Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Proprotein Convertase 2”

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 73 records · Page 4Linked to original sources
PubMed1994

Expression of PC2 and PC1/PC3 in human pheochromocytomas.

Expressions of two Kex2-related proteases, Pc2 and PC1/PC3, and of one of their possible substrates, proenkephalin, were examined in normal (n = 7) and various pathological (n = 48) human adrenal tissues. Northern blot analysis detected the expression of these genes in pheochromocytomas only. In the 20 pheochromocytomas studied with this technique, PC2, PC1/PC3 and proenkephalin were expressed in 85%, 50% and 90%, respectively. The presence of PC2 and PC1/PC3 was further confirmed using the sensitive RT/PCR techniques. Other evidence of human tumoral adrenal medullary PC2 expression was provided by in situ hybridization and immunohistochemistry. In addition, proenkephalin was expressed only in the pheochromocytomas expressing PC2 and/or PC1/PC3. These results demonstrate that functional Kex2-related endoproteases are expressed in human pheochromocytomas and may be involved in the processing of proenkephalin.

Adrenal Gland Neoplasms↗
PubMed1996

Peptide biosynthetic processing: distinguishing prohormone convertases PC1 and PC2.

To determine whether manipulation of time, temperature and intragranular pH could be used to distinguish the actions of two subtilisin-related endoproteases, PC1 and PC2, in peptide biosynthesis, the biosynthetic processing of proneuropeptide Y (proNPY) and proopiomelanocortin (POMC) was examined in pituitary cell lines. AtT-20 cells express PC1 and POMC endogenously; stably transfected AtT-20 lines expressing NPY or PC2 were studied. GH3 cells express PC2 endogenously; NPY-expressing GH3 transfectants were investigated. PC1 mediated rapid processing of NPY and POMC; PC1-dependent cleavages were relatively insensitive to 20 degrees C blockade (which arrests secretory pathway transport at the trans-Golgi network) and do not require an acidic intracellular compartment (as in secretory granules). PC2 mediated much slower processing of proNPY and POMC which was totally blocked at 20 degrees C and required an acidic intracellular compartment. Thus, kinetics, abolition of intracellular pH gradients, and incubation at reduced temperatures can be used to distinguish PC1 and PC2 actions in neuroendocrine cells.

Animals↗
PubMed1992

Differential subcellular distribution of PC1, PC2 and furin in bovine adrenal medulla and secretion of PC1 and PC2 from this tissue.

The subcellular distribution of PC1, PC2 and furin was determined in bovine adrenal medulla by immunoblotting of fractions obtained by density gradient centrifugation. PC1 and PC2 were found to be confined to chromaffin granules whereas furin (C-terminal-peptide) was absent from these organelles. Stimulation of bovine adrenal medulla by carbamoylcholine chloride induced the secretion of PC1 and PC2. The secreted enzymes had the same molecular size as PC1 and PC2 present in chromaffin granules.

Adrenal Medulla↗
PubMed1993

Region specific expression of furin mRNA in the rat brain.

The distribution of furin mRNA was examined in the rat central nervous system. Northern blot analysis reveals the presence of a 4.4 kb band in all brain tissues examined. In situ hybridization analysis of frozen rat brain sections using a radioactively labeled antisense cRNA probe to rat furin demonstrated moderate to low levels of expression in both neuronal and non-neuronal tissue in all areas examined. Interestingly, higher levels of furin were expressed in selective regions which include the ventricles (the choroid plexus and ependymal cells), the islands of Calleja, the hippocampus and the pineal gland. the ubiquitous localization of furin in the brain is consistent with its postulated role as a vital convertase important in the processing of proproteins negotiating the constitutive pathway of secretion. However, the higher expression of furin mRNA in distinct brain areas suggests a more active role in the processing of proproteins synthesized in these tissues.

Animals↗
PubMed1993

Different degrees of processing of secretogranin II in large dense core vesicles of bovine adrenal medulla and sympathetic axons correlate with their content of soluble PC1 and PC2.

We investigated the processing of secretogranin II in large dense core vesicles of adrenal medulla and sympathetic nerve. Despite the fact that both types of vesicles have a very similar biochemical composition, the degree of processing of secretogranin II in vesicles from splenic nerve was significantly higher. The endoproteases PC1 and PC2, two likely candidates for secretogranin II cleavage, are found in both types of vesicles, however, relative to secretogranin II the nerve vesicles have a much higher content of these enzymes. This probably explains the fast and more extensive processing of secretogranin II in these vesicles.

Adrenal Medulla↗
PubMed2005

Inhibition of PC5 expression decreases CCK secretion and increases PC2 expression.

Cholecystokinin (CCK) is produced from pro CCK by a series of enzymatic cleavages. One of the enzymes thought to be important for pro CCK cleavage is prohormone convertase 5 (PC5). STC-1 cells, a mouse intestinal tumor cell line that expresses CCK, PC1, PC2, and PC5 were stably transfected with hairpin loop plasmids encoding siRNA targeting PC5 and clones were selected. CCK secretion was reduced significantly. PC5 mRNA and protein expression as measured by quantitative PCR and Western blot analysis was reduced about 50%. CCK and PC1 mRNA expression were not changed. These cells showed a three-fold increase in PC2 mRNA and protein expression. This increase may represent a compensatory mechanism triggered by the loss of PC5. The decrease in CCK in the media was due largely to loss of CCK 22. These results provide the first direct evidence that PC5 is involved in CCK processing.

Animals↗
PubMed1992

Kex2-like proteolytic activity in adrenal medullary chromaffin granules.

This study demonstrates the presence of boc-Gln-Arg-Arg-MCA cleaving activity in bovine chromaffin granule membranes that resembles yeast Kex2 proteolytic activity. The chromaffin granule boc-Gln-Arg-Arg-MCA cleaving activity, like Kex2 proteolytic activity, shows calcium dependence, optimum activity at pH 7.5-8.2, inhibition by serine protease inhibitors, and preference for cleavage at the COOH-terminal side of Arg-Arg and Lys-Arg, over Lys-Lys, paired basic residues. Potent inhibition by the active-site directed inhibitor [D-Tyr]-Glu-Phe-Lys-Arg-CK (20 microM) provided further evidence for dibasic residue cleavage site specificity. These results are the first report of endogenous mammalian Kex2-like proteolytic activity that may be related to PC1/PC3 and PC2 enzymes, the newly discovered mammalian homologues of Kex2 protease. It will be important to determine the role of this Kex2-like proteolytic activity in processing the precursors of adrenal medullary neuropeptides.

Adrenal Medulla↗
PubMed2001

Prepro-thyrotropin releasing hormone 178-199 immunoreactivity is altered in the hypothalamus of the Wistar-Kyoto strain of rat.

The rat prepro-thyrotropin releasing hormone (TRH) 178-199 is derived from prepro-TRH by the actions of the endopeptidases, prohormone convertase 1 (PC1) and PC2. PPTRH 178-199 attenuates the synthesis and secretion of adrenocorticotropic hormone (ACTH) from the anterior pituitary both in vitro and in vivo, suggesting an inhibitory action on hypothalamic-pituitary-adrenal (HPA) axis function. This peptide also acts centrally to increase activity and decrease anxiety related behaviors. To elucidate the involvement of this peptide in these functions, we have compared the expression of PPTRH 178-199, PPTRH mRNA, and PC1 and PC2 mRNAs in the Wistar-Kyoto (WKY) and Wistar strains of rat. WKY rats have been shown to possess neuroendocrine abnormalities (HPA hyper-activity) and hyper-emotional behavioral characteristics. Immunohistochemical analysis of PPTRH 178-199 demonstrated significant strain differences in the paraventricular nucleus (PVN) of the hypothalamus and the parastrial nucleus (PSN). WKY rats had significantly greater numbers of immunoreactive (IR) cell body profiles (P<0.0005) than Wistar rats in the PVN and a significantly lower fiber density (P<0.002) in the PSN. Levels of PPTRH, PC1, and PC2 mRNA were not different between strains in any brain region examined. These data suggest that altered levels of PPTRH 178-199 in WKY rats could cause, at least in part, the hyper-activity of the HPA axis and the hyper-emotional behavioral characteristics seen in this rat strain. Such data fit with the hypothesis that PPTRH 178-199 is involved in the regulation of the HPA axis and behavior.

Adrenocorticotropic Hormone↗
PubMed1997

Expression of the proprotein convertases PC1 and PC2 mRNAs in thyrotropin releasing hormone neurons of the rat paraventricular nucleus of hypothalamus.

PC1 and PC2 are subtilisin-like processing enzymes capable of cleaving thyrotropin releasing hormone (TRH) precursor (pro-TRH) at paired basic residues in vitro. In the paraventricular nucleus of the hypothalamus (PVN), pro-TRH is synthesized to control adenohypophysial thyrotropin and prolactin release. Biochemical and immunological approaches have shown that in the hypothalamus, pro-TRH is extensively cleaved at pairs of basic amino acids. We quantified, by two different approaches, in situ hybridization (ISH) on consecutive cryostat sections or double label ISH, the proportion of PVN TRH neurons containing either PC1 or PC2 mRNAs. Both techniques gave similar results: PC2 mRNA was present in 60-70% of TRH neurons, and PC1 mRNA in 37-46%. Values were similar in the anterior and medial parts of the parvocellular PVN. TRH neurons containing either PC1 or PC2 mRNA were found throughout the areas containing TRH cells without any evidence of anatomical segregation. These results suggest a biochemical heterogeneity in PVN TRH biosynthetic machinery.

Animals↗
PubMed2000

Evolution of the prohormone convertases: identification of a homologue of PC6 in the protochordate amphioxus.

Many of the protein precursors traversing the secretory pathway undergo cleavage at multibasic sites to generate their bioactive forms. The proprotein convertases (PCs), a family of subtilisin-like proteases, are the major endoproteases that serve this function. Genes encoding seven distinct members of this family have so far been characterized in vertebrates: furin, PC2, PC1/PC3, PC4, PACE4, PC5/PC6 and PC7/PC8/LPC. Multiple PC genes have also been cloned from a number of invertebrates, including Drosophila melanogaster and Caenorhabditis elegans. These findings suggest that gene duplication and diversification of the PCs have occurred throughout metazoan evolution. To investigate the structural and functional changes which have occurred during vertebrate development, we have analyzed the expression of PC genes in the protochordate amphioxus. We have previously shown that amphioxus express homologous PC2 and PC1/PC3 genes [Proc. Natl. Acad. Sci. USA 92 (1995) 3591]. Here we report the characterization of amphioxus cDNAs encoding proteases with a high degree of similarity to mammalian PC6. Three cDNAs encoding three PC6 isoforms differing only in their carboxy-terminal sequences were found, derived by alternative splicing. Two isoforms appear to be soluble enzymes, whereas the third contains a transmembrane hydrophobic segment and thus is likely to be membrane-bound. All three variants contain many repeats of a cysteine-rich motif that is found in several other PC family members. Thus, amphioxus, like the vertebrates, expresses two types of PCs, e.g., PC2 and PC1/PC3 which function in the regulated secretory pathway in neuroendocrine cells, and the more widely expressed PC6 which functions mainly in the constitutive pathway.

Alternative Splicing↗
PubMed2001

Neuronal cell lines expressing PC5, but not PC1 or PC2, process Pro-CCK into glycine-extended CCK 12 and 22.

Endocrine tumor cells in culture and in vitro cleavage assays have shown that PC1 and PC2 are capable of processing pro-CCK into smaller, intermediate and final, bioactive forms. Similar studies have shown that PC5 has the ability to process a number of propeptides. Here, we use GT1-7 (mouse hypothalamic) and SK-N-MC and SK-N-SH (human neuroblastoma) tumor cell lines to study the ability of PC5 to process pro-CCK. RT-PCR and Western blot analysis showed that the cells express PC5 mRNA and protein, but not PC1 or PC2. They were engineered to stably overexpress CCK and cell media was analyzed for pro-CCK expression and cleavage of the prohormone. Radioimmunoassays showed that pro-CCK was expressed, but no amidated CCK was detected. Lack of production of amidated CCK may be due to the lack of the appropriate carboxypeptidase and amidating enzymes. Production of glycine-extended CCK processing products was evaluated by treatment of media with carboxypeptidase B followed by analysis with a CCK Gly RIA. Glycine-extended forms of the peptide were found in the media. The predominant forms co-eluted with CCK 12 Gly and CCK 22 Gly on gel filtration chromatography. The results demonstrate that these cell lines which express PC5 and not PC1 or PC2 have the ability to process pro-CCK into intermediate, glycine-extended forms more closely resembling pro-CCK products in intestine than in brain.

Animals↗
PubMed1997

Immunohistochemical localization of the pro-peptide processing enzymes PC1/PC3 and PC2 in the human anal canal.

The distribution of prohormone/pro-peptide convertases PC1/PC3 and PC2 was investigated in the human anal canal by immunohistochemistry. Both prohormone convertases exhibited region-specific distribution patterns and were observed in neural and neuroendocrine cells and in nonneuroendocrine cellular elements. PC1/PC3 immunoreactivity was present in enteric neurons, subsets of nerve fibers, and neuroendocrine cells, and also in epithelial cells like intestinal stem cells, and a subpopulation of squamous cells. Enteric neurons were PC2 immunoreactive, whereas PC2 immunostaining in nerve fibers was slightly above background levels. Few neuroendocrine cells contained PC2 immunoreactivity, which were located predominantly in the anal transitional zone. In the squamous epithelium, the basal cell layer stained for PC2. The tissue-specific distribution of PC1/PC3 and PC2 indicates region-specific processing of peptides with regulatory functions in the anal canal and further supports the hypothesis that neuropeptides are important regulators of anal functions.

Anal Canal↗
PubMed1997

Endoproteolysis at tetrabasic amino acid sites in procalcitonin gene-related peptide by pituitary cell lines.

The specificity of neuroendocrine prohormone convertases for tetrabasic amino acid sites was investigated. Mutations were introduced into the tetrabasic cleavage site of the procalcitonin gene-related peptide (proCGRP) cDNA and these mutated cDNA's were expressed in AtT-20 cells which predominantly express the endoprotease prohormone convertase-1 (PC1/3), and in GH3 cells which predominantly express prohormone convertase-2 (PC2). Mutations were introduced into the proCGRP cDNA which converted the wild-type ArgArgArgArg site to LysLysArgArg and ArgArgLysLys, and the proCGRP variants were stably transfected into AtT-20 and GH3 cells. ProCGRP containing each of the LysLysArgArg permutations were efficiently cleaved in both AtT-20 and GH3 cells. Cleavage of LysLysArgArg in exogenous proCGRP, but not in endogenous POMC, suggests that the specificity of cleavage at tetrabasic sites is not defined solely by the endoproteases expressed by the cell or by the amino acid sequence at the cleavage site, but is also dependent on the structure of the propeptide.

Amino Acids↗
PubMed1997

Somatostatin-14, somatostatin-28, and prosomatostatin[1-10] are independently and efficiently processed from prosomatostatin in the constitutive secretory pathway in islet somatostatin tumor cells (1027B2).

We have characterized the biosynthetic origin of somatostatin-14 (SS-14), SS-28, and pro-SS[1-10] from pro-SS (PSS) in 1027B2 rat islet tumor cells. Because these cells lack regulated secretion and show unresponsiveness of the SS gene to cAMP, we have additionally carried out morphological and functional studies to elucidate the molecular defect in cAMP signalling and to localize the sites of PSS maturation along the secretory pathway. Cell extracts and secretion media were analysed by high performance liquid chromatography and specific C- and N-terminal radioimmunoassays. Electron microscopic sampling of 1027B2 cell cultures showed that most cells had very few dense core secretory granules for heterogeneous sizes. The cells expressed the endoproteases furin, PC1, and PC2 and contained large quantities of fully processed SS-14 and SS-28 with very little unprocessed PSS (ratio SS-14:SS-28:PSS = 39:51:10%). They secreted high concentrations of SS-14, SS-28, and PSS[1-10] constitutively along with PC1 and PC2. Pulse-chase studies demonstrated that PSS is rapidly (within 15 min), and efficiently processed to SS-14, SS-28, and PSS[1-10] via separate biosynthetic pathways: PSS --> SS-14 + 8 kDa; PSS --> SS-28 + 7 kDa; PSS --> PSS[1-10]. Monensin reduced intracellular SS-like immunoreactivity without altering processing efficiency. Transfection with the catalytic subunit of protein kinase A (PKA-C) activated SS promoter-CAT activating indicating that the defect in cAMP-dependent signaling in 1027B2 cells lies at the level of PKA-C. PKA-C overexpression failed to alter the ratio of processed SS-14 and SS-28. These results demonstrate that SS-14, SS-28, and PSS[1-10] are independently synthesized from PSS and that efficient precursor processing can occur within the constitutive secretory pathway in the relative absence of dense core secretory vesicles.

Adenoma, Islet Cell↗
PubMed2002

Differential regulation of gene expression of neurotensin and prohormone convertases PC1 and PC2 in the bovine ocular ciliary epithelium: possible implications on neurotensin processing.

Prohormone convertases PC1 and PC2 are enzymes involved in the intracellular processing of pro-neurotensin/neuromedin N (pro-NT/NN) through the regulated secretory pathway. In this study, we present evidence of the differential gene expression of pro-NT/NN, pro-PC1 and pro-PC2 in two cell lines established from the neuroendocrine ocular ciliary epithelium. Dexamethasone and forskolin were found to synergistically up-regulate NT/NN mRNA expression in both cell types. The pigmented cells released NT, and this release was enhanced by agents that induced its biosynthesis. In contrast, nonpigmented cells exhibited a significantly reduced neurotensin secretion in response to inducers, leading to an accumulation of the peptide. PC1 and PC2 mRNA expression was induced in a cell-specific manner by the same agents that enhanced pro-NT/NN biosynthesis. These results demonstrate cell-specific processing of pro-NT/NN by the ciliary epithelium.

Animals↗
PubMed1997

Role of prohormone convertases in pro-neuropeptide Y processing: coexpression and in vitro kinetic investigations.

Proneuropeptide Y (ProNPY) undergoes cleavage at a single dibasic site Lys38-Arg39 resulting in the formation of 1-39 amino acid NPY which is further processed successively by carboxypeptidase-like and peptidylglycine alpha-amidating monooxygenase enzymes. To investigate whether prohormone convertases are involved in ProNPY processing, a vaccinia virus derived expression system was used to coexpress recombinant ProNPY with each of the prohormone convertases PC1/3, PC2, furin, and PACE4 in Neuro2A and NIH 3T3 cell lines as regulated neuroendocrine and constitutive prototype cell lines, respectively. The analysis of processed products shows that only PC1/3 generates NPY in NIH 3T3 cells while both PC1/3 and PC2 are able to generate NPY in Neuro2A cells. The convertases furin and PACE4 are unable to process ProNPY in either cell line. Moreover, comparative in vitro cleavage of recombinant NPY precursor by the enzymes PC1/3, PC2 and furin shows that only PC1/3 and PC2 are involved in specific cleavage of the dibasic site. Kinetic studies demonstrate that PC1/3 cleaves ProNPY more efficiently than PC2. The main difference between the cleavage efficiency is observed in the Vmax values whereas no major difference is observed in Km values. In addition the cleavage by PC1/3 and PC2 of two peptides reproducing the dibasic cleavage site with different amino acid sequence lengths namely (20-49)-ProNPY and (28-43)-ProNPY was studied. These shortened ProNPY substrates, when recognized by the enzymes, are more efficiently cleaved than ProNPY itself. The shortest peptide is not cleaved by PC2 while it is by PC1/3. On the basis of these observations it is proposed, first, that the constitutive secreted NPY does not result from the cleavage carried out by ubiquitously expressed enzymes furin and PACE4; second, that PC1/3 and PC2 are not equipotent in the cleavage of ProNPY; and third, substrate peptide length might discriminate PC1/3 and PC2 processing activity.

3T3 Cells↗