Abstract Communication across membranes controls critical cellular processes and is achieved by receptors translating extracellular signals into selective cytoplasmic responses. While receptor tertiary structures can be readily characterized, receptor associations into quaternary structures are challenging to study and their implications in signal transduction remain poorly understood. Here, we report a computational approach for predicting receptor self-associations, and designing receptor oligomers with various quaternary structures and signaling properties. Using this approach, we designed chemokine receptor CXCR4 dimers with reprogrammed binding interactions, conformations, and abilities to activate distinct intracellular signaling proteins. In agreement with our predictions, the designed CXCR4s dimerized through distinct conformations and displayed different quaternary structural changes upon activation. Consistent with the active state models, all engineered CXCR4 oligomers activated the G protein Gi, but only specific dimer structures also recruited β-arrestins. Overall, we demonstrate that quaternary structures represent an important unforeseen mechanism of receptor biased signaling and reveal the existence of a bias switch at the dimer interface of several G protein-coupled receptors including CXCR4, mu-Opioid and type-2 Vasopressin receptors that selectively control the activation of G proteins vs β-arrestin-mediated pathways. The approach should prove useful for predicting and designing receptor associations to uncover and reprogram selective cellular signaling functions.
Significance ERK1/2 are important G protein-coupled receptor (GPCR) signaling effectors, but their role as possible GPCR regulators remains largely uncharted. We report that ERK1/2 activation leads to the phosphorylation of β-arrestin-2 on Ser14 and Thr276, promoting the intracellular sequestration of unliganded GPCRs. This subcellular redistribution results in the dampening of cell responsiveness to GPCRs’ ligand-mediated activation, positioning ERK1/2 as both a downstream effector and a negative regulator of GPCRs. Because ERK1/2 also is stimulated by receptor tyrosine kinases and is deregulated in many diseases, and because GPCRs respond to a large number of hormones and neurotransmitters, this newly uncovered regulatory process is poised to play a central role in controlling cell responsiveness in health and disease.
Dataset submitted in fulfillment of a 2010 Nantucket Biodiversity Initiative grant. From 2006 through 2008, we collected surface invertebrate specimens using pitfall traps from a variety of habitats on Nantucket Island and Tuckernuck Island, Massachusetts. In this project, we sorted 413 harvestmen from these samples, identified all specimens to species, and compared species distributions within four general habitat types. We identified all four species that appear on a historic species list from the late 1920’s and we added the non-native species Phalangium opilio. We found that H. maculosus prefers open heathland habitat over dense heathland and tupelo forest. Other species showed no significant preference for a specific habitat. We continue to sort specimens. allHarvestmentData.csv anovaData.csv - data used for anova dataDictionary.csv mckenna-foster-paradis-nbi-report-2011.pdf mckenna-foster-paradis-nbi-poster-2011.pdf - slides for a poster presentation at the 2011 NBIconference
In human cells, the expression of ∼1,000 genes is modulated throughout the cell cycle. Although some of these genes are controlled by specific transcriptional programs, very little is known about their post-transcriptional regulation. Here, we analyze the expression signature associated with all 687 RNA-binding proteins (RBPs) and identify 39 that significantly correlate with cell cycle mRNAs. We find that NF45 and NF90 play essential roles in mitosis, and transcriptome analysis reveals that they are necessary for the expression of a subset of mitotic mRNAs. Using proteomics, we identify protein clusters associated with the NF45-NF90 complex, including components of Staufen-mediated mRNA decay (SMD). We show that depletion of SMD components increases the binding of mitotic mRNAs to the NF45-NF90 complex and rescues cells from mitotic defects. Together, our results indicate that the NF45-NF90 complex plays essential roles in mitosis by competing with the SMD machinery for a common set of mRNAs.
Dataset submitted in fulfillment of a 2010 Nantucket Biodiversity Initiative grant. From 2006 through 2008, we collected surface invertebrate specimens using pitfall traps from a variety of habitats on Nantucket Island and Tuckernuck Island, Massachusetts. In this project, we sorted 413 harvestmen from these samples, identified all specimens to species, and compared species distributions within four general habitat types. We identified all four species that appear on a historic species list from the late 1920’s and we added the non-native species Phalangium opilio. We found that H. maculosus prefers open heathland habitat over dense heathland and tupelo forest. Other species showed no significant preference for a specific habitat. We continue to sort specimens. allHarvestmentData.csv anovaData.csv - data used for anova dataDictionary.csv mckenna-foster-paradis-nbi-report-2011.pdf mckenna-foster-paradis-nbi-poster-2011.pdf - slides for a poster presentation at the 2011 NBIconference
