scholarly journals The GPIbα intracellular tail - role in transducing VWF- and Collagen/GPVI-mediated signaling

2020 ◽  
Author(s):  
Adela Constantinescu-Bercu ◽  
Yuxiao A Wang ◽  
Kevin Woollard ◽  
Pierre Mangin ◽  
Karen Vanhoorelbeke ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Transgenic Mouse ◽  
Molecular Mechanism ◽  
Related Peptide ◽  
Signaling Events ◽  
Peptide Stimulation

Synergy between GPIbα and GPVI signaling machineries has been suggested previously, however its molecular mechanism remains unclear. We generated a novel GPIbα transgenic mouse (GPIbαΔsig/Δsig) by CRISPR-Cas9 technology to delete the last 24 residues of the GPIbα intracellular tail important for VWF-mediated signaling. GPIbαΔsig/Δsig platelets bound VWF normally under flow but formed fewer filopodia on VWF/botrocetin, demonstrating that the deleted region does not affect ligand binding but appreciably impairs VWF-dependent signaling. Notably, while haemostasis was normal in GPIbαΔsig/Δsig mice, GPIbαΔsig/Δsig platelets exhibited defective responses after collagen-related-peptide stimulation and formed smaller aggregates on collagen-coated microchannels at low and high shears. Flow assays performed with plasma-free blood or in the presence of αIIbβ3- or GPVI-blockers suggested reduced αIIbβ3 activation contributes to the phenotype of the GPIbαΔsig/Δsig platelets. Together, these results reveal a new role for the intracellular tail of GPIbα in transducing both VWF- GPIbα and collagen-GPVI signaling events in platelets.

scholarly journals Exploring Ligand Binding to Calcitonin Gene-Related Peptide Receptors

2021 ◽  
Vol 8 ◽  
Author(s):  
Giuseppe Deganutti ◽  
Silvia Atanasio ◽  
Roxana-Maria Rujan ◽  
Patrick M. Sexton ◽  
Denise Wootten ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ligand Binding ◽  
Calcitonin Gene Related Peptide ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
Approved Drugs ◽  
G Protein Coupled ◽  
Dynamic Docking ◽  
Receptor Family

Class B1 G protein-coupled receptors (GPCRs) are important targets for many diseases, including cancer, diabetes, and heart disease. All the approved drugs for this receptor family are peptides that mimic the endogenous activating hormones. An understanding of how agonists bind and activate class B1 GPCRs is fundamental for the development of therapeutic small molecules. We combined supervised molecular dynamics (SuMD) and classic molecular dynamics (cMD) simulations to study the binding of the calcitonin gene-related peptide (CGRP) to the CGRP receptor (CGRPR). We also evaluated the association and dissociation of the antagonist telcagepant from the extracellular domain (ECD) of CGRPR and the water network perturbation upon binding. This study, which represents the first example of dynamic docking of a class B1 GPCR peptide, delivers insights on several aspects of ligand binding to CGRPR, expanding understanding of the role of the ECD and the receptor-activity modifying protein 1 (RAMP1) on agonist selectivity.

scholarly journals GR chaperone cycle mechanism revealed by cryo-EM: the GR-maturation complex

2020 ◽  
Author(s):  
David Agard ◽  
Chari Noddings ◽  
Ray Wang
Keyword(s):  
Glucocorticoid Receptor ◽  
Ligand Binding ◽  
Molecular Mechanism ◽  
Molecular Chaperone ◽  
Complex Structure ◽  
Binding Domain ◽  
Atomic Resolution ◽  
Native Conformation ◽  
Client Proteins ◽  
Resolution Structure

Abstract Hsp90 is a conserved and essential molecular chaperone responsible for the folding and activation of hundreds of ‘client’ proteins. The glucocorticoid receptor (GR) is a model client that constantly depends on Hsp90 for activity. Previously, we revealed GR ligand binding is inhibited by Hsp70 and restored by Hsp90, aided by the cochaperone p23. However, a molecular understanding of the chaperone-induced transformations that occur between the inactive Hsp70:Hsp90 ‘client-loading complex’ and an activated Hsp90:p23 ‘client-maturation complex’ is lacking for GR, or for any client. Here, we present a 2.56Å cryo-EM structure of the GR-maturation complex (GR:Hsp90:p23), revealing that the GR ligand binding domain is, surprisingly, restored to a folded, ligand-bound conformation, while simultaneously threaded through the Hsp90 lumen. Also, unexpectedly, p23 directly stabilizes native GR using a previously uncharacterized C-terminal helix, resulting in enhanced ligand-binding. This is the highest resolution Hsp90 structure to date and the first atomic resolution structure of a client bound to Hsp90 in a native conformation, sharply contrasting with the unfolded kinase:Hsp90 structure. Thus, aided by direct cochaperone:client interactions, Hsp90 dictates client-specific folding outcomes. Together with the GR-loading complex structure (Wang et al. 2020), we present the molecular mechanism of chaperone-mediated GR remodeling, establishing the first complete chaperone cycle for any client.

Hybrid QM/MM free energy evaluation of drug-resistant mutational effect on binding of an inhibitor Indinavir to HIV protease

2021 ◽  
Author(s):  
Masahiko Taguchi ◽  
Ryo Oyama ◽  
Masahiro Kaneso ◽  
Shigehiko Hayashi
Keyword(s):  
Drug Resistance ◽  
Free Energy ◽  
Ligand Binding ◽  
Transition State ◽  
Molecular Mechanism ◽  
Binding Affinity ◽  
Free Energy Calculations ◽  
Drug Resistant ◽  
Transition State Analog ◽  
Hiv 1

Human immunodeficiency virus 1 (HIV-1) protease is a homo-dimeric aspartic protease essential for replication of HIV. The HIV-1 protease is a target protein in drug discovery for antiretroviral therapy, and various inhibitor molecules of transition state analog were developed. However, serious drug-resistant mutants have emerged. For understanding molecular mechanism of the drug-resistance, accurate examination of the impacts of the mutations on ligand binding as well as enzymatic activity is necessary. Here, we present a molecular simulation study on the ligand binding of Indinavir, a potent transition state analog inhibitor, to the native protein and a V82T/I84V drug-resistant mutant of HIV-1 protease. We employed a hybrid ab initio quantum mechanical/molecular mechanical (QM/MM) free energy optimization technique which combines highly accurate QM description of the ligand molecule and its interaction with statistically ample conformational sampling of MM protein environment by long-time molecular dynamics simulations. Through free energy calculations of protonation states of catalytic groups at the binding pocket and of ligand binding affinity changes upon the mutations, we successfully reproduced the experimentally observed significant reduction of the binding affinity upon the drug-resistant mutations and elucidated the underlying molecular mechanism. The present study opens the way for understanding the molecular mechanism of drug-resistance through direct quantitative comparison of ligand binding and enzymatic reaction with the same accuracy.

scholarly journals The Neuronal Migration Factor srGAP2 Achieves Specificity in Ligand Binding through a Two-Component Molecular Mechanism

Structure ◽  
2015 ◽  
Vol 23 (11) ◽  
pp. 1989-2000 ◽  
Author(s):  
Julia Guez-Haddad ◽  
Michael Sporny ◽  
Yehezkel Sasson ◽  
Lada Gevorkyan-Airapetov ◽  
Naama Lahav-Mankovski ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Molecular Mechanism ◽  
Neuronal Migration ◽  
Migration Factor ◽  
Two Component

scholarly journals MBRS-22. SIGNIFICANCE OF RNF213 IN TUMORGENICITY OF MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_3) ◽  
pp. iii402-iii402
Author(s):  
Yohei Mineharu ◽  
Yuki Oichi ◽  
Takahiko Kamata ◽  
Yasuzumi Matsui ◽  
Takaaki Morimoto ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Mouse Model ◽  
Cerebrovascular Disease ◽  
Wnt Signaling ◽  
Transgenic Mouse ◽  
Molecular Mechanism ◽  
Genomic Instability ◽  
Transgenic Mouse Model ◽  
Spontaneous Generation ◽  
Rnf213 Gene

Abstract RNF213 gene, initially identified as a disease-causing gene for moyamoya cerebrovascular disease, has recently been recognized as a tumor regulator. The gene is known to be associated with WNT signaling, lipid metabolism, angiogenesis and genomic instability. The purpose of this study was to investigate the association of RNF213 in tumorgenicity of medulloblastoma. Incidence of medulloblastoma and histopathological findings were compared among ptch1+/-, ptch1+/- rnf213+/-, and ptch1+/- rnf213-/- mice. Knockout of rnf213 in ptch1+/- transgenic mouse model increased the incidence of spontaneous generation of medulloblastoma from 19.8% (ptch1+/-) to 76.5% (rnf213+/- ptch1+/-) at 9 months (p < 0.001). Heterozygous knockout was equivalent to homozygous knockout. Haploinsufficiency of rnf213 seems to be associated with tumorgenicity in medulloblastoma. Molecular mechanism of medulloblastoma generation needs to be further investigated.

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