Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Proprotein Convertases”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed1991

Kex2-like endoproteases PC2 and PC3 accurately cleave a model prohormone in mammalian cells: evidence for a common core of neuroendocrine processing enzymes.

Two mammalian gene products, PC2 and PC3, have been proposed as candidate neuroendocrine-precursor processing enzymes based on the structural similarity of their catalytic domains to that of the yeast precursor-processing endoprotease Kex2. In this report we demonstrate that these two proteases can cleave proopiomelanocortin (POMC) in the secretory pathway of mammalian cells. Similarly to pituitary corticotrophs, PC3 expressed in processing-deficient BSC-40 cells cleaved native mouse POMC at the -Lys-Arg- sites flanking corticotropin. The -Lys-Arg- within beta-lipotropin was less efficiently cleaved to release beta-endorphin. Expression of PC2 together with PC3 resulted in efficient conversion of beta-lipotropin, as occurs in pituitary melanotrophs. Furthermore, coexpression of PC2 together with mouse POMC in bovine adrenomedullary chromaffin cells resulted in conversion of beta-lipotropin to gamma-lipotropin and beta-endorphin in the regulated secretory pathway. Finally, the processing selectivities of PC3 and PC2 expressed together in BSC-40 cells were determined by using a series of mutant mouse POMCs containing all possible pairs of basic residues at certain sites. The observed pattern of cleavage site selectivities mimicked that of the endogenous endoproteases of the insulinoma and bovine adrenomedullary chromaffin cells, suggesting that PC2 and PC3 may represent important core endoproteases in the catalysis of prohormone processing in many neuroendocrine cell types.

Adrenocorticotropic Hormone↗
PubMed1999

Thyroid hormone receptor-associated proteins and general positive cofactors mediate thyroid hormone receptor function in the absence of the TATA box-binding protein-associated factors of TFIID.

Coactivators previously implicated in ligand-dependent activation functions by thyroid hormone receptor (TR) include p300 and CREB-binding protein (CBP), the steroid receptor coactivator-1 (SRC-1)-related family of proteins, and the multicomponent TR-associated protein (TRAP) complex. Here we show that two positive cofactors (PC2 and PC4) derived from the upstream stimulatory activity (USA) cofactor fraction act synergistically to mediate thyroid hormone (T3)-dependent activation either by TR or by a TR-TRAP complex in an in vitro system reconstituted with purified factors and DNA templates. Significantly, the TRAP-mediated enhancement of activation by TR does not require the TATA box-binding protein-associated factors of TFIID. Furthermore, neither the pleiotropic coactivators CBP and p300 nor members of the SRC-1 family were detected in either the TR-TRAP complex or the other components of the in vitro assay system. These results show that activation by TR at the level of naked DNA templates is enhanced by cooperative functions of the TRAP coactivators and the general coactivators PC2 and PC4, and they further indicate a potential functional redundancy between TRAPs and TATA box-binding protein-associated factors in TFIID. In conjunction with earlier studies on other nuclear receptor-interacting cofactors, the present study also suggests a multistep pathway, involving distinct sets of cofactors, for activation of hormone responsive genes.

Animals↗
PubMed1995

Mutational analysis of PC1 (SPC3) in PC12 cells. 66-kDa PC1 is fully functional.

The proteinase mPC1, a neuroendocrine member of the mammalian family of subtilisin-like enzymes, has previously been shown to be converted to a carboxyl-terminally truncated 66-kDa form during transport through the secretory pathway. The cleavage site and the function of this carboxyl-terminal truncation event are unknown. We have performed site-directed mutagenesis of two paried basic sites in the mPC1 carboxyl-terminal tail and expressed these constructs in PC12 cells, a rat pheochromocytoma known to lack endogenous PC1. We found that the most likely site for the truncation event was at Arg590-Arg591 since mutation of this site to Lys-His prevented processing of 87-kDa PC1. A PC1 mutant carboxyl-terminally truncated at this site and expressed in PC12 cells was efficiently routed to the secretory pathway and stored in secretory granules, indicating that the carboxyl-terminal extension is not required for sorting of this enzyme. The function of the various PC1 constructs was assessed by analyzing proneurotensin cleavage to various forms. The carboxyl-terminally truncated PC1 mutant was found to perform most of the cleavages of this precursor as well as wild-type PC1; however, the blockade mutant processed proneurotensin much less efficiently. Differences between the site preferences of the various enzymes were noted. Our results support the notion that carboxyl-terminal processing of PC1 serves to regulate PC1 activity.

Animals↗
PubMed2006

Genetic susceptibility to myocardial infarction and coronary artery disease.

Atherosclerotic involvement in the coronary arteries, which can result in heart attack and sudden death, is a common disease and prototypic of a complex human trait. To understand its genomic basis, eight linkage studies of sibling pairs have been performed. Although there was limited inter-study concordance of important loci, two gene variants in the leukotriene pathway (ALOX5AP and LTA4) have emerged as susceptibility factors for myocardial infarction (MI). Genome-wide association studies have also been undertaken, and the pro-inflammatory cytokine lymphotoxin-alpha (LTA), and its key ligand galectin-2 (LGALS2) have been identified as genes implicated in predisposition for heart attack. By cueing into the genomic basis for low serum LDL cholesterol levels, much work has been done to advance the importance of the serine protease PCSK9, which modulates LDL receptor function. Lifelong lowered LDL cholesterol associated with PCSK9 point mutations in 2-3% of individuals have been shown to provide marked protection from coronary artery disease (CAD). Most of the success in this field has been with the phenotype of MI, which is considerably more restrictive than CAD. Four principal and interdependent processes--lipoprotein handling, endothelial integrity, arterial inflammation, and thrombosis--have been supported as important via the clustering of genes, thus far implicated in CAD susceptibility. Of note, connecting genes in a single pathway (leukotriene), of a protein and its ligand (LTAalpha) or from one disease to another [age-related macular degeneration (AMD); complement factor H (CFH)], or even three disease characterized by inflammation (MHC2) have now been reported. Although the population attributable risk for any of the genes identified to date is limited, such discovery is likely to be accelerated in the future.

5-Lipoxygenase-Activating Proteins↗
PubMed1993

Identification and functional expression of a new member of the mammalian Kex2-like processing endoprotease family: its striking structural similarity to PACE4.

We used the polymerase chain reaction to identify a mouse cDNA which represented a new member of a growing class of mammalian endoproteases homologous to the yeast Kex2 protease involved in the processing of precursor proteins. This cDNA encoded a 915-residue protein, designated as PC6, containing a subtilisin-like catalytic domain closely related to those of other Kex2-like members (furin, PC2, PC1/3, PC4, and PACE4). It exhibited striking sequence similarity to PACE4 and contained similar protein domains, such as the COOH-terminal Cys-rich region. Northern blot analysis revealed that PC6 mRNA, as with furin and PACE4 mRNAs, was expressed in various tissues and cell lines, with the highest level in the intestine. Transfection experiments revealed that PC6 was capable of cleaving precursors at dibasic sites. These observations suggest that PC6 is a candidate for a processing endoprotease responsible for the maturation of gastrointestinal peptides.

Amino Acid Sequence↗
PubMed1994

Correlation of proteolytic cleavage of F protein precursors in paramyxoviruses with expression of the fur, PACE4 and PC6 genes in mammalian cells.

The fusion (F) protein precursor of virulent Newcastle disease virus (NDV) strains and human parainfluenza virus type 3 (HPIV3) has a multibasic amino acid sequence at the cleavage site, and intracellular cleavage activation occurs in a variety of cells. The host protease responsible for the cleavage has been proposed to be a subtilisin-like protease (subtilase) such as furin (the product of the fur gene). We found that the lymphocyte cell lines MOLT-4, Ramos and Daudi, in addition to NALM6, lacked the ability to fully cleave the F protein precursor of virulent NDV. In contrast, MT4 as well as the non-lymphocyte cell lines HeLa and Hep2 cleaved the F protein precursor efficiently. To investigate the role of subtilases in proteolytic processing, we examined the gene expression of candidate subtilases, furin, PACE4 and PC6 in these cleavage-competent and -incompetent cells. Considerable expression of the fur gene was observed in the cleavage-competent cells, but little or no expression was detected in the cleavage-incompetent cells. PACE4 and PC6 gene expression was observed in some of the cleavage-competent cells but not in the cleavage-incompetent cells. These results suggest that furin is the protease responsible for cleavage activation of the F protein of virulent NDV strains in cultured mammalian cells and the possibility is raised that PACE4 and PC6 also participate in processing in some of the cells. On the other hand, the HPIV3 F protein was cleaved efficiently in lymphocyte cells deficient in subtilases, suggesting that an unknown protease other than furin, PACE4 or PC6 may be involved in the processing.

Amino Acid Sequence↗
PubMed1999

Comparison of substrate specificities against the fusion glycoprotein of virulent Newcastle disease virus between a chick embryo fibroblast processing protease and mammalian subtilisin-like proteases.

The fusion (F) protein precursor of virulent Newcastle disease virus (NDV) strains has two pairs of basic amino acids at the cleavage site, and its intracellular cleavage activation occurs in a variety of cells; therefore, the viruses cause systemic infections in poultry. To explore the protease responsible for the cleavage in the natural host, we examined detailed substrate specificity of the enzyme in chick embryo fibroblasts (CEF) using a panel of the F protein mutants at the cleavage site expressed by vaccinia virus vectors, and compared the specificity with those of mammalian subtilisin-like proteases such as furin, PC6 and PACE4 which are candidates for F protein processing enzymes. It was demonstrated in CEF cells that Arg residues at the -4, -2 and -1 positions upstream of the cleavage site were essential, and that at the -5 position was required for maximal cleavage. Phe at the +1 position was also important for efficient cleavage. On the other hand, furin and PC6 expressed by vaccinia virus vectors showed cleavage specificities against the F protein mutants consistent with that shown by the processing enzyme of CEF cells, but PACE4 hardly cleaved the F proteins including the wild type. These results indicate that the proteolytic processing enzymes of poultry for virulent NDV F proteins could be furin and/or PC6 but not PACE4. The significance of individual contribution of the three amino acids at the -5, -2 and +1 positions to cleavability was discussed in relation to the evolution of virulent and avirulent NDV strains.

Animals↗
PubMed1993

Peptidylglycine alpha-amidating monooxygenase and other processing enzymes in the neurointermediate pituitary.

Studies on the mRNAs encoding PAM and on the various PAM proteins have begun to reveal some of the intricate mechanisms used to optimize the ability of this enzyme to carry out the alpha-amidation of peptides. Comparison of the regulatory elements governing expression of the various enzymes involved in peptide processing should reveal common elements. Knowledge of the processing enzymes themselves should help us to understand how these enzymes function in the secretory granule environment. In addition to their catalytic domains, other processing enzymes, like PAM, may well have processing domains and routing domains designed to optimize their ability to function in secretory granules.

Amino Acid Sequence↗
PubMed2002

Proteolytic processing of chromogranins is modified in brains of transgenic mice.

In normal brain, secretogranin II and chromogranins A and S are extensively converted by endopeptidases to the peptides secretoneurin, GE-19, and PE-11, respectively. After genetic knockout of PC2 or its helper protein 7B2, but not after mutation of carboxypeptidase E, endoproteolytic processing decreased, as indicated by appearance of intermediate-sized processing products.

Animals↗
PubMed2006

Genetic causes of familial hypercholesterolaemia in patients in the UK: relation to plasma lipid levels and coronary heart disease risk.

AIMS: To determine the relative frequency of mutations in three different genes (low-density lipoprotein receptor (LDLR), APOB, PCSK9), and to examine their effect in development of coronary heart disease (CHD) in patients with clinically defined definite familial hypercholesterolaemia in UK. PATIENTS AND METHODS: 409 patients with familial hypercholesterolaemia patients (158 with CHD) were studied. The LDLR was partially screened by single-strand conformational polymorphism (SSCP) (exons 3, 4, 6-10 and 14) and by using a commercial kit for gross deletions or rearrangements. APOB (p.R3500Q) and PCSK9 (p.D374Y) were detected by specific assays. Coding exons of PCSK9 were screened by SSCP. RESULTS: Mutations were detected in 253 (61.9%) PATIENTS: 236 (57.7%) carried LDLR, 10 (2.4%) carried APOB p.Q3500 and 7 (1.7%) PCSK9 p.Y374. No additional mutations were identified in PCSK9. After adjusting for age, sex, smoking and systolic blood pressure, compared to those with no detectable mutation, the odds ratio of having CHD in those with an LDLR mutation was 1.84 (95% CI 1.10 to 3.06), for APOB 3.40 (0.71 to 16.36), and for PCSK9 19.96 (1.88 to 211.5; p = 0.001 overall). The high risk in patients carrying LDLR and PCSK9 p.Y374 was partly explained by their higher pretreatment cholesterol levels (LDLR, PCSK9 and no mutation, 10.29 (1.85), 13.12 and 9.85 (1.90) mmol/l, respectively, p = 0.001). The post-statin treatment lipid profile in PCSK9 p.Y374 carriers was worse than in patients with no identified mutation (LDL-C, 6.77 (1.82) mmol/l v 4.19 (1.26) mmol/l, p = 0.001, HDL-C 1.09 (0.27) mmol/l v 1.36 (0.36) mmol/l, p = 0.03). CONCLUSIONS: The higher CHD risk in patients carrying PCSK9 p.Y347 or a detected LDLR mutation supports the usefulness of DNA testing in the diagnosis and management of patients with familial hypercholesterolaemia. Mutations in PCSK9 appear uncommon in patients with familial hypercholesterolaemia in UK.

Adult↗
PubMed1993

Immunocytochemical localization of the neuropeptide-synthesizing enzyme PC1 in AtT-20 cells.

The subtilisin-like enzyme PC1 (also known as PC3) cleaves the neuropeptide precursor proopiomelanocortin at paired basic residues in transfection experiments, thus providing evidence for a critical role in precursor processing. While mRNA for this enzyme is highly enriched in neuroendocrine tissues, little is known about the tissue and subcellular distribution of the PC1 protein. This study used immunocytochemical techniques to investigate the anatomical distribution of PC1, both alone and compared to met-enkephalin (MET-enk), in AtT-20 pituicytes transfected with proenkephalin cDNA. A high density of PC1 immunostaining was observed in a small region adjacent to the nucleus and in the tips of the processes of these cells. Dual-staining immunocytochemistry of whole cells illustrated that both PC1 and MET-enk immunoreactivity were present in the tips, but PC1 was concentrated in a region adjacent to the nucleus while MET-enk punctate staining was dispersed throughout the soma. This codistribution was confirmed in semithin sections of dual-stained cells cut at 1-1.5 microns through the thickness of the cells. PC1 staining resembled that of TGN38, a marker for the trans-Golgi network. When PC1 immunocytochemistry was performed in cells that were pretreated with brefeldin A, a drug that redistributes the proximal Golgi compartments to the endoplasmic reticulum, there was a complete disruption of the defined locus of PC1 immunoreactivity. Taken together, our data indicate that (1) PC1 is concentrated in a region of the cell body resembling the trans-Golgi network and (2) both the enzyme and the processed peptide are transported to the tips of the processes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗