Publications by authors named "Jens Reimann"

35 Publications

Protein signature of human skin fibroblasts allows the study of the molecular etiology of rare neurological diseases.

Orphanet J Rare Dis 2021 Feb 9;16(1):73. Epub 2021 Feb 9.

Department of Pediatric Neurology, Faculty of Medicine, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.

Background: The elucidation of pathomechanisms leading to the manifestation of rare (genetically caused) neurological diseases including neuromuscular diseases (NMD) represents an important step toward the understanding of the genesis of the respective disease and might help to define starting points for (new) therapeutic intervention concepts. However, these "discovery studies" are often limited by the availability of human biomaterial. Moreover, given that results of next-generation-sequencing approaches frequently result in the identification of ambiguous variants, testing of their pathogenicity is crucial but also depending on patient-derived material.

Methods: Human skin fibroblasts were used to generate a spectral library using pH8-fractionation of followed by nano LC-MS/MS. Afterwards, Allgrove-patient derived fibroblasts were subjected to a data independent acquisition approach. In addition, proteomic signature of an enriched nuclear protein fraction was studied. Proteomic findings were confirmed by immunofluorescence in a muscle biopsy derived from the same patient and cellular lipid homeostasis in the cause of Allgrove syndrome was analysed by fluorescence (BODIPY-staining) and coherent anti-Stokes Raman scattering (CARS) microscopy.

Results: To systematically address the question if human skin fibroblasts might serve as valuable biomaterial for (molecular) studies of NMD, we generated a protein library cataloguing 8280 proteins including a variety of such linked to genetic forms of motoneuron diseases, congenital myasthenic syndromes, neuropathies and muscle disorders. In silico-based pathway analyses revealed expression of a diversity of proteins involved in muscle contraction and such decisive for neuronal function and maintenance suggesting the suitability of human skin fibroblasts to study the etiology of NMD. Based on these findings, next we aimed to further demonstrate the suitability of this in vitro model to study NMD by a use case: the proteomic signature of fibroblasts derived from an Allgrove-patient was studied. Dysregulation of paradigmatic proteins could be confirmed in muscle biopsy of the patient and protein-functions could be linked to neurological symptoms known for this disease. Moreover, proteomic investigation of nuclear protein composition allowed the identification of protein-dysregulations according with structural perturbations observed in the muscle biopsy. BODIPY-staining on fibroblasts and CARS microscopy on muscle biopsy suggest altered lipid storage as part of the underlying disease etiology.

Conclusions: Our combined data reveal that human fibroblasts may serve as an in vitro system to study the molecular etiology of rare neurological diseases exemplified on Allgrove syndrome in an unbiased fashion.
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http://dx.doi.org/10.1186/s13023-020-01669-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7874489PMC
February 2021

Making sense of missense variants in TTN-related congenital myopathies.

Acta Neuropathol 2021 Mar 15;141(3):431-453. Epub 2021 Jan 15.

Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK.

Mutations in the sarcomeric protein titin, encoded by TTN, are emerging as a common cause of myopathies. The diagnosis of a TTN-related myopathy is, however, often not straightforward due to clinico-pathological overlap with other myopathies and the prevalence of TTN variants in control populations. Here, we present a combined clinico-pathological, genetic and biophysical approach to the diagnosis of TTN-related myopathies and the pathogenicity ascertainment of TTN missense variants. We identified 30 patients with a primary TTN-related congenital myopathy (CM) and two truncating variants, or one truncating and one missense TTN variant, or homozygous for one TTN missense variant. We found that TTN-related myopathies show considerable overlap with other myopathies but are strongly suggested by a combination of certain clinico-pathological features. Presentation was typically at birth with the clinical course characterized by variable progression of weakness, contractures, scoliosis and respiratory symptoms but sparing of extraocular muscles. Cardiac involvement depended on the variant position. Our biophysical analyses demonstrated that missense mutations associated with CMs are strongly destabilizing and exert their effect when expressed on a truncating background or in homozygosity. We hypothesise that destabilizing TTN missense mutations phenocopy truncating variants and are a key pathogenic feature of recessive titinopathies that might be amenable to therapeutic intervention.
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http://dx.doi.org/10.1007/s00401-020-02257-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7882473PMC
March 2021

Towards Central Nervous System Involvement in Adults with Hereditary Myopathies.

J Neuromuscul Dis 2020 ;7(4):367-393

Department of Neurology, Section of Neuromuscular Diseases, University Hospital Bonn, Germany.

There is increasing evidence of central nervous system involvement in numerous neuromuscular disorders primarily considered diseases of skeletal muscle. Our knowledge on cerebral affection in myopathies is expanding continuously due to a better understanding of the genetic background and underlying pathophysiological mechanisms. Intriguingly, there is a remarkable overlap of brain pathology in muscular diseases with pathomechanisms involved in neurodegenerative or neurodevelopmental disorders. A rapid progress in advanced neuroimaging techniques results in further detailed insight into structural and functional cerebral abnormalities. The spectrum of clinical manifestations is broad and includes movement disorders, neurovascular complications, paroxysmal neurological symptoms like migraine and epileptic seizures, but also behavioural abnormalities and cognitive dysfunction. Cerebral involvement implies a high socio-economic and personal burden in adult patients sometimes exceeding the everyday challenges associated with muscle weakness. It is especially important to clarify the nature and natural history of brain affection against the background of upcoming specific treatment regimen in hereditary myopathies that should address the brain as a secondary target. This review aims to highlight the character and extent of central nervous system involvement in patients with hereditary myopathies manifesting in adulthood, however also includes some childhood-onset diseases with brain abnormalities that transfer into adult neurological care.
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http://dx.doi.org/10.3233/JND-200507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7592671PMC
January 2020

The genomic and clinical landscape of fetal akinesia.

Genet Med 2020 03 4;22(3):511-523. Epub 2019 Nov 4.

University of Cologne, Center for Molecular Medicine Cologne (CMMC), Cologne, Germany.

Purpose: Fetal akinesia has multiple clinical subtypes with over 160 gene associations, but the genetic etiology is not yet completely understood.

Methods: In this study, 51 patients from 47 unrelated families were analyzed using next-generation sequencing (NGS) techniques aiming to decipher the genomic landscape of fetal akinesia (FA).

Results: We have identified likely pathogenic gene variants in 37 cases and report 41 novel variants. Additionally, we report putative pathogenic variants in eight cases including nine novel variants. Our work identified 14 novel disease-gene associations for fetal akinesia: ADSSL1, ASAH1, ASPM, ATP2B3, EARS2, FBLN1, PRG4, PRICKLE1, ROR2, SETBP1, SCN5A, SCN8A, and ZEB2. Furthermore, a sibling pair harbored a homozygous copy-number variant in TNNT1, an ultrarare congenital myopathy gene that has been linked to arthrogryposis via Gene Ontology analysis.

Conclusion: Our analysis indicates that genetic defects leading to primary skeletal muscle diseases might have been underdiagnosed, especially pathogenic variants in RYR1. We discuss three novel putative fetal akinesia genes: GCN1, IQSEC3 and RYR3. Of those, IQSEC3, and RYR3 had been proposed as neuromuscular disease-associated genes recently, and our findings endorse them as FA candidate genes. By combining NGS with deep clinical phenotyping, we achieved a 73% success rate of solved cases.
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http://dx.doi.org/10.1038/s41436-019-0680-1DOI Listing
March 2020

Teaching Video NeuroImages: Propriospinal myoclonus as a sequela of Guillain-Barré syndrome.

Neurology 2018 07;91(3):e297-e299

From the Departments of Neurology (J.R.B., J.R., S.P., J.Z.) and Radiology (M.N.), University of Bonn, Germany.

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http://dx.doi.org/10.1212/WNL.0000000000005827DOI Listing
July 2018

Endoplasmic Reticulum Stress Induces Myostatin High Molecular Weight Aggregates and Impairs Mature Myostatin Secretion.

Mol Neurobiol 2018 Nov 15;55(11):8355-8373. Epub 2018 Mar 15.

German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, 53127, Bonn, Germany.

Sporadic inclusion body myositis (sIBM) is the most prevalent acquired muscle disorder in the elderly with no defined etiology or effective therapy. Endoplasmic reticulum stress and deposition of myostatin, a secreted negative regulator of muscle growth, have been implicated in disease pathology. The myostatin signaling pathway has emerged as a major target for symptomatic treatment of muscle atrophy. Here, we systematically analyzed the maturation and secretion of myostatin precursor MstnPP and its metabolites in a human muscle cell line. We find that increased MsntPP protein levels induce ER stress. MstnPP metabolites were predominantly retained within the endoplasmic reticulum (ER), also evident in sIBM histology. MstnPP cleavage products formed insoluble high molecular weight aggregates, a process that was aggravated by experimental ER stress. Importantly, ER stress also impaired secretion of mature myostatin. Reduced secretion and aggregation of MstnPP metabolites were not simply caused by overexpression, as both events were also observed in wildtype cells under ER stress. It is tempting to speculate that reduced circulating myostatin growth factor could be one explanation for the poor clinical efficacy of drugs targeting the myostatin pathway in sIBM.
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http://dx.doi.org/10.1007/s12035-018-0997-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6153721PMC
November 2018

TIA1 variant drives myodegeneration in multisystem proteinopathy with SQSTM1 mutations.

J Clin Invest 2018 03 19;128(3):1164-1177. Epub 2018 Feb 19.

Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.

Multisystem proteinopathy (MSP) involves disturbances of stress granule (SG) dynamics and autophagic protein degradation that underlie the pathogenesis of a spectrum of degenerative diseases that affect muscle, brain, and bone. Specifically, identical mutations in the autophagic adaptor SQSTM1 can cause varied penetrance of 4 distinct phenotypes: amyotrophic lateral sclerosis (ALS), frontotemporal dementia, Paget's disease of the bone, and distal myopathy. It has been hypothesized that clinical pleiotropy relates to additional genetic determinants, but thus far, evidence has been lacking. Here, we provide evidence that a TIA1 (p.N357S) variant dictates a myodegenerative phenotype when inherited, along with a pathogenic SQSTM1 mutation. Experimentally, the TIA1-N357S variant significantly enhances liquid-liquid-phase separation in vitro and impairs SG dynamics in living cells. Depletion of SQSTM1 or the introduction of a mutant version of SQSTM1 similarly impairs SG dynamics. TIA1-N357S-persistent SGs have increased association with SQSTM1, accumulation of ubiquitin conjugates, and additional aggregated proteins. Synergistic expression of the TIA1-N357S variant and a SQSTM1-A390X mutation in myoblasts leads to impaired SG clearance and myotoxicity relative to control myoblasts. These findings demonstrate a pathogenic connection between SG homeostasis and ubiquitin-mediated autophagic degradation that drives the penetrance of an MSP phenotype.
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http://dx.doi.org/10.1172/JCI97103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824866PMC
March 2018

Screening for lipoprotein receptor-related protein 4-, agrin-, and titin-antibodies and exploring the autoimmune spectrum in myasthenia gravis.

J Neurol 2017 Jun 17;264(6):1193-1203. Epub 2017 May 17.

Department of Neurology, RWTH Aachen University, Aachen, Germany.

In autoimmune myasthenia gravis (MG), the identification of antibodies and characterization of serological subgroups is of great importance for diagnosis and management of the disease. Our aims were to study the frequency of antibodies against lipoprotein-related protein 4 (LRP4), agrin, and titin using the most recent techniques, and to characterize corresponding clinical features and autoimmune diseases (AID) in 100 MG-patients. The antibody frequencies in the 55 AChR-antibody positive patients were 7% LRP4, 5% agrin, 53% titin, and in the 45 AChR-antibody negative patients 2% MuSK, 2% LRP4, 2% agrin, and 27% titin. LRP4-MG presented late-onset age, mild symptoms, good therapeutic response, and no thymic changes. Agrin-MG showed early onset age, mild-to-severe symptoms, and moderate treatment response. The phenotype of titin-MG depended on AChR-antibodies: AChR-antibody negative patients presented with mostly mild limb muscle weakness, whereas AChR-antibody positive patients showed more frequently severe symptoms, including myasthenic crisis, bulbar predominance, and thymoma. Additional AID were detected in 32% of MG-patients, most frequently Hashimoto's thyroiditis (21%). Based on our data, we recommend the detection of LRP4-antibodies for at least AChR-antibody negative MG-patients and titin-antibodies for all MG-patients. We propose taking an accurate medical history for typical symptoms of Hashimoto's thyroiditis in MG-patients.
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http://dx.doi.org/10.1007/s00415-017-8514-zDOI Listing
June 2017

Sporadic late-onset nemaline myopathy: clinico-pathological characteristics and review of 76 cases.

Orphanet J Rare Dis 2017 05 11;12(1):86. Epub 2017 May 11.

Department of Neurology, University Hospital RWTH Aachen, Aachen, Germany.

Background: Sporadic late-onset nemaline myopathy (SLONM) is a rare, late-onset muscle disorder, characterized by the presence of nemaline rods in muscle fibers. Phenotypic characterization in a large cohort and a comprehensive overview of SLONM are lacking.

Methods: We studied the clinico-pathological features, treatment and outcome in a large cohort of 76 patients with SLONM, comprising 10 new patients and 66 cases derived from a literature meta-analysis (PubMed, 1966-2016), and compared these with 15 reported HIV-associated nemaline myopathy (HIV-NM) cases. In 6 SLONM patients, we performed a targeted next-generation sequencing (NGS) panel comprising 283 myopathy genes.

Results: SLONM patients had a mean age at onset of 52 years. The predominant phenotype consisted of weakness and atrophy of proximal upper limbs in 84%, of proximal lower limbs in 80% and both in 67%. Other common symptoms included axial weakness in 68%, as well as dyspnea in 55% and dysphagia in 47% of the patients. In 53% a monoclonal gammopathy of unknown significance (MGUS) was detected in serum. The mean percentage of muscle fibers containing rods was 28% (range 1-63%). In 2 cases ultrastructural analysis was necessary to detect the rods. The most successful treatment in SLONM patients (all with MGUS) was autologous peripheral blood stem cell therapy. A targeted NGS gene panel in 6 SLONM patients (without MGUS) did not reveal causative pathogenic variants. In a comparison of SLONM patients with and without MGUS, the former comprised significantly more males, had more rapid disease progression, and more vacuolar changes in muscle fibers. Interestingly, the muscle biopsy of 2 SLONM patients with MGUS revealed intranuclear rods, whereas this feature was not seen in any of the biopsies from patients without paraproteinemia. Compared to the overall SLONM cohort, significantly more HIV-NM patients were male, with a lower age at onset (mean 34 years). In addition, immunosuppression was more frequently applied with more favorable outcome, and muscle biopsies revealed a significantly higher degree of inflammation and necrosis in this cohort. Similar to SLONM, MGUS was present in half of the HIV-NM patients.

Conclusions: SLONM presents a challenging, but important differential diagnosis to other neuromuscular diseases of adult onset. Investigations for MGUS and HIV should be performed, as they require distinct but often effective therapeutic approaches. Even though SLONM and HIV-NM show some differences, there exists a large clinico-pathological overlap between the 2 entities.
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http://dx.doi.org/10.1186/s13023-017-0640-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425967PMC
May 2017

Camptocormia and shuffling gait due to a novel mutation: Diagnostic pitfalls.

Neurol Genet 2017 Jun 5;3(3):e147. Epub 2017 Apr 5.

Department of Neurology (J.R., C.K.), Department of Epileptology (W.S.K.), Life and Brain Centre (W.S.K.), and Centre for Rare Diseases Bonn (ZSEB) (C.K.), University Hospital of Bonn, Germany; Department of Neurology (D.L.), University of Halle/S., Germany; and Wellcome Trust Centre for Mitochondrial Research (D.L., S.A.H., G.F., C.V.Y.K., R.L.J., R.W.T.), Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK.

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http://dx.doi.org/10.1212/NXG.0000000000000147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384303PMC
June 2017

Muscle Pathology as a Diagnostic Clue to Allgrove Syndrome.

J Neuropathol Exp Neurol 2017 May;76(5):337-341

From Muscle Lab, Department of Neurology, University of Bonn Medical Centre, Bonn, Germany (JR, KT), Institute of Clinical Genetics, Bonn, Germany (NK), Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany (JW, AR), Department of Neuropathology, University of Bonn Medical Centre, Bonn, Germany (KK), Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Department of Bioanalytics, Tissue Omics group, Dortmund, Germany (AR), John Walton Muscular Dystrophy Research Centre (JWMDRC), Newcastle University, International Centre for Life, Central Parkway, UK, Newcastle upon Tyne (AR).

Allgrove or triple A syndrome is a rare autosomal recessive disorder that can present with a variable range of multi-system manifestations, including optic atrophy, cerebellar ataxia, upper and lower motoneuron signs and various neuropathic abnormalities. These cases are a diagnostic challenge, particularly when the eponymous combination of achalasia, Addisonianism and alacrima is incomplete. Therefore, it is in the differential diagnosis for multisystem conditions and should be known to pathologists who diagnose disorders of skeletal muscle. Here, we describe new findings in skeletal muscle histology from the case of a boy of consanguineous Turkish origin whose achalasia provided the only specific clinical clue to the diagnosis. These include myocyte nuclear abnormalities with partially abnormal anti-lamin A/C immunohistochemistry and altered nuclear ultrastructure but without overt abnormalities of nuclear pore morphology. In this case, the condition was associated with a hitherto unreported c.762delC mutation in the nucleoporin gene AAAS.
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http://dx.doi.org/10.1093/jnen/nlx016DOI Listing
May 2017

Loss of the smallest subunit of cytochrome c oxidase, COX8A, causes Leigh-like syndrome and epilepsy.

Brain 2016 Feb 17;139(Pt 2):338-45. Epub 2015 Dec 17.

1 Department of Epileptology and Life and Brain Centre, University of Bonn, Bonn, Germany

Isolated cytochrome c oxidase (complex IV) deficiency is one of the most frequent respiratory chain defects in humans and is usually caused by mutations in proteins required for assembly of the complex. Mutations in nuclear-encoded structural subunits are very rare. In a patient with Leigh-like syndrome presenting with leukodystrophy and severe epilepsy, we identified a homozygous splice site mutation in COX8A, which codes for the ubiquitously expressed isoform of subunit VIII, the smallest nuclear-encoded subunit of complex IV. The mutation, affecting the last nucleotide of intron 1, leads to aberrant splicing, a frame-shift in the highly conserved exon 2, and decreased amount of the COX8A transcript. The loss of the wild-type COX8A protein severely impairs the stability of the entire cytochrome c oxidase enzyme complex and manifests in isolated complex IV deficiency in skeletal muscle and fibroblasts, similar to the frequent c.845_846delCT mutation in the assembly factor SURF1 gene. Stability and activity of complex IV could be rescued in the patient's fibroblasts by lentiviral expression of wild-type COX8A. Our findings demonstrate that COX8A is indispensable for function of human complex IV and its mutation causes human disease.
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http://dx.doi.org/10.1093/brain/awv357DOI Listing
February 2016

Clinical and morphological variability of the E396K mutation in the neurofilament light chain gene in patients with Charcot-Marie- Tooth disease type 2E.

Clin Neuropathol 2014 Sep-Oct;33(5):335-43

Mutations in the neurofilament light chain (NEFL) gene mostly cause autosomal dominant axonal Charcot-Marie- Tooth neuropathy (CMT2E). The mutation c.1186G>A, p.E396K has been reported in seven unrelated families so far, however, the phenotypic spectrum has not been fully elucidated. Here we describe nine patients with the E396K mutation who had a strikingly discordant clinical severity. The clinical picture in family I (patients I,1-II,8) was characterized by childhood onset, distal and proximal pareses, and loss of ambulation in the 6th decade of life, whereas onset was at age 50 years in patient 9, who had no affected relatives. Electrophysiology and sural nerve biopsy revealed a mixed axonal and demyelinating neuropathy, along with probably coincidental inflammatory small vessel disease in patient 9. Biopsy results in family I suggest that not only axons but also Schwann cells may be primary disease targets in CMT2E. Considerably elevated CK levels in all affected adults of family I as well as pronounced myopathic changes in skeletal muscle biopsies point towards an accompanying muscle involvement as a primary target. Our findings reveal an extended phenotype of CMT2E caused by an identical missense mutation of the NEFL gene.
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http://dx.doi.org/10.5414/NP300742DOI Listing
October 2014

Diagnostic challenge and therapeutic dilemma in necrotizing myopathy.

Neurology 2013 Sep 6;81(10):932-5. Epub 2013 Aug 6.

Department of Neurology, RWTH Aachen University, Aachen, Germany.

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http://dx.doi.org/10.1212/WNL.0b013e3182a35285DOI Listing
September 2013

K7del is a common TPM2 gene mutation associated with nemaline myopathy and raised myofibre calcium sensitivity.

Brain 2013 Feb 31;136(Pt 2):494-507. Epub 2013 Jan 31.

Institute for Neuroscience and Muscle Research, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia

Mutations in the TPM2 gene, which encodes β-tropomyosin, are an established cause of several congenital skeletal myopathies and distal arthrogryposis. We have identified a TPM2 mutation, p.K7del, in five unrelated families with nemaline myopathy and a consistent distinctive clinical phenotype. Patients develop large joint contractures during childhood, followed by slowly progressive skeletal muscle weakness during adulthood. The TPM2 p.K7del mutation results in the loss of a highly conserved lysine residue near the N-terminus of β-tropomyosin, which is predicted to disrupt head-to-tail polymerization of tropomyosin. Recombinant K7del-β-tropomyosin incorporates poorly into sarcomeres in C2C12 myotubes and has a reduced affinity for actin. Two-dimensional gel electrophoresis of patient muscle and primary patient cultured myotubes showed that mutant protein is expressed but incorporates poorly into sarcomeres and likely accumulates in nemaline rods. In vitro studies using recombinant K7del-β-tropomyosin and force measurements from single dissected patient myofibres showed increased myofilament calcium sensitivity. Together these data indicate that p.K7del is a common recurrent TPM2 mutation associated with mild nemaline myopathy. The p.K7del mutation likely disrupts head-to-tail polymerization of tropomyosin, which impairs incorporation into sarcomeres and also affects the equilibrium of the troponin/tropomyosin-dependent calcium switch of muscle. Joint contractures may stem from chronic muscle hypercontraction due to increased myofibrillar calcium sensitivity while declining strength in adulthood likely arises from other mechanisms, such as myofibre decompensation and fatty infiltration. These results suggest that patients may benefit from therapies that reduce skeletal muscle calcium sensitivity, and we highlight late muscle decompensation as an important cause of morbidity.
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http://dx.doi.org/10.1093/brain/aws348DOI Listing
February 2013

ZASPopathy with childhood-onset distal myopathy.

J Neurol 2012 Jul 23;259(7):1494-6. Epub 2012 May 23.

Department of Radiology, University of Bonn, Bonn, Germany.

We report on a German family presenting with a predominantly distal myopathy primarily affecting anterior compartments of lower legs in childhood. Proximal lower limb and hip girdle weakness developed later in early adulthood in the female index patient and likewise in her mother. Consecutive muscle biopsy findings were first attributed to a mild congenital myopathy and later on interpreted as neurogenic changes without clear signs of a myopathy. Molecular genetic analysis was performed because of the clinical impression of a distal myopathy combined with dominant inheritance. The heterozygous mutation c.349G>A (p.D117N) in the ZASP gene could be found. This mutation had been previously associated with an adult-onset, isolated, dilated left ventricular non-compaction cardiomyopathy (OMIM*605906.0007), which was not present in our patients. Our data show that this mutation can be associated with an isolated skeletal muscle phenotype. Second, mutation analysis of the ZASP gene is suggested for distal myopathies of any age, even in cases of uncharacteristic muscle biopsy findings on routine analysis.
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http://dx.doi.org/10.1007/s00415-012-6543-1DOI Listing
July 2012

The phenotypic spectrum of neutral lipid storage myopathy due to mutations in the PNPLA2 gene.

J Neurol 2011 Nov 5;258(11):1987-97. Epub 2011 May 5.

Friedrich-Baur-Institute, Department of Neurology, Ludwig-Maximilians University, Munich, Germany.

Neutral lipid storage disease is caused by mutations in the CGI-58 or the PNPLA2 genes. Lipid storage can be detected in various cell types including blood granulocytes. While CGI-58 mutations are associated with Chanarin-Dorfman syndrome, a condition characterized by lipid storage and skin involvement (ichthyosis), mutations in the patatin-like phospholipase domain-containing protein 2 gene (PNPLA2) were reported with skeletal and cardiac muscle disease only. We describe clinical, myopathological, magnetic resonance imaging (MRI), and genetic findings of six patients carrying different recessive PNPLA2 mutations. Pulse-chase labeling of control and patient cells with supplementation of clenbuterol, salmeterol, and dexamethasone was performed in vitro. The patients share a recognizable phenotype with prominent shoulder girdle weakness and mild pelvic girdle and distal muscle weakness, with highly elevated creatine kinase (CK) and cardiomyopathy developing at later stages. Muscle histology invariably reveals massive accumulation of lipid droplets. New muscle or whole-body MRI techniques may assist diagnosis and may become a useful tool to quantify intramuscular lipid storage. Four novel and two previously reported mutations were detected, affecting different parts of the PNPLA2 gene. Activation of hormone-sensitive lipase by beta-adrenergic substances such as clenbuterol appears to bypass the enzymatic block in PNPLA2-deficient patient cells in vitro. PNPLA2 deficiency is a slowly progressive myopathy with onset around the third decade. Cardiac involvement is relatively common at a later stage. Muscle MRI may detect increased lipid in a characteristic distribution, which could be used for monitoring disease progression. Beta-adrenergic agents may be beneficial in improving triacylglycerol breakdown in patients with PNPLA2 mutations.
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http://dx.doi.org/10.1007/s00415-011-6055-4DOI Listing
November 2011

Mitochondrial dysfunction due to Leber's hereditary optic neuropathy as a cause of visual loss during assessment for epilepsy surgery.

Epilepsy Behav 2011 Jan 9;20(1):38-43. Epub 2010 Dec 9.

Department of Neuropathology, University of Bonn, Bonn, Germany.

Assessment for epilepsy surgery may require invasive measures such as implantation of intracranial electrodes or the Wada test. These investigations are commonly well tolerated. However, complications, including visual disturbances of various etiologies, have been reported. Here we describe two patients with pharmacoresistant temporal lobe epilepsy (TLE) who displayed loss of vision in the context of presurgical assessment and in whom mutations associated with Leber's hereditary optic neuropathy (LHON) were detected. Genetic analysis revealed in one patient the frequent mitochondrial G11778A LHON mutation in ND4. In the second patient, the mitochondrial C4640A mutation in ND2 was detected. This rare LHON mutation enhanced the sensitivity of the patient's muscle and brain tissue to amobarbital, a known blocker of the mitochondrial respiratory chain. Mitochondrial dysfunction has been reported in epilepsy. Thus, the presence of LHON mutations can be a rare cause of visual disturbances in patients with epilepsy and may have predisposed to development of epilepsy.
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http://dx.doi.org/10.1016/j.yebeh.2010.11.008DOI Listing
January 2011

Strumpellin is a novel valosin-containing protein binding partner linking hereditary spastic paraplegia to protein aggregation diseases.

Brain 2010 Oct 9;133(10):2920-41. Epub 2010 Sep 9.

Institute of Biochemistry I, University of Cologne, Joseph-Stelzmann-Street 52, Cologne, Germany.

Mutations of the human valosin-containing protein gene cause autosomal-dominant inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia. We identified strumpellin as a novel valosin-containing protein binding partner. Strumpellin mutations have been shown to cause hereditary spastic paraplegia. We demonstrate that strumpellin is a ubiquitously expressed protein present in cytosolic and endoplasmic reticulum cell fractions. Overexpression or ablation of wild-type strumpellin caused significantly reduced wound closure velocities in wound healing assays, whereas overexpression of the disease-causing strumpellin N471D mutant showed no functional effect. Strumpellin knockdown experiments in human neuroblastoma cells resulted in a dramatic reduction of axonal outgrowth. Knockdown studies in zebrafish revealed severe cardiac contractile dysfunction, tail curvature and impaired motility. The latter phenotype is due to a loss of central and peripheral motoneuron formation. These data imply a strumpellin loss-of-function pathogenesis in hereditary spastic paraplegia. In the human central nervous system strumpellin shows a presynaptic localization. We further identified strumpellin in pathological protein aggregates in inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia, various myofibrillar myopathies and in cortical neurons of a Huntington's disease mouse model. Beyond hereditary spastic paraplegia, our findings imply that mutant forms of strumpellin and valosin-containing protein may have a concerted pathogenic role in various protein aggregate diseases.
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http://dx.doi.org/10.1093/brain/awq222DOI Listing
October 2010

Macrophage migration inhibitory factor in normal human skeletal muscle and inflammatory myopathies.

J Neuropathol Exp Neurol 2010 Jun;69(6):654-62

Department of Neurology, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine secreted by activated T cells and macrophages that has antiapoptotic, proproliferative, and chemotactic effects. Because these cells are major components of many muscle disorders with different etiologies, we investigated the amount and distribution of MIF in inflammatory myopathies. Concentrations of MIF in protein lysates from dermatomyositis (n = 6), polymyositis (n = 7), sporadic inclusion body myositis (n = 9) muscle samples and control biopsies without specific changes (n = 10) were determined by ELISA. In polymyositis, MIF concentrations were higher than in controls (p<0.05), whereas they were not significantly different in other inflammatory myopathies. By immunohistochemistry, MIF was detected not only in inflammatory cells, but also at muscle fiber membranes where they were invaded or bordered infiltrates or necrotic fibers; focal sarcoplasmic reactivity was also observed. A similar distribution was found in areas of infiltration, necrosis, myophagocytosis, degeneration, and regeneration in 8 muscular dystrophy samples. The expression of MIF was verified in human myogenic tissue cultures; MIF immunoreactivity decreased with progressive differentiation, and its distribution changed. These data suggest that MIF is a skeletal muscle cytokine with probable functions beyond inflammatory pathology in the complex regenerative response to muscle fiber damage.
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http://dx.doi.org/10.1097/NEN.0b013e3181e10925DOI Listing
June 2010

Reverse protein arrays as novel approach for protein quantification in muscular dystrophies.

Neuromuscul Disord 2010 May 20;20(5):302-9. Epub 2010 Mar 20.

University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz, Switzerland.

The definite molecular diagnosis in patients with muscular dystrophies often requires the assessment of muscular expression of multiple proteins in small amounts of muscle tissue. The sample material obtained in muscle biopsies is limited and the measurement of multiple proteins is often restricted to conventional, non-quantitative assays, i.e. immunohistochemistry and immunoblotting. Here, we demonstrate that reverse protein arrays are a novel and excellent material-saving method for the measurement and quantification of changes in protein expression between healthy and diseased muscle tissue as well as cultured primary myotubes. We evaluated a set of antibodies and found reproducible differences between Duchenne muscular dystrophy/limb-girdle muscular dystrophy patients and control samples for dystrophin, the sarcoglycans and the dystroglycans. As little as 10 mg of tissue is sufficient for the analysis of all diagnostically relevant proteins. The average coefficient of variation calculated for the sample signals confirmed that the method is highly reproducible. Thus, our experiments provide strong evidence that quantitative protein detection from very small amounts of muscle tissue is possible using reverse protein arrays. This technology may not only be of interest for diagnostic purposes, but also for protein quantification of multiple, follow-up biopsies during clinical trials when protein expression in muscle is considered an important outcome measure or biomarker.
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http://dx.doi.org/10.1016/j.nmd.2010.02.017DOI Listing
May 2010

Structural and functional diversity of novel coronin 1C (CRN2) isoforms in muscle.

J Mol Biol 2009 Oct 3;393(2):287-99. Epub 2009 Aug 3.

Center for Biochemistry, Institute of Biochemistry I, University of Cologne, Germany.

Coronin 1C (synonyms: coronin-3, CRN2), a WD40 repeat-containing protein involved in cellular actin dynamics, is ubiquitously expressed in human tissues. Here, we report on the identification and functional characterization of two novel coronin 1C isoforms, referred to as CRN2i2 and CRN2i3, which also associate with F-actin. Analyses of the coronin 1C gene disclosed a single promoter containing binding sites for myogenic regulatory factors and an alternative first exon 1b present in intron 1, which give rise to the novel isoforms. Chromatin immunoprecipitation studies demonstrate MyoD binding to a region of the CRN2 gene, which contains a highly conserved E-box element in exon 1a. Gel-filtration assays suggest that the largest isoform 3 exists as a monomer, in contrast to isoform 1 and isoform 2 appearing as trimers. CRN2i3, which can be induced by MyoD, is exclusively expressed in well-differentiated myoblasts as well as in mature skeletal muscle tissue. In human skeletal muscle, CRN2i3 is a novel component of postsynaptic neuromuscular junctions and thin filaments of myofibrils. Together, our findings postulate a role for CRN2 isoforms in the structural and functional organization of F-actin in highly ordered protein complexes.
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http://dx.doi.org/10.1016/j.jmb.2009.07.079DOI Listing
October 2009

How much mutant protein is needed to cause a protein aggregate myopathy in vivo? Lessons from an exceptional desminopathy.

Hum Mutat 2009 Mar;30(3):E490-9

Institute of Biochemistry I, Medical Faculty, University of Cologne, Germany.

Myofibrillar myopathies are caused by mutations in desmin, alphaB-crystallin, myotilin, ZASP, and filamin C genes. Since the vast majority of myofibrillar myopathy causing mutations are heterozygous single amino acid substitutions or small in-frame deletions, the pathogenic role of mutant versus wild-type protein cannot be assessed in human skeletal muscle by standard immunodetection techniques. We report on an exceptional desminopathy due to a heterozygous c.735G>C mutation. Immunoblotting detected full-length 53 kDa desmin and a truncated 50 kDa variant in skeletal muscle from three affected patients of two different families. RT-PCR identified three desmin mRNA species encoding for wild-type and two mutant proteins, p.Glu245Asp and p.Asp214_Glu245del. Since previous functional studies on the p.Glu245Asp mutant showed biological properties identical to wild-type desmin, the truncated p.Asp214_Glu245del desmin is the disease-causing mutant. Semiquantitative RT-PCR established a fraction of the truncated desmin mRNA species in a range from 24% to 37%. Initial quantification of corresponding desmin proteins in the muscle biopsy of the index patient of one family indicated a fraction of only 10% of the truncated species. However, serial analyses of different sections from each muscle biopsy revealed a high intra- and interindividual variability of the truncated desmin protein level within a range from 5% to 43%. Desmin assembly studies in vitro have established clear-cut pathogenic ratios of mutant versus wild-type proteins. However, our findings point out a far more complex situation in human skeletal muscle. The heterogeneously distributed mutation load within and between individual specimens, which reflects local differences in the expression and/or turnover of the mutant protein in different areas containing multiple myonuclear domains, renders it impossible to define an exact pathogenic threshold of a specific mutant in vivo.
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http://dx.doi.org/10.1002/humu.20941DOI Listing
March 2009

Clinical, genetic, and cardiac magnetic resonance imaging findings in primary desminopathies.

Neuromuscul Disord 2008 Jun 27;18(6):475-82. Epub 2008 May 27.

Department of Radiology, University Hospital Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.

We report the clinical, genetic and cardiac magnetic resonance imaging (MRI) findings in 11 German patients with heterozygous E245D, D339Y, R350P and L377P desmin mutations and without cardiac symptoms. Clinical evaluation revealed a marked variability of skeletal muscle, respiratory and cardiac involvement even between patients with identical mutations, ranging from asymptomatic to severely affected. While echocardiography did not show any pathological findings in all 11 patients, cine MRI revealed focal left ventricular hypertrophy in 2 patients and MR delayed enhancement imaging displayed intramyocardial fibrosis in the left ventricle in 4 patients indicating early myocardial involvement. Our data argue against distinct genotype-phenotype correlations and suggest that comprehensive cardiac MRI is superior to conventional echocardiography for the detection of early and clinically asymptomatic stages of cardiomyopathy in desminopathy patients. Therefore, cardiac MRI may serve as a screening tool to identify patients at risk, which might benefit from early pharmacological and/or interventional (e.g. implantable cardioverter-defibrillator devices) therapy.
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http://dx.doi.org/10.1016/j.nmd.2008.03.012DOI Listing
June 2008

Novel COLQ mutation 950delC in synaptic congenital myasthenic syndrome and symptomatic heterozygous relatives.

Neuromuscul Disord 2007 Mar 14;17(3):262-5. Epub 2007 Feb 14.

Children's Hospital, University of Bonn, Adenauerallee 119, 53113 Bonn, Germany.

The synaptic form of congenital myasthenic syndrome (CMS) is a rare autosomal recessive disease affecting neuromuscular transmission. Mutations in the COLQ gene that encodes the collagenic tail subunit (ColQ) of asymmetric acetylcholinesterase lead to endplate acetylcholinesterase deficiency. We report two children suffering from synaptic CMS due to two compound heterozygous COLQ mutations, IVS1-1G>A and a novel mutation, 950delC. Furthermore, we found familial occurrence of congenital ptosis in heterozygous carriers of 950delC, mimicking a dominant negative effect. Considering the lack of a clear genotype-phenotype-relation in synaptic CMS, several authors speculated on the influence of additional modifying factors. Consequently, involvement of such factors in this report of familial congenital ptosis cannot be excluded.
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http://dx.doi.org/10.1016/j.nmd.2006.11.010DOI Listing
March 2007

Pathological consequences of VCP mutations on human striated muscle.

Brain 2007 Feb 19;130(Pt 2):381-93. Epub 2006 Sep 19.

Institute of Biochemistry I, University of Cologne, Cologne, Germany.

Mutations in the valosin-containing protein (VCP, p97) gene on chromosome 9p13-p12 cause a late-onset form of autosomal dominant inclusion body myopathy associated with Paget disease of the bone and frontotemporal dementia (IBMPFD). We report on the pathological consequences of three heterozygous VCP (R93C, R155H, R155C) mutations on human striated muscle. IBMPFD skeletal muscle pathology is characterized by degenerative changes and filamentous VCP- and ubiquitin-positive cytoplasmic and nuclear protein aggregates. Furthermore, this is the first report demonstrating that mutant VCP leads to a novel form of dilatative cardiomyopathy with inclusion bodies. In contrast to post-mitotic striated muscle cells and neurons of IBMPFD patients, evidence of protein aggregate pathology was not detected in primary IBMPFD myoblasts or in transient and stable transfected cells using wild-type-VCP and R93C-, R155H-, R155C-VCP mutants. Glutathione S-transferase pull-down experiments showed that all three VCP mutations do not affect the binding to Ufd1, Npl4 and ataxin-3. Structural analysis demonstrated that R93 and R155 are both surface-accessible residues located in the centre of cavities that may enable ligand-binding. Mutations at R93 and R155 are predicted to induce changes in the tertiary structure of the VCP protein. The search for putative ligands to the R93 and R155 cavities resulted in the identification of cyclic sugar compounds with high binding scores. The latter findings provide a novel link to VCP carbohydrate interactions in the complex pathology of IBMPFD.
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http://dx.doi.org/10.1093/brain/awl238DOI Listing
February 2007

The oral antidiabetic pioglitazone protects from neurodegeneration and amyotrophic lateral sclerosis-like symptoms in superoxide dismutase-G93A transgenic mice.

J Neurosci 2005 Aug;25(34):7805-12

Department of Psychiatry and Psychotherapy, University of Bonn, 53127 Bonn, Germany.

Amyotrophic lateral sclerosis (ALS) represents a fatal neurodegenerative disorder characterized by progressive death of the upper and lower motor neurons. Because accompanying inflammation may interact with and promote neurodegeneration, anti-inflammatory treatment strategies are being evaluated. Because peroxisome proliferator-activated receptor gamma (PPARgamma) agonists act as potent anti-inflammatory drugs, we tested whether superoxide dismutase (SOD1)-G93A transgenic mice, a mouse model of ALS, benefit from oral treatment with the PPARgamma agonist pioglitazone (Pio). Pio-treated transgenic mice revealed improved muscle strength and body weight, exhibited a delayed disease onset, and survived significantly longer than nontreated SOD1-G93A mice. Quantification of motor neurons of the spinal cord at day 90 revealed complete neuroprotection by Pio, whereas nontreated SOD1-G93A mice had lost 30% of motor neurons. This was paralleled by preservation of the median fiber diameter of the quadriceps muscle, indicating not only morphological but also functional protection of motor neurons by Pio. Activated microglia were significantly reduced at sites of neurodegeneration in Pio-treated SOD1-G93A mice, as were the protein levels of cyclooxygenase 2 and inducible nitric oxide synthase. Interestingly, mRNA levels of the suppressor of cytokine signaling 1 and 3 genes were increased by Pio, whereas both the mRNA and protein levels of endogenous mouse SOD1 and of transgenic human SOD1 remained unaffected.
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http://dx.doi.org/10.1523/JNEUROSCI.2038-05.2005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6725264PMC
August 2005

Pax7 distribution in human skeletal muscle biopsies and myogenic tissue cultures.

Cell Tissue Res 2004 Feb 26;315(2):233-42. Epub 2003 Nov 26.

Department of Neurology, University of Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany.

Demonstration of the importance of the paired box transcription factor Pax7 for the murine myosatellite cell population, with persistent expression in mature skeletal muscle, prompted us to investigate the distribution of Pax7 protein in biopsy samples of normal and pathological human skeletal limb muscle. Immunostaining for M-cadherin, an adhesion molecule present at the interface between myofibre and satellite cell, and the characteristic position adjacent to the muscle fibre and beneath the fibre's basement membrane were used to identify satellite cells. Anti-Pax7 reactivity was found in the majority of satellite cells but a small population was Pax7 negative. Neither could we identify Pax7-positive nuclei in freshly regenerating myotubes or in presumed myoblasts in these biopsies. Similarly, in myogenic cell cultures derived from the explantation of human foetal muscle Pax7 expression was low or undetectable at the proliferative myoblast stage but it became prominent in an increasing proportion of mononucleate cells after the induction of differentiation. This expression was, however, restricted to mononucleate cells; it did not persist into the differentiation stage of newly formed multinucleate myotubes. Despite this, in the biopsy samples, we occasionally found Pax7-positive nuclei in muscle fibres that seemed to be undergoing degenerative changes. Most of these were found to be the nuclei of cells engaged in focal regenerative processes, but Pax7 re-expression by myonuclei "in distress" cannot be ruled out entirely.
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http://dx.doi.org/10.1007/s00441-003-0833-yDOI Listing
February 2004