Lafora progressive myoclonus epilepsy: NHLRC1 mutations affect glycogen metabolism

11 páginas, 8 figuras, 1 tabla.Lafora disease is a fatal autosomal recessive form of progressive myoclonus epilepsy. Patients manifest myoclonus and tonic-clonic seizures, visual hallucinations, intellectual, and progressive neurologic deterioration beginning in adolescence. The two genes known to be involved in Lafora disease are EPM2A and NHLRC1 (EPM2B). The EPM2A gene encodes laforin, a dual-specificity protein phosphatase, and the NHLRC1 gene encodes malin, an E3-ubiquitin ligase. The two proteins interact with each other and, as a complex, are thought to regulate glycogen synthesis. Here, we report three Lafora families with two novel pathogenic mutations (C46Y and L261P) and two recurrent mutations (P69A and D146N) in NHLRC1. Investigation of their functional consequences in cultured mammalian cells revealed that malin(C46Y), malin(P69A), malin(D146N), and malin(L261P) mutants failed to downregulate the level of R5/PTG, a regulatory subunit of protein phosphatase 1 involved in glycogen synthesis. Abnormal accumulation of intracellular glycogen was observed with all malin mutants, reminiscent of the polyglucosan inclusions (Lafora bodies) present in patients with Lafora disease.Peer reviewe

Exhaustive analysis of BH4 and dopamine biosynthesis genes in patients with Dopa-responsive dystonia

Dopa-responsive dystonia is a childhood-onset dystonic disorder, characterized by a dramatic response to low dose of l-Dopa. Dopa-responsive dystonia is mostly caused by autosomal dominant mutations in the GCH1 gene (GTP cyclohydrolase1) and more rarely by autosomal recessive mutations in the TH (tyrosine hydroxylase) or SPR (sepiapterin reductase) genes. In addition, mutations in the PARK2 gene (parkin) which causes autosomal recessive juvenile parkinsonism may present as Dopa-responsive dystonia. In order to evaluate the relative frequency of the mutations in these genes, but also in the genes involved in the biosynthesis and recycling of BH4, and to evaluate the associated clinical spectrum, we have studied a large series of index patients (n = 64) with Dopa-responsive dystonia, in whom dystonia improved by at least 50% after l-Dopa treatment. Fifty seven of these patients were classified as pure Dopa-responsive dystonia and seven as Dopa-responsive dystonia-plus syndromes. All patients were screened for point mutations and large rearrangements in the GCH1 gene, followed by sequencing of the TH and SPR genes, then PTS (pyruvoyl tetrahydropterin synthase), PCBD (pterin-4a-carbinolamine dehydratase), QDPR (dihydropteridin reductase) and PARK2 (parkin) genes. We identified 34 different heterozygous point mutations in 40 patients, and six different large deletions in seven patients in the GCH1 gene. Except for one patient with mental retardation and a large deletion of 2.3 Mb encompassing 10 genes, all patients had stereotyped clinical features, characterized by pure Dopa-responsive dystonia with onset in the lower limbs and an excellent response to low doses of l-Dopa. Dystonia started in the first decade of life in 40 patients (85%) and before the age of 1 year in one patient (2.2%). Three of the 17 negative GCH1 patients had mutations in the TH gene, two in the SPR gene and one in the PARK2 gene. No mutations in the three genes involved in the biosynthesis and recycling of BH4 were identified. The clinical presentations of patients with mutations in TH and SPR genes were strikingly more complex, characterized by mental retardation, oculogyric crises and parkinsonism and they were all classified as Dopa-responsive dystonia-plus syndromes. Patient with mutation in the PARK2 gene had Dopa-responsive dystonia with a good improvement with l-Dopa, similar to Dopa-responsive dystonia secondary to GCH1 mutations. Although the yield of mutations exceeds 80% in pure Dopa-responsive dystonia and Dopa-responsive dystonia-plus syndromes groups, the genes involved are clearly different: GCH1 in the former and TH and SPR in the late

Genome-wide analysis of the fasciclin-like arabinogalactan (FLA) gene family in Populus trichocarpa and their expression profiling in tension wood

International audienceIn response to environmental stimuli such as wind, snow, slope or asymmetric crown shape, leaning woody plants form a special tissue, named reaction wood, which allows tree axis reorientation. In angiosperm trees, this reaction wood is associated with tensile strains and consequently has been named tension wood (TW). It occurs at the upper face of leaning stems and branches, and can be obtained in a controlled way on young trees by simply tilting the stem. Inpoplar, TW is mainly characterized by xylem fibres which are poorly lignified and have an extra thick gelatinous secondary layer, named G layer, in the secondary cell wall. This G layer contains almost completely pure crystalline cellulose with microfibrils oriented nearly parallel to the axis of the fibre. Different models have been proposed in order to link these biochemical and ultrastructural features to the mechanical properties of TW. To assess the validity of these models we need to find out the molecular mechanisms involved in the formation of the G layer. With the aim to identify such mechanisms we looked for genes differentially expressed between TW and OW. We have previously shown that l0 fasciclin-like arabinogalactan (FLAs) poplar genes were highly expressed in the xylem of tension wood [1, 2]. Five other popFLAs (l I to l5) were shown to be expressed in xylem but not differentially between TW and ow t2l. These 15 popFLAs belong to the class of arabinogalactan-proteins (AGPs) containing one fasciclin-like domain surounded by two AGP- like domains. While the fasciclin-like domain appears well conserved among the different proteins, we find more variability in the AGPlike domains which carry the arabinogalaotosylation sites. Thanks to the recent publication of the poplar genome sequence we identified 41 additional poplar genes encoding putative fasciclin-like protein. Two-thirds of the predicted genes contain one FASI (fasciclin-like) domain as defined by the reference "IPR000782" in InterPro database, the other 17 genes carrying 2 FAS1 domains. In addition, 70% of the sequences are predicted to be anchored to a glycosyl-phosphatidylinositol (GpI). It has been postulated that this dual presence of fasciclin-like domain and GPI-anchor could support a putative function of these proteins in cell adhesion and signaling. In regard to the phylogenic analysis of this large gene family we investigated the expression profiling of these 56 poplar FLAs. This has been done through electronic northern and from genome-wide expression data collected on Affymetrix poplar array experiments. Electronic northern were done from 200.199 expressed sequence tags (ESTs) available in public databases representing 37 different non normalized cDNA libraries. Genome-wide expression patterns were investigated in tension wood in response l) to nyctemeral variation and 2) to re-watering after water shortage. The aim of thefirst experiment was to see if nyctemer variation of FLAs gene could be correlated with expression pattern of other cell-wall related genes. In the second experiment, re-watering induces xylem re-growth together with a significant increase of differentiation of vessel elements. Expression analyses of these FLAs in these experiments will be presented and discussed

Exhaustive analysis of BH4 and dopamine biosynthesis genes in patients with Dopa-responsive dystonia

Dopa-responsive dystonia is a childhood-onset dystonic disorder, characterized by a dramatic response to low dose of L-Dopa. Dopa-responsive dystonia is mostly caused by autosomal dominant mutations in the GCH1 gene (GTP cyclohydrolase1) and more rarely by autosomal recessive mutations in the TH (tyrosine hydroxylase) or SPR (sepiapterin reductase) genes. In addition, mutations in the PARK2 gene (parkin) which causes autosomal recessive juvenile parkinsonism may present as Dopa-responsive dystonia. In order to evaluate the relative frequency of the mutations in these genes, but also in the genes involved in the biosynthesis and recycling of BH4, and to evaluate the associated clinical spectrum, we have studied a large series of index patients (n = 64) with Dopa-responsive dystonia, in whom dystonia improved by at least 50% after L-Dopa treatment. Fifty seven of these patients were classified as pure Dopa-responsive dystonia and seven as Dopa-responsive dystonia-plus syndromes. All patients were screened for point mutations and large rearrangements in the GCH1 gene, followed by sequencing of the TH and SPR genes, then PTS (pyruvoyl tetrahydropterin synthase), PCBD (pterin-4a-carbinolamine dehydratase), QDPR (dihydropteridin reductase) and PARK2 (parkin) genes. We identified 34 different heterozygous point mutations in 40 patients, and six different large deletions in seven patients in the GCH1 gene. Except for one patient with mental retardation and a large deletion of 2.3 Mb encompassing 10 genes, all patients had stereotyped clinical features, characterized by pure Dopa-responsive dystonia with onset in the lower limbs and an excellent response to low doses of L-Dopa. Dystonia started in the first decade of life in 40 patients (85%) and before the age of 1 year in one patient (2.2%). Three of the 17 negative GCH1 patients had mutations in the TH gene, two in the SPR gene and one in the PARK2 gene. No mutations in the three genes involved in the biosynthesis and recycling of BH4 were identified. The clinical presentations of patients with mutations in TH and SPR genes were strikingly more complex, characterized by mental retardation, oculogyric crises and parkinsonism and they were all classified as Dopa-responsive dystonia-plus syndromes. Patient with mutation in the PARK2 gene had Dopa-responsive dystonia with a good improvement with L-Dopa, similar to Dopa-responsive dystonia secondary to GCH1 mutations. Although the yield of mutations exceeds 80% in pure Dopa-responsive dystonia and Dopa-responsive dystonia-plus syndromes groups, the genes involved are clearly different: GCH1 in the former and TH and SPR in the later