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The Path to Therapeutic Furin Inhibitors: From Yeast Pheromones to SARS-CoV-2. Int J Mol Sci 2022; 23:ijms23073435. [PMID: 35408793 PMCID: PMC8999023 DOI: 10.3390/ijms23073435] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 02/06/2023] Open
Abstract
The spurious acquisition and optimization of a furin cleavage site in the SARS-CoV-2 spike protein is associated with increased viral transmission and disease, and has generated intense interest in the development and application of therapeutic furin inhibitors to thwart the COVID-19 pandemic. This review summarizes the seminal studies that informed current efforts to inhibit furin. These include the convergent efforts of endocrinologists, virologists, and yeast geneticists that, together, culminated in the discovery of furin. We describe the pioneering biochemical studies which led to the first furin inhibitors that were able to block the disease pathways which are broadly critical for pathogen virulence, tumor invasiveness, and atherosclerosis. We then summarize how these studies subsequently informed current strategies leading to the development of small-molecule furin inhibitors as potential therapies to combat SARS-CoV-2 and other diseases that rely on furin for their pathogenicity and progression.
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König S, Luger TA, Scholzen TE. Monitoring neuropeptide-specific proteases: processing of the proopiomelanocortin peptides adrenocorticotropin and alpha-melanocyte-stimulating hormone in the skin. Exp Dermatol 2006; 15:751-61. [PMID: 16984256 DOI: 10.1111/j.1600-0625.2006.00472.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The neuroendocrine precursor protein proopiomelanocortin (POMC) and its derived neuropeptides are involved in a number of important regulatory processes in the central nervous system as well as in peripheral tissues. Despite its important role in controlling the local activation of melanocortin (MC) receptors, the extracellular proteolytic processing of POMC peptides has received little attention. The mechanisms relevant for controlling the bioavailability of adrenocorticotropin and melanocyte-stimulating hormones for the corresponding MC receptors in the skin by specific peptidases such as neprilysin (neutral endopeptidase; NEP) or angiotensin-converting enzyme (ACE) have been addressed in a number of recent investigations. This review summarizes the current body of knowledge concerning the qualitative and quantitative POMC peptide processing with respect to the action and specificity of NEP and ACE and discusses relevant recent analytical methodologies.
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Affiliation(s)
- Simone König
- Integrated Functional Genomics, Interdisciplinary Center for Clinical Research, University of Münster, Von-Esmarch-Strasse 58, 48149 Münster, Germany
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Zhu H, Liu K, Cerny J, Imoto T, Moudgil KD. Insertion of the dibasic motif in the flanking region of a cryptic self-determinant leads to activation of the epitope-specific T cells. THE JOURNAL OF IMMUNOLOGY 2005; 175:2252-60. [PMID: 16081793 DOI: 10.4049/jimmunol.175.4.2252] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Efficient induction of self tolerance is critical for avoiding autoimmunity. The T cells specific for the well-processed and -presented (dominant) determinants of a native self protein are generally tolerized in the thymus, whereas those potentially directed against the inefficiently processed and presented (cryptic) self epitopes escape tolerance induction. We examined whether the crypticity of certain determinants of mouse lysozyme-M (ML-M) could be attributed to the nonavailability of a proteolytic site, and whether it could be reversed to immunodominance by engraftment of a novel cleavage site in the flanking region of the epitope. Using site-directed mutagenesis, we created the dibasic motif (RR or RK; R = arginine, K = lysine), a target of intracellular proteases, in the region adjoining one of the three cryptic epitopes (46-61, 66-79, or 105-119) of ML-M. Interestingly, the mutated lysozyme proteins, but not unmutated ML-M, were immunogenic in mice. The T cell response to the altered lysozyme was attributable to the efficient processing and presentation of the previously cryptic epitope, and this response was both epitope and MHC haplotype specific. In addition, the anti-self T cell response was associated with the generation of autoantibodies against self lysozyme. However, the results using one of three mutated lysozymes suggested that the naturally processed, dibasic motif-marked epitope may not always correspond precisely to the cryptic determinant within a synthetic peptide. This is the first report describing the circumvention of self tolerance owing to the targeted reversal of crypticity to dominance in vivo of a specific epitope within a native self Ag.
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Affiliation(s)
- Hui Zhu
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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[4] Use of vaccinia virus vectors to study neuropeptide processing. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s1043-9471(06)80115-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Zhou A, Mains R. Endoproteolytic processing of proopiomelanocortin and prohormone convertases 1 and 2 in neuroendocrine cells overexpressing prohormone convertases 1 or 2. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32459-6] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Brakch N, Rholam M, Boussetta H, Cohen P. Role of beta-turn in proteolytic processing of peptide hormone precursors at dibasic sites. Biochemistry 1993; 32:4925-30. [PMID: 8490028 DOI: 10.1021/bi00069a029] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Proteolytic activation of prohormones and proproteins occurs most frequently at the level of basic amino acids arranged in doublets. Previous predictions by Rholam et al. [Rholam, M., Nicolas, P., & Cohen, P. (1986) FEBS Lett. 207. 1-6] have indicated, on the basis of 20 prohormone sequences containing 53 dibasic potential processing sites, that dibasic sites situated in, or next to, beta-turns were cleaved in vivo, whereas sites included in ordered structures like beta-sheets or alpha-helices were not. We have used peptide analogs of the proocytocin/neurophysin processing domain and a purified preparation of the putative proocytocin convertase from bovine tissues as a model to demonstrate that (1) processing at dibasic sites is associated with a prohormone sequence organized in a beta-turn structure; (2) the beta-turn is an interchangeable motif since the original sequence could be replaced by an heterologous one possessing the ability to organize as a beta-turn; and (3) this particular secondary structure participates in the catalytic reaction, most likely by favoring the interactions of the substrate with the processing endoprotease. It is concluded that, in addition to the dibasic and other amino acids around the cleavage loci, the beta-turn constitutes a key feature in the proteolytic processing reaction in participating as the favorable conformation for optimal substrate-enzyme active site recognition.
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Affiliation(s)
- N Brakch
- Université Pierre et Marie Curie, Unité de Recherches Associée au CNRS 1682, Paris, France
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Day NC, Lin H, Ueda Y, Meador-Woodruff JH, Akil H. Characterization of pro-opiomelanocortin processing in heterologous neuronal cells that express PC2 mRNA. Neuropeptides 1993; 24:253-62. [PMID: 8327069 DOI: 10.1016/0143-4179(93)90013-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have investigated processing of monkey pro-opiomelanocortin (POMC) following transfection into heterologous neuronal Neuro 2A (N2A) cells. In several separately transfected stable cell lines (termed N2A/POMC2-like; n = 4), POMC was processed to beta E only, by direct cleavage from the precursor. Thus, these cell lines did not produce beta E in the orderly manner observed in the pituitary, that is, via the intermediate peptide beta LPH. Analysis of one representative N2A/POMC2 cell line revealed that the extent of processing to beta E appeared to be negatively correlated with precursor expression level, suggesting that the processing enzyme(s) in these cells was present in limiting amounts. Northern analysis of PC1 and PC2, two recently cloned processing enzymes, showed that N2A/POMC2 cells expressed low levels of PC2 mRNA, but no detectable PC1 mRNA. These data suggest that (1) the order of processing observed in the pituitary is not exclusively determined by tertiary folding of the precursor, but rather by the complement of processing enzymes in a particular cell, and (2) if PC2 is responsible for POMC processing in N2A/POMC2 cells, this enzyme, expressed in limiting amounts, appeared to show selectivity for the beta E amino terminal processing site.
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Affiliation(s)
- N C Day
- Mental Health Research Institute, University of Michigan, Ann Arbor 48109-0720
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Rhodes C, Thorne B, Lincoln B, Nielsen E, Hutton J, Thomas G. Processing of proopiomelanocortin by insulin secretory granule proinsulin processing endopeptidases. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)53605-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Leduc R, Molloy S, Thorne B, Thomas G. Activation of human furin precursor processing endoprotease occurs by an intramolecular autoproteolytic cleavage. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49712-3] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Halban PA. Structural domains and molecular lifestyles of insulin and its precursors in the pancreatic beta cell. Diabetologia 1991; 34:767-78. [PMID: 1769434 DOI: 10.1007/bf00408349] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Insulin is both produced and degraded within the pancreatic Beta cell. Production involves the synthesis of the initial insulin precursor preproinsulin, which is converted to proinsulin shortly after (or during) translocation into the lumen of the rough endoplasmic reticulum. Proinsulin is then transported to the trans-cisternae of the Golgi complex where it is directed towards nascent secretory granules. Conversion of proinsulin to insulin and C-peptide arises within secretory granules, and is dependent upon their acidification. Granule contents are discharged by exocytosis in response to an appropriate stimulus. This represents the regulated secretory pathway to which more than 99% of proinsulin is directed in Beta cells of a healthy individual. An alternative route also exists in the Beta cell, the constitutive secretory pathway. It involves the rapid transfer of products from the Golgi complex to the plasma membrane for immediate release, with, it is supposed, little occasion for prohormone conversion. Even if delivered appropriately to secretory granules, not all insulin is released; some is degraded by fusion of granules with lysosomes (crinophagy). Each event in the molecular lifestyles of insulin and its precursors in the Beta cell will be seen to be governed by their own discrete functional domains. The identification and characterisation of these protein domains will help elucidate the steps responsible for delivery of proinsulin to secretory granules and conversion to insulin. Understanding the molecular mechanism of these steps may, in turn, help to explain defective insulin production in certain disease states including diabetes mellitus.
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Affiliation(s)
- P A Halban
- Laboratoires de Recherche Louis Jeantet, University of Geneva Medical Centre, Switzerland
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Affiliation(s)
- J C Hutton
- Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK
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Takeuchi T, Dickinson C, Taylor I, Yamada T. Expression of human pancreatic polypeptide in heterologous cell lines. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)47388-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Resnick NM, Maloy WL, Guy HR, Zasloff M. A novel endopeptidase from Xenopus that recognizes alpha-helical secondary structure. Cell 1991; 66:541-54. [PMID: 1868549 DOI: 10.1016/0092-8674(81)90017-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The magainin peptides of Xenopus laevis are broad-spectrum antimicrobial agents. Upon discharge from the skin glands, these basic, amphipathic peptides are each further processed at a single Xaa-Lys bond into half-peptides by a cosecreted protease. We describe the characterization and purification to homogeneity of this endopeptidase from Xenopus skin. The enzyme is a metalloprotease 110 kd in size. Analyses of substrate specificity revealed that the endopeptidase recognizes peptides that share the ability to adopt an amphipathic, alpha-helical motif composed of at least 12 residues, with one face strongly hydrophobic. Cleavage occurs on the amino side of a specific lysine that must be precisely positioned relative to the hydrophobic face of the alpha helix. This enzyme, which we propose to call "magaininase," represents a novel class of endopeptidases that hydrolyzes peptides on the basis of specific secondary structure rather than primary amino acid sequence.
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Affiliation(s)
- N M Resnick
- Division of Human Genetics Children's Hospital of Philadelphia, Pennsylvania
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Seethaler G, Huttner W. Secretory protein sorting, processing and granule biogenesis. Trends Cell Biol 1991; 1:35-6. [PMID: 14731808 DOI: 10.1016/0962-8924(91)90068-k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- G Seethaler
- Molecular Biology Institute, Austrian Academy of Sciences, Salzburg, Austria
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Heterologous expression of preprosomatostatin. Intracellular degradation of prosomatostatin-II. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92919-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Nagahama M, Nakayama K, Murakami K. Sequence requirements for prohormone processing in mouse pituitary AtT-20 cells. Analysis using prorenins as model substrates. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 197:135-40. [PMID: 2015816 DOI: 10.1111/j.1432-1033.1991.tb15891.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Although cleavage of peptides at sites marked by paired basic amino acids is a common feature of prohormone processing, little is known about the properties of endoprotease(s) responsible for cleavage of the precursor. To examine the cleavage specificity of a processing endoprotease, we have altered the Lys-Arg cleavage site of human prorenin to Arg-Arg, Lys-Lys and Arg-Lys by site-directed mutagenesis, and expressed the native and mutated precursors in mouse pituitary AtT-20 cells which are known to process foreign prohormones, including prorenin, at paired basic sites during the regulated secretory process. All native and mutated human prorenins were sorted into the regulated secretory pathway. The mutated precursor with Arg-Arg instead of the Lys-Arg native pair was processed at about half the efficiency of the native one, while the Lys-Lys and Arg-Lys mutants were not processed. Rat prorenin, which naturally has a Lys-Lys pair, was not processed in the cells. In addition, mouse Ren2 prorenin, which has a Ser residue next to the Lys-Arg pair, but not mouse Ren1 prorenin, which has a Pro residue next to the pair, was processed. These results suggest that the Arg residue at the COOH side of the basic pair is essential for cleavage of prorenins by a processing enzyme during the regulated secretory process in AtT-20 cells, although the NH2-side Lys residue also plays a role. The results also demonstrate that the processing enzyme cannot cleave the Arg-Pro peptide bond.
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Affiliation(s)
- M Nagahama
- Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan
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Hutton JC. Subtilisin-like proteinases involved in the activation of proproteins of the eukaryotic secretory pathway. Curr Opin Cell Biol 1990; 2:1131-42. [PMID: 2099807 DOI: 10.1016/0955-0674(90)90167-d] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- J C Hutton
- Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK
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