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Andreas Roos - One of the best experts on this subject based on the ideXlab platform.
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Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome.
Frontiers in neurology, 2019Co-Authors: Christian Gatz, Thomas Labisch, Stephan Buchkremer, Joachim Weis, Denisa Hathazi, Ute Münchberg, Ben Munro, Rita Horvath, Ana Töpf, Andreas RoosAbstract:Background and objective: Recessive mutations in the SIL1 gene cause Marinesco-Sjogren Syndrome (MSS), a rare neuropediatric disorder. MSS-patients typically present with congenital cataracts, intellectual disability, cerebellar ataxia and progressive vacuolar myopathy. However, atypical clinical presentations associated with SIL1 mutations have been described over the last years; compound heterozygosity of SIL1 missense mutations even resulted in a phenotype not fulfilling the clinical diagnostic criteria of MSS. Thus, a read-out system to evaluate reliably the pathogenicity of amino acid changes in SIL1 is needed. Here, we aim to provide suitable cellular biomarkers enabling the robust evaluation of pathogenicity of SIL1 mutations. Methods: Five SIL1 variants including one polymorphism (p.K132Q), three known pathogenic mutations (p.V231_I232del, p.G312R, and p.L457P) and one ambiguous missense variant (p.R92W) were studied along with the wild-type proteins in Hek293 in vitro models by cell biological assays, immunoprecipitation, immunoblotting, and immunofluorescence as well as electron microscopy. Moreover, the SIL1-interactomes were interrogated by tandem-affinity-purification and subsequent mass spectrometry. Results: Our combined studies confirmed the pathogenicity of p.V231_I232del, p.G312R, and p.L457P by showing instability of the proteins as well as tendency to form aggregates. This observation is in line with altered structure of the ER-Golgi system and vacuole formation upon expression of these pathogenic SIL1-mutants as well as the presence of oxidative or ER-stress. Reduced cellular fitness along with abnormal mitochondrial architecture could also be observed. Notably, both the polymorphic p.K132Q and the ambiguous p.R92W variants did not elicit such alterations. Study of the SIL1-interactome identified POC1A as a novel binding partner of wild-type SIL1; the interaction is disrupted upon the presence of pathogenic mutants but not influenced by the presence of benign variants. Disrupted SIL1-POC1A interaction is associated with centrosome disintegration. Conclusions: We developed a combination of cellular outcome measures to evaluate the pathogenicity of SIL1 variants in suitable in vitro models and demonstrated that the p. R92W missense variant is a polymorphism rather than a pathogenic mutation leading to MSS.
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In-depth phenotyping of lymphoblastoid cells suggests selective cellular vulnerability in Marinesco-Sjögren Syndrome.
Oncotarget, 2017Co-Authors: Laxmikanth Kollipara, Stephan Buchkremer, José Andrés González Coraspe, Joachim Weis, René P. Zahedi, Denisa Hathazi, Jan Senderek, Andreas RoosAbstract:// Laxmikanth Kollipara 1, * , Stephan Buchkremer 2, * , Jose Andres Gonzalez Coraspe 2 , Denisa Hathazi 1 , Jan Senderek 3 , Joachim Weis 2 , Rene P. Zahedi 1, ** and Andreas Roos 1, 2, 4, ** 1 Leibniz-Institut fur Analytische Wissenschaften–ISAS –e.V., 44227 Dortmund, Germany 2 Institute of Neuropathology, University Hospital Aachen, RWTH Aachen, 5274 Aachen, Germany 3 Friedrich-Baur-Institute, Medical Faculty, Ludwig-Maximilians-University, 80336 Munich, Germany 4 The John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK * First authors contributed equally to this work ** Senior authors contributed equally to this work Correspondence to: Andreas Roos, email: andreas.roos@ncl.ac.uk , andreas.roos@isas.de Keywords: Marinesco-Sjogren Syndrome, woozy mouse, SIL1, ataxin-10, chaperonopathy Received: May 03, 2016 Accepted: May 28, 2017 Published: July 28, 2017 ABSTRACT SIL1 is a ubiquitous protein of the Endoplasmic Reticulum (ER) acting as a co-chaperone for the ER-resident chaperone, BiP. Recessive mutations of the corresponding gene lead to vulnerability of skeletal muscle and central nervous system in man (Marinesco-Sjogren Syndrome; MSS) and mouse. However, it is still unclear how loss of ubiquitous SIL1 leads to selective vulnerability of the nervous system and skeletal muscle whereas other cells and organs are protected from clinical manifestations. In this study we aimed to disentangle proteins participating in selective vulnerability of SIL1-deficient cells and tissues: morphological examination of MSS patient-derived lymphoblastoid cells revealed altered organelle structures (ER, nucleus and mitochondria) thus showing subclinical vulnerability. To correlate structural perturbations with biochemical changes and to identify proteins potentially preventing phenotypical manifestation, proteomic studies have been carried out. Results of proteomic profiling are in line with the morphological findings and show affection of nuclear, mitochondrial and cytoskeletal proteins as well as of such responsible for cellular viability. Moreover, expression patterns of proteins known to be involved in neuromuscular disorders or in development and function of the nervous system were altered. Paradigmatic findings were confirmed by immunohistochemistry of splenic lymphocytes and the cerebellum of SIL1-deficient mice. Ataxin-10, identified with increased abundance in our proteome profile, is necessary for the neuronal survival but also controls muscle fiber apoptosis, thus declaring this protein as a plausible candidate for selective tissue vulnerability. Our combined results provide first insights into the molecular causes of selective cell and tissue vulnerability defining the MSS phenotype.
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Search for cryptic subtelomeric aberrations in patients with non-classical Marinesco-Sjögren phenotype
Journal of pediatric neurology, 2015Co-Authors: Andreas Roos, Gesa Schwanitz, Irmgard Diepolder, Jan Senderek, Katja EggermannAbstract:Marinesco-Sjogren Syndrome (MSS) is a multiorgan disorder firstly described in 1931 by Gheorge Marinescu. During the last seven decades, research into the clinical picture of MSS has led to the description of varying MSS phenotypes and since 2005, it is known that mutations within the SIL1 gene cause MSS in a part of these patients. Among these “SIL1-related MSS cases”, “classical and non-classical phenotypes” are distinguished. All “SIL1-related MSS cases” show at least an ataxia due to cerebellar atrophy, congenital or infantile cataracts and a progressive myopathy as well as mental impairment (“classical MSS phenotype”). Additional clinical features are for example in some cases short stature, hypogonadism, scoliosis, nystagmus and strabismus (“non-classical MSS phenotype”). However, the primary pathology has remained unknown in non-SIL1-related MSS cases. As the clinical features detected in “classical MSS phenotype” and “non-classical MSS phenotype” may also be associated with cryptic subtelomeric rearrangements and as a frequent localization of for example cataract-related genes/loci within these regions is proven, we performed subtelomere screening in a series of 23 patients with “non-SIL1-related non-classical MSS phenotypes” presenting with at least three features like early cataracts, mental retardation, brain malformations, muscular hypotonia, growth retardation and skeletal abnormalities. Karyotype and the SIL1 coding sequence were normal in all cases. Subtelomere screening by multiplex ligation-dependent probe amplification did not identify any subtelomeric imbalances. Therefore, a causative role of these regions in manifesting "non-SIL1-related non-classical MSS phenotypes" seems to be unlikely.
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Marinesco-Sjogren Syndrome protein SIL1 regulates motor neuron subtype-selective ER stress in ALS
Nature neuroscience, 2015Co-Authors: Audrey Filézac De L’etang, Andreas Roos, Niran Maharjan, Marisa Cordeiro Braña, Céline Ruegsegger, Ruth Rehmann, Anand Goswami, Dirk Troost, Bernard L. Schneider, Joachim WeisAbstract:Mechanisms underlying motor neuron subtype-selective endoplasmic reticulum (ER) stress and associated axonal pathology in amyotrophic lateral sclerosis (ALS) remain unclear. Here we show that the molecular environment of the ER between motor neuron subtypes is distinct, with characteristic signatures. We identify cochaperone SIL1, mutated in Marinesco-Sjögren Syndrome (MSS), as being robustly expressed in disease-resistant slow motor neurons but not in ER stress-prone fast-fatigable motor neurons. In a mouse model of MSS, we demonstrate impaired ER homeostasis in motor neurons in response to loss of SIL1 function. Loss of a single functional Sil1 allele in an ALS mouse model (SOD1-G93A) enhanced ER stress and exacerbated ALS pathology. In SOD1-G93A mice, SIL1 levels were progressively and selectively reduced in vulnerable fast-fatigable motor neurons. Mechanistically, reduction in SIL1 levels was associated with lowered excitability of fast-fatigable motor neurons, further influencing expression of specific ER chaperones. Adeno-associated virus-mediated delivery of SIL1 to familial ALS motor neurons restored ER homeostasis, delayed muscle denervation and prolonged survival.
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myopathy in Marinesco Sjogren Syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology
Acta Neuropathologica, 2014Co-Authors: Andreas Roos, Thomas Labisch, Stephan Buchkremer, Laxmikanth Kollipara, Christian Gatz, Kay Nolte, Eva Brauers, Manuela Zitzelsberger, Michael J Schroder, Janbernd KirschnerAbstract:Marinesco–Sjogren Syndrome (MSS) features cerebellar ataxia, mental retardation, cataracts, and progressive vacuolar myopathy with peculiar myonuclear alterations. Most MSS patients carry homozygous or compound heterozygous SIL1 mutations. SIL1 is a nucleotide exchange factor for the endoplasmic reticulum resident chaperone BiP which controls a plethora of essential processes in the endoplasmic reticulum. In this study we made use of the spontaneous Sil1 mouse mutant woozy to explore pathomechanisms leading to Sil1 deficiency-related skeletal muscle pathology. We found severe, progressive myopathy characterized by alterations of the sarcoplasmic reticulum, accumulation of autophagic vacuoles, mitochondrial changes, and prominent myonuclear pathology including nuclear envelope and nuclear lamina alterations. These abnormalities were remarkably similar to the myopathy in human patients with MSS. In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles. We found that these structures are derived from the nuclear envelope and nuclear lamina and associate with proliferations of the sarcoplasmic reticulum. In line with impaired function of BiP secondary to loss of its nucleotide exchange factor Sil1, we observed activation of the unfolded protein response and the endoplasmic-reticulum-associated protein degradation-pathway. Despite initiation of the autophagy–lysosomal system, autophagic clearance was found ineffective which is in agreement with the formation of autophagic vacuoles. This report identifies woozy muscle as a faithful phenocopy of the MSS myopathy. Moreover, we provide a link between two well-established disease mechanisms in skeletal muscle, dysfunction of chaperones and nuclear envelope pathology.
A Bagala - One of the best experts on this subject based on the ideXlab platform.
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vitamin e deficiency due to chylomicron retention disease in Marinesco Sjogren Syndrome
Annals of Neurology, 2000Co-Authors: Umberto Aguglia, Ferdinanda Annesi, A A Pasqua, Francesca Cavalcanti, L Crescibene, Grazia Annesi, Gianandrea Pasquinelli, Antonio Gambardella, Patrizia Spadafora, A BagalaAbstract:We report on 2 brothers (aged 19 and 12 years) with Marinesco-Sjogren Syndrome who also had very low serum vitamin E concentrations with an absence of postprandial chylomicrons. The molecular study ruled out ataxia with isolated vitamin E deficiency, abetalipoproteinemia, and hypobetalipoproteinemia. The electron microscopy of the intestinal mucosa was consistent with a chylomicron retention disease. We speculate that both chylomicron retention disease and Marinesco-Sjogren Syndrome are related to defects in a gene crucial for the assembly or secretion of the chylomicron particles, leading to very low serum levels of vitamin E. Ann Neurol 2000;47:260–264
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vitamin e deficiency due to chylomicron retention disease in Marinesco Sjogren Syndrome
Annals of Neurology, 2000Co-Authors: Umberto Aguglia, Ferdinanda Annesi, A A Pasqua, Francesca Cavalcanti, L Crescibene, Grazia Annesi, Gianandrea Pasquinelli, Antonio Gambardella, Patrizia Spadafora, A BagalaAbstract:We report on 2 brothers (aged 19 and 12 years) with Marinesco-Sjogren Syndrome who also had very low serum vitamin E concentrations with an absence of postprandial chylomicrons. The molecular study ruled out ataxia with isolated vitamin E deficiency, abetalipoproteinemia, and hypobetalipoproteinemia. The electron microscopy of the intestinal mucosa was consistent with a chylomicron retention disease. We speculate that both chylomicron retention disease and Marinesco-Sjogren Syndrome are related to defects in a gene crucial for the assembly or secretion of the chylomicron particles, leading to very low serum levels of vitamin E.
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Vitamin E deficiency due to chylomicron retention disease in Marinesco‐Sjögren Syndrome
Annals of neurology, 2000Co-Authors: Umberto Aguglia, Ferdinanda Annesi, A A Pasqua, Francesca Cavalcanti, L Crescibene, Grazia Annesi, Gianandrea Pasquinelli, Antonio Gambardella, Patrizia Spadafora, A BagalaAbstract:We report on 2 brothers (aged 19 and 12 years) with Marinesco-Sjogren Syndrome who also had very low serum vitamin E concentrations with an absence of postprandial chylomicrons. The molecular study ruled out ataxia with isolated vitamin E deficiency, abetalipoproteinemia, and hypobetalipoproteinemia. The electron microscopy of the intestinal mucosa was consistent with a chylomicron retention disease. We speculate that both chylomicron retention disease and Marinesco-Sjogren Syndrome are related to defects in a gene crucial for the assembly or secretion of the chylomicron particles, leading to very low serum levels of vitamin E.
Linda M. Hendershot - One of the best experts on this subject based on the ideXlab platform.
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Role of the HSP70 Co-Chaperone SIL1 in Health and Disease
International journal of molecular sciences, 2021Co-Authors: Viraj P. Ichhaporia, Linda M. HendershotAbstract:Cell surface and secreted proteins provide essential functions for multicellular life. They enter the endoplasmic reticulum (ER) lumen co-translationally, where they mature and fold into their complex three-dimensional structures. The ER is populated with a host of molecular chaperones, associated co-factors, and enzymes that assist and stabilize folded states. Together, they ensure that nascent proteins mature properly or, if this process fails, target them for degradation. BiP, the ER HSP70 chaperone, interacts with unfolded client proteins in a nucleotide-dependent manner, which is tightly regulated by eight DnaJ-type proteins and two nucleotide exchange factors (NEFs), SIL1 and GRP170. Loss of SIL1′s function is the leading cause of Marinesco-Sjogren Syndrome (MSS), an autosomal recessive, multisystem disorder. The development of animal models has provided insights into SIL1′s functions and MSS-associated pathologies. This review provides an in-depth update on the current understanding of the molecular mechanisms underlying SIL1′s NEF activity and its role in maintaining ER homeostasis and normal physiology. A precise understanding of the underlying molecular mechanisms associated with the loss of SIL1 may allow for the development of new pharmacological approaches to treat MSS.
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SIL1, the endoplasmic-reticulum-localized BiP co-chaperone, plays a crucial role in maintaining skeletal muscle proteostasis and physiology.
Disease models & mechanisms, 2018Co-Authors: Viraj P. Ichhaporia, Jieun Kim, Kanisha Kavdia, Peter Vogel, Linda Horner, Sharon Frase, Linda M. HendershotAbstract:Mutations in SIL1, a cofactor for the endoplasmic reticulum (ER)-localized Hsp70 chaperone, BiP, cause Marinesco-Sjogren Syndrome (MSS), an autosomal recessive disorder. Using a mouse model, we characterized molecular aspects of the progressive myopathy associated with MSS. Proteomic profiling of quadriceps at the onset of myopathy revealed that SIL1 deficiency affected multiple pathways critical to muscle physiology. We observed an increase in ER chaperones prior to the onset of muscle weakness, which was complemented by upregulation of multiple components of cellular protein degradation pathways. These responses were inadequate to maintain normal expression of secretory pathway proteins, including insulin and IGF-1 receptors. There was a paradoxical enhancement of downstream PI3K-AKT-mTOR signaling and glucose uptake in SIL1-disrupted skeletal muscles, all of which were insufficient to maintain skeletal muscle mass. Together, these data reveal a disruption in ER homeostasis upon SIL1 loss, which is countered by multiple compensatory responses that are ultimately unsuccessful, leading to trans-organellar proteostasis collapse and myopathy.
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c terminal mutations destabilize sil1 bap and can cause Marinesco Sjogren Syndrome
Journal of Biological Chemistry, 2012Co-Authors: Jennifer E. Howes, Yuichiro Shimizu, Matthias J. Feige, Linda M. HendershotAbstract:Marinesco-Sjogren Syndrome (MSS) is an autosomal recessive, neurodegenerative, multisystem disorder characterized by severe phenotypes developing in infancy. Recently, mutations in the endoplasmic reticulum (ER)-associated co-chaperone SIL1/BAP were identified to be the major cause of MSS. SIL1 acts as a nucleotide exchange factor for BiP, the ER Hsp70 orthologue, which plays an essential role in the folding and assembly of nascent polypeptide chains in the ER. SIL1 facilitates the release of BiP from unfolded protein substrates, enabling the subsequent folding and transport of the protein. Although most mutations leading to MSS result in deletion of the majority of the protein, three separate mutations have been identified that disrupt only the last five or six amino acids of the protein, which were assumed to encode a divergent ER retention motif. This study presents an in depth analysis of two of these mutants and reveals that the phenotype in the affected individuals is not likely to be due to depletion of SIL1 from the ER via secretion. Instead, our analyses show that the mutant proteins are particularly unstable and either form large aggregates in the ER or are rapidly degraded via the proteasome. In agreement with our findings, homology modeling suggests that the very C-terminal residues of SIL1 play a role in its structural integrity rather than its localization. These new insights might be a first step toward a possible pharmacological treatment of certain types of MSS by specifically stabilizing the mutant SIL1 protein.
F Ebinger - One of the best experts on this subject based on the ideXlab platform.
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t2 hyperintense cerebellar cortex in Marinesco Sjogren Syndrome
Neurology, 2004Co-Authors: Inga Harting, A Blaschek, Nicole I Wolf, Angelika Seitz, M Haupt, H H Goebel, D Rating, K Sartor, F EbingerAbstract:Hyperintensity of the cerebellar cortex on T2-weighted images is a rare finding and has been considered pathognomonic for infantile neuroaxonal dystrophy (INAD).1 However, we present three children with Marinesco–Sjogren Syndrome (MSS; OMIM 248800) and hyperintense cerebellar cortex on MRI. Additional findings were widened cerebellar fissures, an enlarged fourth ventricle, reduced N -acetylaspartate, and elevated myo-inositol on 1H-MR spectroscopy (MRS) of the cerebellum. ### Patients. Patient 1 is the 5-year-old son of consanguineous parents; Patients 2 (girl, age 7 years) and 3 (boy, age 14 months) are siblings of nonconsanguineous parents. Hypotonia, developmental delay, strabismus, and short stature were present in all patients. Ataxia was present in Patients 1 and 2. Tendon reflexes were normal, and pyramidal tract signs were absent. Bilateral cataracts were diagnosed in Patient 1 (age 4.5 years) and Patient 2 (age 6.8 years). At age 14 months, cataracts had not yet developed in Patient 3. Serum creatine (Cr) kinase levels were normal in Patient 1 and slightly elevated in Patients 2 and 3. Extensive …
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T2-hyperintense cerebellar cortex in Marinesco–Sjögren Syndrome
Neurology, 2004Co-Authors: Inga Harting, A Blaschek, Nicole I Wolf, Angelika Seitz, M Haupt, H H Goebel, D Rating, K Sartor, F EbingerAbstract:Hyperintensity of the cerebellar cortex on T2-weighted images is a rare finding and has been considered pathognomonic for infantile neuroaxonal dystrophy (INAD).1 However, we present three children with Marinesco–Sjogren Syndrome (MSS; OMIM 248800) and hyperintense cerebellar cortex on MRI. Additional findings were widened cerebellar fissures, an enlarged fourth ventricle, reduced N -acetylaspartate, and elevated myo-inositol on 1H-MR spectroscopy (MRS) of the cerebellum. ### Patients. Patient 1 is the 5-year-old son of consanguineous parents; Patients 2 (girl, age 7 years) and 3 (boy, age 14 months) are siblings of nonconsanguineous parents. Hypotonia, developmental delay, strabismus, and short stature were present in all patients. Ataxia was present in Patients 1 and 2. Tendon reflexes were normal, and pyramidal tract signs were absent. Bilateral cataracts were diagnosed in Patient 1 (age 4.5 years) and Patient 2 (age 6.8 years). At age 14 months, cataracts had not yet developed in Patient 3. Serum creatine (Cr) kinase levels were normal in Patient 1 and slightly elevated in Patients 2 and 3. Extensive …
Stephan Buchkremer - One of the best experts on this subject based on the ideXlab platform.
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Identification of Cellular Pathogenicity Markers for SIL1 Mutations Linked to Marinesco-Sjögren Syndrome.
Frontiers in neurology, 2019Co-Authors: Christian Gatz, Thomas Labisch, Stephan Buchkremer, Joachim Weis, Denisa Hathazi, Ute Münchberg, Ben Munro, Rita Horvath, Ana Töpf, Andreas RoosAbstract:Background and objective: Recessive mutations in the SIL1 gene cause Marinesco-Sjogren Syndrome (MSS), a rare neuropediatric disorder. MSS-patients typically present with congenital cataracts, intellectual disability, cerebellar ataxia and progressive vacuolar myopathy. However, atypical clinical presentations associated with SIL1 mutations have been described over the last years; compound heterozygosity of SIL1 missense mutations even resulted in a phenotype not fulfilling the clinical diagnostic criteria of MSS. Thus, a read-out system to evaluate reliably the pathogenicity of amino acid changes in SIL1 is needed. Here, we aim to provide suitable cellular biomarkers enabling the robust evaluation of pathogenicity of SIL1 mutations. Methods: Five SIL1 variants including one polymorphism (p.K132Q), three known pathogenic mutations (p.V231_I232del, p.G312R, and p.L457P) and one ambiguous missense variant (p.R92W) were studied along with the wild-type proteins in Hek293 in vitro models by cell biological assays, immunoprecipitation, immunoblotting, and immunofluorescence as well as electron microscopy. Moreover, the SIL1-interactomes were interrogated by tandem-affinity-purification and subsequent mass spectrometry. Results: Our combined studies confirmed the pathogenicity of p.V231_I232del, p.G312R, and p.L457P by showing instability of the proteins as well as tendency to form aggregates. This observation is in line with altered structure of the ER-Golgi system and vacuole formation upon expression of these pathogenic SIL1-mutants as well as the presence of oxidative or ER-stress. Reduced cellular fitness along with abnormal mitochondrial architecture could also be observed. Notably, both the polymorphic p.K132Q and the ambiguous p.R92W variants did not elicit such alterations. Study of the SIL1-interactome identified POC1A as a novel binding partner of wild-type SIL1; the interaction is disrupted upon the presence of pathogenic mutants but not influenced by the presence of benign variants. Disrupted SIL1-POC1A interaction is associated with centrosome disintegration. Conclusions: We developed a combination of cellular outcome measures to evaluate the pathogenicity of SIL1 variants in suitable in vitro models and demonstrated that the p. R92W missense variant is a polymorphism rather than a pathogenic mutation leading to MSS.
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sil1 deficiency causes degenerative changes of peripheral nerves and neuromuscular junctions in fish mice and human
Neurobiology of Disease, 2019Co-Authors: Vietxuan Phan, Stephan Buchkremer, Rita Horvath, Daniel Cox, Silvia Cipriani, Sally Spendiff, Emily Oconnor, Hans H. GoebelAbstract:Abstract Background Marinesco-Sjogren Syndrome (MSS) is a rare neuromuscular condition caused by recessive mutations in the SIL1 gene resulting in the absence of functional SIL1 protein, a co-chaperone for the major ER chaperone, BiP. As BiP is decisive for proper protein processing, loss of SIL1 results in the accumulation of misshaped proteins. This accumulation likely damages and destroys cells in vulnerable tissues, leading to congenital cataracts, cerebellar ataxia, vacuolar myopathy and other MSS phenotypes. Whether the peripheral nervous system (PNS) is affected in MSS has not been conclusively shown. Methods To study PNS vulnerability in MSS, intramuscular nerves fibres from MSS patients and from SIL1-deficient mice (woozy) as well as sciatic nerves and neuromuscular junctions (NMJ) from these mice have been investigated via transmission electron microscopic and immunofluorescence studies accompanied by transcript studies and unbiased proteomic profiling. In addition, PNS and NMJ integrity were analyzed via immunofluorescence studies in an MSS-zebrafish model which has been generated for that purpose. Results Electron microscopy revealed morphological changes indicative of impaired autophagy and mitochondrial maintenance in distal axons and in Schwann cells. Moreover, changes of the morphology of NMJs as well as of transcripts encoding proteins important for NMJ function were detected in woozy mice. These findings were in line with a grossly abnormal structure of NMJs in SIL1-deficient zebrafish embryos. Proteome profiling of sciatic nerve specimens from woozy mice revealed altered levels of proteins implicated in neuronal maintenance suggesting the activation of compensatory mechanisms. Conclusion Taken together, our combined data expand the spectrum of tissues affected by SIL1-loss and suggest that impaired neuromuscular transmission might be part of MSS pathophysiology.
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In-depth phenotyping of lymphoblastoid cells suggests selective cellular vulnerability in Marinesco-Sjögren Syndrome.
Oncotarget, 2017Co-Authors: Laxmikanth Kollipara, Stephan Buchkremer, José Andrés González Coraspe, Joachim Weis, René P. Zahedi, Denisa Hathazi, Jan Senderek, Andreas RoosAbstract:// Laxmikanth Kollipara 1, * , Stephan Buchkremer 2, * , Jose Andres Gonzalez Coraspe 2 , Denisa Hathazi 1 , Jan Senderek 3 , Joachim Weis 2 , Rene P. Zahedi 1, ** and Andreas Roos 1, 2, 4, ** 1 Leibniz-Institut fur Analytische Wissenschaften–ISAS –e.V., 44227 Dortmund, Germany 2 Institute of Neuropathology, University Hospital Aachen, RWTH Aachen, 5274 Aachen, Germany 3 Friedrich-Baur-Institute, Medical Faculty, Ludwig-Maximilians-University, 80336 Munich, Germany 4 The John Walton Muscular Dystrophy Research Centre, MRC Centre for Neuromuscular Diseases, Newcastle University, Newcastle upon Tyne, NE1 3BZ, UK * First authors contributed equally to this work ** Senior authors contributed equally to this work Correspondence to: Andreas Roos, email: andreas.roos@ncl.ac.uk , andreas.roos@isas.de Keywords: Marinesco-Sjogren Syndrome, woozy mouse, SIL1, ataxin-10, chaperonopathy Received: May 03, 2016 Accepted: May 28, 2017 Published: July 28, 2017 ABSTRACT SIL1 is a ubiquitous protein of the Endoplasmic Reticulum (ER) acting as a co-chaperone for the ER-resident chaperone, BiP. Recessive mutations of the corresponding gene lead to vulnerability of skeletal muscle and central nervous system in man (Marinesco-Sjogren Syndrome; MSS) and mouse. However, it is still unclear how loss of ubiquitous SIL1 leads to selective vulnerability of the nervous system and skeletal muscle whereas other cells and organs are protected from clinical manifestations. In this study we aimed to disentangle proteins participating in selective vulnerability of SIL1-deficient cells and tissues: morphological examination of MSS patient-derived lymphoblastoid cells revealed altered organelle structures (ER, nucleus and mitochondria) thus showing subclinical vulnerability. To correlate structural perturbations with biochemical changes and to identify proteins potentially preventing phenotypical manifestation, proteomic studies have been carried out. Results of proteomic profiling are in line with the morphological findings and show affection of nuclear, mitochondrial and cytoskeletal proteins as well as of such responsible for cellular viability. Moreover, expression patterns of proteins known to be involved in neuromuscular disorders or in development and function of the nervous system were altered. Paradigmatic findings were confirmed by immunohistochemistry of splenic lymphocytes and the cerebellum of SIL1-deficient mice. Ataxin-10, identified with increased abundance in our proteome profile, is necessary for the neuronal survival but also controls muscle fiber apoptosis, thus declaring this protein as a plausible candidate for selective tissue vulnerability. Our combined results provide first insights into the molecular causes of selective cell and tissue vulnerability defining the MSS phenotype.
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myopathy in Marinesco Sjogren Syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology
Acta Neuropathologica, 2014Co-Authors: Andreas Roos, Thomas Labisch, Stephan Buchkremer, Laxmikanth Kollipara, Christian Gatz, Kay Nolte, Eva Brauers, Manuela Zitzelsberger, Michael J Schroder, Janbernd KirschnerAbstract:Marinesco–Sjogren Syndrome (MSS) features cerebellar ataxia, mental retardation, cataracts, and progressive vacuolar myopathy with peculiar myonuclear alterations. Most MSS patients carry homozygous or compound heterozygous SIL1 mutations. SIL1 is a nucleotide exchange factor for the endoplasmic reticulum resident chaperone BiP which controls a plethora of essential processes in the endoplasmic reticulum. In this study we made use of the spontaneous Sil1 mouse mutant woozy to explore pathomechanisms leading to Sil1 deficiency-related skeletal muscle pathology. We found severe, progressive myopathy characterized by alterations of the sarcoplasmic reticulum, accumulation of autophagic vacuoles, mitochondrial changes, and prominent myonuclear pathology including nuclear envelope and nuclear lamina alterations. These abnormalities were remarkably similar to the myopathy in human patients with MSS. In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles. We found that these structures are derived from the nuclear envelope and nuclear lamina and associate with proliferations of the sarcoplasmic reticulum. In line with impaired function of BiP secondary to loss of its nucleotide exchange factor Sil1, we observed activation of the unfolded protein response and the endoplasmic-reticulum-associated protein degradation-pathway. Despite initiation of the autophagy–lysosomal system, autophagic clearance was found ineffective which is in agreement with the formation of autophagic vacuoles. This report identifies woozy muscle as a faithful phenocopy of the MSS myopathy. Moreover, we provide a link between two well-established disease mechanisms in skeletal muscle, dysfunction of chaperones and nuclear envelope pathology.
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Myopathy in Marinesco–Sjögren Syndrome links endoplasmic reticulum chaperone dysfunction to nuclear envelope pathology
Acta neuropathologica, 2013Co-Authors: Andreas Roos, Thomas Labisch, Stephan Buchkremer, Laxmikanth Kollipara, Christian Gatz, Kay Nolte, Eva Brauers, Manuela Zitzelsberger, J. Michael Schröder, Janbernd KirschnerAbstract:Marinesco–Sjogren Syndrome (MSS) features cerebellar ataxia, mental retardation, cataracts, and progressive vacuolar myopathy with peculiar myonuclear alterations. Most MSS patients carry homozygous or compound heterozygous SIL1 mutations. SIL1 is a nucleotide exchange factor for the endoplasmic reticulum resident chaperone BiP which controls a plethora of essential processes in the endoplasmic reticulum. In this study we made use of the spontaneous Sil1 mouse mutant woozy to explore pathomechanisms leading to Sil1 deficiency-related skeletal muscle pathology. We found severe, progressive myopathy characterized by alterations of the sarcoplasmic reticulum, accumulation of autophagic vacuoles, mitochondrial changes, and prominent myonuclear pathology including nuclear envelope and nuclear lamina alterations. These abnormalities were remarkably similar to the myopathy in human patients with MSS. In particular, the presence of perinuclear membranous structures which have been reported as an ultrastructural hallmark of MSS-related myopathy could be confirmed in woozy muscles. We found that these structures are derived from the nuclear envelope and nuclear lamina and associate with proliferations of the sarcoplasmic reticulum. In line with impaired function of BiP secondary to loss of its nucleotide exchange factor Sil1, we observed activation of the unfolded protein response and the endoplasmic-reticulum-associated protein degradation-pathway. Despite initiation of the autophagy–lysosomal system, autophagic clearance was found ineffective which is in agreement with the formation of autophagic vacuoles. This report identifies woozy muscle as a faithful phenocopy of the MSS myopathy. Moreover, we provide a link between two well-established disease mechanisms in skeletal muscle, dysfunction of chaperones and nuclear envelope pathology.