1
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Li J, Canham SM, Wu H, Henault M, Chen L, Liu G, Chen Y, Yu G, Miller HR, Hornak V, Brittain SM, Michaud GA, Tutter A, Broom W, Digan ME, McWhirter SM, Sivick KE, Pham HT, Chen CH, Tria GS, McKenna JM, Schirle M, Mao X, Nicholson TB, Wang Y, Jenkins JL, Jain RK, Tallarico JA, Patel SJ, Zheng L, Ross NT, Cho CY, Zhang X, Bai XC, Feng Y. Activation of human STING by a molecular glue-like compound. Nat Chem Biol 2024; 20:365-372. [PMID: 37828400 PMCID: PMC10907298 DOI: 10.1038/s41589-023-01434-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 09/02/2023] [Indexed: 10/14/2023]
Abstract
Stimulator of interferon genes (STING) is a dimeric transmembrane adapter protein that plays a key role in the human innate immune response to infection and has been therapeutically exploited for its antitumor activity. The activation of STING requires its high-order oligomerization, which could be induced by binding of the endogenous ligand, cGAMP, to the cytosolic ligand-binding domain. Here we report the discovery through functional screens of a class of compounds, named NVS-STGs, that activate human STING. Our cryo-EM structures show that NVS-STG2 induces the high-order oligomerization of human STING by binding to a pocket between the transmembrane domains of the neighboring STING dimers, effectively acting as a molecular glue. Our functional assays showed that NVS-STG2 could elicit potent STING-mediated immune responses in cells and antitumor activities in animal models.
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Affiliation(s)
- Jie Li
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Stephen M Canham
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA.
| | - Hua Wu
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Martin Henault
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Lihao Chen
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Guoxun Liu
- Novartis Institutes for BioMedical Research, San Diego, CA, USA
| | - Yu Chen
- Novartis Institutes for BioMedical Research, San Diego, CA, USA
| | - Gary Yu
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Howard R Miller
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Viktor Hornak
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | | | - Antonin Tutter
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Wendy Broom
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | | | | | - Helen T Pham
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | - George S Tria
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | - Markus Schirle
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Xiaohong Mao
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | - Yuan Wang
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | - Rishi K Jain
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | | | - Sejal J Patel
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Lianxing Zheng
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Nathan T Ross
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Charles Y Cho
- Novartis Institutes for BioMedical Research, San Diego, CA, USA
| | - Xuewu Zhang
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Xiao-Chen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Yan Feng
- Novartis Institutes for BioMedical Research, Cambridge, MA, USA.
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2
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Mason JW, Chow YT, Hudson L, Tutter A, Michaud G, Westphal MV, Shu W, Ma X, Tan ZY, Coley CW, Clemons PA, Bonazzi S, Berst F, Briner K, Liu S, Zécri FJ, Schreiber SL. DNA-encoded library-enabled discovery of proximity-inducing small molecules. Nat Chem Biol 2024; 20:170-179. [PMID: 37919549 PMCID: PMC10917151 DOI: 10.1038/s41589-023-01458-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 09/24/2023] [Indexed: 11/04/2023]
Abstract
Small molecules that induce protein-protein associations represent powerful tools to modulate cell circuitry. We sought to develop a platform for the direct discovery of compounds able to induce association of any two preselected proteins, using the E3 ligase von Hippel-Lindau (VHL) and bromodomains as test systems. Leveraging the screening power of DNA-encoded libraries (DELs), we synthesized ~1 million DNA-encoded compounds that possess a VHL-targeting ligand, a variety of connectors and a diversity element generated by split-and-pool combinatorial chemistry. By screening our DEL against bromodomains in the presence and absence of VHL, we could identify VHL-bound molecules that simultaneously bind bromodomains. For highly barcode-enriched library members, ternary complex formation leading to bromodomain degradation was confirmed in cells. Furthermore, a ternary complex crystal structure was obtained for our most enriched library member with BRD4BD1 and a VHL complex. Our work provides a foundation for adapting DEL screening to the discovery of proximity-inducing small molecules.
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Affiliation(s)
- Jeremy W Mason
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Yuen Ting Chow
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Liam Hudson
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Antonin Tutter
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Gregory Michaud
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Matthias V Westphal
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Wei Shu
- Structural and Biophysical Chemistry, Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Xiaolei Ma
- Structural and Biophysical Chemistry, Novartis Institutes for BioMedical Research, Emeryville, CA, USA
| | - Zher Yin Tan
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Connor W Coley
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
| | - Paul A Clemons
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA
| | - Simone Bonazzi
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Frédéric Berst
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Novartis Campus, Basel, Switzerland
| | - Karin Briner
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Cambridge, MA, USA
| | - Shuang Liu
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
| | - Frédéric J Zécri
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Cambridge, MA, USA.
| | - Stuart L Schreiber
- Chemical Biology and Therapeutics Science, Broad Institute, Cambridge, MA, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
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3
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Liu S, Tong B, Mason JW, Ostrem JM, Tutter A, Hua BK, Tang SA, Bonazzi S, Briner K, Berst F, Zécri F, Schreiber SL. Rational Screening for Cooperativity in Small-Molecule Inducers of Protein-Protein Associations. J Am Chem Soc 2023; 145:23281-23291. [PMID: 37816014 PMCID: PMC10603787 DOI: 10.1021/jacs.3c08307] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Indexed: 10/12/2023]
Abstract
The hallmark of a molecular glue is its ability to induce cooperative protein-protein interactions, leading to the formation of a ternary complex, despite weaker binding toward one or both individual proteins. Notably, the extent of cooperativity distinguishes molecular glues from bifunctional compounds, which constitute a second class of inducers of protein-protein interactions. However, apart from serendipitous discovery, there have been limited rational screening strategies for the high cooperativity exhibited by molecular glues. Here, we propose a binding-based screen of DNA-barcoded compounds on a target protein in the presence or absence of a presenter protein, using the "presenter ratio", the ratio of ternary enrichment to binary enrichment, as a predictive measure of cooperativity. Through this approach, we identified a range of cooperative, noncooperative, and uncooperative compounds in a single DNA-encoded library screen with bromodomain containing protein (BRD)9 and the VHL-elongin C-elongin B (VCB) complex. Our most cooperative hit compound, 13-7, exhibits micromolar binding affinity to BRD9 but nanomolar affinity for the ternary complex with BRD9 and VCB, with cooperativity comparable to classical molecular glues. This approach may enable the rational discovery of molecular glues for preselected proteins and thus facilitate the transition to a new paradigm of small-molecule therapeutics.
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Affiliation(s)
- Shuang Liu
- Chemical
Biology and Therapeutics Science, Broad
Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Bingqi Tong
- Chemical
Biology and Therapeutics Science, Broad
Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Global
Discovery Chemistry, Novartis Institutes
for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jeremy W. Mason
- Chemical
Biology and Therapeutics Science, Broad
Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Global
Discovery Chemistry, Novartis Institutes
for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jonathan M. Ostrem
- Chemical
Biology and Therapeutics Science, Broad
Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
| | - Antonin Tutter
- Chemical
Biology and Therapeutics, Novartis Institutes
for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Bruce K. Hua
- Chemical
Biology and Therapeutics Science, Broad
Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Sunny A. Tang
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Simone Bonazzi
- Global
Discovery Chemistry, Novartis Institutes
for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Karin Briner
- Global
Discovery Chemistry, Novartis Institutes
for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Frédéric Berst
- Global
Discovery Chemistry, Novartis Institutes
for BioMedical Research, Novartis Campus, Basel, CH-4002, Switzerland
| | - Frédéric
J. Zécri
- Global
Discovery Chemistry, Novartis Institutes
for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Stuart L. Schreiber
- Chemical
Biology and Therapeutics Science, Broad
Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, United States
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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4
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Liu S, Tong B, Mason JW, Ostrem JM, Tutter A, Hua BK, Tang SA, Bonazzi S, Briner K, Berst F, Zécri FJ, Schreiber SL. Rational screening for cooperativity in small-molecule inducers of protein-protein associations. bioRxiv 2023:2023.05.22.541439. [PMID: 37292909 PMCID: PMC10245867 DOI: 10.1101/2023.05.22.541439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The hallmark of a molecular glue is its ability to induce cooperative protein-protein interactions, leading to the formation of a ternary complex, despite weaker binding towards one or both individual proteins. Notably, the extent of cooperativity distinguishes molecular glues from bifunctional compounds, a second class of inducers of protein-protein interactions. However, apart from serendipitous discovery, there have been limited rational screening strategies for the high cooperativity exhibited by molecular glues. Here, we propose a binding-based screen of DNA-barcoded compounds on a target protein in the presence and absence of a presenter protein, using the "presenter ratio", the ratio of ternary enrichment to binary enrichment, as a predictive measure of cooperativity. Through this approach, we identified a range of cooperative, noncooperative, and uncooperative compounds in a single DNA-encoded library screen with bromodomain (BRD)9 and the VHL-elongin C-elongin B (VCB) complex. Our most cooperative hit compound, 13-7 , exhibits micromolar binding affinity to BRD9 but nanomolar affinity for the ternary complex with BRD9 and VCB, with cooperativity comparable to classical molecular glues. This approach may enable the discovery of molecular glues for pre-selected proteins and thus facilitate the transition to a new paradigm of molecular therapeutics.
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5
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Rothman D, Gao X, George E, Rasmusson T, Bhatia D, Alimov I, Wang L, Kamel A, Hatsis P, Feng Y, Tutter A, Michaud G, McDonald E, Venkatesan K, Farley D, Digan M, Ni Y, Harbinski F, Gunduz M, Wilson C, Buckler A, Labow M, Tallarico J, Myer V, Porter J, Wang S. Metabolic Enzyme Sulfotransferase 1A1 Is the Trigger for N-Benzyl Indole Carbinol Tumor Growth Suppression. ACTA ACUST UNITED AC 2015; 22:1228-37. [DOI: 10.1016/j.chembiol.2015.06.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 06/17/2015] [Accepted: 06/17/2015] [Indexed: 12/30/2022]
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6
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Salcius M, Bauer AJ, Hao Q, Li S, Tutter A, Raphael J, Jahnke W, Rondeau JM, Bourgier E, Tallarico J, Michaud GA. SEC-TID: A Label-Free Method for Small-Molecule Target Identification. ACTA ACUST UNITED AC 2014; 19:917-27. [PMID: 24554445 DOI: 10.1177/1087057114522691] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 01/08/2014] [Indexed: 11/16/2022]
Abstract
Bioactive small molecules are an invaluable source of therapeutics and chemical probes for exploring biological pathways. Yet, significant hurdles in drug discovery often come from lacking a comprehensive view of the target(s) for both early tool molecules and even late-stage drugs. To address this challenge, a method is provided that allows for assessing the interactions of small molecules with thousands of targets without any need to modify the small molecule of interest or attach any component to a surface. We describe size-exclusion chromatography for target identification (SEC-TID), a method for accurately and reproducibly detecting ligand-macromolecular interactions for small molecules targeting nucleic acid and several protein classes. We report the use of SEC-TID, with a library consisting of approximately 1000 purified proteins derived from the protein databank (PDB), to identify the efficacy targets tankyrase 1 and 2 for the Wnt inhibitor XAV939. In addition, we report novel interactions for the tumor-vascular disrupting agent vadimezan/ASA404 (interacting with farnesyl pyrophosphate synthase) and the diuretic mefruside (interacting with carbonic anhydrase XIII). We believe this method can dramatically enhance our understanding of the mechanism of action and potential liabilities for small molecules in drug discovery pipelines through comprehensive profiling of candidate druggable targets.
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Affiliation(s)
- Michael Salcius
- Developmental and Molecular Pathways Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Andras J Bauer
- Developmental and Molecular Pathways Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Qin Hao
- Analytical Sciences, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Shu Li
- Analytical Sciences, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Antonin Tutter
- Developmental and Molecular Pathways Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Jacob Raphael
- Developmental and Molecular Pathways Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Wolfgang Jahnke
- Center for Proteomic Chemistry, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Jean-Michel Rondeau
- Center for Proteomic Chemistry, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - Emmanuelle Bourgier
- Center for Proteomic Chemistry, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - John Tallarico
- Developmental and Molecular Pathways Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
| | - Gregory A Michaud
- Developmental and Molecular Pathways Department, Novartis Institutes for Biomedical Research, Cambridge, MA, USA
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7
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Tutter A, McAlpine GS, Jones KA. Mechanism of chromatin recognition and transcriptional regulation by LEF-1 and the Wnt/Wg-responsive LEF-1:beta-catenin complex. Cold Spring Harb Symp Quant Biol 2001; 64:445-52. [PMID: 11232320 DOI: 10.1101/sqb.1999.64.445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- A Tutter
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037-1099, USA
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8
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Affiliation(s)
- A Tutter
- Regulatory Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037-1099, USA
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9
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Tutter A, Brodeur P, Shlomchik M, Riblet R. Structure, map position, and evolution of two newly diverged mouse Ig VH gene families. J Immunol 1991; 147:3215-23. [PMID: 1680926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have characterized two novel mouse VH gene families, VH3609N and VHSM7. These VH families have recently diverged from previously defined VH families. The VH3609N family, which may contain only one member in most inbred strains of mice, shares sequence similarity with the VHJ606 family and is located to the 3' side of VHJ606. VHSM7, with at least three members, is related to the VHJ558 family but maps 3' of VHJ558. These findings suggest that physical displacement of VH sequences may facilitate their subsequent divergence. During the early stages of VH gene family evolution that are exemplified by these new families, amino acid replacements have been selected against in frame-work regions and selected for in complementarity-determining regions. This pattern of nucleotide substitution appears to reflect evolutionary pressures to maintain germ-line VH diversity and, possibly, to select for new antibody specificities, as well as to select against mutations resulting in aberrant Ig. The classification of VH sequences with borderline similarity to previously defined VH families is discussed.
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Affiliation(s)
- A Tutter
- Medical Biology Institute, La Jolla, CA 92037
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10
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Tutter A, Brodeur P, Shlomchik M, Riblet R. Structure, map position, and evolution of two newly diverged mouse Ig VH gene families. The Journal of Immunology 1991. [DOI: 10.4049/jimmunol.147.9.3215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
We have characterized two novel mouse VH gene families, VH3609N and VHSM7. These VH families have recently diverged from previously defined VH families. The VH3609N family, which may contain only one member in most inbred strains of mice, shares sequence similarity with the VHJ606 family and is located to the 3' side of VHJ606. VHSM7, with at least three members, is related to the VHJ558 family but maps 3' of VHJ558. These findings suggest that physical displacement of VH sequences may facilitate their subsequent divergence. During the early stages of VH gene family evolution that are exemplified by these new families, amino acid replacements have been selected against in frame-work regions and selected for in complementarity-determining regions. This pattern of nucleotide substitution appears to reflect evolutionary pressures to maintain germ-line VH diversity and, possibly, to select for new antibody specificities, as well as to select against mutations resulting in aberrant Ig. The classification of VH sequences with borderline similarity to previously defined VH families is discussed.
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Affiliation(s)
- A Tutter
- Medical Biology Institute, La Jolla, CA 92037
| | - P Brodeur
- Medical Biology Institute, La Jolla, CA 92037
| | - M Shlomchik
- Medical Biology Institute, La Jolla, CA 92037
| | - R Riblet
- Medical Biology Institute, La Jolla, CA 92037
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11
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Abstract
The evolution of the mouse immunoglobulin heavy chain variable region (Igh-V) locus was investigated by the comprehensive analysis of variable region (Vh) gene family content and restriction fragment polymorphism in the genus Mus. The examination of natural Mus domesticus populations suggests an important role for recombination in the generation of the considerable restriction fragment polymorphism found at the Igh-V locus. Although the sizes of individual Vh gene families vary widely both within and between different Mus species, evolutionary trends of Vh gene family copy number are revealed by the analysis of homologues of mouse Vh gene families in Rattus and Peromyscus. Processes of duplication, deletion, and sequence divergence all contribute to the evolution of Vh gene copy number. Certain Vh gene families have expanded or contracted differently in the various muroid lineages examined. Collectively, these findings suggest that the evolution of individual Vh family size is not driven by strong selective pressure but is relatively neutral, and that gene flow, rather than selection, serves to maintain the high level of restriction fragment polymorphism seen in M. domesticus.
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Affiliation(s)
- A Tutter
- Medical Biology Institute, La Jolla, CA 92037
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12
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Abstract
Blot-hybridization and DNA sequence analyses reveal the particular evolutionary conservation of a group of immunoglobulin heavy-chain variable-region (VH) genes in all mammalian species examined. These particular genes are group III genes--the VH7183 family in the mouse and the homologous VH III family in human. This conservation is localized to sequences encoding framework regions 1 and 3 of the antibody variable region and is exerted at the nucleotide level. Because selection acting at the amino acid level alone cannot explain the conservation of these sequences, these sequences must have a noncoding function. The preferential rearrangement of VH7183 and VH III genes, together with the similarity of the conserved sequences to elements implicated in recombination in other systems, suggest that these sequences function to target the series of rearrangements that assemble complete immunoglobulin genes.
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Affiliation(s)
- A Tutter
- Medical Biology Institute, La Jolla, CA 92037
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13
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Abstract
The evolution of variable region (Vh) gene family copy number and polymorphism was investigated by the analysis of the immunoglobulin heavy chain variable region (Igh-V) locus in 74 inbred strains and substrains of mice. Several strains were found to have slight differences from Igh-V haplotypes previously identified, usually involving the gain or loss of one or a few members of a single Vh gene family. These results indicate that the evolution of copy number in the mouse Igh-V locus proceeds largely by the accumulation of incremental changes, reflecting the clustered organization of the mouse Igh-V locus. We have found no evidence of very large or frequent duplication or deletion events indicative of rapid expansion or contraction processes. The existence of one or more particularly large Vh gene families most likely reflects random copy number variation, rather than selection for the amplification of their members. The identification of strains with recombinant Vh gene arrays demonstrates that recombination, both within and between haplotypes, appears to be the predominant mechanism generating the high restriction fragment length polymorphism in the Igh-V locus.
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Affiliation(s)
- A Tutter
- Medical Biology Institute, La Jolla, CA 92037
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14
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