of TrkB cell surface expression — a mechanism for modulation of neuronal responsiveness to brain-derived neurotrophic factor}, series = {Cell and Tissue Research}, volume = {382}, journal = {Cell and Tissue Research}, doi = {10.1007/s00441-020-03224-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-235055}, pages = {5-14}, year = {2020}, abstract = {Neurotrophin signaling via receptor tyrosine kinases is essential for the development and function of the nervous system in vertebrates. TrkB activation and signaling show substantial differences to other receptor tyrosine kinases of the Trk family that mediate the responses to nerve growth factor and neurotrophin-3. Growing evidence suggests that TrkB cell surface expression is highly regulated and determines the sensitivity of neurons to brain-derived neurotrophic factor (BDNF). This translocation of TrkB depends on co-factors and modulators of cAMP levels, N-glycosylation, and receptor transactivation. This process can occur in very short time periods and the resulting rapid modulation of target cell sensitivity to BDNF could represent a mechanism for fine-tuning of synaptic plasticity and communication in complex neuronal networks. This review focuses on those modulatory mechanisms in neurons that regulate responsiveness to BDNF via control of TrkB surface expression.}, language = {en} } @article{vonCollenbergSchmittRuelickeetal.2019, author = {von Collenberg, Cora R. and Schmitt, Dominique and R{\"u}licke, Thomas and Sendtner, Michael and Blum, Robert and Buchner, Erich}, title = {An essential role of the mouse synapse-associated protein Syap1 in circuits for spontaneous motor activity and rotarod balance}, series = {Biology Open}, volume = {8}, journal = {Biology Open}, doi = {10.1242/bio.042366}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201986}, pages = {bio042366}, year = {2019}, abstract = {Synapse-associated protein 1 (Syap1) is the mammalian homologue of synapse-associated protein of 47 kDa (Sap47) in Drosophila. Genetic deletion of Sap47 leads to deficiencies in short-term plasticity and associative memory processing in flies. In mice, Syap1 is prominently expressed in the nervous system, but its function is still unclear. We have generated Syap1 knockout mice and tested motor behaviour and memory. These mice are viable and fertile but display distinct deficiencies in motor behaviour. Locomotor activity specifically appears to be reduced in early phases when voluntary movement is initiated. On the rotarod, a more demanding motor test involving control by sensory feedback, Syap1-deficient mice dramatically fail to adapt to accelerated speed or to a change in rotation direction. Syap1 is highly expressed in cerebellar Purkinje cells and cerebellar nuclei. Thus, this distinct motor phenotype could be due to a so-far unknown function of Syap1 in cerebellar sensorimotor control. The observed motor defects are highly specific since other tests in the modified SHIRPA exam, as well as cognitive tasks like novel object recognition, Pavlovian fear conditioning, anxiety-like behaviour in open field dark-light transition and elevated plus maze do not appear to be affected in Syap1 knockout mice.}, language = {en} } @article{DekkerDiekstraPulitetal.2019, author = {Dekker, Annelot M. and Diekstra, Frank P. and Pulit, Sara L. and Tazelaar, Gijs H. P. and van der Spek, Rick A. and van Rheenen, Wouter and van Eijk, Kristel R. and Calvo, Andrea and Brunetti, Maura and Van Damme, Philip and Robberecht, Wim and Hardiman, Orla and McLaughlin, Russell and Chi{\`o}, Adriano and Sendtner, Michael and Ludolph, Albert C. and Weishaupt, Jochen H. and Pardina, Jesus S. Mora and van den Berg, Leonard H. and Veldink, Jan H.}, title = {Exome array analysis of rare and low frequency variants in amyotrophic lateral sclerosis}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-019-42091-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-223686}, year = {2019}, abstract = {Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that affects 1 in ~350 individuals. Genetic association studies have established ALS as a multifactorial disease with heritability estimated at ~61\%, and recent studies show a prominent role for rare variation in its genetic architecture. To identify rare variants associated with disease onset we performed exome array genotyping in 4,244 cases and 3,106 controls from European cohorts. In this largest exome-wide study of rare variants in ALS to date, we performed single-variant association testing, gene-based burden, and exome-wide individual set-unique burden (ISUB) testing to identify single or aggregated rare variation that modifies disease risk. In single-variant testing no variants reached exome-wide significance, likely due to limited statistical power. Gene-based burden testing of rare non-synonymous and loss-of-function variants showed NEK1 as the top associated gene. ISUB analysis did not show an increased exome-wide burden of deleterious variants in patients, possibly suggesting a more region-specific role for rare variation. Complete summary statistics are released publicly. This study did not implicate new risk loci, emphasizing the immediate need for future large-scale collaborations in ALS that will expand available sample sizes, increase genome coverage, and improve our ability to detect rare variants associated to ALS.}, language = {en} } @article{LueningschroerBinottiDombertetal.2017, author = {L{\"u}ningschr{\"o}r, Patrick and Binotti, Beyenech and Dombert, Benjamin and Heimann, Peter and Perez-Lara, Angel and Slotta, Carsten and Thau-Habermann, Nadine and von Collenberg, Cora R. and Karl, Franziska and Damme, Markus and Horowitz, Arie and Maystadt, Isabelle and F{\"u}chtbauer, Annette and F{\"u}chtbauer, Ernst-Martin and Jablonka, Sibylle and Blum, Robert and {\"U}{\c{c}}eyler, Nurcan and Petri, Susanne and Kaltschmidt, Barbara and Jahn, Reinhard and Kaltschmidt, Christian and Sendtner, Michael}, title = {Plekhg5-regulated autophagy of synaptic vesicles reveals a pathogenic mechanism in motoneuron disease}, series = {Nature Communications}, volume = {8}, journal = {Nature Communications}, number = {678}, doi = {10.1038/s41467-017-00689-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170048}, year = {2017}, abstract = {Autophagy-mediated degradation of synaptic components maintains synaptic homeostasis but also constitutes a mechanism of neurodegeneration. It is unclear how autophagy of synaptic vesicles and components of presynaptic active zones is regulated. Here, we show that Pleckstrin homology containing family member 5 (Plekhg5) modulates autophagy of synaptic vesicles in axon terminals of motoneurons via its function as a guanine exchange factor for Rab26, a small GTPase that specifically directs synaptic vesicles to preautophagosomal structures. Plekhg5 gene inactivation in mice results in a late-onset motoneuron disease, characterized by degeneration of axon terminals. Plekhg5-depleted cultured motoneurons show defective axon growth and impaired autophagy of synaptic vesicles, which can be rescued by constitutively active Rab26. These findings define a mechanism for regulating autophagy in neurons that specifically targets synaptic vesicles. Disruption of this mechanism may contribute to the pathophysiology of several forms of motoneuron disease.}, language = {en} } @article{SchmittFunkBlumetal.2016, author = {Schmitt, Dominique and Funk, Natalia and Blum, Robert and Asan, Esther and Andersen, Lill and R{\"u}licke, Thomas and Sendtner, Michael and Buchner, Erich}, title = {Initial characterization of a Syap1 knock-out mouse and distribution of Syap1 in mouse brain and cultured motoneurons}, series = {Histochemistry and Cell Biology}, volume = {146}, journal = {Histochemistry and Cell Biology}, number = {4}, doi = {10.1007/s00418-016-1457-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187258}, pages = {489-512}, year = {2016}, abstract = {Synapse-associated protein 1 (Syap1/BSTA) is the mammalian homologue of Sap47 (synapse-associated protein of 47 kDa) in Drosophila. Sap47 null mutant larvae show reduced short-term synaptic plasticity and a defect in associative behavioral plasticity. In cultured adipocytes, Syap1 functions as part of a complex that phosphorylates protein kinase B alpha/Akt1 (Akt1) at Ser\(^{473}\) and promotes differentiation. The role of Syap1 in the vertebrate nervous system is unknown. Here, we generated a Syap1 knock-out mouse and show that lack of Syap1 is compatible with viability and fertility. Adult knock-out mice show no overt defects in brain morphology. In wild-type brain, Syap1 is found widely distributed in synaptic neuropil, notably in regions rich in glutamatergic synapses, but also in perinuclear structures associated with the Golgi apparatus of specific groups of neuronal cell bodies. In cultured motoneurons, Syap1 is located in axons and growth cones and is enriched in a perinuclear region partially overlapping with Golgi markers. We studied in detail the influence of Syap1 knockdown and knockout on structure and development of these cells. Importantly, Syap1 knockout does not affect motoneuron survival or axon growth. Unexpectedly, neither knockdown nor knockout of Syap1 in cultured motoneurons is associated with reduced Ser\(^{473}\) or Thr\(^{308}\) phosphorylation of Akt. Our findings demonstrate a widespread expression of Syap1 in the mouse central nervous system with regionally specific distribution patterns as illustrated in particular for olfactory bulb, hippocampus, and cerebellum.}, language = {en} } @article{MaassDuezelBrigadskietal.2016, author = {Maass, Anne and D{\"u}zel, Sandra and Brigadski, Tanja and Goerke, Monique and Becke, Andreas and Sobieray, Uwe and Neumann, Katja and L{\"o}vd{\´e}n, Martin and Lindenberger, Ulman and B{\"a}ckman, Lars and Braun-Dullaeus, R{\"u}diger and Ahrens, D{\"o}rte and Heinze, Hans-Jochen and M{\"u}ller, Notger G. and Lessmann, Volkmar and Sendtner, Michael and D{\"u}zel, Emrah}, title = {Relationships of peripheral IGF-1, VEGF and BDNF levels to exercise-related changes in memory, hippocampal perfusion and volumes in older adults}, series = {NeuroImage}, volume = {131}, journal = {NeuroImage}, doi = {10.1016/j.neuroimage.2015.10.084}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-189219}, pages = {142-154}, year = {2016}, abstract = {Animal models point towards a key role of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-I (IGF-I) and vascular endothelial growth factor (VEGF) in mediating exercise-induced structural and functional changes in the hippocampus. Recently, also platelet derived growth factor-C (PDGF-C) has been shown to promote blood vessel growth and neuronal survival. Moreover, reductions of these neurotrophic and angiogenic factors in old age have been related to hippocampal atrophy, decreased vascularization and cognitive decline. In a 3-month aerobic exercise study, forty healthy older humans (60 to 77 years) were pseudo-randomly assigned to either an aerobic exercise group (indoor treadmill, n = 21) or to a control group (indoor progressive-muscle relaxation/stretching, n = 19). As reported recently, we found evidence for fitness-related perfusion changes of the aged human hippocampus that were closely linked to changes in episodic memory function. Here, we test whether peripheral levels of BDNF, IGF-I, VEGF or PDGF-C are related to changes in hippocampal blood flow, volume and memory performance. Growth factor levels were not significantly affected by exercise, and their changes were not related to changes in fitness or perfusion. However, changes in IGF-I levels were positively correlated with hippocampal volume changes (derived by manual volumetry and voxel-based morphometry) and late verbal recall performance, a relationship that seemed to be independent of fitness, perfusion or their changes over time. These preliminary findings link IGF-I levels to hippocampal volume changes and putatively hippocampus-dependent memory changes that seem to occur over time independently of exercise. We discuss methodological shortcomings of our study and potential differences in the temporal dynamics of how IGF-1, VEGF and BDNF may be affected by exercise and to what extent these differences may have led to the negative findings reported here.}, language = {en} } @article{DuezelvanPraagSendtner2016, author = {D{\"u}zel, Emrah and van Praag, Henriette and Sendtner, Michael}, title = {Can physical exercise in old age improve memory and hippocampal function?}, series = {Brain}, volume = {139}, journal = {Brain}, number = {3}, doi = {10.1093/brain/awv407}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-190721}, pages = {662-673}, year = {2016}, abstract = {Physical exercise can convey a protective effect against cognitive decline in ageing and Alzheimer's disease. While the long-term health-promoting and protective effects of exercise are encouraging, it's potential to induce neuronal and vascular plasticity in the ageing brain is still poorly understood. It remains unclear whether exercise slows the trajectory of normal ageing by modifying vascular and metabolic risk factors and/or consistently boosts brain function by inducing structural and neurochemical changes in the hippocampus and related medial temporal lobe circuitry—brain areas that are important for learning and memory. Hence, it remains to be established to what extent exercise interventions in old age can improve brain plasticity above and beyond preservation of function. Existing data suggest that exercise trials aiming for improvement and preservation may require different outcome measures and that the balance between the two may depend on exercise intensity and duration, the presence of preclinical Alzheimer's disease pathology, vascular and metabolic risk factors and genetic variability.}, language = {en} } @article{YadavSelvarajBenderetal.2016, author = {Yadav, Preeti and Selvaraj, Bhuvaneish T. and Bender, Florian L. P. and Behringer, Marcus and Moradi, Mehri and Sivadasan, Rajeeve and Dombert, Benjamin and Blum, Robert and Asan, Esther and Sauer, Markus and Julien, Jean-Pierre and Sendtner, Michael}, title = {Neurofilament depletion improves microtubule dynamics via modulation of Stat3/stathmin signaling}, series = {Acta Neuropathologica}, volume = {132}, journal = {Acta Neuropathologica}, number = {1}, doi = {10.1007/s00401-016-1564-y}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188234}, pages = {93-110}, year = {2016}, abstract = {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.}, language = {en} }