ABSTRACT
Abiotic and biotic environments influence a myriad of plant-related processes, including growth, development, and the establishment and maintenance of interaction(s) with microbes. In the case of the latter, elevated temperature has been shown to be a key factor that underpins host resistance and pathogen virulence. In this study, we elucidate a role for Arabidopsis NON-RACE-SPECIFIC DISEASE RESISTANCE1 (NDR1) by exploiting effector-triggered immunity to define the regulation of plant host immunity in response to both pathogen infection and elevated temperature. We generated time-series RNA sequencing data of WT Col-0, an NDR1 overexpression line, and ndr1 and ics1-2 mutant plants under elevated temperature. Not surprisingly, the NDR1-overexpression line showed genotype-specific gene expression changes related to defense response and immune system function. The results described herein support a role for NDR1 in maintaining cell signaling during simultaneous exposure to elevated temperature and avirulent pathogen stressors.
Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis/metabolism , Arabidopsis Proteins/metabolism , Gene Expression Regulation, Plant , Plant Diseases/genetics , Plants/metabolism , Pseudomonas syringae , Temperature , Transcription Factors/metabolismABSTRACT
A new resveratrol trimer, vateriferol (1), having four cis-oriented methine protons and constituting four contiguous stereocenters, was isolated from the bark extract of Vateria copallifera by bioassay-guided fractionation using a combination of normal, reversed phase, and size exclusion column chromatography. The structure was established based on its spectroscopic data. Vateriferol (1) was evaluated in vitro for its antioxidant capacity, enzyme inhibitory activity, growth inhibitory activity on a number of cancer cell lines, neuroprotective activity, and anti-inflammatory activity. Vateriferol (1) exhibited AChE inhibitory activity (IC50 8.4 ± 0.2 µM), ORAC activity (2079 ± 0.20 TE/g), and neuroprotective activity at 1.5 µM using PC12 cells deprived of oxygen and glucose and lowered NO levels in lipopolysaccharide-stimulated SIM-A9 microglial cells at 14.7 and 73.6 µM. Vateriferol (1) exhibited weak cytotoxic potency (<50% growth inhibition) against the tested cell lines at 147.2 µM.
Subject(s)
Dipterocarpaceae/chemistry , Resveratrol/chemistry , Animals , Antineoplastic Agents, Phytogenic/isolation & purification , Antineoplastic Agents, Phytogenic/pharmacology , Antioxidants/chemistry , Antioxidants/isolation & purification , Antioxidants/pharmacology , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/isolation & purification , Enzyme Inhibitors/pharmacology , Molecular Structure , Neuroprotective Agents/chemistry , Neuroprotective Agents/isolation & purification , Neuroprotective Agents/pharmacology , PC12 Cells , Plant Bark/chemistry , Rats , Sri LankaABSTRACT
Interactions of cytosolic G protein coupled receptor kinase 2 (GRK2) with activated G protein coupled receptors (GPCRs) induce receptor phosphorylation and desensitization. GRK2 is recruited to active M3-muscarinic receptors (M3R) with the participation of the receptor, Gαq and Gßγ. Since we have shown that signaling efficacy of Gßγ is governed by its Gγ subtype identity, the present study examined whether recruitment of GRK2 to M3R is also Gγ subtype dependent. To capture the dynamics of GRK2-recruitment concurrently with GPCR-G protein activation, we employed live cell confocal imaging and a novel assay based on Gßγ translocation. Data show that M3R activation-induced GRK2 recruitment is Gγ subtype dependent in which Gßγ dimers with low PM-affinity Gγ9 exhibited a two-fold higher GRK2-recruitment compared to high PM affinity Gγ3 expressing cells. Since 12-mammalian Gγ types exhibit a cell and tissue specific expressions and the PM-affinity of a Gγ is linked to its subtype identity, our results indicate a mechanism by which Gγ profile of a cell controls GRK2 signaling and GPCR desensitization.
Subject(s)
G-Protein-Coupled Receptor Kinase 2/metabolism , GTP-Binding Protein beta Subunits/metabolism , GTP-Binding Protein gamma Subunits/metabolism , Receptor, Muscarinic M3/metabolism , Cell Membrane/metabolism , G-Protein-Coupled Receptor Kinase 2/genetics , GTP-Binding Protein beta Subunits/chemistry , GTP-Binding Protein beta Subunits/genetics , GTP-Binding Protein gamma Subunits/chemistry , GTP-Binding Protein gamma Subunits/classification , HeLa Cells , Humans , Kinetics , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Models, Molecular , Protein Interaction Domains and Motifs , Protein Transport/drug effects , Receptor, Muscarinic M3/genetics , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Signal Transduction/drug effects , Xanthenes/pharmacologyABSTRACT
Heterotrimeric guanine nucleotide-binding proteins (G proteins) deliver external signals to the cell interior, upon activation by the external signal stimulated G protein-coupled receptors (GPCRs).While the activated GPCRs control several pathways independently, activated G proteins control the vast majority of cellular and physiological functions, ranging from vision to cardiovascular homeostasis. Activated GPCRs dissociate GαGDPßγ heterotrimer into GαGTP and free Gßγ. Earlier, GαGTP was recognized as the primary signal transducer of the pathway and Gßγ as a passive signaling modality that facilitates the activity of Gα. However, Gßγ later found to regulate more number of pathways than GαGTP does. Once liberated from the heterotrimer, free Gßγ interacts and activates a diverse range of signaling regulators including kinases, lipases, GTPases, and ion channels, and it does not require any posttranslation modifications. Gßγ family consists of 48 members, which show cell- and tissue-specific expressions, and recent reports show that cells employ the subtype diversity in Gßγ to achieve desired signaling outcomes. In addition to activated GPCRs, which induce free Gßγ generation and the rate of GTP hydrolysis in Gα, which sequester Gßγ in the heterotrimer, terminating Gßγ signaling, additional regulatory mechanisms exist to regulate Gßγ activity. In this chapter, we discuss structure and function, subtype diversity and its significance in signaling regulation, effector activation, regulatory mechanisms as well as the disease relevance of Gßγ in eukaryotes.
Subject(s)
GTP-Binding Protein beta Subunits/metabolism , GTP-Binding Protein gamma Subunits/metabolism , Signal Transduction , Amino Acid Sequence , Animals , Binding Sites , GTP-Binding Protein beta Subunits/chemistry , GTP-Binding Protein gamma Subunits/chemistry , Humans , Models, BiologicalABSTRACT
Melanopsin (Opn4), a ubiquitously expressed photoreceptor in all classes of vertebrates, is crucial for both visual and non-visual signaling. Opn4 supports visual functions of the eye by sensing radiance levels and discriminating contrast and brightness. Non-image-forming functions of Opn4 not only regulate circadian behavior, but also control growth and development processes of the retina. It is unclear how a single photoreceptor could govern such a diverse range of physiological functions; a role in genetic hardwiring could be one explanation, but molecular and mechanistic evidence is lacking. In addition to its role in canonical Gq pathway activation, here we demonstrate that Opn4 efficiently activates Gi heterotrimers and signals through the G protein ßγ. Compared with the low levels of Gi pathway activation observed for several Gq-coupled receptors, the robust Gαi and Gßγ signaling of Opn4 led to both generation of PIP3 and directional migration of RAW264.7 macrophages. We propose that the ability of Opn4 to signal through Gαi and Gßγ subunits is a major contributor to its functional diversity.
