PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Proprotein Convertase 1”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 217 records · Page 12Linked to original sources
PubMed2001

Proprotein convertase PACE4 is down-regulated by the basic helix-loop-helix transcription factor hASH-1 and MASH-1.

PACE4 is a mammalian subtilisin-like proprotein convertase that activates transforming growth factor (TGF)-beta-related proteins such as bone morphogenetic protein 2 (BMP2), BMP4 and Nodal and exhibits a dynamic expression pattern during embryogenesis. We recently determined that the 1 kb 5'-upstream region of the PACE4 gene contains 12 E-box (E1-E12) elements and that an E-box cluster (E4-E9) acts as a negative regulator [Tsuji, Yoshida, Hasegawa, Bando, Yoshida, Koide, Mori and Matsuda (1999) J. Biochem. (Tokyo) 126, 494-502]. It is known that the mammalian achaete-scute homologue 1 (MASH-1) binds specifically to an E-box (CACCTG) sequence in collaboration with E47, a ubiquitously expressed basic helix-loop-helix (bHLH) factor. To identify the roles of the bHLH factor and E-box elements in regulating PACE4 gene expression in neural development, we analysed the effects of human achaete-scute homologue 1 (hASH-1) on PACE4 gene expression with various neuroblastoma cell lines. The expressions of PACE4 and hASH-1 are correlated inversely in these cell lines. The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression but has no effect on the expression of other subtilisin-like proprotein convertases such as furin, PC5/6 and PC7/8. In contrast, other neural bHLH factors (MATH-1, MATH-2, neurogenin 1, neurogenin 2, neurogenin 3 and E47) did not affect PACE4 gene expression. Furthermore, an E-box cluster was a negative regulatory element for the promoter activity in NBL-S cells expressing hASH-1 at high level as determined by a luciferase assay. Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay. In the present study we identified the PACE4 gene as one of the targets of hASH-1, which is a key factor in the initiation of neural differentiation. These results suggest that the alteration of PACE4 gene expression by hASH-1 causes rapid changes in the biological activities of TGF-beta-related proteins via post-translational modification of these proteins.

Basic Helix-Loop-Helix Proteins↗
PubMed2004

Pathogenic factors in vascular dementia and Alzheimer's disease. Multiple actions of heparin that probably are beneficial.

The following areas are discussed in this review: atherogenesis; cerebrovascular factors; hypoperfusion; beta-amyloid production; beta-amyloid fibril formation; beta-sheets; metal cations; reactive oxygen species/free radicals; chronic inflammatory factors; endogenous plasma heparin; lipoprotein lipase; polyamines; protein kinase C; casein kinases; phospholipase A2; serine proteases; myeloperoxidase; cyclooxygenase 2; cysteine proteases; caspases; proprotein convertases; aspartic proteases; cyclin proteinases; thrombin; tau hyperphosphorylation; advanced glycosylation end products; activator protein 1; calcium; apolipoprotein E epsilon4; histamine; blood-brain barrier; glutamate; transglutaminase; insulin-like growth factor 1.

Aged↗
PubMed2000

Molecular cloning demonstrates structural features of homologous bovine prohormone convertases 1 and 2.

PC1 and PC2 (prohormone convertase) represent neuroendocrine members of the mammalian subtilisin-like family of proprotein convertases. The goal of this study was to compare the primary sequence motifs of bovine PC1 and PC2 with those of homologs from other mammalian species to establish the structural basis for PC1 and PC2 activities in bovine that resemble other mammalian homologs. Molecular cloning from bovine adrenal medulla resulted in the isolation of cDNAs for bovine PC1 and PC2 with highly conserved primary sequences with respect to signal sequence, prosegment, catalytic domain, and P domain. Bovine PC1 and PC2 contained the catalytic triad residues Asp, His, Ser, which are identical to the triads in PC1 and PC2 from other mammalian species. Bovine PCl contained Asn as the oxyanion hole residue; in contrast, bovine PC2 contained Asp as the oxyanion hole residue, which is identical to PC2 in other mammalian species. Bovine PC1 and PC2 possessed the P domain that contains the functional RRGDL motif. The cloned cDNAs detected expression of PC1 and PC2 mRNAs in bovine adrenal medulla. These results establish the defined structural domains of bovine PC1 and PC2 that are known to be essential for the activities of these enzymes in various species.

Adrenal Medulla↗
PubMed2003

Structural investigation of the HIV-1 envelope glycoprotein gp160 cleavage site, 2: relevance of an N-terminal helix.

Proteolytic activation of the HIV-1 envelope glycoprotein gp160 is selectively performed by the proprotein convertase furin at the C-terminus of the sequence R508-E-K-R511 (site 1), in spite of the presence of another consensus sequence, Lys500-Ala-Lys-Arg503 (site 2). On the basis of the solution structural analysis of the synthetic peptide p498, spanning the gp160 sequence Pro498-Gly516, we previously suggested a possible role of an N-terminal helix in regulating the exposure and accessibility of the gp160 physiological cleavage site, enclosed in a loop. Here we report on the activity and conformation of the 23-residue peptide h-REKR, designed to exhibit a large N-terminal helix, followed by the gp160 native sequence, Arg508-Gly516. h-REKR is digested by furin with high efficiency, comparable to the full native p498. Circular dichroism analyses, in mixtures from pure water to 98 % trifluoroethanol, outline a significant content of helical structure in the peptide conformation. The molecular model obtained from NMR data collected in trifluoroethanol/water, by means of DYANA and AMBER simulations, indeed has helical structure on a large N-terminal segment. Such a long helix does not seem to affect the loop conformation of the C-terminal site 1-containing sequence, which exhibits the same proton chemical shifts already observed for the full native p498.

Amino Acid Sequence↗
PubMed1999

Transport-dependent proteolysis of SREBP: relocation of site-1 protease from Golgi to ER obviates the need for SREBP transport to Golgi.

Cholesterol homeostasis in animal cells is achieved by regulated cleavage of membrane-bound transcription factors, designated SREBPs. Proteolytic release of the active domains of SREBPs from membranes requires a sterol-sensing protein, SCAP, which forms a complex with SREBPs. In sterol-depleted cells, SCAP escorts SREBPs from ER to Golgi, where SREBPs are cleaved by Site-1 protease (S1P). Sterols block this transport and abolish cleavage. Relocating active S1P from Golgi to ER by treating cells with brefeldin A or by fusing the ER retention signal KDEL to S1P obviates the SCAP requirement and renders cleavage insensitive to sterols. Transport-dependent proteolysis may be a common mechanism to regulate the processing of membrane proteins.

Animals↗
PubMed2000

Cholesterol homeostasis: ESCAPe from the ER.

Transcriptional regulation and membrane traffic have traditionally been quite separate fields of biology, but they have been brought under the same roof by recent advances in understanding the cellular control of cholesterol metabolism.

Animals↗
PubMed2003

Site-1 protease is required for cartilage development in zebrafish.

gonzo (goz) is a zebrafish mutant with defects in cartilage formation. The goz phenotype comprises cartilage matrix defects and irregular chondrocyte morphology. Expression of endoderm, mesoderm, and cartilage marker genes is, however, normal, indicating a defect in chondrocyte morphogenesis. The mutated gene responsible for the goz phenotype, identified by positional cloning and confirmed by phosphomorpholino knockdown, encodes zebrafish site-1 protease (s1p). S1P has been shown to process and activate sterol regulatory element-binding proteins (SREBPs), which regulate expression of key enzymes of lipid biosynthesis or transport. This finding is consistent with the abnormal distribution of lipids in goz embryos. Knockdown of site-2 protease, which is also involved in activation of SREBPs, results in similar lipid and cartilage phenotypes as S1P knockdown. However, knockdown of SREBP cleavage-activating protein, which forms a complex with SREBP and is essential for S1P cleavage, results only in lipid phenotypes, whereas cartilage appears normal. This indicates that the cartilage phenoptypes of goz are caused independently of the lipid defects.

Animals↗
PubMed1999

A proteolytic pathway that controls the cholesterol content of membranes, cells, and blood.

The integrity of cell membranes is maintained by a balance between the amount of cholesterol and the amounts of unsaturated and saturated fatty acids in phospholipids. This balance is maintained by membrane-bound transcription factors called sterol regulatory element-binding proteins (SREBPs) that activate genes encoding enzymes of cholesterol and fatty acid biosynthesis. To enhance transcription, the active NH(2)-terminal domains of SREBPs are released from endoplasmic reticulum membranes by two sequential cleavages. The first is catalyzed by Site-1 protease (S1P), a membrane-bound subtilisin-related serine protease that cleaves the hydrophilic loop of SREBP that projects into the endoplasmic reticulum lumen. The second cleavage, at Site-2, requires the action of S2P, a hydrophobic protein that appears to be a zinc metalloprotease. This cleavage is unusual because it occurs within a membrane-spanning domain of SREBP. Sterols block SREBP processing by inhibiting S1P. This response is mediated by SREBP cleavage-activating protein (SCAP), a regulatory protein that activates S1P and also serves as a sterol sensor, losing its activity when sterols overaccumulate in cells. These regulated proteolytic cleavage reactions are ultimately responsible for controlling the level of cholesterol in membranes, cells, and blood.

Animals↗
PubMed1999

Sterols regulate cycling of SREBP cleavage-activating protein (SCAP) between endoplasmic reticulum and Golgi.

The proteolytic cleavage of sterol regulatory element-binding proteins (SREBPs) is regulated by SREBP cleavage-activating protein (SCAP), which forms complexes with SREBPs in membranes of the endoplasmic reticulum (ER). In sterol-depleted cells, SCAP facilitates cleavage of SREBPs by Site-1 protease, thereby initiating release of active NH(2)-terminal fragments from the ER membrane so that they can enter the nucleus and activate gene expression. In sterol-overloaded cells, the activity of SCAP is blocked, SREBPs remain bound to membranes, and transcription of sterol-regulated genes declines. Here, we provide evidence that sterols act by inhibiting the cycling of SCAP between the ER and Golgi. We use glycosidases, glycosidase inhibitors, and a glycosylation-defective mutant cell line to demonstrate that the N-linked carbohydrates of SCAP are modified by Golgi enzymes in sterol-depleted cells. After modification, SCAP returns to the ER, as indicated by experiments that show that the Golgi-modified forms of SCAP cofractionate with ER membranes on density gradients. In sterol-overloaded cells, the Golgi modifications of SCAP do not occur, apparently because SCAP fails to leave the ER. Golgi modifications of SCAP are restored when sterol-overloaded cells are treated with brefeldin A, which causes Golgi enzymes to translocate to the ER. These studies suggest that sterols regulate the cleavage of SREBPs by modulating the ability of SCAP to transport SREBPs to a post-ER compartment that houses active Site-1 protease.

Animals↗
PubMed2002

Secretion of active anti-Ras single-chain Fv antibody by the yeasts Yarrowia lipolytica and Kluyveromyces lactis.

Yarrowia lipolytica and Kluyveromyces lactis secretion vectors were constructed and assessed for the expression of heterologous proteins. An anti-Ras single-chain antibody fragment (scFv) coding sequence was fused in-frame to different pre- or prepro-regions, or downstream from a reporter secretory gene (Arxula adeninivorans glucoamylase), separated by a Kex2 protease (Kex2p)-like processing sequence. Both organisms are able to secrete soluble scFv, with yields depending on the nature of the expression cassette, up to levels ranging from 10 to 20 mg l(-1). N-terminal sequence analysis of the purified scFv showed that fusions are correctly processed to the mature scFv by a signal peptidase or a Kex2p-type endoprotease present in Y. lipolytica and K. lactis. The scFv protein also retains the capacity to bind to a glutathioneS-transferase (GST)-Harvey-Ras(Val12) fusion, indicating that the antibody is functional. These results indicate that the yeasts Y. lipolytica and K. lactis have potential for industrial production of soluble and active scFv.

Fungal Proteins↗
PubMed2004

Regulation of matrix metalloproteinase MT1-MMP/MMP-2 in cardiac fibroblasts by TGF-beta1 involves furin-convertase.

OBJECTIVE: Heart failure is characterized by an imbalance of matrix synthesis/turnover, finally resulting in fibrosis. Cardiac myocytes and fibroblasts play a pivotal role in the remodeling process. Cardiac remodeling involves the expression of TGF-beta1 and matrix metalloproteinases (MMPs) in cardiac fibroblasts (CFBs). Furin, a subtilisin/kexin-like proprotein convertase (PC), activates TGF-beta1 and membrane-bound MT1-MMP, which facilitates pro-gelatinase A (MMP-2) activation. Even though several reports identified TGF-beta1 as a pro-fibrotic cytokine in the heart, it increases MMP-activity and cell migration/invasion in several cell types. The present study was done to investigate the contribution of TGF-beta1 and furin to CFBs MMP-activity and motility. METHODS AND RESULTS: Stimulation of CFBs from adult Sprague-Dawley rats with TGF-beta1 (20 ng/ml) induced furin, but had no effect on the closely related PC5. Inhibition of furin inhibited angiotensin II-induced TGF-beta1 activation, indicating that TGF-beta1 amplifies its activating convertase in CFBs. Pretreatment of CFBs with TGF-beta1 (20 ng/ml, 24 h) increased their migration by about two-fold (p<0.05), which was accompanied by an enhanced expression and activity of MT1-MMP and MMP-2. Brefeldin A (BFA), a Golgi-disturbing agent, inhibited MT1-MMP activation, indicating that it occurs in the trans-Golgi network (TGN), where furin is concentrated and colocalized with MT1-MMP. Inhibition of furin significantly inhibited TGF-beta1-induced MT1-MMP/MMP-2 activation. Furthermore, inhibition of furin attenuated TGF-beta1-enhanced migration on gelatin-coated membranes (p<0.05). This was comparable to the effects of the MMP-inhibitor GM6001, pointing out that MMPs are major mediators of TGF-beta1-enhanced CFB motility. CONCLUSION: We demonstrate that TGF-beta1 induces MMP-activity in CFBs, thereby facilitating CFBs motility. Furthermore, TGF-beta1 amplifies its activating convertase furin, which is also required for MT1-MMP/MMP-2 activation in CFBs. Thus, furin is central for TGF-beta1 and MT1-MMP activation and might be a novel target in cardiac remodeling.

Animals↗
PubMed2004

Plasticity of extended subsites facilitates divergent substrate recognition by Kex2 and furin.

Yeast Kex2 and human furin are subtilisin-related proprotein convertases that function in the late secretory pathway and exhibit similar though distinguishable patterns of substrate recognition. Although both enzymes prefer Arg at P(1) and basic residues at P(2), the two differ in recognition of P(4) and P(6) residues. To probe P(4) and P(6) recognition by Kex2p, furin-like substitutions were made in the putative S(4) and S(6) subsites of Kex2. T252D and Q283E mutations were introduced to increase the preference for Arg at P(4) and P(6), respectively. Glu(255) was replaced with Ile to limit recognition of P(4) Arg. The effects of putative S(4) and S(6) mutations were determined by examining the cleavage by purified mutant enzymes of a series of fluorogenic substrates with systematic changes in P(4) and/or P(6). Whereas wild Kex2 exhibited little preference type for Arg at P(6), the T252D mutant and T252D/Q283E double mutant exhibited clear interactions with P(6) Arg. Moreover, the T252D and T252D/Q283E substitutions altered the influence of the P(6) residue on P(4) recognition. We infer that cross-talk between S(4) and S(6), not seen in furin, allows wild type and mutant forms of Kex2 to adapt their subsites for altered modes of recognition. This apparent plasticity may allow the subsites to rearrange their local environment to interact with different substrates in a productive manner. E255I-Kex2 exhibited significantly decreased recognition of P(4) Arg in a tetrapeptide substrate with Lys at P(1), although the general pattern of selectivity for aliphatic residues at P(4) remained unchanged.

Amino Acid Sequence↗
PubMed1990

Processing of yeast exoglucanase (beta-glucosidase) in a KEX2-dependent manner.

We have detected proteolytic processing of a form of exoglucanase representative of the endoplasmic reticulum (form A). This processing did not take place when form A was obtained from protoplasts lysed in the presence of either EDTA or leupeptin, two wel-characterized inhibitors of KEX2 endoprotease from Saccharomyces cerevisiae. Sequencing of the amino terminus of an A-like form of enzyme secreted by a kex2 mutant indicated the presence of 4 amino acids, with a pair of basic residues (Lys-Arg) at their carboxyl side, preceding the amino terminus of the wild-type external exoglucanase.

Amino Acid Sequence↗
PubMed1999

Overexpression of insulin-like growth factor II (IGFII) in ZR-75-1 human breast cancer cells: higher threshold levels of receptor (IGFIR) are required for a proliferative response than for effects on specific gene expression.

Previous transfection experiments using a zinc-inducible expression vector have shown that overexpression of insulin-like growth factor II (IGFII) in MCF7 human breast cancer cells can reduce dependence on oestrogen for cell growth in vitro (DALY RJ, HARRIS WH, WANG DY, DARBRE PD. (1991) Cell Growth Differentiation 2, 457-464.). Parallel transfections now performed into another oestrogen-dependent human breast cancer cell line (ZR-75-1) yielded three clones of transfected ZR-75-1 cells that produced levels of zinc-inducible IGFII mRNA and secreted mature IGFII protein similar to those found in the transfected MCF7 cells. However, unlike in MCF7 cells, no resulting effects were found on cell growth in the ZR-75-1 clones, even though the ZR-75-1 clones possessed receptors capable of binding 125I-IGFI and showed a growth response to exogenously added IGFII. Medium conditioned by the ZR-75-1 clones could stimulate growth of untransfected MCF7 cells, indicating that the secreted IGFII protein was bioactive. Furthermore, zinc-induced IGFII was capable of increasing both pS2 mRNA levels and CAT activity from a transiently transfected AP1-CAT gene in the ZR-75-1 clones. Constitutive co-overexpression of the protein processing enzyme PC2 resulted in reduced levels of large forms of zinc-inducible IGFII, but zinc treatment still produced no effect on cell growth rate. Finally, however, constitutive co-overexpression of the type I IGF receptor (IGFIR) did result in zinc-inducible increased basal cell growth and reduced dependence on oestrogen for cell growth. These results demonstrate that while overexpression of IGFII per se was sufficient to deregulate MCF7 cell growth, the ZR-75-1 cells are limited in their proliferative response by their intrinsic receptor levels. However, although the proliferative response was limited, molecular responses (expression of pS2 and AP1-CAT) were not limited, indicating that different cellular responses can have different threshold receptor level requirements.

Breast Neoplasms↗
PubMed1997

Role of the prohormone convertase PC3 in the processing of proglucagon to glucagon-like peptide 1.

Proglucagon is processed differentially in pancreatic alpha-cells and intestinal endocrine L cells to release either glucagon or glucagon-like peptide-1-(7-36amide) (tGLP-1), two peptide hormones with opposing biological actions. Previous studies have demonstrated that the prohormone convertase PC2 is responsible for the processing of proglucagon to glucagon, and have suggested that the related endoprotease PC3 is involved in the formation of tGLP-1. To understand better the biosynthetic pathway of tGLP-1, proglucagon processing was studied in the mouse pituitary cell line AtT-20, a cell line that mimics the intestinal pathway of proglucagon processing and in the rat insulinoma cell line INS-1. In both of these cell lines, proglucagon was initially cleaved to glicentin and the major proglucagon fragment (MPGF) at the interdomain site Lys70-Arg71. In both cell lines, MPGF was cleaved successively at the monobasic site Arg77 and then at the dibasic site Arg109-Arg110, thus releasing tGLP-1, the cleavages being less extensive in INS-1 cells. Glicentin was completely processed to glucagon in INS-1 cells, but was partially converted to oxyntomodulin and very low levels of glucagon in AtT-20 cells in the face of generation of tGLP-1. Adenovirus-mediated co-expression of PC3 and proglucagon in GH4C1 cells (normally expressing no PC2 or PC3) resulted in the formation of tGLP-1, glicentin, and oxyntomodulin, but no glucagon. When expressed in alphaTC1-6 (transformed pancreatic alpha-cells) or in rat primary pancreatic alpha-cells in culture, PC3 converted MPGF to tGLP-1. Finally, GLP-1-(1-37) was cleaved to tGLP-1 in vitro by purified recombinant PC3. Taken together, these results indicate that PC3 has the same specificity as the convertase that is responsible for the processing of proglucagon to tGLP-1, glicentin and oxyntomodulin in the intestinal L cell, and it is concluded that this enzyme is thus able to act alone in this processing pathway.

Animals↗
PubMed2004

Development of protein-based inhibitors of the proprotein of convertase SKI-1/S1P: processing of SREBP-2, ATF6, and a viral glycoprotein.

Processing of membrane-bound transcription factors such as sterol regulatory element-binding proteins (SREBPs) and the ER-stress response factor ATF6, and glycoproteins of some hemorrhagic fever viruses are initiated by the proprotein convertase SKI-1/S1P. So far, no cellular protein-based inhibitor of the hydrophobic-amino acid specific SKI-1 is known. The prosegment of the basic-amino acid specific convertases (e.g. furin and PC5) or alpha(1)-PDX, a variant of alpha(1)-antitrypsin (alpha(1)-AT) exhibiting an RIPR(358) sequence at the reactive site loop, were shown to potently inhibit these secretory proteinases. Accordingly, we tested the SKI-1-inhibitory potential of various point mutants of either the 198 amino acid preprosegment of SKI-1-(1-198) or alpha(1)-AT. Transient transfections data showed that, out of numerous mutants studied, the R134E prosegment mutant or the alpha(1)-AT reactive site loop variants RRVL(358), RRYL(358) and RRIL(358) are the best specific cellular inhibitors of SKI-1. The observed inhibition of the processing of endogenous SREBP-2, exogenous ATF6 and a PDGF-A (RRLL(86)) variant were >55% and reach approximately 80% in stable transfectants. We also show that SKI-1 forms SDS-stable complexes with these alpha(1)-AT variants, but not with wild-type alpha(1)-AT or alpha(1)-PDX. Finally, these inhibitors were also shown to affect the processing and stability of the Crimean-Congo hemorrhagic fever virus glycoprotein.

Activating Transcription Factor 6↗