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Enea Menegatti - One of the best experts on this subject based on the ideXlab platform.
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the bovine basic pancreatic trypsin inhibitor kunitz inhibitor a milestone protein
Current Protein & Peptide Science, 2003Co-Authors: Paolo Ascenzi, Alessio Bocedi, Martino Bolognesi, Andrea Spallarossa, Massimo Coletta, Raimondo De Cristofaro, Enea MenegattiAbstract:The pancreatic Kunitz inhibitor, also known as aprotinin, bovine basic pancreatic trypsin inhibitor (BPTI), and trypsin-kallikrein inhibitor, is one of the most extensively studied globular proteins. It has proved to be a particularly attractive and powerful tool for studying protein conformation as well as molecular bases of protein / protein interaction(s) and (macro)molecular recognition. BPTI has a relatively broad specificity, inhibiting trypsin- as well as chymotrypsinand elastase-like serine (pro)enzymes endowed with very different primary specificity. BPTI reacts rapidly with serine proteases to form stable complexes, but the enzyme:inhibitor complex formation may involve several intermediates corresponding to discrete reaction steps. Moreover, BPTI inhibits the nitric oxide synthase type-I and -II action and impairs K+ transport by Ca2+-activated K+ channels. Clinically, the use of BPTI in selected surgical interventions, such as cardiopulmonary surgery and orthotopic liver transplantation, is advised, as it significantly reduces hemorrhagic complications and thus blood-transfusion requirements. Here, the structural, inhibition, and bio-medical aspects of BPTI are reported.
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crystal structure of the bovine alpha chymotrypsin kunitz inhibitor complex an example of multiple protein protein recognition sites
Journal of Molecular Recognition, 1997Co-Authors: Clemente Capasso, Paolo Ascenzi, Enea Menegatti, Menico Rizzi, Martino BolognesiAbstract:The crystal structure of bovine α-chymotrypsin (α-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 A resolution (R-factor=0.18). The proteinase:inhibitor complex forms a compact dimer (two α-CHT and two BPTI molecules), which may be stabilized by surface-bound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between α-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P1 residue of BPTI, however, does not occupy the α-CHT S1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217. © 1997 John Wiley & Sons, Ltd.
William C K Pomerantz - One of the best experts on this subject based on the ideXlab platform.
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opportunity knocks for uncovering the new function of an understudied nucleosome remodeling complex member the bromodomain phd finger transcription factor BPTF
Current Opinion in Chemical Biology, 2021Co-Authors: Huda Zahid, Noelle M Olson, William C K PomerantzAbstract:Nucleosome remodeling provides access to genomic DNA for recruitment of the transcriptional machinery to mediate gene expression. The aberrant function of nucleosome remodeling complexes has been correlated to human cancer, making them emerging therapeutic targets. The bromodomain PHD finger transcription factor, BPTF, is the largest member of the human nucleosome remodeling factor NURF. Over the last five years, BPTF has become increasingly identified as a protumorigenic factor, prompting investigations into the molecular mechanisms associated with BPTF function. Despite a druggable bromodomain, small molecule discovery is at an early stage. Here we highlight recent investigations into the biology being discovered for BPTF, chemical biology approaches used to study its function, and small molecule inhibitors being designed as future chemical probes and therapeutics.
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new inhibitors for the BPTF bromodomain enabled by structural biology and biophysical assay development
Organic and Biomolecular Chemistry, 2020Co-Authors: Peter D Ycas, Jorden A Johnson, Huda Zahid, A Chan, Noelle M Olson, Siva Kumar Talluri, Ernst Schonbrunn, William C K PomerantzAbstract:Bromodomain-containing proteins regulate transcription through protein-protein interactions with chromatin and serve as scaffolding proteins for recruiting essential members of the transcriptional machinery. One such protein is the bromodomain and PHD-containing transcription factor (BPTF), the largest member of the nucleosome remodeling complex, NURF. Despite an emerging role for BPTF in regulating a diverse set of cancers, small molecule development for inhibiting the BPTF bromodomain has been lacking. Here we cross-validate three complementary biophysical assays to further the discovery of BPTF bromodomain inhibitors for chemical probe development: two direct binding assays (protein-observed 19F (PrOF) NMR and surface plasmon resonance (SPR)) and a competitive inhibition assay (AlphaScreen). We first compare the assays using three small molecules and acetylated histone peptides with reported affinity for the BPTF bromodomain. Using SPR with both unlabeled and fluorinated BPTF, we further determine that there is a minimal effect of 19F incorporation on ligand binding for future PrOF NMR experiments. To guide medicinal chemistry efforts towards chemical probe development, we subsequently evaluate two new BPTF inhibitor scaffolds with our suite of biophysical assays and rank-order compound affinities which could not otherwise be determined by PrOF NMR. Finally, we cocrystallize a subset of small molecule inhibitors and present the first published small molecule-protein structures with the BPTF bromodomain. We envision the biophysical assays described here and the structural insights from the crystallography will guide researchers towards developing selective and potent BPTF bromodomain inhibitors.
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specific acetylation patterns of h2a z form transient interactions with the BPTF bromodomain
Biochemistry, 2017Co-Authors: Gabriella T Perell, Peter D Ycas, Neeraj K Mishra, Babu Sudhamalla, Kabirul Islam, William C K PomerantzAbstract:Post-translational lysine acetylation of histone tails affects both chromatin accessibility and recruitment of multifunctional bromodomain-containing proteins for modulating transcription. The bromodomain- and PHD finger-containing transcription factor (BPTF) regulates transcription but has also been implicated in high gene expression levels in a variety of cancers. In this report, the histone variant H2A.Z, which replaces H2A in chromatin, is evaluated for its affinity for BPTF with a specific recognition pattern of acetylated lysine residues of the N-terminal tail region. Although BPTF immunoprecipitates H2A.Z-containing nucleosomes, a direct interaction with its bromodomain has not been reported. Using protein-observed fluorine nuclear magnetic resonance (PrOF NMR) spectroscopy, we identified a diacetylation of H2A.Z on lysine residues 4 and 11, with the highest affinity for BPTF with a Kd of 780 μM. A combination of subsequent 1H NMR Carr–Purcell–Meiboom–Gill experiments and photo-cross-linking furthe...
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BPTF maintains chromatin accessibility and the self renewal capacity of mammary gland stem cells
Stem cell reports, 2017Co-Authors: Wesley D Frey, Steven E Kirberger, William C K Pomerantz, Anisha Chaudhry, Priscila Ferreira Slepicka, Adam M Ouellette, Gregory J Hannon, Camila Dos O SantosAbstract:Chromatin remodeling is a key requirement for transcriptional control of cellular differentiation. However, the factors that alter chromatin architecture in mammary stem cells (MaSCs) are poorly understood. Here, we show that BPTF, the largest subunit of the NURF chromatin remodeling complex, is essential for MaSC self-renewal and differentiation of mammary epithelial cells (MECs). BPTF depletion arrests cells at a previously undefined stage of epithelial differentiation that is associated with an incapacity to achieve the luminal cell fate. Moreover, genome-wide analysis of DNA accessibility following genetic or chemical inhibition, suggests a role for BPTF in maintaining the open chromatin landscape at enhancers regions in MECs. Collectively, our study implicates BPTF in maintaining the unique epigenetic state of MaSCs.
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dual screening of BPTF and brd4 using protein observed fluorine nmr uncovers new bromodomain probe molecules
ACS Chemical Biology, 2015Co-Authors: Andrew K Urick, Camila Dos O Santos, Neeraj K Mishra, Laura M L Hawk, Melissa K Cassel, Shuai Liu, Neeta Adhikari, Wei Zhang, Jennifer L Hall, William C K PomerantzAbstract:Bromodomain-containing protein dysregulation is linked to cancer, diabetes, and inflammation. Selective inhibition of bromodomain function is a newly proposed therapeutic strategy. We describe a 19F NMR dual screening method for small molecule discovery using fluorinated tryptophan resonances on two bromodomain-containing proteins. The chemical shift dispersion of 19F resonances within fluorine-labeled proteins enables the simultaneous analysis of two fluorinated bromodomains by NMR. A library of 229 small molecules was screened against the first bromodomain of Brd4 and the BPTF bromodomain. We report the first small molecule selective for BPTF over Brd4, termed AU1. The Kd = 2.8 μM for AU1, which is active in a cell-based reporter assay. No binding is detected with Brd4. Three new Brd4 inhibitors with submicromolar affinity were also discovered. Brd4 hits were validated in a thermal stability assay and potency determined via fluorescence anisotropy. The speed, ease of interpretation, and low protein conc...
Paolo Ascenzi - One of the best experts on this subject based on the ideXlab platform.
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the bovine basic pancreatic trypsin inhibitor kunitz inhibitor a milestone protein
Current Protein & Peptide Science, 2003Co-Authors: Paolo Ascenzi, Alessio Bocedi, Martino Bolognesi, Andrea Spallarossa, Massimo Coletta, Raimondo De Cristofaro, Enea MenegattiAbstract:The pancreatic Kunitz inhibitor, also known as aprotinin, bovine basic pancreatic trypsin inhibitor (BPTI), and trypsin-kallikrein inhibitor, is one of the most extensively studied globular proteins. It has proved to be a particularly attractive and powerful tool for studying protein conformation as well as molecular bases of protein / protein interaction(s) and (macro)molecular recognition. BPTI has a relatively broad specificity, inhibiting trypsin- as well as chymotrypsinand elastase-like serine (pro)enzymes endowed with very different primary specificity. BPTI reacts rapidly with serine proteases to form stable complexes, but the enzyme:inhibitor complex formation may involve several intermediates corresponding to discrete reaction steps. Moreover, BPTI inhibits the nitric oxide synthase type-I and -II action and impairs K+ transport by Ca2+-activated K+ channels. Clinically, the use of BPTI in selected surgical interventions, such as cardiopulmonary surgery and orthotopic liver transplantation, is advised, as it significantly reduces hemorrhagic complications and thus blood-transfusion requirements. Here, the structural, inhibition, and bio-medical aspects of BPTI are reported.
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crystal structure of the bovine alpha chymotrypsin kunitz inhibitor complex an example of multiple protein protein recognition sites
Journal of Molecular Recognition, 1997Co-Authors: Clemente Capasso, Paolo Ascenzi, Enea Menegatti, Menico Rizzi, Martino BolognesiAbstract:The crystal structure of bovine α-chymotrypsin (α-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 A resolution (R-factor=0.18). The proteinase:inhibitor complex forms a compact dimer (two α-CHT and two BPTI molecules), which may be stabilized by surface-bound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between α-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P1 residue of BPTI, however, does not occupy the α-CHT S1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217. © 1997 John Wiley & Sons, Ltd.
Martino Bolognesi - One of the best experts on this subject based on the ideXlab platform.
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the bovine basic pancreatic trypsin inhibitor kunitz inhibitor a milestone protein
Current Protein & Peptide Science, 2003Co-Authors: Paolo Ascenzi, Alessio Bocedi, Martino Bolognesi, Andrea Spallarossa, Massimo Coletta, Raimondo De Cristofaro, Enea MenegattiAbstract:The pancreatic Kunitz inhibitor, also known as aprotinin, bovine basic pancreatic trypsin inhibitor (BPTI), and trypsin-kallikrein inhibitor, is one of the most extensively studied globular proteins. It has proved to be a particularly attractive and powerful tool for studying protein conformation as well as molecular bases of protein / protein interaction(s) and (macro)molecular recognition. BPTI has a relatively broad specificity, inhibiting trypsin- as well as chymotrypsinand elastase-like serine (pro)enzymes endowed with very different primary specificity. BPTI reacts rapidly with serine proteases to form stable complexes, but the enzyme:inhibitor complex formation may involve several intermediates corresponding to discrete reaction steps. Moreover, BPTI inhibits the nitric oxide synthase type-I and -II action and impairs K+ transport by Ca2+-activated K+ channels. Clinically, the use of BPTI in selected surgical interventions, such as cardiopulmonary surgery and orthotopic liver transplantation, is advised, as it significantly reduces hemorrhagic complications and thus blood-transfusion requirements. Here, the structural, inhibition, and bio-medical aspects of BPTI are reported.
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crystal structure of the bovine alpha chymotrypsin kunitz inhibitor complex an example of multiple protein protein recognition sites
Journal of Molecular Recognition, 1997Co-Authors: Clemente Capasso, Paolo Ascenzi, Enea Menegatti, Menico Rizzi, Martino BolognesiAbstract:The crystal structure of bovine α-chymotrypsin (α-CHT) in complex with the bovine basic pancreatic trypsin inhibitor (BPTI) has been solved and refined at 2.8 A resolution (R-factor=0.18). The proteinase:inhibitor complex forms a compact dimer (two α-CHT and two BPTI molecules), which may be stabilized by surface-bound sulphate ions, in the crystalline state. Each BPTI molecule, at opposite ends, is contacting both proteinase molecules in the dimer, through the reactive site loop and through residues next to the inhibitor's C-terminal region. Specific recognition between α-CHT and BPTI occurs at the (re)active site interface according to structural rules inferred from the analysis of homologous serine proteinase:inhibitor complexes. Lys15, the P1 residue of BPTI, however, does not occupy the α-CHT S1 specificity pocket, being hydrogen bonded to backbone atoms of the enzyme surface residues Gly216 and Ser217. © 1997 John Wiley & Sons, Ltd.
Bing Shao - One of the best experts on this subject based on the ideXlab platform.
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Mechanism of bisphenol AF-induced progesterone inhibition in human chorionic gonadotrophin-stimulated mouse Leydig tumor cell line (mLTC-1) cells.
Environmental toxicology, 2018Co-Authors: Yixing Feng, Zhihao Jiao, Jiachen Shi, Hejun Duan, Bing ShaoAbstract:Bisphenol AF (BPAF) has been shown to inhibit testicular steroidogenesis in male rats. However, the precise mechanisms related to the toxic effects of BPAF on reproduction remain poorly understood. In the present study, a mouse Leydig tumor cell line (mLTC-1) was used as a model to investigate the mechanism of steroidogenic inhibition and to identify the molecular target of BPAF. Levels of progesterone and the concentration of cyclic adenosine monophosphate (cAMP) in cells exposed to BPAF were detected, and expression of key genes and proteins in steroid biosynthesis was assessed. The results showed that BPAF exposure decreased human chorionic gonadotrophin (hCG)-stimulated progesterone production in a dose-dependent manner. The 24-h IC50 (half maximal inhibitory concentration) value for BPAF regarding progesterone production was 70.2 µM. A dramatic decrease in cellular cAMP concentration was also observed. Furthermore, BPAF exposure inhibited expression of genes and proteins involved in cholesterol transport and progesterone biosynthesis. Conversely, the protein levels of steroidogenic acute regulatory protein (StAR) were not altered, and those of progesterone were still decreased upon 22R-hydroxycholesterol treatment of cells exposed to higher doses of BPAF. Together, these data indicate that BPAF exposure inhibits progesterone secretion in hCG-stimulated mLTC-1 cells by reducing expression of scavenger receptor class B type I (SR-B1) and cytochrome P450 (P450scc) due to the adverse effects of cAMP. However, StAR might not be the molecular target in this process.
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Bisphenol AF-Induced Endogenous Transcription Is Mediated by ERa and ERK1/2 Activation in Human Breast Cancer
2016Co-Authors: Jing Guo, Jing Zhang, Wenhui Gao, Xiaoyu Han, Bing ShaoAbstract:Bisphenol AF (BPAF)-induced transcriptional activity has been evaluated by luciferase reporter assay. However, the molecular mechanism of BPAF-induced endogenous transcription in human breast cancer cells has not been fully elucidated. In the present study, we investigated the effect and mechanism of BPAF-induced endogenous transcription detected by real-time PCR in human breast cancer cells. We found that BPAF stimulated transcription of estrogen responsive genes, such as trefoil factor 1 (TFF1), growth regulation by estrogen in breast cancer 1 (GREB1) and cathepsin D (CTSD), through dose-dependent and time-dependent manners in T47D and MCF7 cells. Gene-silencing of ERa, ERb and G protein-coupled estrogen receptor 1 (GPER) by small interfering RNA revealed that BPAF-induced endogenous transcription was dependent on ERa and GPER, implying both genomic and nongenomic pathways might be involved in the endogenous transcription induced by BPAF. ERa-mediated gene transcription was further confirmed by inhibition of ER activity using ICI 182780 in ERa-positive T47D and MCF7 cells as well as overexpression of ERa in ERa-negative MDA-MB-231 breast cancer cells. Moreover, we utilized Src tyrosine kinase inhibitor PP2 and two MEK inhibitors PD98059 and U0126 to elucidate the rapid nongenomic activation of Src/MEK/ERK1/2 cascade on endogenous transcription. Our data showed that BPAF-induced transcription could be significantly blocked by PP2, PD98059 and U0126, suggesting activation of ERK1/2 was also required to regulate endogenous transcription. Taken together, these results indicate that BPAF-induced endogenous transcriptio
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bisphenol af induced endogenous transcription is mediated by erα and erk1 2 activation in human breast cancer cells
PLOS ONE, 2014Co-Authors: Jing Guo, Jing Zhang, Wenhui Gao, Xiaoyu Han, Bing ShaoAbstract:Bisphenol AF (BPAF)-induced transcriptional activity has been evaluated by luciferase reporter assay. However, the molecular mechanism of BPAF-induced endogenous transcription in human breast cancer cells has not been fully elucidated. In the present study, we investigated the effect and mechanism of BPAF-induced endogenous transcription detected by real-time PCR in human breast cancer cells. We found that BPAF stimulated transcription of estrogen responsive genes, such as trefoil factor 1 (TFF1), growth regulation by estrogen in breast cancer 1 (GREB1) and cathepsin D (CTSD), through dose-dependent and time-dependent manners in T47D and MCF7 cells. Gene-silencing of ERα, ERβ and G protein-coupled estrogen receptor 1 (GPER) by small interfering RNA revealed that BPAF-induced endogenous transcription was dependent on ERα and GPER, implying both genomic and nongenomic pathways might be involved in the endogenous transcription induced by BPAF. ERα-mediated gene transcription was further confirmed by inhibition of ER activity using ICI 182780 in ERα-positive T47D and MCF7 cells as well as overexpression of ERα in ERα-negative MDA-MB-231 breast cancer cells. Moreover, we utilized Src tyrosine kinase inhibitor PP2 and two MEK inhibitors PD98059 and U0126 to elucidate the rapid nongenomic activation of Src/MEK/ERK1/2 cascade on endogenous transcription. Our data showed that BPAF-induced transcription could be significantly blocked by PP2, PD98059 and U0126, suggesting activation of ERK1/2 was also required to regulate endogenous transcription. Taken together, these results indicate that BPAF-induced endogenous transcription of estrogen responsive genes is mediated through both genomic and nongenomic pathways involving the ERα and ERK1/2 activation in human breast cancer cells.
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Bisphenol AF may cause testosterone reduction by directly affecting testis function in adult male rats.
Toxicology letters, 2012Co-Authors: Yixing Feng, Jie Yin, Zhihao Jiao, Jiachen Shi, Bing ShaoAbstract:Although in vitro studies have indicated that Bisphenol AF (BPAF) might be a more dangerous endocrine disruptor than Bisphenol A (BPA), no information on reproductive toxicity in animals is available. In this study, the effects of BPAF exposure on the testis and the related mechanisms of toxicity were investigated. Sprague-Dawley (SD) male rats were exposed to BPAF (0, 2, 10, 50 and 200 mg/kg/d) for 14 days. Total cholesterol levels in serum were decreased in rats given a dose of 50 and 200 mg/kg/d. BPAF concentration in the testes increased with increasing doses of BPAF. Reduced serum testosterone and increased luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were observed in rats in the higher dose groups. Furthermore, BPAF exposure resulted in a dramatic decline in genes and protein involved in cholesterol biosynthesis, transport and steroid biosynthesis. Similarly, the testicular mRNA levels of inhibin B, estrogen receptor (ERα) and luteinizing hormone receptor (LHR) also decreased in rats given a dosage of 200 mg/kg/d BPAF. Together, these data demonstrate that BPAF-induced inhibition of testosterone production primarily resulted from the alteration of genes and proteins in the testosterone biosynthesis pathway.