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Nature Communications Mar 2021A widely regarded model for glucocorticoid receptor (GR) action postulates that dimeric binding to DNA regulates unfavorable metabolic pathways while monomeric receptor...
A widely regarded model for glucocorticoid receptor (GR) action postulates that dimeric binding to DNA regulates unfavorable metabolic pathways while monomeric receptor binding promotes repressive gene responses related to its anti-inflammatory effects. This model has been built upon the characterization of the GRdim mutant, reported to be incapable of DNA binding and dimerization. Although quantitative live-cell imaging data shows GRdim as mostly dimeric, genomic studies based on recovery of enriched half-site response elements suggest monomeric engagement on DNA. Here, we perform genome-wide studies on GRdim and a constitutively monomeric mutant. Our results show that impairing dimerization affects binding even to open chromatin. We also find that GRdim does not exclusively bind half-response elements. Our results do not support a physiological role for monomeric GR and are consistent with a common mode of receptor binding via higher order structures that drives both the activating and repressive actions of glucocorticoids.
Topics: Animals; Chromatin; DNA; Gene Expression Regulation; Genome-Wide Association Study; Glucocorticoids; Humans; Mice; Mutation; Protein Binding; Protein Multimerization; Receptors, Glucocorticoid; Response Elements; Signal Transduction
PubMed: 33790284
DOI: 10.1038/s41467-021-22234-9 -
Frontiers in Immunology 2021Plasma membrane provides a biophysical and biochemical platform for immune cells to trigger signaling cascades and immune responses against attacks from foreign... (Review)
Review
Plasma membrane provides a biophysical and biochemical platform for immune cells to trigger signaling cascades and immune responses against attacks from foreign pathogens or tumor cells. Mounting evidence suggests that the biophysical-chemical properties of this platform, including complex compositions of lipids and cholesterols, membrane tension, and electrical potential, could cooperatively regulate the immune receptor functions. However, the molecular mechanism is still unclear because of the tremendous compositional complexity and spatio-temporal dynamics of the plasma membrane. Here, we review the recent significant progress of dynamical regulation of plasma membrane on immune receptors, including T cell receptor, B cell receptor, Fc receptor, and other important immune receptors, to proceed mechano-chemical sensing and transmembrane signal transduction. We also discuss how biophysical-chemical cues couple together to dynamically tune the receptor's structural conformation or orientation, distribution, and organization, thereby possibly impacting their ligand binding and related signal transduction. Moreover, we propose that electrical potential could potentially induce the biophysical-chemical coupling change, such as lipid distribution and membrane tension, to inevitably regulate immune receptor activation.
Topics: Animals; Binding Sites; Cell Membrane; Chemical Phenomena; Electrophysiological Phenomena; Humans; Mechanical Phenomena; Membrane Lipids; Protein Binding; Receptors, Immunologic; Signal Transduction
PubMed: 33679752
DOI: 10.3389/fimmu.2021.613185 -
Journal of Cardiovascular Pharmacology Jul 2017G protein-coupled receptors (GPCRs) comprise the largest family of receptors in humans. Traditional activation of GPCRs involves binding of a ligand to the receptor,... (Review)
Review
G protein-coupled receptors (GPCRs) comprise the largest family of receptors in humans. Traditional activation of GPCRs involves binding of a ligand to the receptor, activation of heterotrimeric G proteins and induction of subsequent signaling molecules. It is now known that GPCR signaling occurs through G protein-independent pathways including signaling through β-arrestin and transactivation of other receptor types. Generally, transactivation occurs when activation of one receptor leads to the activation of another receptor(s). GPCR-mediated transactivation is an essential component of GPCR signaling, as activation of other receptor types, such as receptor tyrosine kinases, allows GPCRs to expand their signal transduction and affect various cellular responses. Several mechanisms have been identified for receptor transactivation downstream of GPCRs, one of which involves activation of extracellular proteases, such as a disintegrin and metalloprotease, and matrix metalloproteases . These proteases cleave and release ligands that are then able to activate their respective receptors. A disintegrin and metalloprotease, and matrix metalloproteases can be activated via various mechanisms downstream of GPCR activation, including activation via second messenger, direct phosphorylation, or direct G protein interaction. Additional understanding of the mechanisms involved in GPCR-mediated protease activation and subsequent receptor transactivation could lead to identification of new therapeutic targets.
Topics: Animals; Extracellular Fluid; Humans; Matrix Metalloproteinases; Peptide Hydrolases; Receptors, G-Protein-Coupled; Signal Transduction; Transcriptional Activation
PubMed: 28195946
DOI: 10.1097/FJC.0000000000000475 -
Cells Jun 2023The glucocorticoid receptor α (GRα) is a member of the nuclear receptor superfamily and functions as a glucocorticoid (GC)-responsive transcription factor. GR can halt... (Review)
Review
The glucocorticoid receptor α (GRα) is a member of the nuclear receptor superfamily and functions as a glucocorticoid (GC)-responsive transcription factor. GR can halt inflammation and kill off cancer cells, thus explaining the widespread use of glucocorticoids in the clinic. However, side effects and therapy resistance limit GR's therapeutic potential, emphasizing the importance of resolving all of GR's context-specific action mechanisms. Fortunately, the understanding of GR structure, conformation, and stoichiometry in the different GR-controlled biological pathways is now gradually increasing. This information will be crucial to close knowledge gaps on GR function. In this review, we focus on the various domains and mechanisms of action of GR, all from a structural perspective.
Topics: Humans; Glucocorticoids; Receptors, Glucocorticoid; Transcription Factors
PubMed: 37371105
DOI: 10.3390/cells12121636 -
Cellular Signalling Jan 2014Annexin A1 (ANXA1) is the first characterized member of the annexins superfamily. It binds the cellular membrane phospholipids in Ca(2+) regulated manner. Annexin A1 has... (Review)
Review
Annexin A1 (ANXA1) is the first characterized member of the annexins superfamily. It binds the cellular membrane phospholipids in Ca(2+) regulated manner. Annexin A1 has been found in several tissues and many physiological roles as hormones secretion, vesiculation, inflammatory response, apoptosis and differentiation have been shown. Its subcellular localization and binding with many partner proteins are altered accordingly with its physiological role. The Annexin A1 membrane localization is crucial for binding to receptors, suggesting a paracrine and juxtacrine extracellular action. Annexin A1 is subjected to several post-translational modifications. In particular the protein is phosphorylated on several residues both on the N-terminal functional domain and on the C-terminus core. Different kinases have been identified as responsible for the phosphorylation status of selective residues. The specific change in the phosphorylation status on the different sites alters ANXA1 localization, binding properties and functions. This review shows the physiological relevance of the ANXA1 phosphorylation leading to the conclusion that numerous and different roles of Annexin A1 could be associated with different phosphorylations to alter not only intracellular localization and bindings to its partners but also the extracellular receptor interactions.
Topics: Amino Acids; Animals; Annexin A1; Cell Membrane; Humans; Models, Biological; Phosphorylation; Protein Transport
PubMed: 24103589
DOI: 10.1016/j.cellsig.2013.09.020 -
Nature Communications May 2023The epidermal growth factor receptor (EGFR) is a central regulator of cell physiology. EGFR is activated by ligand binding, triggering receptor dimerization, activation...
The epidermal growth factor receptor (EGFR) is a central regulator of cell physiology. EGFR is activated by ligand binding, triggering receptor dimerization, activation of kinase activity, and intracellular signaling. EGFR is transiently confined within various plasma membrane nanodomains, yet how this may contribute to regulation of EGFR ligand binding is poorly understood. To resolve how EGFR nanoscale compartmentalization gates ligand binding, we developed single-particle tracking methods to track the mobility of ligand-bound and total EGFR, in combination with modeling of EGFR ligand binding. In comparison to unliganded EGFR, ligand-bound EGFR is more confined and distinctly regulated by clathrin and tetraspanin nanodomains. Ligand binding to unliganded EGFR occurs preferentially in tetraspanin nanodomains, and disruption of tetraspanin nanodomains impairs EGFR ligand binding and alters the conformation of the receptor's ectodomain. We thus reveal a mechanism by which EGFR confinement within tetraspanin nanodomains regulates receptor signaling at the level of ligand binding.
Topics: Ligands; Signal Transduction; ErbB Receptors; Phosphorylation; Tetraspanins
PubMed: 37160944
DOI: 10.1038/s41467-023-38390-z -
Frontiers in Cell and Developmental... 2021G protein-coupled receptors (GPCRs) are the largest class of human membrane proteins that bind extracellular ligands at their orthosteric binding pocket to transmit...
G protein-coupled receptors (GPCRs) are the largest class of human membrane proteins that bind extracellular ligands at their orthosteric binding pocket to transmit signals to the cell interior. Ligand binding evokes conformational changes in GPCRs that trigger the binding of intracellular interaction partners (G proteins, G protein kinases, and arrestins), which initiate diverse cellular responses. It has become increasingly evident that the preference of a GPCR for a certain intracellular interaction partner is modulated by a diverse range of factors, e.g., ligands or lipids embedding the transmembrane receptor. Here, by means of molecular dynamics simulations of the β-adrenergic receptor and β-arrestin2, we study how membrane lipids and receptor phosphorylation regulate GPCR-arrestin complex conformation and dynamics. We find that phosphorylation drives the receptor's intracellular loop 3 (ICL3) away from a native negatively charged membrane surface to interact with arrestin. If the receptor is embedded in a neutral membrane, the phosphorylated ICL3 attaches to the membrane surface, which widely opens the receptor core. This opening, which is similar to the opening in the G protein-bound state, weakens the binding of arrestin. The loss of binding specificity is manifested by shallower arrestin insertion into the receptor core and higher dynamics of the receptor-arrestin complex. Our results show that receptor phosphorylation and the local membrane composition cooperatively fine-tune GPCR-mediated signal transduction. Moreover, the results suggest that deeper understanding of complex GPCR regulation mechanisms is necessary to discover novel pathways of pharmacological intervention.
PubMed: 35004696
DOI: 10.3389/fcell.2021.807913 -
Endocrine-related Cancer Aug 2017With few exceptions, the almost 30,000 prostate cancer deaths annually in the United States are due to failure of androgen deprivation therapy. Androgen deprivation... (Review)
Review
With few exceptions, the almost 30,000 prostate cancer deaths annually in the United States are due to failure of androgen deprivation therapy. Androgen deprivation therapy prevents ligand-activation of the androgen receptor. Despite initial remission after androgen deprivation therapy, prostate cancer almost invariably progresses while continuing to rely on androgen receptor action. Androgen receptor's transcriptional output, which ultimately controls prostate cancer behavior, is an alternative therapeutic target, but its molecular regulation is poorly understood. Recent insights in the molecular mechanisms by which the androgen receptor controls transcription of its target genes are uncovering gene specificity as well as context-dependency. Heterogeneity in the androgen receptor's transcriptional output is reflected both in its recruitment to diverse cognate DNA binding motifs and in its preferential interaction with associated pioneering factors, other secondary transcription factors and coregulators at those sites. This variability suggests that multiple, distinct modes of androgen receptor action that regulate diverse aspects of prostate cancer biology and contribute differentially to prostate cancer's clinical progression are active simultaneously in prostate cancer cells. Recent progress in the development of peptidomimetics and small molecules, and application of Chem-Seq approaches indicate the feasibility for selective disruption of critical protein-protein and protein-DNA interactions in transcriptional complexes. Here, we review the recent literature on the different molecular mechanisms by which the androgen receptor transcriptionally controls prostate cancer progression, and we explore the potential to translate these insights into novel, more selective forms of therapies that may bypass prostate cancer's resistance to conventional androgen deprivation therapy.
Topics: Androgen Antagonists; Animals; DNA; Humans; Male; Prostatic Neoplasms; Receptors, Androgen; Response Elements
PubMed: 28566530
DOI: 10.1530/ERC-17-0121 -
Pharmacological Research Jul 2011Pregnane x receptor (PXR, NR1I2) was originally characterized as a broad spectrum entero-hepatic xenobiotic 'sensor' and master-regulator of drug inducible gene... (Review)
Review
Pregnane x receptor (PXR, NR1I2) was originally characterized as a broad spectrum entero-hepatic xenobiotic 'sensor' and master-regulator of drug inducible gene expression. A compelling description of ligand-mediated gene activation has been unveiled in the last decade that firmly establishes this receptor's central role in the metabolism and transport of xenobiotics in mammals. Interestingly, pharmacotherapy with potent PXR ligands produces several profound side effects including decreased capacities for gluconeogenesis, lipid metabolism, and inflammation; likely due to PXR-mediated repression of gene expression programs underlying these pivotal physiological functions. An integrated model is emerging that reveals a sophisticated interplay between ligand binding and the ubiquitylation, phosphorylation, SUMOylation, and acetylation status of this important nuclear receptor protein. These discoveries point to a key role for the post-translational modification of PXR in the selective suppression of gene expression, and open the door to the study of completely new modes of regulation of the biological activity of PXR.
Topics: Animals; Gene Expression Regulation; Humans; Pregnane X Receptor; Protein Processing, Post-Translational; Receptors, Steroid
PubMed: 21397695
DOI: 10.1016/j.phrs.2011.02.011 -
Biochimica Et Biophysica Acta.... Jun 2021In this study, we developed a method to analyze liposomal binding to a cell membrane receptor using fluorescence-labeled liposomes and demonstrated that scavenger class...
In this study, we developed a method to analyze liposomal binding to a cell membrane receptor using fluorescence-labeled liposomes and demonstrated that scavenger class B type 1 (SR-B1) plays a crucial role in binding of liposomes containing phosphatidylcholine (PC) to HEK293T cell membrane and phosphatidic acid (PA) can modulate it. Site-directed mutagenesis of SR-B1 revealed that S112F and T175A mutations in its ectodomain abrogated binding and endocytosis of PC liposomes in HEK293T cells. K151A and K156A mutations attenuated their binding and endocytosis too. Although the effects of mutations on binding and endocytosis were similar between PC liposomes and PC/PA and PA liposomes, SR-B1 dependency appeared to be PC > PC/PA > PA liposomes. Our data indicate that (i) nanoparticles including high-density lipoprotein (HDL), silica, and liposomes bind to a common or close site of SR-B1, and (ii) PC/PA and PA liposomes bind not only to SR-B1 but also other receptor(s) in HEK293T cells. In addition, PC/PA liposomes induced lipid droplet (LD) formation in HEK293T cells more than PC liposomes. Treatment of HEK293T cells with SR-B1 siRNA suppressed PC/PA liposome-induced LD formation. Taken together, our results demonstrate that SR-B1 plays an essential role in binding PC-containing liposomes and the subsequent induction of cellular responses, while PA can modulate them.
Topics: Biophysical Phenomena; HEK293 Cells; Humans; Liposomes; Phosphatidic Acids; Phosphatidylcholines; Protein Binding; Receptors, Scavenger; Scavenger Receptors, Class B
PubMed: 33862056
DOI: 10.1016/j.bbamcr.2021.119043