Gene expression profiling in equine polysaccharide storage myopathy revealed inflammation, glycogenesis inhibition, hypoxia and mitochondrial dysfunctions

<p>Abstract</p> <p>Background</p> <p>Several cases of myopathies have been observed in the horse Norman Cob breed. Muscle histology examinations revealed that some families suffer from a polysaccharide storage myopathy (PSSM). It is assumed that a gene expression signature related to PSSM should be observed at the transcriptional level because the glycogen storage disease could also be linked to other dysfunctions in gene regulation. Thus, the functional genomic approach could be conducted in order to provide new knowledge about the metabolic disorders related to PSSM. We propose exploring the PSSM muscle fiber metabolic disorders by measuring gene expression in relationship with the histological phenotype.</p> <p>Results</p> <p>Genotypying analysis of GYS1 mutation revealed 2 homozygous (AA) and 5 heterozygous (GA) PSSM horses. In the PSSM muscles, histological data revealed PAS positive amylase resistant abnormal polysaccharides, inflammation, necrosis, and lipomatosis and active regeneration of fibers. Ultrastructural evaluation revealed a decrease of mitochondrial number and structural disorders. Extensive accumulation of an abnormal polysaccharide displaced and partially replaced mitochondria and myofibrils. The severity of the disease was higher in the two homozygous PSSM horses.</p> <p>Gene expression analysis revealed 129 genes significantly modulated (p < 0.05). The following genes were up-regulated over 2 fold: IL18, CTSS, LUM, CD44, FN1, GST01. The most down-regulated genes were the following: mitochondrial tRNA, SLC2A2, PRKCα, VEGFα. Data mining analysis showed that protein synthesis, apoptosis, cellular movement, growth and proliferation were the main cellular functions significantly associated with the modulated genes (p < 0.05). Several up-regulated genes, especially IL18, revealed a severe muscular inflammation in PSSM muscles. The up-regulation of glycogen synthase kinase-3 (GSK3β) under its active form could be responsible for glycogen synthase (GYS1) inhibition and hypoxia-inducible factor (HIF1α) destabilization.</p> <p>Conclusion</p> <p>The main disorders observed in PSSM muscles could be related to mitochondrial dysfunctions, glycogenesis inhibition and the chronic hypoxia of the PSSM muscles.</p

Étude de la myopathie héréditaire par surcharge en polysaccharides chez les chevaux Cob normand

The genetic basis of predisposition to the polysaccharide storage myopathy (PSSM) was investigated in the horse. PSSM is one of the causes of “tying-up” syndrome developed by draught breeds : lower performances, lameness, cramps, myoglobinurie. The phenotype of the affection was better defined in terms of epidemiology, lesions and pathogenesis. Functional analysis of gene expression in affected muscles revealed an inflammation, an inhibition of the mitochondria activity, an energetic metabolism disorder and an hypoxia. The structural and functional characterisation of the glycogen debranching enzyme gene (AGL) revealed a new equine splice variant. An association study between the phenotype and polymorphisms in four candidate genes confirmed the origin of this myopathy : a new single base mutation in the muscle glycogen synthase gene (GYS1). This new type of glycogenosis behaves as an autosomal dominant trait.Nous avons recherché la base génétique de la prédisposition à la myopathie par surcharge en polysaccharides. C'est une des causes du syndrome « coup de sang » de certains chevaux lourds : baisse de performances, boiterie, crampes, myoglobinurie. L'étude du phénotype chez le Cob normand a précisé l'épidémiologie, les lésions et la pathogénie de cette affection. L'analyse fonctionnelle de l'expression des gènes dans les muscles atteints montre une inflammation, une inhibition de l'activité mitochondriale, une perturbation du métabolisme énergétique et une hypoxie. La caractérisation structurale et fonctionnelle du gène de l'enzyme débranchante du glycogène (AGL) a mis en évidence un nouveau transcrit équin. Une étude d'association entre le phénotype et les polymorphismes de quatre gènes candidats a confirmé l'origine de cette myopathie : une mutation ponctuelle du gène de la glycogène synthase (GYS1). Cette nouvelle forme de glycogénose se comporte selon un mode autosomique dominant

Etude de la myopathie héréditaire par surcharge en polysaccharides chez les chevaux Cob normand

Nous avons recherché la base génétique de la prédisposition à la myopathie par surcharge en polysaccharides. C est une des causes du syndrome coup de sang de certains chevaux lourds : baisse de performances, boiterie, crampes, myoglobinurie. L étude du phénotype chez le Cob normand a précisé l épidémiologie, les lésions et la pathogénie de cette affection. L analyse fonctionnelle de l expression des gènes dans les muscles atteints montre une inflammation, une inhibition de l activité mitochondriale, une perturbation du métabolisme énergétique et une hypoxie. La caractérisation structurale et fonctionnelle du gène de l enzyme débranchante du glycogène (AGL) a mis en évidence un nouveau transcrit équin. Une étude d association entre le phénotype et les polymorphismes de quatre gènes candidats a confirmé l origine de cette myopathie : une mutation ponctuelle du gène de la glycogène synthase (GYS1). Cette nouvelle forme de glycogénose se comporte selon un mode autosomique dominant.The genetic basis of predisposition to the polysaccharide storage myopathy (PSSM) was investigated in the horse. PSSM is one of the causes of tying-up syndrome developed by draught breeds : lower performances, lameness, cramps, myoglobinurie. The phenotype of the affection was better defined in terms of epidemiology, lesions and pathogenesis. Functional analysis of gene expression in affected muscles revealed an inflammation, an inhibition of the mitochondria activity, an energetic metabolism disorder and an hypoxia. The structural and functional characterisation of the glycogen debranching enzyme gene (AGL) revealed a new equine splice variant. An association study between the phenotype and polymorphisms in four candidate genes confirmed the origin of this myopathy : a new single base mutation in the muscle glycogen synthase gene (GYS1). This new type of glycogenose behaves as an autosomal dominant trait.VERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceF

Characterization of a novel Xenopus tropicalis cell line as a model for in vitro studies

Chantier qualité GACell lines are useful tools to facilitate in vitro studies of many biological and molecular processes. We describe a new permanent fibroblast-type cell line obtained from disaggregated Xenopus tropicalis limb bud. The cell line population doubling time was _ 24 h. Its karyotype was genetically stable with a chromosome number of 2n 5 21 and a chromosome 10 trisomy. These cells could be readily transfected and expressed transgenes faithfully. We obtained stable transformants using transposon-based gene transfer technology. These cells responded to thyroid hormone and thus can provide a complementary research tool to study thyroid hormone signaling events. In conclusion, this cell line baptized ‘‘Speedy’’ should prove useful to couple in vitro and in vivo biological studies in the X. tropicalis frog model