Tapping the translation potential of cAMP signalling: molecular basis for selectivity in cAMP agonism and antagonism as revealed by NMR

2014 ◽  
Vol 42 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Stephen Boulton ◽  
Madoka Akimoto ◽  
Bryan VanSchouwen ◽  
Kody Moleschi ◽  
Rajeevan Selvaratnam ◽  
...  
Keyword(s):  
Cardiovascular Diseases ◽  
Molecular Basis ◽  
Structural Basis ◽  
Signalling Pathways ◽  
Potential Drug ◽  
Cellular Functions ◽  
Camp Signalling ◽  
Binding Domains ◽  
Drug Leads ◽  
Kinase A

Eukaryotic CBDs (cAMP-binding domains) control multiple cellular functions (e.g. phosphorylation, guanine exchange and ion channel gating). Hence the manipulation of cAMP-dependent signalling pathways has a high translational potential. However, the ubiquity of eukaryotic CBDs also poses a challenge in terms of selectivity. Before the full translational potential of cAMP signalling can be tapped, it is critical to understand the structural basis for selective cAMP agonism and antagonism. Recent NMR investigations have shown that structurally homologous CBDs respond differently to several CBD ligands and that these unexpected differences arise at the level of either binding (i.e. affinity) or allostery (i.e. modulation of the autoinhibitory equilibria). In the present article, we specifically address how the highly conserved CBD fold binds cAMP with markedly different affinities in PKA (protein kinase A) relative to other eukaryotic cAMP receptors, such as Epac (exchange protein directly activated by cAMP) and HCN (hyperpolarization-activated cyclic-nucleotide-modulated channel). A major emerging determinant of cAMP affinity is hypothesized to be the position of the autoinhibitory equilibrium of the apo-CBD, which appears to vary significantly across different CBDs. These analyses may assist the development of selective CBD effectors that serve as potential drug leads for the treatment of cardiovascular diseases.

scholarly journals Recent Advances in EPAC-Targeted Therapies: A Biophysical Perspective

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1462 ◽  
Author(s):  
Alveena Ahmed ◽  
Stephen Boulton ◽  
Hongzhao Shao ◽  
Madoka Akimoto ◽  
Amarnath Natarajan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Basis ◽  
Competitive Inhibitor ◽  
Low Molecular Weight ◽  
Specific Interactions ◽  
False Negatives ◽  
Colloidal Aggregates ◽  
Drug Leads ◽  
Specific Inhibitors ◽  
Kinase A

The universal second messenger cAMP regulates diverse intracellular processes by interacting with ubiquitously expressed proteins, such as Protein Kinase A (PKA) and the Exchange Protein directly Activated by cAMP (EPAC). EPAC is implicated in multiple pathologies, thus several EPAC-specific inhibitors have been identified in recent years. However, the mechanisms and molecular interactions underlying the EPAC inhibition elicited by such compounds are still poorly understood. Additionally, being hydrophobic low molecular weight species, EPAC-specific inhibitors are prone to forming colloidal aggregates, which result in non-specific aggregation-based inhibition (ABI) in aqueous systems. Here, we review from a biophysical perspective the molecular basis of the specific and non-specific interactions of two EPAC antagonists—CE3F4R, a non-competitive inhibitor, and ESI-09, a competitive inhibitor of EPAC. Additionally, we discuss the value of common ABI attenuators (e.g., TX and HSA) to reduce false positives at the expense of introducing false negatives when screening aggregation-prone compounds. We hope this review provides the EPAC community effective criteria to evaluate similar compounds, aiding in the optimization of existing drug leads, and informing the development of the next generation of EPAC-specific inhibitors.

scholarly journals Structural basis of the TAL effector–DNA interaction

2012 ◽  
Vol 393 (10) ◽  
pp. 1055-1066 ◽  
Author(s):  
Matthias Bochtler
Keyword(s):  
Molecular Basis ◽  
Dna Interaction ◽  
Structural Basis ◽  
Transcription Activator ◽  
Tal Effector ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Hydrogen Bonding Interactions ◽  
Van Der Waals Contacts ◽  
Helical Parameters

Abstract Phytopathogen transcription activator-like effectors (TALEs) bind DNA in a sequence specific manner in order to manipulate host transcription. TALE specificity correlates with repeat variable diresidues in otherwise highly stereotypical 34–35mer repeats. Recently, the crystal structures of two TALE DNA-binding domains have illustrated the molecular basis of the TALE cipher. The structures show that the TALE repeats form a right-handed superhelix that is wound around largely undistorted B-DNA to match its helical parameters. Surprisingly, repeat variable residue 1 is not in contact with the bases. Instead, it is involved in hydrogen bonding interactions that stabilize the overall structure of the protein. Repeat variable residue 2 contacts the top strand base and forms sequence-specific hydrogen bonds and/or van der Waals contacts. Very unexpectedly, bottom strand bases are exposed to solvent and do not make any direct contacts with the protein. This review contains a summary of TALE biology and applications and a detailed description of the recent breakthroughs that have provided insights into the molecular basis of the TALE code.

scholarly journals The Molecular Basis of Human Anophthalmia and Microphthalmia

2019 ◽  
Vol 7 (3) ◽  
pp. 16 ◽  
Author(s):  
Harding ◽  
Moosajee
Keyword(s):  
Molecular Basis ◽  
Pluripotent Stem Cell ◽  
Eye Development ◽  
Induced Pluripotent Stem Cell ◽  
Structural Basis ◽  
Signalling Pathways ◽  
Temporal Expression ◽  
Key Genes ◽  
Induced Pluripotent ◽  
Eye Formation

Human eye development is coordinated through an extensive network of genetic signalling pathways. Disruption of key regulatory genes in the early stages of eye development can result in aborted eye formation, resulting in an absent eye (anophthalmia) or a small underdeveloped eye (microphthalmia) phenotype. Anophthalmia and microphthalmia (AM) are part of the same clinical spectrum and have high genetic heterogeneity, with >90 identified associated genes. By understanding the roles of these genes in development, including their temporal expression, the phenotypic variation associated with AM can be better understood, improving diagnosis and management. This review describes the genetic and structural basis of eye development, focusing on the function of key genes known to be associated with AM. In addition, we highlight some promising avenues of research involving multiomic approaches and disease modelling with induced pluripotent stem cell (iPSC) technology, which will aid in developing novel therapies.

Compartmentalization of adenylate cyclase and cAMP signalling

2005 ◽  
Vol 33 (6) ◽  
pp. 1319-1322 ◽  
Author(s):  
D.M.F. Cooper
Keyword(s):  
Plasma Membrane ◽  
Signalling Pathways ◽  
Scaffolding Proteins ◽  
Subcellular Targeting ◽  
Camp Signalling ◽  
Cellular Processes ◽  
Cyclic Nucleotide Gated Channels ◽  
Anchoring Protein ◽  
Raft Domains ◽  
Kinase A

Concepts of cAMP signalling have changed dramatically from the linear cascades of just a few years ago, with the realization that numerous cellular processes affect this motif. These influences include other signalling pathways – most significantly Ca2+, scaffolding proteins (which are themselves variously regulated) to organize the elements of the pathway, and subcellular targeting of components. An obvious implication of this organization is that global measurements of cAMP may trivialize the complexity of the cAMP signals and obscure the regulation of targets. In this presentation, current developments on the targeting and assembly of ACs (adenylate cyclases) and their delivery to selected raft or non-raft domains of the plasma membrane will be discussed, along with the susceptibility of raft-targeted ACs to very discrete modes of increases in the intracellular Ca2+ concentration. Single-cell explorations of cAMP dynamics, as measured with cyclic nucleotide-gated channels, are also described in this paper, particularly as applied to cells in which the composition of AKAP (A-kinase anchoring protein)–PKA (protein kinase A)–PDE (phosphodiesterase) assemblies is probed by RNA interference ablation of defined AKAPs.

scholarly journals Tubulin glycylation controls axonemal dynein activity, flagellar beat, and male fertility

Science ◽  
2021 ◽  
Vol 371 (6525) ◽  
pp. eabd4914
Author(s):  
Sudarshan Gadadhar ◽  
Gonzalo Alvarez Viar ◽  
Jan Niklas Hansen ◽  
An Gong ◽  
Aleksandr Kostarev ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Male Fertility ◽  
Electron Tomography ◽  
Structural Basis ◽  
Cellular Functions ◽  
Flagellar Beat ◽  
Cryo Electron Tomography ◽  
Axonemal Dynein ◽  
Dynein Arms ◽  
Cilia And Flagella

Posttranslational modifications of the microtubule cytoskeleton have emerged as key regulators of cellular functions, and their perturbations have been linked to a growing number of human pathologies. Tubulin glycylation modifies microtubules specifically in cilia and flagella, but its functional and mechanistic roles remain unclear. In this study, we generated a mouse model entirely lacking tubulin glycylation. Male mice were subfertile owing to aberrant beat patterns of their sperm flagella, which impeded the straight swimming of sperm cells. Using cryo–electron tomography, we showed that lack of glycylation caused abnormal conformations of the dynein arms within sperm axonemes, providing the structural basis for the observed dysfunction. Our findings reveal the importance of microtubule glycylation for controlled flagellar beating, directional sperm swimming, and male fertility.

scholarly journals Phytochemicals against SARS-CoV as potential drug leads

2020 ◽  
Author(s):  
Shasank Sekhar Swain ◽  
Sujogya Kumar Panda ◽  
Walter Luyten
Keyword(s):  
Potential Drug ◽  
Drug Leads

New insights into the structural basis of integrin activation

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1155-1159 ◽  
Author(s):  
Jian-Ping Xiong ◽  
Thilo Stehle ◽  
Simon L. Goodman ◽  
M. Amin Arnaout
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Structural Basis ◽  
Integrin Activation ◽  
Cellular Functions ◽  
Electron Microscopic ◽  
The Past ◽  
Intracellular Signals ◽  
Bidirectional Signaling ◽  
New Hypothesis

Abstract Integrins are cell adhesion receptors that communicate biochemical and mechanical signals in a bidirectional manner across the plasma membrane and thus influence most cellular functions. Intracellular signals switch integrins into a ligand-competent state as a result of elicited conformational changes in the integrin ectodomain. Binding of extracellular ligands induces, in turn, structural changes that convey distinct signals to the cell interior. The structural basis of this bidirectional signaling has been the focus of intensive study for the past 3 decades. In this perspective, we develop a new hypothesis for integrin activation based on recent crystallographic, electron microscopic, and biochemical studies.

scholarly journals Protein Kinase A Signaling Pathway Regulates Transcriptional Activity of SAF-1 by Unmasking Its DNA-binding Domains

2003 ◽  
Vol 278 (25) ◽  
pp. 22586-22595 ◽  
Author(s):  
Alpana Ray ◽  
Papiya Ray ◽  
Nicole Guthrie ◽  
Arvind Shakya ◽  
Deepak Kumar ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Dna Binding ◽  
Protein Kinase A ◽  
Signaling Pathway ◽  
Transcriptional Activity ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Kinase A

Neuroinflammation, diabetes, and COVID-19: Perspectives coming from Ca2+/cAMP signalling

2021 ◽  
Vol 14 ◽  
Author(s):  
Leandro Bueno Bergantin
Keyword(s):  
Observational Studies ◽  
Poor Prognosis ◽  
Inflammatory Diseases ◽  
Signalling Pathways ◽  
Camp Signalling ◽  
People With Dementia ◽  
Bidirectional Relationship ◽  
Patients With Diabetes ◽  
Clinical Relationship

Background: A link between inflammatory diseases, e.g., epilepsy, dementia, diabetes, and COVID-19, has been established. For instance, observational studies with several individuals established that people with epilepsy have shown an enhanced incidence of manifesting dysfunctions related to cognition, e.g., dementia, while people with dementia have a higher incidence of manifesting epilepsy, thus an evident bidirectional relationship between epilepsy and dementia might occur. In addition, epilepsy commonly cooccurs in patients with diabetes, so an association between these two disorders is also discussed. Intriguingly, some reports have also observed a poor prognosis for people with both diabetes and COVID-19. It is recognized that a dyshomeostasis of both Ca2+ and cAMP signalling pathways could be a molecular connection for these disorders. Objectives: Therefore, clarifying this clinical relationship among epilepsy, dementia, diabetes, and COVID-19 may outcome in novel hypotheses for identifying the etiology of these disorders.

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