Phase separation of signaling molecules promotes T cell receptor signal transduction

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of American Association for the Advancement of Science for personal use, not for redistribution. The definitive version was published in Science 352 (2016): 595-599, doi:10.1126/science.aad9964.Activation of various cell surface receptors triggers the reorganization of downstream signaling molecules into micron- or submicron-sized clusters. However, the functional consequences of such clustering has been unclear. We biochemically reconstituted a 12-component signaling pathway on model membranes, beginning with T cell receptor (TCR) activation and ending with actin assembly. When TCR phoshophorylation was triggered, downstream signaling proteins spontaneously separated into liquid-like clusters that promoted signaling outputs both in vitro and in human Jurkat T cells. Reconstituted clusters were enriched in kinases but excluded phosphatases, and enhanced actin filament assembly by recruiting and organizing actin regulators. These results demonstrate that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling.This work was supported by the HCIA program of HHMI, the NIH (R01-GM56322 to M.K.R.) and Welch Foundation (I–1544 to M.K.R.). X.S. was supported by CRI Irvington postdoctoral fellowship. J.A.D. was supported by NRSA F32 award 5-F32-DK101188. E.H. was supported as a fellow of the Leukemia and Lymphoma Society. J.O. was supported by funds from Tobacco-Related Disease Research Program of the University of California (19FT-0090).2016-10-0

Mechanism of Activation and Inhibition of the HER4/ErbB4 Kinase

SummaryHER4/ErbB4 is a ubiquitously expressed member of the EGF/ErbB family of receptor tyrosine kinases that is essential for normal development of the heart, nervous system, and mammary gland. We report here crystal structures of the ErbB4 kinase domain in active and lapatinib-inhibited forms. Active ErbB4 kinase adopts an asymmetric dimer conformation essentially identical to that observed to be important for activation of the EGF receptor/ErbB1 kinase. Mutagenesis studies of intact ErbB4 in Ba/F3 cells confirm the importance of this asymmetric dimer for activation of intact ErbB4. Lapatinib binds to an inactive form of the ErbB4 kinase in a mode equivalent to its interaction with the EGF receptor. All ErbB4 residues contacted by lapatinib are conserved in the EGF receptor and HER2/ErbB2, which lapatinib also targets. These results demonstrate that key elements of kinase activation and inhibition are conserved among ErbB family members

Can authority change through deliberative politics? Lessons from the four decades of participatory forest policy reform in Nepal

Based on the review of relevant literature, this paper investigates how forest authority is produced or reproduced in the course of forest policy change, by drawing on the past four decades of participatory forest policy reform in Nepal. We analyze various waves of deliberative politics that emerged in different contexts related to the Himalayan crisis, the flow of international aid for conservation and development projects, civil conflict and democratic transition, and most recently the policy responses to climate change. The analysis shows how such deliberative politics contributed to the change or continuity of conventional authorities around forest policy and practice. It shows that despite notable participatory policy reform, the conventional authority has become further re-entrenched. Based on this analysis, we argue that efforts to understand forest policy change can be more meaningful if attention is paid to whether and how deliberative politics emerge to challenge the hegemonic claims to power and knowledge about resource governance practices. Such approach to policy analysis can open new possibilities for understanding democratic policy reform by explicating the nuances of deliberation and policy politics occurring at multiple scales

Phase separation of signaling molecules promotes T cell receptor signal transduction.

Activation of various cell surface receptors triggers the reorganization of downstream signaling molecules into micrometer- or submicrometer-sized clusters. However, the functional consequences of such clustering have been unclear. We biochemically reconstituted a 12-component signaling pathway on model membranes, beginning with T cell receptor (TCR) activation and ending with actin assembly. When TCR phosphorylation was triggered, downstream signaling proteins spontaneously separated into liquid-like clusters that promoted signaling outputs both in vitro and in human Jurkat T cells. Reconstituted clusters were enriched in kinases but excluded phosphatases and enhanced actin filament assembly by recruiting and organizing actin regulators. These results demonstrate that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling

Phase separation of signaling molecules promotes T cell receptor signal transduction

Activation of various cell surface receptors triggers the reorganization of downstream signaling molecules into micron- or submicron-sized clusters. However, the functional consequences of such clustering has been unclear. We biochemically reconstituted a 12-component signaling pathway on model membranes, beginning with T cell receptor (TCR) activation and ending with actin assembly. When TCR phoshophorylation was triggered, downstream signaling proteins spontaneously separated into liquid-like clusters that promoted signaling outputs both in vitro and in human Jurkat T cells. Reconstituted clusters were enriched in kinases but excluded phosphatases, and enhanced actin filament assembly by recruiting and organizing actin regulators. These results demonstrate that protein phase separation can create a distinct physical and biochemical compartment that facilitates signaling

Can Evidence and Voice Influence Policy? A Critical Assessment of Nepal's Forestry Sector Strategy, 2014

This article examines Nepal’s recently prepared Forestry Sector Strategy (FSS) (as of 2014) in terms of the use of scientific evidence and the quality of stakeholder participation. By reviewing the content and analyzing the context of its development during 2012–2014, we found that the transitional politics and overt influence of international development agencies dominated the process and content of the FSS. Although the FSS was developed through a significant stakeholder engagement, there was limited use of the available scientific evidence. The FSS was narrowly conceived as a deliverable of supporting aid programs, with limited demand for a politically meaningful policy processes. While civil society groups were consulted, they largely failed to present an independent voice due to their dependence on funding agencies. Our assessment calls for rethinking policy development in a way that facilitates assertive and independent participation by a range of actors and make better use of the available research

Computed structures of core eukaryotic protein complexes

Protein-protein interactions play critical roles in biology, but the structures of many eukaryotic protein complexes are unknown, and there are likely many interactions not yet identified. We take advantage of advances in proteome-wide amino acid coevolution analysis and deep-learning-based structure modeling to systematically identify and build accurate models of core eukaryotic protein complexes within the Saccharomyces cerevisiae proteome. We use a combination of RoseTTAFold and AlphaFold to screen through paired multiple sequence alignments for 8.3 million pairs of yeast proteins, identify 1505 likely to interact, and build structure models for 106 previously unidentified assemblies and 806 that have not been structurally characterized. These complexes, which have as many as five subunits, play roles in almost all key processes in eukaryotic cells and provide broad insights into biological function.N