Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.59 (MIP)
 4,906 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is known that during lens differentiation a number of fibre cell specific membrane proteins change their expression profiles. In this study we have investigated how the profiles of the two most abundant fibre cell membrane proteins AQP0 (formerly known as Major Intrinsic Protein, MIP) and MP20 change as a function of fibre cell differentiation. While AQP0 was always found associated with fibre cell membranes, MP20 was initially found in the cytoplasm of peripheral fibre cells before becoming inserted into the membranes of deeper fibre cells. To determine at what stage in fibre cell differentiation MP20 becomes inserted into the membrane, sections were double-labelled with an antibody against MP20, and propidium iodide, a marker of cell nuclei. This showed that membrane insertion of MP20 occurs in a discrete transition zone that coincided with the degradation of cell nuclei. To test the significance of the membrane insertion of MP20 to overall lens function, whole lenses were incubated for varying times in a solution containing either Texas Red-dextran or Lucifer yellow as markers of extracellular space. Lenses were fixed and then processed for immunocytochemistry. Analysis of these sections showed that both tracer dyes were excluded from the extracellular space in an area that coincided with insertion of MP20 into the plasma membrane. Our results suggest that the insertion of MP20 into fibre cell membranes coincides with the creation of a barrier that restricts the diffusion of molecules into the lens core via the extracellular space.
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PMID:Insertion of MP20 into lens fibre cell plasma membranes correlates with the formation of an extracellular diffusion barrier. 1455 Mar 98

We have conducted a survey of the expression patterns of five genes encoding three different classes of major lens proteins during eye degeneration in the blind cavefish Astyanax mexicanus. This species consists of two forms, an eyed surface-dwelling form (surface fish) and a blind cave-dwelling (cavefish) form. Cavefish form an optic primordium with a lens vesicle and optic cup. In contrast to surface fish, however, the cavefish lens does not differentiate fiber cells and undergoes massive apoptosis. The genes encoding the lens intrinsic membrane proteins MIP and MP19 and the divergent betaB1- and gammaM2-crystallins are expressed during cavefish lens development, although their levels are reduced because of a smaller lens, and the spatial distribution of their transcripts is modified because of the lack of differentiated fiber cells. In contrast, the alphaA-crystallin gene, which encodes a heat shock protein-related chaperone with antiapoptotic activity, is substantially downregulated in the developing cavefish lens. The results suggest that suppression of alphaA-crystallin antiapoptotic activity may be involved in cavefish eye degeneration.
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PMID:Lens gene expression analysis reveals downregulation of the anti-apoptotic chaperone alphaA-crystallin during cavefish eye degeneration. 1802 50

Congenital cataract is the common cause of visual disability in children. Inherited isolated (non-syndromic) cataract represents one third of cases. Currently, at least 22 specific genes associated with isolated inherited cataract have been identified: ten crystallin genes: CRYAA, CRYAB, CRYBA1/A3, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD, CRYGS; 4 membrane protein genes: GJA3, GJA8, MIP, LIM2; three growth and transcription factor genes: PITX3, MAF, HSF4; two cytoskeletal protein gene: BSFP1, BSFP2; chromatin modifying protein-4B gene: CHMP4B, EPHA2 and NHS, it is likely that more genes remain to be discovered. Some of the genes have been studied for their function by expression in cells or/and by knock-out animal models. The increasing availability of more detailed information about their functions makes it possible to understand the pathophysiology of congenital cataracts.
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PMID:[Progress in pathogenic genes and their functions of congenital cataract]. 2045 Jun 75

Congenital cataract is a highly heterogeneous disorder at both the genetic and the clinical-phenotypic levels. A unique cataract was observed in a 4-generation Chinese family, which was characterized by autosomal dominant inheritance and late-onset. Mutations in the 13 known genes (CRYAA, CRYAB, CRYBB1, CRYBB2, CRYGC, CRYBA1/A3, CRYGD, Connexin50, Connexin46, intrinsic membrane protein LIM2, cytoskeletal protein BFSP2, the major intrinsic protein-MIP and the heat shock factor HSF4) have previously been demonstrated to be the frequent reason for isolated congenital cataracts, but the exact molecular basis and underlying mechanisms of congenital cataract still remain unclear. This study was designed to find whether these 13 genes developed any mutation in the family members and to identify the disease-causing gene. Polymerase chain reaction (PCR) and direct DNA sequence analysis were carried out to detect the 13 genes. The results showed that no mutation causing amino acid alternations was found in these potential candidate genes among all patients in the family, and only several single-nucleotide polymorphisms (SNPs) were identified. A transitional mutation in the fourth intron of CRYBB2 and some silent mutations in the first exon of BFSP2 and CRYGD were found in the cataract family, but further study showed that these mutations could also be found in normal controls. It was concluded that some unidentified genes may underlie the occurrence of late-onset cataract in this family. A genome-wide screening will be carried out in the next study.
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PMID:Molecular genetic analysis of autosomal dominant late-onset cataract in a Chinese Family. 2118 74

Congenital cataract is a crystallin severe blinding disease and genetic factors in disease development are important. Crystallin growth is under a combination of genes and their products in time and space to complete the coordination role of the guidance. Congenital cataract-related genes, included crystallin protein gene (CRYAA, CRYAB, CRYBA1/A3, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD, CRYGS), gap junction channel protein gene (GJA1, GJA3, GJA8), membrane protein gene (GJA3, GJA8, MIP, LIM2), cytoskeletal protein gene (BF-SP2), transcription factor genes (HSF4, MAF, PITX3, PAX6), ferritin light chain gene (FTL), fibroblast growth factor (FGF) and so on. Currently, there are about 39 genetic loci isolated to which primary cataracts have been mapped, although the number is constantly increasing and depends to some extent on definition. We summarized the recent advances on epidemiology and genetic locations of congenital cataract in this review.
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PMID:Epidemiology and molecular genetics of congenital cataracts. 2255 94