Charles E Whitehurst | Boehringer Ingelheim (original) (raw)
Papers by Charles E Whitehurst
Molecular and Cellular Biology, Aug 15, 2004
To investigate the role of promoters in regulating variable gene rearrangement and allelic exclus... more To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V13 promoter was either deleted (P13 ؊/؊ ) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13 R/R ). In P13 ؊/؊ mice, cleavage, rearrangement, and transcription of V13, but not the flanking V gene segments, were significantly inhibited. In P13 R/R mice, inhibition of V13 rearrangement was less severe and was not associated with any apparent reduction in V13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V13-recombination signal sequence junction and V13 coding joint formation of both wild-type and mutant V13 alleles. However, a low level of aberrant V13 cleavage was consistently detected, especially in TCR transgenic P13 R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V cleavages during allelic exclusion.
Mol Cell Biol, 2004
To investigate the role of promoters in regulating variable gene rearrangement and allelic exclus... more To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V13 promoter was either deleted (P13 ؊/؊ ) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13 R/R ). In P13 ؊/؊ mice, cleavage, rearrangement, and transcription of V13, but not the flanking V gene segments, were significantly inhibited. In P13 R/R mice, inhibition of V13 rearrangement was less severe and was not associated with any apparent reduction in V13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V13-recombination signal sequence junction and V13 coding joint formation of both wild-type and mutant V13 alleles. However, a low level of aberrant V13 cleavage was consistently detected, especially in TCR transgenic P13 R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V cleavages during allelic exclusion.
Proceedings of the National Academy of Sciences, 2003
The precise function of cis elements in regulating V(D)J recombination is still controversial. He... more The precise function of cis elements in regulating V(D)J recombination is still controversial. Here, we determined the effect of inactivation of the TCRbeta enhancer (Ebeta) on cleavage and rearrangement of Dbeta1, Dbeta2, Jbeta1, and Jbeta2 gene segments in CD4-CD8- [double-negative (DN)] and CD4+CD8+ [double-positive (DP)] thymocytes. In Ebeta-deficient mice, (i) Dbeta1 rearrangements were more severely impaired than Dbeta2 rearrangements; (ii) most of the Dbeta and Jbeta cleavages and rearrangements occurred in DP, rather than in DN, thymocytes; and (iii) most of the 3' Dbeta1 cleavages were coupled to 5' Dbeta2 cleavages instead of to Jbeta cleavages, resulting in nonstandard Dbeta1-Dbeta2-Jbeta2 joints. These findings suggest that the Ebeta regulates TCRbeta rearrangement by promoting accessibility of Dbeta and Jbeta gene segments in DN thymocytes and proper pairing between Dbeta1 and Jbeta gene segments for cleavage and joining in DP thymocytes.
Molecular and Cellular Biology, 2004
To investigate the role of promoters in regulating variable gene rearrangement and allelic exclus... more To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V13 promoter was either deleted (P13 ؊/؊ ) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13 R/R ). In P13 ؊/؊ mice, cleavage, rearrangement, and transcription of V13, but not the flanking V gene segments, were significantly inhibited. In P13 R/R mice, inhibition of V13 rearrangement was less severe and was not associated with any apparent reduction in V13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V13-recombination signal sequence junction and V13 coding joint formation of both wild-type and mutant V13 alleles. However, a low level of aberrant V13 cleavage was consistently detected, especially in TCR transgenic P13 R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V cleavages during allelic exclusion.
The Journal of Immunology, 2002
Journal of Clinical Investigation, 1992
Address reprint requests to Dr. Lipsky,
Journal of Biomolecular Screening, 2005
Screening assays using target-based affinity selection coupled with high-sensitivity detection te... more Screening assays using target-based affinity selection coupled with high-sensitivity detection technologies to identify smallmolecule hits from chemical libraries can provide a useful discovery approach that complements traditional assay systems. Affinity selection-mass spectrometry (AS-MS) is one such methodology that holds promise for providing selective and sensitive high-throughput screening platforms. Although AS-MS screening platforms have been used to discover smallmolecule ligands of proteins from many target families, they have not yet been used routinely to screen integral membrane proteins. The authors present a proof-of-concept study using size exclusion chromatography coupled to AS-MS to perform a primary screen for small-molecule ligands of the purified muscarinic M 2 acetylcholine receptor, a G-protein-coupled receptor. AS-MS is used to characterize the binding mechanisms of 2 newly discovered ligands. NGD-3350 is a novel M 2 -specific orthosteric antagonist of M 2 function. NGD-3366 is an allosteric ligand with binding properties similar to the allosteric antagonist W-84, which decreases the dissociation rate of N-methyl-scopolamine from the M 2 receptor. Binding properties of the ligands discerned from AS-MS assays agree with those from in vitro biochemical assays. The authors conclude that when used with appropriate small-molecule libraries, AS-MS may provide a useful high-throughput assay system for the discovery and characterization of all classes of integral membrane protein ligands, including allosteric modulators. (Journal of Biomolecular
Current Opinion in Chemical Biology, 2007
Affinity selection-mass spectrometry (AS-MS) techniques assess the binding of candidate molecules... more Affinity selection-mass spectrometry (AS-MS) techniques assess the binding of candidate molecules to immobilized or soluble receptors, and these methods are gaining acceptance in high throughput screening laboratories as valuable complements to traditional drug discovery technologies. A diversity of receptor types have been evaluated by AS-MS, including those that are difficult to screen using traditional biochemical approaches. AS-MS techniques that couple liquid chromatography-MS with size-based separation methods, such as ultrafiltration, gel permeation, or size-exclusion chromatography, are particularly amenable to the demands of MS-based screening and have demonstrated the greatest success across a broad range of drug targets. MS measurements of receptor function have many of the same advantages as AS-MS screening and are increasingly used for drug discovery as well.
Combinatorial Chemistry & High Throughput Screening, 2012
Affinity selection-mass spectrometry (AS-MS) is a sensitive technology for identifying small mole... more Affinity selection-mass spectrometry (AS-MS) is a sensitive technology for identifying small molecules that bind to target proteins, and assays enabled by AS-MS can be used to delineate relative binding affinities of ligands for proteins. 'Indirect' AS-MS assays employ size-exclusion techniques to separate target-ligand complexes from unbound ligands, and target-associated ligands are then specifically detected by liquid chromatography mass spectrometry. We report how indirect AS-MS binding assays with known reference control compounds were used as guideposts for development of an optimized purification method for CXCR4, a G-protein coupled chemokine receptor, for which we sought novel antagonists. The CXCR4 purification method that was developed was amenable to scale-up and enabled the screening of purified recombinant human CXCR4 against a large combinatorial library of small molecules by high throughput indirect AS-MS. The screen resulted in the discovery of new ligands that competed off binding of reference compounds to CXCR4 in AS-MS binding assays and that antagonized SDF1α-triggered responses and CXCR4-mediated HIV1 viral uptake in cell-based assays. This report provides a methodological paradigm whereby indirect AS-MS-based ligand binding assays may be used to guide optimal integral membrane protein purification methods that enable downstream affinity selection-based applications such as high throughput AS-MS screens.
Bioorganic & Medicinal Chemistry Letters, 2013
Conformation restriction of linear N-alkylanilide MK2 inhibitors to their E-conformer was develop... more Conformation restriction of linear N-alkylanilide MK2 inhibitors to their E-conformer was developed. This strategy enabled rapid advance in identifying a series of potent non-ATP competitive inhibitors that exhibited cell based activity in anti-TNFα assay.
Bioorganic & Medicinal Chemistry, 2012
The STAT6 (signal transducer and activator of transcription 6) protein facilitates T-helper cell ... more The STAT6 (signal transducer and activator of transcription 6) protein facilitates T-helper cell 2 (Th2) mediated responses that control IgE-mediated atopic diseases such as asthma. We have identified compounds that bind to STAT6 and inhibit STAT6 tyrosine phosphorylation induced by IL-4. In the bronchial epithelial cell line BEAS-2B, compound (R)-84 inhibits the secretion of eotaxin-3, a chemokine eliciting eosinophil infiltration. (R)-84 appears to prevent STAT6 from assuming the active dimer configuration by directly binding the protein and inhibiting tyrosine phosphorylation.
ACS Medicinal Chemistry Letters, 2011
A novel series of non-ATP-competitive MK2 inhibitors based on a furan-2-carboxyamide scaffold was... more A novel series of non-ATP-competitive MK2 inhibitors based on a furan-2-carboxyamide scaffold was discovered through high-throughput screening using the affinity selection-mass spectrometry-based Automated Ligand Identification System platform. Medicinal chemistry efforts optimized the initial screening hit to leadlike compounds with significant improvements in biochemical and cellular potencies, while maintaining excellent kinase selectivity and in vitro pharmacokinetic properties. Biophysical and biochemical studies confirmed the unique non-ATP-competitive binding mode of this series and suggested that highly selective inhibitors of MK2 should be feasible by targeting the outside ATP pocket.
Bioorganic & Medicinal Chemistry Letters, 2013
Chemistry has been developed to access both imidazo[1,2-a]pyrazines and imidazo[1,2-c]pyrimidines... more Chemistry has been developed to access both imidazo[1,2-a]pyrazines and imidazo[1,2-c]pyrimidines. Small structural modifications in both series led to a switch of potency between two kinases involved in mediating cell cycle checkpoint control, CHK1 and MK2.
Molecular and Cellular Biology, Aug 15, 2004
To investigate the role of promoters in regulating variable gene rearrangement and allelic exclus... more To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V13 promoter was either deleted (P13 ؊/؊ ) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13 R/R ). In P13 ؊/؊ mice, cleavage, rearrangement, and transcription of V13, but not the flanking V gene segments, were significantly inhibited. In P13 R/R mice, inhibition of V13 rearrangement was less severe and was not associated with any apparent reduction in V13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V13-recombination signal sequence junction and V13 coding joint formation of both wild-type and mutant V13 alleles. However, a low level of aberrant V13 cleavage was consistently detected, especially in TCR transgenic P13 R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V cleavages during allelic exclusion.
Mol Cell Biol, 2004
To investigate the role of promoters in regulating variable gene rearrangement and allelic exclus... more To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V13 promoter was either deleted (P13 ؊/؊ ) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13 R/R ). In P13 ؊/؊ mice, cleavage, rearrangement, and transcription of V13, but not the flanking V gene segments, were significantly inhibited. In P13 R/R mice, inhibition of V13 rearrangement was less severe and was not associated with any apparent reduction in V13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V13-recombination signal sequence junction and V13 coding joint formation of both wild-type and mutant V13 alleles. However, a low level of aberrant V13 cleavage was consistently detected, especially in TCR transgenic P13 R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V cleavages during allelic exclusion.
Proceedings of the National Academy of Sciences, 2003
The precise function of cis elements in regulating V(D)J recombination is still controversial. He... more The precise function of cis elements in regulating V(D)J recombination is still controversial. Here, we determined the effect of inactivation of the TCRbeta enhancer (Ebeta) on cleavage and rearrangement of Dbeta1, Dbeta2, Jbeta1, and Jbeta2 gene segments in CD4-CD8- [double-negative (DN)] and CD4+CD8+ [double-positive (DP)] thymocytes. In Ebeta-deficient mice, (i) Dbeta1 rearrangements were more severely impaired than Dbeta2 rearrangements; (ii) most of the Dbeta and Jbeta cleavages and rearrangements occurred in DP, rather than in DN, thymocytes; and (iii) most of the 3' Dbeta1 cleavages were coupled to 5' Dbeta2 cleavages instead of to Jbeta cleavages, resulting in nonstandard Dbeta1-Dbeta2-Jbeta2 joints. These findings suggest that the Ebeta regulates TCRbeta rearrangement by promoting accessibility of Dbeta and Jbeta gene segments in DN thymocytes and proper pairing between Dbeta1 and Jbeta gene segments for cleavage and joining in DP thymocytes.
Molecular and Cellular Biology, 2004
To investigate the role of promoters in regulating variable gene rearrangement and allelic exclus... more To investigate the role of promoters in regulating variable gene rearrangement and allelic exclusion, we constructed mutant mice in which a 1.2-kb region of the V13 promoter was either deleted (P13 ؊/؊ ) or replaced with the simian virus 40 minimal promoter plus five copies of Gal4 DNA sequences (P13 R/R ). In P13 ؊/؊ mice, cleavage, rearrangement, and transcription of V13, but not the flanking V gene segments, were significantly inhibited. In P13 R/R mice, inhibition of V13 rearrangement was less severe and was not associated with any apparent reduction in V13 cleavage. Expression of a T-cell receptor (TCR) transgene blocked cleavages at the normal V13-recombination signal sequence junction and V13 coding joint formation of both wild-type and mutant V13 alleles. However, a low level of aberrant V13 cleavage was consistently detected, especially in TCR transgenic P13 R/R mice. These findings suggest that the variable gene promoter is required for promoting local recombination accessibility of the associated V gene segment. Although the promoter is dispensable for allelic exclusion, it appears to suppress aberrant V cleavages during allelic exclusion.
The Journal of Immunology, 2002
Journal of Clinical Investigation, 1992
Address reprint requests to Dr. Lipsky,
Journal of Biomolecular Screening, 2005
Screening assays using target-based affinity selection coupled with high-sensitivity detection te... more Screening assays using target-based affinity selection coupled with high-sensitivity detection technologies to identify smallmolecule hits from chemical libraries can provide a useful discovery approach that complements traditional assay systems. Affinity selection-mass spectrometry (AS-MS) is one such methodology that holds promise for providing selective and sensitive high-throughput screening platforms. Although AS-MS screening platforms have been used to discover smallmolecule ligands of proteins from many target families, they have not yet been used routinely to screen integral membrane proteins. The authors present a proof-of-concept study using size exclusion chromatography coupled to AS-MS to perform a primary screen for small-molecule ligands of the purified muscarinic M 2 acetylcholine receptor, a G-protein-coupled receptor. AS-MS is used to characterize the binding mechanisms of 2 newly discovered ligands. NGD-3350 is a novel M 2 -specific orthosteric antagonist of M 2 function. NGD-3366 is an allosteric ligand with binding properties similar to the allosteric antagonist W-84, which decreases the dissociation rate of N-methyl-scopolamine from the M 2 receptor. Binding properties of the ligands discerned from AS-MS assays agree with those from in vitro biochemical assays. The authors conclude that when used with appropriate small-molecule libraries, AS-MS may provide a useful high-throughput assay system for the discovery and characterization of all classes of integral membrane protein ligands, including allosteric modulators. (Journal of Biomolecular
Current Opinion in Chemical Biology, 2007
Affinity selection-mass spectrometry (AS-MS) techniques assess the binding of candidate molecules... more Affinity selection-mass spectrometry (AS-MS) techniques assess the binding of candidate molecules to immobilized or soluble receptors, and these methods are gaining acceptance in high throughput screening laboratories as valuable complements to traditional drug discovery technologies. A diversity of receptor types have been evaluated by AS-MS, including those that are difficult to screen using traditional biochemical approaches. AS-MS techniques that couple liquid chromatography-MS with size-based separation methods, such as ultrafiltration, gel permeation, or size-exclusion chromatography, are particularly amenable to the demands of MS-based screening and have demonstrated the greatest success across a broad range of drug targets. MS measurements of receptor function have many of the same advantages as AS-MS screening and are increasingly used for drug discovery as well.
Combinatorial Chemistry & High Throughput Screening, 2012
Affinity selection-mass spectrometry (AS-MS) is a sensitive technology for identifying small mole... more Affinity selection-mass spectrometry (AS-MS) is a sensitive technology for identifying small molecules that bind to target proteins, and assays enabled by AS-MS can be used to delineate relative binding affinities of ligands for proteins. 'Indirect' AS-MS assays employ size-exclusion techniques to separate target-ligand complexes from unbound ligands, and target-associated ligands are then specifically detected by liquid chromatography mass spectrometry. We report how indirect AS-MS binding assays with known reference control compounds were used as guideposts for development of an optimized purification method for CXCR4, a G-protein coupled chemokine receptor, for which we sought novel antagonists. The CXCR4 purification method that was developed was amenable to scale-up and enabled the screening of purified recombinant human CXCR4 against a large combinatorial library of small molecules by high throughput indirect AS-MS. The screen resulted in the discovery of new ligands that competed off binding of reference compounds to CXCR4 in AS-MS binding assays and that antagonized SDF1α-triggered responses and CXCR4-mediated HIV1 viral uptake in cell-based assays. This report provides a methodological paradigm whereby indirect AS-MS-based ligand binding assays may be used to guide optimal integral membrane protein purification methods that enable downstream affinity selection-based applications such as high throughput AS-MS screens.
Bioorganic & Medicinal Chemistry Letters, 2013
Conformation restriction of linear N-alkylanilide MK2 inhibitors to their E-conformer was develop... more Conformation restriction of linear N-alkylanilide MK2 inhibitors to their E-conformer was developed. This strategy enabled rapid advance in identifying a series of potent non-ATP competitive inhibitors that exhibited cell based activity in anti-TNFα assay.
Bioorganic & Medicinal Chemistry, 2012
The STAT6 (signal transducer and activator of transcription 6) protein facilitates T-helper cell ... more The STAT6 (signal transducer and activator of transcription 6) protein facilitates T-helper cell 2 (Th2) mediated responses that control IgE-mediated atopic diseases such as asthma. We have identified compounds that bind to STAT6 and inhibit STAT6 tyrosine phosphorylation induced by IL-4. In the bronchial epithelial cell line BEAS-2B, compound (R)-84 inhibits the secretion of eotaxin-3, a chemokine eliciting eosinophil infiltration. (R)-84 appears to prevent STAT6 from assuming the active dimer configuration by directly binding the protein and inhibiting tyrosine phosphorylation.
ACS Medicinal Chemistry Letters, 2011
A novel series of non-ATP-competitive MK2 inhibitors based on a furan-2-carboxyamide scaffold was... more A novel series of non-ATP-competitive MK2 inhibitors based on a furan-2-carboxyamide scaffold was discovered through high-throughput screening using the affinity selection-mass spectrometry-based Automated Ligand Identification System platform. Medicinal chemistry efforts optimized the initial screening hit to leadlike compounds with significant improvements in biochemical and cellular potencies, while maintaining excellent kinase selectivity and in vitro pharmacokinetic properties. Biophysical and biochemical studies confirmed the unique non-ATP-competitive binding mode of this series and suggested that highly selective inhibitors of MK2 should be feasible by targeting the outside ATP pocket.
Bioorganic & Medicinal Chemistry Letters, 2013
Chemistry has been developed to access both imidazo[1,2-a]pyrazines and imidazo[1,2-c]pyrimidines... more Chemistry has been developed to access both imidazo[1,2-a]pyrazines and imidazo[1,2-c]pyrimidines. Small structural modifications in both series led to a switch of potency between two kinases involved in mediating cell cycle checkpoint control, CHK1 and MK2.