Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive disorder with a high spontaneous mutation rate and no effective treatment, hence development of genetic based therapies is an important goal. We report that expression of a recombinant human minidystrophin cDNA, compatible with current viral vectors, can significantly reduce the myopathic phenotype in transgenic mdx mice, even when expressed at only 20-30% of endogenous dystrophin levels at the sarcolemma. To the extent that data obtained in mouse studies are applicable to DMD, the virtual elimination of morphological and biochemical abnormalities in the mdx mouse supports the use of this cDNA in somatic gene therapy protocols for DMD.
Hum Mol Genet 1995 Aug
PMID:Expression of human full-length and minidystrophin in transgenic mdx mice: implications for gene therapy of Duchenne muscular dystrophy. 758 60

Duchenne and Becker muscular dystrophy are caused by defects in the dystrophin gene, and are candidates for treatment by gene therapy. We have shown previously that overexpression of a full-length dystrophin cDNA prevents the development of dystrophic symptoms in mdx mice. We show here that this functional correction can be achieved by expressing the full-length muscle isoform at a lower level than is present in control animals. Gene therapy for DMD may necessitate the use of truncated dystrophin mini-genes to accommodate the limited cloning capacity of current-generation viral delivery vectors. We have constructed both murine and human mini-genes deleted for exons 17-48, and have demonstrated that expression of either mini-gene can almost completely prevent the development of dystrophic symptoms in transgenic mdx mice. These results suggest that viral-mediated expression of moderate levels of a truncated dystrophin could be an effective treatment for DMD.
Hum Mol Genet 1995 Aug
PMID:Expression of full-length and truncated dystrophin mini-genes in transgenic mdx mice. 758 61

This paper describes a knowledge-based system for molecular diagnostics, and its application to fully automated diagnosis of X-linked genetic disorders. Molecular diagnostic information is used in clinical practice for determining genetic risks, such as carrier determination and prenatal diagnosis. Initially, blood samples are obtained from related individuals, and PCR amplification is performed. Linkage-based molecular diagnosis then entails three data analysis steps. First, for every individual, the alleles (i.e., DNA composition) are determined at specified chromosomal locations. Second, the flow of genetic material among the individuals is established. Third, the probability that a given individual is either a carrier of the disease or affected by the disease is determined. The current practice is to perform each of these three steps manually, which is costly, time consuming, labor-intensive, and error-prone. As such, the knowledge-intensive data analysis and interpretation supersede the actual experimentation effort as the major bottleneck in molecular diagnostics. By examining the human problem solving for the task, we have designed and implemented a prototype knowledge-based system capable of fully automating linkage-based molecular diagnostics in X-linked genetic disorders, including Duchenne Muscular Dystrophy (DMD). Our system uses knowledge-based interpretation of gel electrophoresis images to determine individual DNA marker labels, a constraint satisfaction search for consistent genetic flow among individuals, and a blackboard-style problem solver for risk assessment. We describe the system's successful diagnosis of DMD carrier and affected individuals from raw clinical data.
Proc Int Conf Intell Syst Mol Biol 1994
PMID:Intelligent DNA-based molecular diagnostics using linked genetic markers. 758 9

We have applied two-colour fluorescence in situ hybridization (FISH) to DNA fibers and combined it with digital imaging microscopy for the mapping of large cosmid contigs. The technique was validated using a set of unique plasmids and a cosmid contig both originating from the thyroglobulin (Tg) gene and previously mapped by restriction analysis. The resolution proved to be close to the theoretical lower limit of approximately 1 kb, ranging > or = 400 kb. Subsequently a 400 kb cosmid contig derived from a DMD-YAC was directly mapped by Fiber-FISH. The resulting map is in full agreement with the restriction map. Two-colour Fiber-FISH mapping thus showed to be capable for accurately sizing gaps and overlaps, and to identify chimeric or repeat sequence containing cosmids across a 400 kb region at once. The generated 400 kb 'colour bar-code' was subsequently used to map two DMD deletion breakpoints in patient DNA with an accuracy of 1-2 kb. The results underscore the value of this method for the delineation of chromosomal rearrangements for positional cloning and single patient clinical studies.
Hum Mol Genet 1995 May
PMID:High-resolution DNA Fiber-FISH for genomic DNA mapping and colour bar-coding of large genes. 763 42

Dystrophin is present in the outer plexiform layer of the retina and is required for normal retinal function as measured by electroretinography. We describe the identification of a novel isoform of dystrophin (Dp260) present in the mouse retina. The unique 5' terminus of the mRNA originates from a newly identified exon and is spliced in frame to exon 30 of the Duchenne muscular dystrophy (DMD) gene. The retinal isoform of dystrophin has 13 novel amino acids as its N-terminus followed by most of the dystrophin rod domain and the cysteine-rich C-terminal domains. Analysis of mouse tissues indicated this isoform of dystrophin is expressed in retina, brain and cardiac tissue. Comparison of retinal electrophysiology in mdx and mdxCv3 mouse suggests that Dp260 is required for normal retinal function.
Hum Mol Genet 1995 May
PMID:A novel dystrophin isoform is required for normal retinal electrophysiology. 763 43

We have identified a 7.5 kb transcript from the dystrophin locus which encodes a novel 140 kDa protein (Dp140). Based on immunoblotting Dp140 consists of the distal rod domain and C-terminus of 427 kDa dystrophin and is found throughout the CNS. This protein is transcribed from an alternative promoter in the dystrophin locus upstream to exon 45. The unique 5' first exon is conserved between rat and human. The transcript has a 1 kb 5' untranslated region, and the first methionine initiation codon occurs in exon 51, predicting a protein of 140 kDa. Several studies report that Duchenne dystrophy patients with deletions in the exon 45-52 region have an increased incidence of cognitive impairment. Such deletions would affect expression of 427 kDa dystrophin and this shorter 140 kDa isoform but not the recently described small distal transcripts Dp116 or Dp71, suggesting particular importance to CNS function.
Hum Mol Genet 1995 Mar
PMID:Dp140: a novel 140 kDa CNS transcript from the dystrophin locus. 779 84

Duchenne muscular dystrophy (DMD) is accompanied by varying degrees of mental retardation. The molecular basis for this is unknown, although at least four dystrophin transcripts regulated by specific promoters and undergoing elaborate splicing control are present in brain areas associated with cognitive function. In muscle the absence of dystrophin causes instability of a dystrophin-associated protein complex (DAPC) linking the cytoskeleton to the extracellular matrix; this disruption is accompanied by muscle necrosis. The laminin-binding component of DAPC, dystroglycan, in contrast to other components of DAPC, has been found in brain homogenates. This suggests that the link between the membrane cytoskeleton and extracellular matrix mediated by dystrophin-dystroglycan may play a functional role in brain. We have cloned a mouse dystroglycan partial cDNA and have mapped this gene in the mouse to chromosome 9. Further, in situ hybridisation to mouse brain sections shows that the dystroglycan gene is expressed in relatively few structures and co-localises with dystrophin mRNA in hippocampus, dentate gyrus, olfactory bulb and Purkinje neurons but, surprisingly, not in the cortex. Dystroglycan is also expressed in those brain areas where the dystrophin-related protein (utrophin) is present. Our results provide a basis for a future characterisation of the role of dystrophin-dystroglycan association in the brain.
Hum Mol Genet 1994 Sep
PMID:Dystroglycan: brain localisation and chromosome mapping in the mouse. 783 16

The C-terminal domain of dystrophin is alternatively spliced to produce a variety of tissue and developmental stage-specific isoforms. Recent studies suggest that the C-terminal domain binds to the dystrophin-associated glycoprotein complex (DGC) in muscle, but little is known about the functional significance of the alternative splicing or what role individual isoforms may play in specific tissues. The major dystrophin transcript in brain lacks exons 71-74, and encodes an isoform not observed in skeletal muscle. To explore the capacity of this truncated isoform to function in muscle, we have generated transgenic mice expressing a murine dystrophin mini-gene missing exons 71-74. Uniform expression of this construct on a mutant mdx mouse background results in normal muscle morphology and physiology, and prevents the development of muscular dystrophy. These mice also display normal expression and localization of the DGC, suggesting that the alternatively spliced exons are not required for dystrophin function in skeletal muscle. An additional line of mice was analyzed that had a mosaic pattern of expression. These mice display a markedly milder phenotype than mdx mice, despite the expression of dystrophin in only half the muscle fibers. These results indicate that viral delivery of dystrophin to a simple majority of fibers in a muscle group would greatly reduce the dystrophic pathology associated with Duchenne muscular dystrophy.
Hum Mol Genet 1994 Oct
PMID:Prevention of dystrophic pathology in mdx mice by a truncated dystrophin isoform. 784 95

A lack of dystrophin results in muscle degeneration in Duchenne muscular dystrophy. Dystrophin-deficient human and mouse muscle cells have higher resting levels of intracellular free calcium ([Ca2+]i) and show a related increase in single-channel open probabilities of calcium leak channels. Elevated [Ca2+]i results in high levels of calcium-dependent proteolysis, which in turn increases calcium leak channel activity. This process could initiate muscle degeneration by further increasing [Ca2+]i and proteolysis in a positive feedback loop. Here, we tested the direct effect of restoration of dystrophin on [Ca2+]i and channel activity in primary myotubes from mdx mice made transgenic for full-length dystrophin. Transgenic mdx mice have been previously shown to have normal dystrophin localization and no muscle degeneration. Fura-2 calcium measurements and single-channel patch recordings showed that resting [Ca2+]i levels and open probabilities of calcium leak channels of transgenic mdx myotubes were similar to normal levels and significantly lower than mdx littermate controls (mdx) that lack dystrophin. Thus, restoration of normal calcium regulation in transgenic mdx mice may underlie the resulting absence of degeneration.
Mol Biol Cell 1994 Oct
PMID:Myotubes from transgenic mdx mice expressing full-length dystrophin show normal calcium regulation. 786 81

Two promoters in the distal half of the Duchenne Muscular Dystrophy gene drive transcription of mRNAs which have novel first exons and encode the shortened forms of dystrophin, apo-dystrophin-1 (Dp71) and apo-dystrophin-2 (Dp116). Apo-dystrophin-1 has a G + C rich promoter and is expressed in a wide range of cell types, whilst apo-dystrophin-2 is confined to peripheral nerve and brain. We have isolated and sequenced the unique 5' exon of rat apo-dystrophin-2 mRNA. Conceptual translation of this sequence indicates that apo-dystrophin-2 contains a unique 23 amino acid terminal peptide. Using specific probes derived from sequences at the 5' ends of apo-dystrophin-1 and apo-dystrophin-2 we have determined the expression of these two mRNAs during mouse embryonic development by RNA in situ hybridization. In contrast to full-length dystrophin, neither of these short dystrophin transcripts appear before organogenesis is well established. Apo-dystrophin-1 mRNA is detected in midline cells of the ventral neural tube and later, in the ependymal cells lining the ventricles of the brain. These results suggest that apo-dystrophin-1 mRNA is associated with glial cells in the CNS. Apo-dystrophin-1 transcripts are also abundant in the teeth primordia throughout their development. In contrast apo-dystrophin-2 mRNA is largely undetectable during development, although transcripts are seen in the newborn brain. Western blots of late human fetal tissue extracts confirm that apo-dystrophin-2 is most abundant in brain and analysis of RNA and protein in cultured cell lines reveal expression of apo-dystrophin-1 and apo-dystrophin-2 in glioma cells.
Hum Mol Genet 1994 Aug
PMID:Apo-dystrophin-1 and apo-dystrophin-2, products of the Duchenne muscular dystrophy locus: expression during mouse embryogenesis and in cultured cell lines. 798 7


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