Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01034 (cystatin C)
 3,397 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The study made use of transiently transfected RPE cells expressing mature cystatin C (lacking the 26 amino acids leader sequence of the precursor cystatin C) fused to enhanced green fluorescent protein (EGFP) and, in control transfections, EGFP on its own. The findings demonstrate that 'leaderless' cystatin C is not processed through the secretory pathway of RPE cells. Since a polymorphism in the leader sequence has recently been associated with increased risk for development of exudative age-related macular degeneration (AMD), the present findings lend support to the hypothesis that impairment of function of the leader sequence may contribute to the aetiology of exudative AMD.
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PMID:Fate of cystatin C lacking the leader sequence in RPE cells. 1274 58

Cystatin C is abundantly expressed by the retinal pigment epithelium (RPE) of the eye. Targeting of cystatin C to the Golgi apparatus and processing through the secretory pathway of RPE cells are dependent upon a 26-amino acid signal sequence of precursor cystatin C. A variant with an alanine (A) to threonine (T) mutation in the penultimate amino acid of the signal sequence (A25T) was recently correlated with increased risk of developing exudative age-related macular degeneration. The biochemical consequence of the A25T mutation upon targeting of the protein is reported here. Targeting and trafficking of full-length mutant (A25T) precursor cystatin C-enhanced green fluorescent protein fusion protein were studied in living, cultured retinal pigment epithelial and HeLa cells. Confocal microscopy studies were substantiated by immunodetection. In striking contrast to wild-type precursor cystatin C fusion protein conspicuously targeted to the Golgi apparatus, the threonine variant was associated principally with mitochondria. Some diffuse fluorescence was also observed throughout the cytoplasm and nucleus (but not nucleoli). Secretion of fusion protein derived from the threonine variant was reduced by approximately 50% compared with that of the wild-type cystatin C fusion protein. Expression of the variant fusion protein did not appear to impair expression or secretion of endogenous cystatin C.
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PMID:Unexpected intracellular localization of the AMD-associated cystatin C variant. 1547 53

Cystatin C is the major inhibitor of the cysteine cathepsins. Polymorphisms in the cystatin C gene have recently been associated with the risk of developing Age-related Macular Degeneration (AMD). Oxidative stress is also thought to play a key role in the pathogenesis of AMD. We surveyed the retinal pigment epithelium (RPE) and choroid of the C57BL/6J mouse for the expression of the cysteine cathepsins under normoxic and hyperoxic (75% O(2)) conditions. Microarray analysis of RPE/choroid mRNA revealed the expression of cathepsins B and L, as well as cystatin C under all experimental conditions. The microarray results were confirmed by real-time quantitative polymerase chain reaction (PCR). Localization of the mRNA species for cystatin C and cathepsin B, as well as, localization of protein species for cystatin C, cathepsins B and L were performed to evaluate the tissue distribution of these species. Our results indicate that cystatin C is largely synthesized in the RPE and secreted from the basal side. Cathepsin B is the major cysteine protease in the RPE and choroid. The expression of all mRNAs and proteins was elevated by exposure to oxidative stress.
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PMID:Regulation of cysteine cathepsin expression by oxidative stress in the retinal pigment epithelium/choroid of the mouse. 1668 24

Cystatin C is a strong inhibitor of cysteine proteinases expressed by diverse cells. Variant B cystatin C, which was associated with increased risk of developing age-related macular degeneration, differs from the wild type protein by a single amino acid (A25T) in the signal sequence responsible for its targeting to the secretory pathway. The same variant conveys susceptibility to Alzheimer disease. Our investigations of the trafficking and processing of variant B cystatin C in living RPE cells highlight impaired secretion of extracellular modulators and inappropriate protein retention in RPE cells as potential molecular mechanisms underpinning macular, and possibly neuronal, degeneration.
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PMID:Cystatin C in macular and neuronal degenerations: implications for mechanism(s) of age-related macular degeneration. 1991 2

Recent progress of fundamental and clinical studies on cystatin C was reviewed. Most of key studies are indebted to prof. Grubb A and his groups. International contributions from Japanese research work are included here. The protein is a basic low molecular weight protein of 13,300 with 120 amino acid residues and pI 9.3, functioning as a cysteine protease inhibitor. With an introduction of ERM-DA471, international reference material for serum cystatin C, global standardization for immunoassay systems has been much facilitated. No serious problems are present in the pre-analytical stage. Serum reference intervals are properly set in all Asian populations including Japanese with age and gender-related differences. The protein is a powerful serum intrinsic marker for glomerular filtration rate. Estimated glomerular filtration rate (eGFRcysC) in coupled with eGFRCr will definitely be a clinical routine for early detection and prevention of altered kidney function and cardiovascular events in general population. Genetic tests clinically indicated include hereditary cystatin C amyloid angiopathy (L68Q) and adult macular degeneration (A25T) although their frequency is extremely low.
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PMID:[Fundamental and clinical aspects of cystatin C]. 2319 37

Variant B (VB) of cystatin C has a mutation in its signal peptide (A25T), which interferes with its processing leading to reduced secretion and partial retention in the vicinity of the mitochondria. There are genetic evidences of the association of VB with Alzheimer's disease (AD) and age-related macular degeneration (AMD). Here, we investigated aggregation and amyloid propensities of unprocessed VB combining computational and in vitro studies. Aggregation predictors revealed the presence of four aggregation-prone regions, with a strong one at the level of the signal peptide, which indeed formed toxic aggregates and mature amyloid fibrils in solution. In light of these results, we propose for the first time the role of the signal peptide in pathogenesis of AD and AMD.
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PMID:Amyloid properties of the leader peptide of variant B cystatin C: implications for Alzheimer and macular degeneration. 2686 59

CRISPR/Cas9 causes double-stranded DNA breaks that can undergo DNA repair either via non-homologous end joining (NHEJ) or, in the presence of a template, homology-directed repair (HDR). HDR is typically used to insert a specific genetic modification into the genome but has low efficiency compared to NHEJ, which is lowered even further when trying to create a homozygous change. In this study we devised a novel approach for homozygous single base editing based on utilising simultaneously two donor DNA templates cloned in plasmids with different antibiotic resistant genes. The donor templates were co-transfected alongside the CRISPR/Cas9 machinery into cells and a double antibiotic selection was optimised and allowed the isolation of viable desired clones. We applied the method for obtaining isogenic cells homozygous for variant B cystatin C, a recessive risk factor for age-related macular degeneration and Alzheimer's disease, in both induced Pluripotent Stem Cells (iPSCs) and a human RPE cell line. Bi-allelic gene edited clones were validated by sequencing, demonstrating that the double antibiotic templates approach worked efficiently for both iPSCs and human differentiated cells. We propose that this one step gene editing approach can be used to improve the specificity and frequency of introducing homozygous modifications in mammalian cells.
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PMID:CRISPR/Cas9-mediated one step bi-allelic change of genomic DNA in iPSCs and human RPE cells in vitro with dual antibiotic selection. 3065 67