scholarly journals Membrane-Tethered Ligands: Tools for Cell-Autonomous Pharmacological Manipulation of Biological Circuits

Physiology ◽  
2013 ◽  
Vol 28 (3) ◽  
pp. 164-171 ◽  
Author(s):  
Charles Choi ◽  
Michael N. Nitabach
Keyword(s):  
Cell Surface ◽  
Biological Significance ◽  
Cell Surface Receptors ◽  
Surface Receptors ◽  
Membrane Tethering ◽  
A Cell ◽  
Cellular Circuits ◽  
Communication Pathway ◽  
Tethered Ligands

Detection of secreted signaling molecules by cognate cell surface receptors is a major intercellular communication pathway in cellular circuits that control biological processes. Understanding the biological significance of these connections would allow us to understand how cellular circuits operate as a whole. Membrane-tethered ligands are recombinant transgenes with structural modules that allow them to act on cell-surface receptors and ion channel subtypes with pharmacological specificity in a cell-autonomous manner. Membrane-tethered ligands have been successful in the specific manipulation of ion channels as well as G-protein-coupled receptors, and, in combination with cell-specific promoters, such manipulations have been restricted to genetically defined subpopulations within cellular circuits in vivo to induce specific phenotypes controlled by those circuits. These studies establish the membrane-tethering approach as a generally applicable method for dissecting neural and physiological circuits.

scholarly journals Redirecting Retroviral Tropism by Insertion of Short, Nondisruptive Peptide Ligands into Envelope

2002 ◽  
Vol 76 (7) ◽  
pp. 3558-3563 ◽  
Author(s):  
Timothy J. Gollan ◽  
Michael R. Green
Keyword(s):  
Cell Surface ◽  
Leukemia Virus ◽  
Envelope Proteins ◽  
Peptide Ligands ◽  
Viral Envelope ◽  
Moloney Murine Leukemia Virus ◽  
Cell Surface Receptors ◽  
Wild Type ◽  
Surface Receptors

ABSTRACT A potentially powerful approach for in vivo gene delivery is to target retrovirus to specific cells through interactions between cell surface receptors and appropriately modified viral envelope proteins. Previously, relatively large (>100 residues) protein ligands to cell surface receptors have been inserted at or near the N terminus of retroviral envelope proteins. Although viral tropism could be altered, the chimeric envelope proteins lacked full activity, and coexpression of wild-type envelope was required for production of transducing virus. Here we analyze more than 40 derivatives of ecotropic Moloney murine leukemia virus (MLV) envelope, containing insertions of short RGD-containing peptides, which are ligands for integrin receptors. In many cases pseudotyped viruses containing only the chimeric envelope protein could transduce human cells. The precise location, size, and flanking sequences of the ligand affected transduction specificity and efficiency. We conclude that retroviral tropism can be rationally reengineered by insertion of short peptide ligands and without the need to coexpress wild-type envelope.

scholarly journals Sulfated polysaccharides identified as inducers of neuropilin-1 internalization and functional inhibition of VEGF165 and semaphorin3A

Blood ◽  
2008 ◽  
Vol 111 (8) ◽  
pp. 4126-4136 ◽  
Author(s):  
Masashi Narazaki ◽  
Marta Segarra ◽  
Giovanna Tosato
Keyword(s):  
Cell Surface ◽  
Dextran Sulfate ◽  
Receptor Internalization ◽  
Sulfated Polysaccharides ◽  
Cell Surface Receptors ◽  
Ligand Interaction ◽  
Surface Receptors ◽  
Neuropilin 1

Abstract Neuropilin-1 (NRP1) and NRP2 are cell surface receptors shared by class 3 semaphorins and vascular endothelial growth factor (VEGF). Ligand interaction with NRPs selects the specific signal transducer, plexins for semaphorins or VEGF receptors for VEGF, and promotes NRP internalization, which effectively shuts down receptor-mediated signaling by a second ligand. Here, we show that the sulfated polysaccharides dextran sulfate and fucoidan, but not others, reduce endothelial cell-surface levels of NRP1, NRP2, and to a lesser extent VEGFR-1 and VEGFR-2, and block the binding and in vitro function of semaphorin3A and VEGF165. Administration of fucoidan to mice reduces VEGF165-induced angiogenesis and tumor neovascularization in vivo. We find that dextran sulfate and fucoidan can bridge the extracellular domain of NRP1 to that of the scavenger receptor expressed by endothelial cells I (SREC-I), and induce NRP1 and SREC-I coordinate internalization and trafficking to the lysosomes. Overexpression of SREC-I in SREC-I–negative cells specifically reduces cell-surface levels of NRP1, indicating that SREC-I mediates NRP1 internalization. These results demonstrate that engineered receptor internalization is an effective strategy for reducing levels and function of cell-surface receptors, and identify certain sulfated polysaccharides as “internalization inducers.”

In Vivo Internalization of the Somatostatin sst2A Receptor in Rat Brain: Evidence for Translocation of Cell-Surface Receptors into the Endosomal Recycling Pathway

2001 ◽  
Vol 17 (4) ◽  
pp. 646-661 ◽  
Author(s):  
Zsolt Csaba ◽  
Véronique Bernard ◽  
Lone Helboe ◽  
Marie-Thérèse Bluet-Pajot ◽  
Bertrand Bloch ◽  
...  
Keyword(s):  
Cell Surface ◽  
Rat Brain ◽  
Cell Surface Receptors ◽  
Surface Receptors ◽  
Endosomal Recycling ◽  
Recycling Pathway

Metabolic biotinylation of cell surface receptors for in vivo imaging

2006 ◽  
Vol 3 (5) ◽  
pp. 391-396 ◽  
Author(s):  
Bakhos A Tannous ◽  
Jan Grimm ◽  
Katherine F Perry ◽  
John W Chen ◽  
Ralph Weissleder ◽  
...  
Keyword(s):  
Cell Surface ◽  
In Vivo Imaging ◽  
Cell Surface Receptors ◽  
Surface Receptors

Interactions of VEGF isoforms with VEGFR-1, VEGFR-2, and neuropilin in vivo: a computational model of human skeletal muscle

2007 ◽  
Vol 292 (1) ◽  
pp. H459-H474 ◽  
Author(s):  
Feilim Mac Gabhann ◽  
Aleksander S. Popel
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Cell Surface ◽  
Computational Model ◽  
Receptor Activation ◽  
Cell Surface Receptors ◽  
Vastus Lateralis Muscle ◽  
Surface Receptors ◽  
Vegf Isoforms

The vascular endothelial growth factor (VEGF) family of cytokines is involved in the maintenance of existing adult blood vessels as well as in angiogenesis, the sprouting of new vessels. To study the proangiogenic activation of VEGF receptors (VEGFRs) by VEGF family members in skeletal muscle, we develop a computational model of VEGF isoforms (VEGF121, VEGF165), their cell surface receptors, and the extracellular matrix in in vivo tissue. We build upon our validated model of the biochemical interactions between VEGF isoforms and receptor tyrosine kinases (VEGFR-1 and VEGFR-2) and nonsignaling neuropilin-1 coreceptors in vitro. The model is general and could be applied to any tissue; here we apply the model to simulate the transport of VEGF isoforms in human vastus lateralis muscle, which is extensively studied in physiological experiments. The simulations predict the distribution of VEGF isoforms in resting (nonexercising) muscle and the activation of VEGFR signaling. Little of the VEGF protein in muscle is present as free, unbound extracellular cytokine; the majority is bound to the cell surface receptors or to the extracellular matrix. However, interstitial sequestration of VEGF165 does not affect steady-state receptor binding. In the absence of neuropilin, VEGF121 and VEGF165 behave similarly, but neuropilin enhances the binding of VEGF165 to VEGFR-2. This model is the first to study VEGF tissue distribution and receptor activation in human muscle, and it provides a platform for the design and evaluation of therapeutic approaches.

scholarly journals Computational kinetic model of VEGF trapping by soluble VEGF receptor-1: effects of transendothelial and lymphatic macromolecular transport

2009 ◽  
Vol 38 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Florence T. H. Wu ◽  
Marianne O. Stefanini ◽  
Feilim Mac Gabhann ◽  
Christopher D. Kontos ◽  
Brian H. Annex ◽  
...  
Keyword(s):  
Cell Surface ◽  
Transport Processes ◽  
Dominant Negative ◽  
Cell Surface Receptors ◽  
Vegf Receptor ◽  
Healthy Human ◽  
Receptor System ◽  
Surface Receptors ◽  
Macromolecular Transport

Vascular endothelial growth factor (VEGF) signal transduction through the cell surface receptors VEGFR1 and VEGFR2 regulates angiogenesis—the growth of new capillaries from preexistent microvasculature. Soluble VEGF receptor-1 (sVEGFR1), a nonsignaling truncated variant of VEGFR1, has been postulated to inhibit angiogenic signaling via direct sequestration of VEGF ligands or dominant-negative heterodimerization with surface VEGFRs. The relative contributions of these two mechanisms to sVEGFR1's purported antiangiogenic effects in vivo are currently unknown. We previously developed a computational model for predicting the compartmental distributions of VEGF and sVEGFR1 throughout the healthy human body by simulating the molecular interaction networks of the VEGF ligand-receptor system as well as intercompartmental macromolecular biotransport processes. In this study, we decipher the dynamic processes that led to our prior prediction that sVEGFR1, through its ligand trapping mechanism alone, does not demonstrate significant steady-state antiangiogenic effects. We show that sVEGFR1-facilitated tissue-to-blood shuttling of VEGF accounts for a counterintuitive and drastic elevation in plasma free VEGF concentrations after both intramuscular and intravascular sVEGFR1 infusion. While increasing intramuscular VEGF production reduces free sVEGFR1 levels through increased VEGF-sVEGFR1 complex formation, we demonstrate a competing and opposite effect in which increased VEGF occupancy of neuropilin-1 (NRP1) and the corresponding reduction in NRP1 availability for internalization of sVEGFR1 unexpectedly increases free sVEGFR1 levels. In conclusion, dynamic intercompartmental transport processes give rise to our surprising prediction that VEGF trapping alone does not account for sVEGFR1's antiangiogenic potential. sVEGFR1's interactions with cell surface receptors such as NRP1 are also expected to affect its molecular interplay with VEGF.

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