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

Apolipoprotein (apo-) B100 is the exclusive apolipoprotein of low density lipoproteins (LDL0, which transport most of the plasma cholesterol in humans. Mutations in apo-B100 can cause either hypocholesterolemia or hypercholesterolemia. Familial hypobetalipoproteinemia, which leads to hypocholesterolemia, has been shown to be caused by defects in the apo-B gene that terminate translation prematurely and result in the production of truncated proteins. The mutations responsible for the hypocholesterolemia have been either single nucleotide substitutions or deletions. Familial defective apo-B100, which leads to hypercholesterolemia, is caused by a point mutation in the receptor-binding domain of apo-B100. The mutation disrupts the binding of LDL to the LDL receptor, thereby disrupting LDL receptor-mediated catabolism and resulting in hypercholesterolemia. A variant form of apo-B, apo-B48, is also critical for lipoprotein metabolism. Apolipoprotein B48 is obligatory for the secretion of chylomicrons. It is formed from an RNA-edited apo-B mRNA in which codon 2153 has been converted from a CAA (glutamine) codon to a premature UAA (stop) codon. The first cytosine in this codon is deaminated to form uracil. The minimum nucleotide recognition sequence for the editing mechanism has been reported to be between 26 and more than 63 nucleotides surrounding codon 2153. The apo-B mRNA editing mechanism, which appears to be a cytosine deaminase, and its regulation are being actively investigated.
 ...
PMID:Mutations and variants of apolipoprotein B that affect plasma cholesterol levels. 185 54

Apolipoprotein (apo) B-100 is the major protein component in low density lipoprotein (LDL); it contains the binding domain for the LDL receptor and the attachment site for apolipoprotein(a) in lipoprotein(a). ApoB-48 is colinear with the amino-terminal half of apoB-100 and misses the part of the molecule required for LDL receptor interaction and lipoprotein(a) formation. ApoB-48 mRNA is produced by the editing of apoB-100 mRNA, a process by which the codon CAA for Gln-2153 is changed to UAA, an in-frame stop codon. We used the cloned catalytic component of the rat apoB mRNA-editing enzyme (REPR) to construct a replication-defective recombinant adenoviral vector containing REPR cDNA (AvREPR) and a control vector (Av1LacZ4) containing a beta-galactosidase cDNA to investigate the effect of REPR gene delivery in C57BL/6 mice. Intravenous injection of AvREPR in mice resulted in efficient transduction of liver cells, where REPR mRNA and protein were overexpressed, reaching a peak at 7 and 12 days, returning toward control levels at 39 days after AvREPR administration. ApoB mRNA editing activity in liver extracts showed changes parallel to those of REPR mRNA expression; the proportion of edited apoB mRNA in the total hepatic apoB mRNA increased from approximately 60% to more than 90% at the peak of REPR expression. The proportion of plasma apoB-100 in AvREPR-transduced animals decreased from approximately 50% to < 10% of total plasma apoB concentration. Plasma very low density lipoproteins were polydisperse in control animals with an average diameter of 54.9 +/- 20.6 nm (uninjected control) and 54.7 +/- 16.8 nm (Av1LacZ4-treated), respectively. They became much smaller (average diameter 39.3 +/- 12.7 nm) and more uniform in size at day 12 following AvREPR administration. On the same day, the normal plasma LDL (26.2-25.5 nm) was almost completely eliminated in treated animals. Adenovirus-mediated transfer of the REPR cDNA is an efficient method to reduce plasma apoB-100 and normal LDL production.
 ...
PMID:Adenovirus-mediated gene transfer of rat apolipoprotein B mRNA-editing protein in mice virtually eliminates apolipoprotein B-100 and normal low density lipoprotein production. 796 18

Human atherosclerotic lesions overexpress the lysosomal cysteine protease cathepsin S (Cat S), one of the most potent mammalian elastases known. In contrast, atheromata have low levels of the endogenous Cat S inhibitor cystatin C compared with normal arteries, suggesting involvement of this protease in atherogenesis. The present study tested this hypothesis directly by crossing Cat S-deficient (CatS(-/-)) mice with LDL receptor-deficient (LDLR(-/-)) mice that develop atherosclerosis on a high-cholesterol diet. Compared with LDLR(-/-) mice, double-knockout mice (CatS(-/-)LDLR(-/-)) developed significantly less atherosclerosis, as indicated by plaque size (plaque area and intimal thickening) and stage of development. These mice also had markedly reduced content of intimal macrophages, lipids, smooth muscle cells, collagen, CD4(+) T lymphocytes, and levels of IFN-gamma. CatS(-/-)LDLR(-/-) monocytes showed impaired subendothelial basement membrane transmigration, and aortas from CatS(-/-)LDLR(-/-) mice had preserved elastic laminae. These findings establish a pivotal role for Cat S in atherogenesis.
 ...
PMID:Deficiency of cathepsin S reduces atherosclerosis in LDL receptor-deficient mice. 1263 96

Atherosclerosis is an inflammatory disease characterized by extensive remodeling of the extracellular matrix architecture of the arterial wall. Although matrix metalloproteinases and serine proteases participate in these pathologic events, recent data from atherosclerotic patients and animals suggest the participation of lysosomal cysteine proteases in atherogenesis. Atherosclerotic lesions in humans overexpress the elastolytic and collagenolytic cathepsins S, K, and L but show relatively reduced expression of cystatin C, their endogenous inhibitor, suggesting a shift in the balance between cysteine proteases and their inhibitor that favors remodeling of the vascular wall. Extracts of human atheromatous tissue show greater elastolytic activity in vitro than do those from healthy donors. The cysteinyl protease inhibitor E64d limits this increased elastolysis, indicating involvement of cysteine proteases in elastin degradation during atherogenesis. Furthermore, inflammatory cytokines augment expression and secretion of active cysteine proteases from cultured monocyte-derived macrophages, vascular smooth muscle cells, and endothelial cells and increase degradation of extracellular elastin and collagen. Cathepsin S-deficient cells or those treated with E64d show significantly impaired elastolytic or collagenolytic activity. Additionally, recent in vivo studies of atherosclerosis-prone, LDL receptor-null mice lacking cathepsin S show participation of this enzyme in the initial infiltration of leukocytes, medial elastic lamina degradation, endothelial cell invasion, and neovascularization, illustrating an important role for cysteine proteases in arterial remodeling and atherogenesis.
 ...
PMID:Lysosomal cysteine proteases in atherosclerosis. 1517 58

Apolipoprotein B (apo B) circulates in two distinct isomorphic forms, each the product of a single gene. The larger form, referred to as apo B-100, is the major protein of plasma low-density lipoproteins (LDLs) and is synthesized by the human liver. The smaller form, referred to as apo B-48, is produced in the small intestine as a result of a site-specific cytidine deamination, which alters a CAA codon, encoding glutamine in the unedited (apo B-100) mRNA to UAA, which specifies an in-frame stop codon. Apo B-48 lacks the domains involved in LDL receptor interaction and in complex formation with apolipoprotein(a). DNA sequence analysis of the gene that mediates this site-specific cytidine deamination suggests that apo B mRNA editing is an evolutionary adaptation to limit the atherogenic potential of intestinal lipoproteins.
 ...
PMID:RNA editing of the apolipoprotein B gene A mechanism to regulate the atherogenic potential of intestinal lipoproteins? 2124 72