Dataset Information

A nationwide survey on Marinesco-Sjogren syndrome in Japan.

ABSTRACT: BACKGROUND: Marinesco-Sjögren syndrome (MSS) is an autosomal recessive multisystem disorder characterized by the tetralogy of cerebellar ataxia, congenital cataracts, intellectual disability, and progressive muscle weakness due to myopathy. MSS is extremely rare, and its clinical, pathological, and genetic features are not yet fully understood. METHODS: We conducted a nationwide, questionnaire-based survey on MSS in Japan and carefully reviewed the medical records of 36 patients suspected of having this disease. In addition, pathological examinations of muscles, sequence and haplotype analysis in SIL1 were performed. RESULTS: The patients had been examined between the ages of 2 and 52 years. Delayed psychomotor development and cataracts from early childhood were observed in all patients, whereas no life-threatening events were observed. Mutations in SIL1 were identified in 24 of the 27 patients tested, and 43 of the 48 chromosomes possessed the SIL1 c.936dupG (p.Leu313fs) mutation. The haplotype analysis revealed that 31 of the 32 chromosomes (96.9%) with the c.936dupG mutation had the same haplotype. CONCLUSIONS: The results of haplotype analysis suggested the presence of a founder effect. The clinical features of patients without SIL1 mutations were indistinguishable from those with SIL1 mutations, suggesting the genetic heterogeneity of MSS.

SUBMITTER: Goto M

PROVIDER: S-EPMC4021608 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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A nationwide survey on Marinesco-Sjögren syndrome in Japan.

Goto Masahide M Okada Mari M Komaki Hirofumi H Sugai Kenji K Sasaki Masayuki M Noguchi Satoru S Nonaka Ikuya I Nishino Ichizo I Hayashi Yukiko K YK

Orphanet journal of rare diseases 20140423

<h4>Background</h4>Marinesco-Sjögren syndrome (MSS) is an autosomal recessive multisystem disorder characterized by the tetralogy of cerebellar ataxia, congenital cataracts, intellectual disability, and progressive muscle weakness due to myopathy. MSS is extremely rare, and its clinical, pathological, and genetic features are not yet fully understood.<h4>Methods</h4>We conducted a nationwide, questionnaire-based survey on MSS in Japan and carefully reviewed the medical records of 36 patients sus ...[more]

PMID: 24755310

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Project description:Marinesco-Sjogren syndrome (MSS) is a rare multisystem pediatric disorder, caused by loss-of-function mutations in the gene encoding the endoplasmic reticulum cochaperone SIL1. SIL1 acts as a nucleotide exchange factor for BiP, which plays a central role in secretory protein folding. SIL1 mutant cells have reduced BiP-assisted protein folding, cannot fulfil their protein needs, and experience chronic activation of the unfolded protein response (UPR). Maladaptive UPR may explain the cerebellar and skeletal muscle degeneration responsible for the ataxia and muscle weakness typical of MSS. However, the cause of other more variable, clinical manifestations, such as mild to severe mental retardation, hypogonadism, short stature, and skeletal deformities, is less clear. To gain insights into the pathogenic mechanisms and/or adaptive responses to SIL1 loss, we carried out cell biological and proteomic investigations in skin fibroblasts derived from a young patient carrying the SIL1 R111X mutation. Despite fibroblasts not being overtly affected in MSS, we found morphological and biochemical changes indicative of UPR activation and altered cell metabolism. All the cell machineries involved in RNA splicing and translation were strongly downregulated, while protein degradation via lysosome-based structures was boosted, consistent with an attempt of the cell to reduce the workload of the endoplasmic reticulum and dispose of misfolded proteins. Cell metabolism was extensively affected as we observed a reduction in lipid synthesis, an increase in beta oxidation, and an enhancement of the tricarboxylic acid cycle, with upregulation of eight of its enzymes. Finally, the catabolic pathways of various amino acids, including valine, leucine, isoleucine, tryptophan, lysine, aspartate, and phenylalanine, were enhanced, while the biosynthetic pathways of arginine, serine, glycine, and cysteine were reduced. These results indicate that, in addition to UPR activation and increased protein degradation, MSS fibroblasts have profound metabolic alterations, which may help them cope with the absence of SIL1.

Project description:BackgroundMarinesco-Sjögren syndrome (MSS) is an autosomal recessive neuromuscular disorder that arises in early childhood and is characterized by congenital cataracts, myopathy associated with muscle weakness, and degeneration of Purkinje neurons leading to ataxia. About 60% of MSS patients have loss-of-function mutations in the SIL1 gene. Sil1 is an endoplasmic reticulum (ER) protein required for the release of ADP from the master chaperone Bip, which in turn will release the folded proteins. The expression of non-functional Sil1 leads to the accumulation of unfolded proteins in the ER and this triggers the unfolded protein response (UPR). A dysfunctional UPR could be a key element in the pathogenesis of MSS, although our knowledge of the molecular pathology of MSS is still incomplete.MethodsRNA-Seq transcriptomics was analysed using the String database and the Ingenuity Pathway Analysis platform. Fluorescence confocal microscopy was used to study the remodelling of the extracellular matrix (ECM). Transmission electron microscopy (TEM) was used to reveal the morphology of the ECM in vitro and in mouse tendon.ResultsOur transcriptomic analysis, performed on patient-derived fibroblasts, revealed 664 differentially expressed (DE) transcripts. Enrichment analysis of DE genes confirmed that the patient fibroblasts have a membrane trafficking issue. Furthermore, this analysis indicated that the extracellular space/ECM and the cell adhesion machinery, which together account for around 300 transcripts, could be affected in MSS. Functional assays showed that patient fibroblasts have a reduced capacity of ECM remodelling, reduced motility, and slower spreading during adhesion to Petri dishes. TEM micrographs of negative-stained ECM samples from these fibroblasts show differences of filaments in terms of morphology and size. Finally, structural analysis of the myotendinous junction of the soleus muscle and surrounding regions of the Achilles tendon revealed a disorganization of collagen fibres in the mouse model of MSS (woozy).ConclusionsECM alterations can affect the proper functioning of several organs, including those damaged in MSS such as the central nervous system, skeletal muscle, bone and lens. On this basis, we propose that aberrant ECM is a key pathological feature of MSS and may help explain most of its clinical manifestations.

Dataset Information

A nationwide survey on Marinesco-Sjogren syndrome in Japan.

Publications

A nationwide survey on Marinesco-Sjögren syndrome in Japan.

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