In situ visualization of endothelial cell-derived extracellular vesicle formation in steady state and malignant conditions.

Endothelial cells are integral components of all vasculature within complex organisms. As they line the blood vessel wall, endothelial cells are constantly exposed to a variety of molecular factors and shear force that can induce cellular damage and stress. However, how endothelial cells are removed or eliminate unwanted cellular contents, remains unclear.

Cytomegalovirus drives Vδ1 γδ T cell expansion and clonality in common variable immunodeficiency.

The function and phenotype of γδ T cells in the context of common variable immunodeficiency (CVID) has not been explored. CVID is a primary immunodeficiency disorder characterized by impaired antibody responses resulting in increased susceptibility to infections. γδ T cells are a subset of unconventional T cells that play crucial roles in host defence against infections.

Activation of the human insulin receptor by non-insulin-related peptides.

The human insulin receptor signalling system plays a critical role in glucose homeostasis. Insulin binding brings about extensive conformational change in the receptor extracellular region that in turn effects trans-activation of the intracellular tyrosine kinase domains and downstream signalling. Of particular therapeutic interest is whether insulin receptor signalling can be replicated by molecules other than insulin.

How insulin-like growth factor I binds to a hybrid insulin receptor type 1 insulin-like growth factor receptor.

Monomers of the insulin receptor and type 1 insulin-like growth factor receptor (IGF-1R) can combine stochastically to form heterodimeric hybrid receptors. These hybrid receptors display ligand binding and signaling properties that differ from those of the homodimeric receptors. Here, we describe the cryoelectron microscopy structure of such a hybrid receptor in complex with insulin-like growth factor I (IGF-I).

Case Report: Cytomegalovirus Disease Is an Under-Recognized Contributor to Morbidity and Mortality in Common Variable Immunodeficiency.

Background: Common Variable Immunodeficiency (CVID) is classified as a 'Predominantly Antibody Deficiency' (PAD), but there is emerging evidence of cellular immunodeficiency in a subset of patients. This evidence includes CVID patients diagnosed with cytomegalovirus (CMV) infection, a hallmark of 'combined immunodeficiency'. CMV infection also has the potential to drive immune dysregulation contributing to significant morbidity and mortality in CVID.

How IGF-II Binds to the Human Type 1 Insulin-like Growth Factor Receptor.

Human type 1 insulin-like growth factor receptor (IGF-1R) signals chiefly in response to the binding of insulin-like growth factor I. Relatively little is known about the role of insulin-like growth factor II signaling via IGF-1R, despite the affinity of insulin-like growth factor II for IGF-1R being within an order of magnitude of that of insulin-like growth factor I. Here, we describe the cryoelectron microscopy structure of insulin-like growth factor II bound to a leucine-zipper-stabilized IGF-1R ectodomain, determined in two conformations to a maximum average resolution of 3.

The signalling conformation of the insulin receptor ectodomain.

Understanding the structural biology of the insulin receptor and how it signals is of key importance in the development of insulin analogs to treat diabetes. We report here a cryo-electron microscopy structure of a single insulin bound to a physiologically relevant, high-affinity version of the receptor ectodomain, the latter generated through attachment of C-terminal leucine zipper elements to overcome the conformational flexibility associated with ectodomain truncation. The resolution of the cryo-electron microscopy maps is 3.

How ligand binds to the type 1 insulin-like growth factor receptor.

Human type 1 insulin-like growth factor receptor is a homodimeric receptor tyrosine kinase that signals into pathways directing normal cellular growth, differentiation and proliferation, with aberrant signalling implicated in cancer. Insulin-like growth factor binding is understood to relax conformational restraints within the homodimer, initiating transphosphorylation of the tyrosine kinase domains. However, no three-dimensional structures exist for the receptor ectodomain to inform atomic-level understanding of these events.

Insulin Mimetic Peptide Disrupts the Primary Binding Site of the Insulin Receptor.

Sets of synthetic peptides that interact with the insulin receptor ectodomain have been discovered by phage display and reported in the literature. These peptides were grouped into three classes termed Site 1, Site 2, and Site 3 based on their mutual competition of binding to the receptor. Further refinement has yielded, in particular, a 36-residue Site 2-Site 1 fusion peptide, S519, that binds the insulin receptor with subnanomolar affinity and exhibits agonist activity in both lipogenesis and glucose uptake assays.

Higher-Resolution Structure of the Human Insulin Receptor Ectodomain: Multi-Modal Inclusion of the Insert Domain.

Insulin receptor (IR) signaling is critical to controlling nutrient uptake and metabolism. However, only a low-resolution (3.8 Å) structure currently exists for the IR ectodomain, with some segments ill-defined or unmodeled due to disorder.

Structural Congruency of Ligand Binding to the Insulin and Insulin/Type 1 Insulin-like Growth Factor Hybrid Receptors.

The homodimeric insulin and type 1 insulin-like growth factor receptors (IR and IGF-1R) share a common architecture and each can bind all three ligands within the family: insulin and insulin-like growth factors I and II (IGF-I and IFG-II). The receptor monomers also assemble as heterodimers, the primary ligand-binding sites of which each comprise the first leucine-rich repeat domain (L1) of one receptor type and an α-chain C-terminal segment (αCT) of the second receptor type. We present here crystal structures of IGF-I bound to such a hybrid primary binding site and of a ligand-free version of an IR αCT peptide bound to an IR L1 plus cysteine-rich domain construct (IR310.

How insulin engages its primary binding site on the insulin receptor.

Insulin receptor signalling has a central role in mammalian biology, regulating cellular metabolism, growth, division, differentiation and survival. Insulin resistance contributes to the pathogenesis of type 2 diabetes mellitus and the onset of Alzheimer's disease; aberrant signalling occurs in diverse cancers, exacerbated by cross-talk with the homologous type 1 insulin-like growth factor receptor (IGF1R). Despite more than three decades of investigation, the three-dimensional structure of the insulin-insulin receptor complex has proved elusive, confounded by the complexity of producing the receptor protein.

Solution structure of ectodomains of the insulin receptor family: the ectodomain of the type 1 insulin-like growth factor receptor displays asymmetry of ligand binding accompanied by limited conformational change.

The insulin receptor (IR) and the homologous Type 1 insulin-like growth factor receptor (IGF-1R) are cell-surface tyrosine kinase receptors that effect signaling within the respective pathways of glucose metabolism and normal human growth. While ligand binding to these receptors is assumed to result in a structural transition within the receptor ectodomain that then effects signal transduction across the cell membrane, little is known about the molecular detail of these events. Presented here are small-angle X-ray scattering data obtained from the IR and IGF-1R ectodomains in solution.

A thermodynamic study of ligand binding to the first three domains of the human insulin receptor: relationship between the receptor alpha-chain C-terminal peptide and the site 1 insulin mimetic peptides.

The C-terminal segment of the insulin receptor (IR) alpha-chain plays a critical role in insulin binding. This 16-residue peptide together with the central beta-sheet of the receptor L1 domain forms one of the insulin binding surfaces of the IR monomer. Here we use isothermal titration calorimetry to assay directly the binding of the IR alphaCT peptide to an IR construct (IR485) consisting of the three N-terminal domains of the receptor monomer.