Kinetics in Signal Transduction Pathways Involving Promiscuous Oligomerizing Receptors Can Be Determined by Receptor Specificity: Apoptosis Induction by TRAIL

Abstract

Here we show by computer modeling that kinetics and outcome of signal transduction in case of hetero-oligomerizing receptors of a promiscuous ligand largely depend on the relative amounts of its receptors. Promiscuous ligands can trigger the formation of nonproductive receptor complexes, which slows down the formation of active receptor complexes and thus can block signal transduction. Our model predicts that increasing the receptor specificity of the ligand without changing its binding parameters should result in faster receptor activation and enhanced signaling. We experimentally validated this hypothesis using the cytokine tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its four membrane-bound receptors as an example. Bypassing ligand-induced receptor hetero-oligomerization by receptor-selective TRAIL variants enhanced the kinetics of receptor activation and augmented apoptosis. Our results suggest that control of signaling pathways by promiscuous ligands could result in apparent slow biological kinetics and blocking signal transmission. By modulating the relative amount of the different receptors for the ligand, signaling processes like apoptosis can be accelerated or decelerated and even inhibited. It also implies that more effective treatments using protein therapeutics could be achieved simply by altering specificity Molecular & Cellular Proteomics

Decoy receptors block TRAIL sensitivity at a supracellular level: the role of stromal cells in controlling tumour TRAIL sensitivity

“…We used Colo205 cells where we have previously shown that neutralisation of DcR1 and DcR2 enhanced WT TRAILinduced apoptosis. 27 Colo205 cells were treated with neutralising antibodies against DcR1 and DcR2 for 1 h before treatment with TRAIL45 mutants for 3 h. The percentage of apoptotic cells was determined using Annexin V. As expected, neutralisation of DcR1 and DcR2 significantly enhanced WT TRAIL-mediated apoptosis, but it had no effect on the pro-apoptotic potency of TRAIL45-a, TRAIL45-c and TRAIL45-d confirming that these mutants have lost the ability to bind to the DcRs and thus provided us with a valuable tool to test the role of DcRs in tissue-level/transregulation of TRAIL sensitivity (Figure 2e). …”

“…Using the FoldX protein design algorithm, [23][24][25][26] amino-acid residues that form the ligand receptor-binding interface of TRAIL were mutated in silico to all possible natural aminoacid permutations and the change in the binding energy to all four TRAIL receptors was calculated as described previously. [24][25][26][27] Amino-acid substitutions that increased the energy of interaction between TRAIL-DcR1/DcR2 (that is, reduced binding affinity, positive ΔΔG i ) and mutations that decreased the energy of interaction between TRAIL and DR4/DR5 have been identified (Supplementary Figure 5).…”

“…27 Briefly, Colo205 cells were Abbreviations: DcR1, decoy receptor 1; DR4, death receptor 4; TRAIL, tumour necrosis factor-related apoptosis-inducing ligand. K D ratios were calculated relative to WT TRAIL.…”

Cell Death via DR5, but not DR4, Is Regulated by p53 in Myeloma Cells

“…Recently, Reis and colleagues showed that the increased sensitivity to a DR4-selective TRAIL mutant was associated with an increase in the activation of caspase-8 (43). Moreover, Szegezdi and colleagues showed that receptor-selective TRAIL variants enhanced the kinetics of receptor activation and that apoptosis largely depends on the relative amounts of its receptors (44). In melanoma, Kurbanov and colleagues showed that the resistance of cells to DR4-mediated apoptosis was related to the low level of caspase-8 or -10 and DR4 (45).…”

The Design and Characterization of Receptor-selective APRIL Variants

“…Receptor-selective TNF family ligands have been previously generated by employing rational design-or directed evolutionbased methods. Rational design approaches have been previously used to design receptor-selective TNF-␣ variants (35) and TRAIL variants (22,23,26,36). Directed evolution methods employing phage display were also used to generate receptorselective TRAIL variants (37), a receptor-selective TNF␣ antagonist (38), and a LIGHT/LT␤ variant that does not bind DcR3 (39).…”