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Chu YH, Lin JD, Nath S, Schachtrup C. Id proteins: emerging roles in CNS disease and targets for modifying neural stemcell behavior. Cell Tissue Res 2021; 387:433-449. [PMID: 34302526 PMCID: PMC8975794 DOI: 10.1007/s00441-021-03490-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/18/2021] [Indexed: 12/14/2022]
Abstract
Neural stem/progenitor cells (NSPCs) are found in the adult brain and spinal cord, and endogenous or transplanted NSPCs contribute to repair processes and regulate immune responses in the CNS. However, the molecular mechanisms of NSPC survival and integration as well as their fate determination and functionality are still poorly understood. Inhibitor of DNA binding (Id) proteins are increasingly recognized as key determinants of NSPC fate specification. Id proteins act by antagonizing the DNA-binding activity of basic helix-loop-helix (bHLH) transcription factors, and the balance of Id and bHLH proteins determines cell fate decisions in numerous cell types and developmental stages. Id proteins are central in responses to environmental changes, as they occur in CNS injury and disease, and cellular responses in adult NSPCs implicate Id proteins as prime candidates for manipulating stemcell behavior. Here, we outline recent advances in understanding Id protein pleiotropic functions in CNS diseases and propose an integrated view of Id proteins and their promise as potential targets in modifying stemcell behavior to ameliorate CNS disease.
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Affiliation(s)
- Yu-Hsuan Chu
- Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Jia-di Lin
- Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Suvra Nath
- Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Christian Schachtrup
- Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
- Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany.
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2
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Mailig M, Liu F. The Application of Isoacyl Structural Motifs in Prodrug Design and Peptide Chemistry. Chembiochem 2019; 20:2017-2031. [DOI: 10.1002/cbic.201900260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Melrose Mailig
- Discovery ChemistryNovo Nordisk Research Center Seattle 530 Fairview Ave N Seattle WA 98109 USA
| | - Fa Liu
- Discovery ChemistryNovo Nordisk Research Center Seattle 530 Fairview Ave N Seattle WA 98109 USA
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3
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Grassi L, Roschger C, Stanojlović V, Cabrele C. An explorative study towards the chemical synthesis of the immunoglobulin G1 Fc CH3 domain. J Pept Sci 2018; 24:e3126. [PMID: 30346065 PMCID: PMC6646916 DOI: 10.1002/psc.3126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 08/26/2018] [Accepted: 09/06/2018] [Indexed: 12/16/2022]
Abstract
Monoclonal antibodies, fusion proteins including the immunoglobulin fragment c (Ig Fc) CH2‐CH3 domains, and engineered antibodies are prominent representatives of an important class of drugs and drug candidates, which are referred to as biotherapeutics or biopharmaceuticals. These recombinant proteins are highly heterogeneous due to their glycosylation pattern. In addition, enzyme‐independent reactions, like deamidation, dehydration, and oxidation of sensitive side chains, may contribute to their heterogeneity in a minor amount. To investigate the biological impact of a spontaneous chemical modification, especially if found to be recurrent in a biotherapeutic, it would be necessary to reproduce it in a homogeneous manner. Herein, we undertook an explorative study towards the chemical synthesis of the IgG1 Fc CH3 domain, which has been shown to undergo spontaneous changes like succinimide formation and methionine oxidation. We used Fmoc‐solid‐phase peptide synthesis (SPPS) and native chemical ligation (NCL) to test the accessibility of large fragments of the IgG1 Fc CH3 domain. In general, the incorporation of pseudoproline dipeptides improved the quality of the crude peptide precursors; however, sequences larger than 44 residues could not be achieved by standard stepwise elongation with Fmoc‐SPPS. In contrast, the application of NCL with cysteine residues, which were either native or introduced ad hoc, allowed the assembly of the C‐terminal IgG1 Fc CH3 sequence 371 to 450. The syntheses reported here show advantages and limitations of the chemical approaches chosen for the preparation of the synthetic IgG1 Fc CH3 domain and will guide future plans towards the synthesis of both the native and selectively modified full‐length domain.
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Affiliation(s)
- Luigi Grassi
- Christian Doppler Laboratory for Innovative Tools for Biosimilar Characterization, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria.,Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Cornelia Roschger
- Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Vesna Stanojlović
- Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Chiara Cabrele
- Christian Doppler Laboratory for Innovative Tools for Biosimilar Characterization, University of Salzburg, Hellbrunner Strasse 34, 5020, Salzburg, Austria.,Department of Biosciences, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
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4
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The Recombinant Inhibitor of DNA Binding Id2 Forms Multimeric Structures via the Helix-Loop-Helix Domain and the Nuclear Export Signal. Int J Mol Sci 2018; 19:ijms19041105. [PMID: 29642431 PMCID: PMC5979349 DOI: 10.3390/ijms19041105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 03/31/2018] [Accepted: 04/03/2018] [Indexed: 12/24/2022] Open
Abstract
The inhibitor of DNA binding and cell differentiation 2 (Id2) is a helix-loop-helix (HLH) protein that acts as negative dominant regulator of basic-HLH transcription factors during development and in cancer. The structural properties of Id2 have been investigated so far by using synthetic or recombinant fragments reproducing single domains (N-terminus, HLH, C-terminus): the HLH domain tends to dimerize into a four-helix bundle, whereas the flanking regions are flexible. In this work, the intact protein was expressed in E. coli, solubilized from inclusion bodies with urea, purified and dissolved in water at pH~4. Under these conditions, Id2 was obtained with both cysteine residues disulfide-bonded to β-mercaptoethanol that was present during the solubilization process. Moreover, it existed in a self-assembled state, in which the N-terminus remained highly flexible, while the HLH domain and, surprisingly, part of the C-terminus, which corresponds to the nuclear export signal (NES), both were involved in slowly tumbling, rigid structures. The protein oligomers also formed twisted fibrils that were several micrometers long and up to 80 nm thick. These results show that self-assembly decreases the backbone flexibility of those two protein regions (HLH and NES) that are important for interaction with basic-HLH transcription factors or for nucleocytoplasmic shuttling.
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5
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Neukirchen S, Krieger V, Roschger C, Schubert M, Elsässer B, Cabrele C. Impact of the amino acid sequence on the conformation of side chain lactam-bridged octapeptides. J Pept Sci 2017; 23:587-596. [PMID: 28370688 DOI: 10.1002/psc.2997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 01/22/2023]
Abstract
Synthetic helical peptides are valuable scaffolds for the development of modulators of protein-protein interactions involving helical motifs. Backbone-to-side chain or side chain-to-side chain constraints have been and still are intensively exploited to stabilize short α-helices. Very often, these constraints have been combined with backbone modifications induced by Cα-tetrasubstituted, β-, or γ-amino acids, which facilitate the α-peptide or α/β/γ-peptide adopting an α-helical conformation. In this work, we investigated the helical character of octapeptides that were cyclized by a Lys-Asp-(i,i + 4)-lactam bridge. We started with two sequences extracted from the helix-loop-helix region of the Id proteins, which are inhibitors of cell differentiation during development and in cancer. Nineteen analogs containing the lactam bridge at different positions and displaying different amino acid core triads (i + 1,2,3) as well as outer residues were prepared by solid-phase methodology. Their conformation in water and water/2,2,2-trifluoroethanol mixtures was investigated by circular dichroism (CD) spectroscopy. The cyclopeptides could be grouped in helix-prone and non-helix-prone structures. Both the amino acid core triad (i + 1,2,3) and the pendant residues positively or negatively affected the formation of a helical structure. Computational studies based on the NMR-derived helical structure of a cyclopeptide containing Aib at position (i + 2) of the triad were generally in agreement with the secondary structure propensity of the cyclopeptides observed by CD spectroscopy. In conclusion, the Lys-Asp-(i,i + 4)-lactam bridge may succeed or fail in the stabilization of short helices, depending on the primary structure. Moreover, computational methods may be valuable tools to discriminate helix-prone from non-helix-prone peptide-based macrolactams. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.
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Affiliation(s)
- Saskia Neukirchen
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria.,Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany
| | - Viktoria Krieger
- Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.,Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Cornelia Roschger
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Mario Schubert
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Brigitta Elsässer
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
| | - Chiara Cabrele
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020, Salzburg, Austria
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Abstract
Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.
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Affiliation(s)
- Cornelia Roschger
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria
| | - Chiara Cabrele
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria.
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Roschger C, Cabrele C. The Id-protein family in developmental and cancer-associated pathways. Cell Commun Signal 2017; 15:7. [PMID: 28122577 PMCID: PMC5267474 DOI: 10.1186/s12964-016-0161-y] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/29/2016] [Indexed: 01/15/2023] Open
Abstract
Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.
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Affiliation(s)
- Cornelia Roschger
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria
| | - Chiara Cabrele
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria.
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Beisswenger M, Cabrele C. Self-recognition behavior of a helix-loop-helix domain by a fragment scan. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1675-83. [PMID: 24981796 DOI: 10.1016/j.bbapap.2014.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 06/09/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
The inhibitors of DNA binding Id1-4 are helix-loop-helix (HLH) proteins that exert their biological function by interacting with members of the basic-HLH (bHLH) transcription-factor family. The HLH domains of the Id and bHLH proteins allow both self- and hetero-association. Due to their abnormal expression in cancer cells, the Id proteins are potential protein targets for cancer treatment. Suitable Id-protein inactivators should promote self-association and/or prevent hetero-association. In this work we evaluated the ability of the Id-protein HLH domain to recognize itself in form of short sequences extracted from the helical and loop regions. We performed a peptide scan of the Id1 HLH domain 64-106 based on three-residue overlapping octapeptides. Interaction of each octapeptide with the natively folded Id1 HLH domain was investigated by CD and fluorescence spectroscopy. The results from both techniques showed that the helix-based but not the loop-based octapeptides interacted with the Id1 HLH domain in the low-micromolar range. In contrast, a nitrotyrosine-containing analog of the Id1 HLH region, which was unable to reproduce the native-like conformation, quenched only the 2-amino-benzoyl-(Abz)-labeled loop-based octapeptides. This opposite self-recognition pattern suggests that the short helix-based and loop-based sequences should be able to distinguish different folding states of the Id1 HLH domain. This feature may be biologically relevant, as the Id proteins are predicted to behave as intrinsically disordered proteins, being in equilibrium between rapidly exchanging monomeric conformations and structurally better-defined homo-/heterodimers displaying the parallel four-helix bundle.
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Affiliation(s)
- Michael Beisswenger
- Faculty of Chemistry and Biochemistry, Ruhr-University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany
| | - Chiara Cabrele
- Faculty of Chemistry and Biochemistry, Ruhr-University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany; Department of Molecular Biology, Division of Chemistry and Bioanalytics, Paris-Lodron University Salzburg, Billrothstrasse 11, 5020 Salzburg, Austria.
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