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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Like Duchenne and Becker muscular dystrophies, Emery-Dreifuss muscular dystrophy (EDMD) is characterized by myopathic and cardiomyopathic abnormalities. EDMD has the particularity of being linked to mutations in nuclear proteins. The X-linked form of EDMD is caused by mutations in the emerin gene, whereas autosomal dominant EDMD is caused by mutations in the lamin A/C gene. Emerin colocalizes with lamin A/C in interphase cells, and binds in vitro to lamin A/C. Recent work suggests that lamin A/C might serve as a receptor for emerin. We have undertaken a structural analysis of emerin, and in particular of its N-terminal domain, which is comprised in the emerin segment critical for binding to lamin A/C. We show that region 2-54 of emerin adopts the LEM fold. This fold was originally described in the two N-terminal domains of another inner nuclear membrane protein called lamina-associated protein 2 (LAP2). The existence of a conserved solvent-exposed surface on the LEM domains of LAP2 and emerin is discussed, as well as the nature of a possible common target.
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PMID:Structural analysis of emerin, an inner nuclear membrane protein mutated in X-linked Emery-Dreifuss muscular dystrophy. 1147 Feb 79

Emery-Dreifuss muscular dystrophy (EDMD) is characterized by slowly progressive muscle wasting and weakness; early contractures of the elbows, Achilles tendons, and spine; and cardiomyopathy associated with cardiac conduction defects. Clinically indistinguishable X-linked and autosomal forms of EDMD have been described. Mutations in the STA gene, encoding the nuclear envelope protein emerin, are responsible for X-linked EDMD, while mutations in the LMNA gene encoding lamins A and C by alternative splicing have been found in patients with autosomal dominant, autosomal recessive, and sporadic forms of EDMD. We report mutations in LMNA found in four familial and seven sporadic cases of EDMD, including seven novel mutations. Nine missense mutations and two small in-frame deletions were detected distributed throughout the gene. Most mutations (7/11) were detected within the LMNA exons encoding the central rod domain common to both lamins A/C. All of these missense mutations alter residues in the lamin A/C proteins conserved throughout evolution, implying an essential structural and/or functional role of these residues. One severely affected patient possesed two mutations, one specific to lamin A that may modify the phenotype of this patient. Mutations in LMNA were frequently identified among patients with sporadic and familial forms of EDMD. Further studies are needed to identify the factors modifying disease phenotype among patients harboring mutations within lamin A/C and to determine the effect of various mutations on lamin A/C structure and function.
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PMID:Novel and recurrent mutations in lamin A/C in patients with Emery-Dreifuss muscular dystrophy. 1150 64

Considerable interest has been focused on the nuclear envelope in recent years following the realization that several human diseases are linked to defects in genes encoding nuclear envelope specific proteins, most notably A-type lamins and emerin. These disorders, described as laminopathies or nuclear envelopathies, include both X-linked and autosomal dominant forms of Emery-Dreifuss muscular dystrophy, dilated cardiomyopathy with conduction system defects, limb girdle muscular dystrophy 1B with atrioventricular conduction disturbances, and Dunnigan-type familial partial lipodystrophy. Certain of these diseases are associated with nuclear structural abnormalities that can be seen in a variety of cells and tissues. These observations clearly demonstrate that A-type lamins in particular play a central role, not only in the maintenance of nuclear envelope integrity but also in the large-scale organization of nuclear architecture. What is not obvious, however, is why defects in nuclear envelope proteins that are found in most adult cell types should give rise to pathologies associated predominantly with skeletal and cardiac muscle and adipocytes. The recognition of these various disorders now raises the novel possibility that the nuclear envelope may have functions that go beyond housekeeping and which impact upon cell-type specific nuclear processes.
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PMID:The nuclear envelope in muscular dystrophy and cardiovascular diseases. 1157 43

X-linked Emery-Dreifuss muscular dystrophy is usually caused by absence of the nuclear membrane protein, emerin, due to nonsense mutations or deletions, but a few missense mutations also exist. A pathogenic g993t mutation causes a Q133H change in the nuclear targeting region of emerin, but it may also reduce emerin levels by affecting mRNA splicing. We have introduced the g993t mutation by in vitro mutagenesis and studied the effect of Q133H on nuclear targeting by transfection of COS-7 cells. No qualitative or quantitative differences in nuclear targeting were observed between normal and mutant emerin. Quantitative BIAcore analysis showed no significant change in lamin A binding to emerin when the mutation was present. We conclude that Q133 is not essential for nuclear targeting of emerin or its interaction with lamin A. Reduced emerin levels due to altered splicing or defective interaction with an unidentified binding partner remain possible pathogenic mechanisms.
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PMID:How does a g993t mutation in the emerin gene cause Emery-Dreifuss muscular dystrophy? 1158 40

The X-linked form of Emery-Dreifuss muscular dystrophy (X-EDMD) is caused by absence, or greatly reduced amounts, of the inner nuclear-membrane protein, emerin. The autosomal dominant form (AD-EDMD) is caused by missense mutations in lamins A and C, two components of the nuclear lamina that interact directly with emerin. Lamin A/C mutations also cause one form of dilated cardiomyopathy (CMD1A) and one form of limb-girdle muscular dystrophy (LGMD1B), both of which have clinical features in common with EDMD, as well as a rare, unrelated form of lipodystrophy (FPLD). Evidence is now emerging that defective assembly of the nuclear lamina is a feature of all these diseases, although not necessarily the direct cause. Why only heart and skeletal muscle, and possibly connective tissue, are affected in EDMD and why expression of the disease is so extremely variable between individuals remains to be explained.
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PMID:The role of the nuclear envelope in Emery-Dreifuss muscular dystrophy. 1173 21

Emerin is the nuclear membrane protein defective in X-linked Emery-Dreifuss muscular dystrophy (X-EDMD). The majority of X-EDMD patients have no detectable emerin. However, there are cases that produce mutant forms of emerin, which can be used to study its function. Our previous studies have shown that the emerin mutants S54F, P183T, P183H, Del95-99, Del236-241 (identified in X-EDMD patients) are targeted to the nuclear membrane but to a lesser extent than wild-type emerin. In this paper, we have studied how the mislocalisation of these mutant emerins may affect nuclear functions associated with the cell cycle using flow cytometry and immunofluorescence microscopy. We have established that cells expressing the emerin mutant Del236-241 (a deletion in the transmembrane domain), which was mainly localised in the cytoplasm, exhibited an aberrant cell cycle length. Thereafter, by examining the intracellular localisation of endogenously expressed lamin A/C and exogenously expressed wild-type and mutant forms of emerin after a number of cell divisions, we determined that the mutant forms of emerin redistributed endogenous lamin A/C. The extent of lamin A/C redistribution correlated with the amount of EGFP-emerin that was mislocalised. The amount of EGFP-emerin mislocalized, in turn, was associated with alterations in the nuclear envelope morphology. The nuclear morphology and redistribution of lamin A/C was most severely affected in the cells expressing the emerin mutant Del236-241. It is believed that emerin is part of a novel nuclear protein complex consisting of the barrier-to-autointegration factor (BAF), the nuclear lamina, nuclear actin and other associated proteins. The data presented here show that lamin A/C localisation is dominantly directed by its interaction with certain emerin mutants and perhaps wild-type emerin as well. These results suggest that emerin links A-type lamins to the nuclear envelope and that the correct localisation of these nuclear proteins is important for maintaining cell cycle timing.
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PMID:The cell cycle dependent mislocalisation of emerin may contribute to the Emery-Dreifuss muscular dystrophy phenotype. 1183 86

Emerin belongs to the LEM-domain family of nuclear membrane proteins, which are conserved in metazoans from C. elegans to humans. Loss of emerin in humans causes the X-linked form of Emery-Dreifuss muscular dystrophy (EDMD), but the disease mechanism is not understood. We have begun to address the function of emerin in C. elegans, a genetically tractable nematode. The emerin gene (emr-1) is conserved in C. elegans. We detect Ce-emerin protein in the nuclear envelopes of all cell types except sperm, and find that Ce-emerin co-immunoprecipitates with Ce-lamin from embryo lysates. We show for the first time in any organism that nuclear lamins are essential for the nuclear envelope localization of emerin during early development. We further show that four other types of nuclear envelope proteins, including fellow LEM-domain protein Ce-MAN1, as well as Ce-lamin, UNC-84 and nucleoporins do not depend on Ce-emerin for their localization. This result suggests that emerin is not essential to organize or localize the only lamin (B-type) expressed in C. elegans. We also analyzed the RNAi phenotype resulting from the loss of emerin function in C. elegans under laboratory growth conditions, and found no detectable phenotype throughout development. We propose that C. elegans is an appropriate system in which to study the molecular mechanisms of emerin function in vivo.
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PMID:The expression, lamin-dependent localization and RNAi depletion phenotype for emerin in C. elegans. 1187 Feb 11

To clarify the molecular nature of the pathogenesis in X-linked Emery-Dreifuss muscular dystrophy (EDMD), we monitored the expression of 2400 genes in control and EDMD fibroblasts by using complementary DNA (cDNA) microarray techniques. A total of 60 genes whose expression was altered in EDMD fibroblasts when compared with control fibroblasts were identified. Twenty-eight genes whose expression was altered with the emerin deficiency were rescued by infection with a recombinant adenovirus expressing emerin. The altered expression in five genes, including the lamin A/C gene, was confirmed by reverse transcription-polymerase chain reaction. Our preliminary results suggest a correlation between disease similarity and gene expression. We conclude that the cDNA microarray is a very efficient tool to clarify genetic and pathological features of diseases.
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PMID:CDNA microarray analysis of gene expression in fibroblasts of patients with X-linked Emery-Dreifuss muscular dystrophy. 1211 80

Nuclear muscular dystrophies are referred to as inherited muscular dystrophies caused by mutations in genes--(STA) or lamina (LMNA)--encoding components of the nuclear envelope. Phenotypically, they present as Emery-Dreifuss muscular dystrophy (EDMD), limb-girdle muscle dystrophy 1B (LGMD1B), or dilated cardiomyopathy with conduction defects (DCM-CD). Genetically related are the Dunnigan-type of familial partial lipodystrophy (FPLD) and Charcot-Marie-Tooth neuropathy type 2 (CMT2B). Until now, approximately 70 unique STA mutations, leading to X-linked EDMD or DCM-CD, have resulted mostly in a complete lack of emerin. Further 50 mostly missense mutations in LMNA result in autosomal-dominant EDMD, autosomal-recessive EDMD, LGMD1B, DCM-CD, FPLD, or CMT2B. Independent of type or location of the mutations, emerinopathies and laminopathies show wide clinical intrafamilial and interfamilial variability. Although structural abnormalities of nuclei in animal and cell models have been observed, the molecular pathology of the nuclear muscular dystrophies needs still to be elucidated.
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PMID:The nuclear muscular dystrophies. 1213 94

Emery-Dreifuss muscular dystrophy (EDMD) is caused by mutations in the gene encoding the nuclear membrane protein emerin (X-linked EDMD) or in the gene encoding lamins A/C (autosomal dominant EDMD). One hypothesis explaining the disease suggests that the mutations lead to weakness of the nuclear lamina. To test this hypothesis we investigated lamin solubility and distribution in skin fibroblasts from X-EDMD patients. Using in situ extraction of cells and immunofluorescence microscopy or biochemical fractionation and immunoblotting, we found that all lamin subtypes displayed increased solubility properties in fibroblasts from X-EDMD patients compared to normal individuals. Lamin and emerin solubility was mildly increased in fibroblasts from an X-EDMD carrier. Biochemical fractionation and immunoblotting also indicated that lamin C but no other lamin became redistributed from the nuclear lamina to the nucleoplasm in X-EDMD fibroblasts. Indirect immunofluorescence and confocal microscopy studies using lamin A- and lamin C-specific antibodies confirmed that lamin C but not lamin A became redistributed to the nucleoplasm. Interestingly, the lamin A/C binding protein LAP2alpha was also mislocalized in X-EDMD fibroblasts.
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PMID:Increased solubility of lamins and redistribution of lamin C in X-linked Emery-Dreifuss muscular dystrophy fibroblasts. 1249 Jan 72


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