Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0086543 (cataract)
 29,165 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Urea-soluble and intrinsic membrane proteins from normal and galactose cataractous rat lenses were analyzed by SDS-PAGE. During cataract formation, MP22 increased whereas MP26 decreased almost to nil and MP24 emerged. However, the relative amount of MP18 remained essentially unchanged. These results suggested a conversion of MP26 to MP22 during cataract formation. We also observed the changes in the relative abundance of the polypeptides of the urea-soluble fraction with cataractogenesis.
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PMID:Changes of urea-soluble and intrinsic membrane proteins in rat lenses during the formation of galactose cataract. 147 76

The Emory mouse is presumed to be a model for studies on human senile cataracts. The cataract develops in 5-8 months after birth, and it does not appear to have an osmotic component. To date, no specific metabolic lesion has been uncovered as a probable cause to this cataract. Several studies have shown that the Emory mouse undergoes accelerated aging changes, possibly leading to development of senile-type cataracts. In this study we quantitated changes that might occur in the population of various mRNAs for proteins presumed to be essential for lens transparency, and for proteins that may contribute to development of cataracts. By Northern blot hybridization analysis we quantitated the mRNAs for: alpha A-crystallin, beta B1-crystallin, gamma-crystallin, the main lens intrinsic membrane protein, MP26, and aldose reductase; all in lenses of Emory mouse early cataract strain (EMEC), and of an age-matched cataract resistant strain (CR). These measurements were done in increments of 1 month over a 6-month period, then at both 9 and 12 months. The results show that all of these mRNAs decrease with age and with development of cataracts; although in some cases the initial concentrations at 1 month appear to be lower in the EMEC than in the CR strain. The most dramatic change occurred with the MP26 mRNA. In the CR strain, MP26 mRNA maintained its high concentration for a period of about 6 months before it began its decline to the 12 month level (about 25% of the 1 month level).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Profile of messenger RNA decay in the Emory mouse lens in cataractogenesis and in aging. 148 8

The reversal and prevention of the galactose-induced cataract in rats were employed to study their effects on the acceleration of the limited proteolysis of MP26 into MP23-24 previously observed in cataractous lenses of galactose-fed animals. Lenses of rats on a cataract reversal-diet demonstrated the reversal of MP23-24 and MP26 levels to control levels in the clearing cortical areas but not in remaining cataractous nuclear areas. Acceleration of the limited proteolysis of MP26 was observed in the nucleus but not the cortex in the clear lenses of animals on a cataract prevention-diet. The results demonstrated that the limited proteolysis of MP26 may form part of a gradual aging process that although not directly (causally) related to cataractogenesis may at least be accelerated by cataractogenic agents or conditions.
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PMID:Reversal of the limited proteolysis of MP26 during the reversal and prevention of the galactose cataract in rat lenses. 218 87

The late onset cataract of the Emory mouse has appealed to many investigators as a useful animal model for human senile cataract. It has been the subject of about 15 publications, beginning in 1982. These have explored many features, including histology, chromatography and isoelectric focusing of the crystallins, enzyme profiles, amino acid and ion transport, membrane studies including changes in MP24 and MP26, analysis for a number of biochemical constituents, and its use as an assay system for testing the effect of anticataractogenic drugs and dietary restriction. These investigations have not uncovered a single metabolic lesion marked enough to be considered an important cause of this cataract. There is some evidence that the effect of oxidation may be a major factor; likewise there is evidence for faulty protein synthesis. In many cases, the changes in cataractogenesis appear to be accelerated aging changes. For this reason, any study of this cataract must employ age-matched controls of the cataract-resistant strain. A recent discovery is the finding that many earlier studies used a mixture of both early and late-onset forms, accounting for the wide variability in analytical results. The two substrains may have somewhat different applications in cataract research. Thus, the availability of these two substrains should extend the usefulness of this animal model.
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PMID:Late onset hereditary cataract of the emory mouse. A model for human senile cataract. 219 6

Purified lens fiber membrane fractions from Emory mouse lenses and cataract-resistant control lenses were compared by SDS-PAGE. The differences in polypeptide patterns were determined for three ages. There was a striking alteration in MP24/MP26 ratio during aging and cataractogenesis which appears to be due to a normal age-dependent conversion of MP26 to MP24, and which is accelerated during cataractogenesis.
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PMID:Alterations of urea-insoluble membrane fraction, MP26, of Emory mouse lenses in aging and cataractogenesis. 234 82

Previous work from this laboratory has suggested that swollen nucleated fiber cells can survive in mature galactose-cataracts. Evidence for this observation was derived from analysis on the in vitro translation products of mRNA isolated from normal lens and lens undergoing development of galactose-cataracts. Additional studies on the abundance of a fiber cell specific gene product (MP26 mRNA) in both normal and cataractous lens mapped out gene response to: (1) differentiation of epithelial cells to fiber cells, (2) levels of this differential gene activity and its anatomical location in initiation and maturation of galactose-cataracts, and (3) distribution of MP26 mRNA in fibers of normal and cataractous lens. The results from these studies demonstrated that mRNA subsistence in lens undergoing osmotic cataract development might be an indication of occurrence of mechanisms responsible for the reversibility of that type of cataracts. Presumably, reversibility requires propagation and maintenance of the total population of lens specific mRNAs, as our data suggests.
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PMID:Messenger RNA population in normal and cataractous rat lens. A minireview. 248 80

The authors studied a four-generation family with autosomal dominant congenital cataracts (ADCCs) using linkage analysis with 23 polymorphic phenotypic markers and DNA restriction fragment length polymorphisms (RFLPs) detected by lens-specific DNA probes. A total of 19 family members were studied and the ten affected members had embryonal lens opacities. Close linkage was rejected with DNA probes encoding beta-crystallin, gamma-crystallin, and the major intrinsic protein of the lens fiber membrane (MIP) excluding defects of these genes as the cause of the cataract in this family. No statistically significant lod scores were produced with the polymorphic phenotypic markers. These results support the genetic heterogeneity of ADCCs.
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PMID:Genetic linkage analysis of autosomal dominant congenital cataracts with lens-specific DNA probes and polymorphic phenotypic markers. 317 13

Experimental nuclear cataract produced by an overdose of sodium selenite exhibited limited proteolysis, including breakdown of main intrinsic polypeptide (MIP26) to 24 and 22 kD fragments. Micro-sequencing and site specific immunologic probes were used in the present study to determine regions of cleavage in MIP26 during selenite cataractogenesis. Data suggested that proteolysis occurred in the C-terminus of MIP26. This may have lead to exposure of normally hidden amino acid residues on the C-terminal extension of MIP26. Loss of antigenicity of the N-terminus occurred. These significant changes to the MIP26 molecule might adversely affect communication between lens fiber cells and contribute to selenite cataract.
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PMID:Proteolytic changes in main intrinsic polypeptide (MIP26) from membranes in selenite cataract. 328 27

Lenses of rats maintained on a 50% galactose diet displayed the development of a progressive cataract which was cortical at 3-11 days, and progressively internalized (nuclear as well) and mature at 16-20 days of feeding. Lens fiber plasma membranes were isolated from female rats subjected to the galactose diet and from controls at 11, 19, and 31 days of feeding, and analyzed by SDS-PAGE. Examination of the fiber plasma membranes from whole lenses of galactose-fed rats demonstrated the limited proteolysis of MP26 into MP23-24, in both the cortical and mature stages of the resultant cataracts. The limited proteolysis of MP26 was first evident in the lens cortex at 11 days of galactose feeding, and was evident as well, and more severe in proportion, in the lens nucleus at 19 days of feeding. The greatest proportion in MP26 limited proteolysis was observed in whole lenses at 31 days of galactose feeding. The regional progression of MP26 limited proteolysis closely paralleled the morphological progression of the galactose-induced cataract in the rat. The proportion of lens MP26 which underwent limited proteolysis into MP23-24 increased the longer the animals were kept on the galactose diet.
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PMID:Limited proteolysis of MP26 in lens fiber plasma membranes of the galactose-induced cataract in the rat. 353 34

The formation of membrane protein disulfide was investigated at various stages of development of X-ray-induced cataract in the rabbit. Intermolecular disulfide bonding of lens membrane proteins was detected not only in the mature cataract (occurring 8-9 weeks after the X-ray dose) but also at 1 week prior to maturation, in which no significant increase in lens hydration occurs and where opacification is confined mainly to the posterior subcapsular region. Two-dimensional diagonal electrophoresis revealed that polypeptides with apparent molecular weights of 21, 23, 25, 31, 35, 46 and 53 kilodaltons were involved in cross-linking. The MP26 membrane polypeptide was not significantly involved in the disulfide bonding. The oxidation of membrane proteins in stages other than mature was evident only in the lens nucleus (which remained clear) and not in the cortex. The results of this study indicate that an intermolecular disulfide linkage of cytosolic proteins to membranes occurs prior to formation of mature cataract, and may be a precursor to protein aggregation and insolubilization in the mature nuclear cataract.
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PMID:Disulfide-linked membrane proteins in X-ray-induced cataract. 365 24


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