Lung nociceptors initiate cough and bronchoconstriction. To elucidate if these fibers also contribute to allergic airway inflammation, we stimulated lung nociceptors with capsaicin and observed ...increased neuropeptide release and immune cell infiltration. In contrast, ablating Nav1.8+ sensory neurons or silencing them with QX-314, a charged sodium channel inhibitor that enters via large-pore ion channels to specifically block nociceptors, substantially reduced ovalbumin- or house-dust-mite-induced airway inflammation and bronchial hyperresponsiveness. We also discovered that IL-5, a cytokine produced by activated immune cells, acts directly on nociceptors to induce the release of vasoactive intestinal peptide (VIP). VIP then stimulates CD4+ and resident innate lymphoid type 2 cells, creating an inflammatory signaling loop that promotes allergic inflammation. Our results indicate that nociceptors amplify pathological adaptive immune responses and that silencing these neurons with QX-314 interrupts this neuro-immune interplay, revealing a potential new therapeutic strategy for asthma.
•Nociceptor sensory neuron ablation reduces allergic airway inflammation•QX-314 enters through large-pore ion channels to silence airway sensory neurons•IL-5 triggers sensory neuron release of peptides that drive immune cell responses•Silencing nociceptors is a new strategy to treat type 2 inflammation and allergies
Talbot et al. provide mechanistic insights into how neuro-immune interplay amplifies type 2 allergic airway inflammation. Based on this, they propose a new treatment strategy for asthma, using charged sodium channel blockers to selectively silence sensory neurons in the lung.
Irisin is secreted by muscle, increases with exercise, and mediates certain favorable effects of physical activity. In particular, irisin has been shown to have beneficial effects in adipose tissues, ...brain, and bone. However, the skeletal response to exercise is less clear, and the receptor for irisin has not been identified. Here we show that irisin binds to proteins of the αV class of integrins, and biophysical studies identify interacting surfaces between irisin and αV/β5 integrin. Chemical inhibition of the αV integrins blocks signaling and function by irisin in osteocytes and fat cells. Irisin increases both osteocytic survival and production of sclerostin, a local modulator of bone remodeling. Genetic ablation of FNDC5 (or irisin) completely blocks osteocytic osteolysis induced by ovariectomy, preventing bone loss and supporting an important role of irisin in skeletal remodeling. Identification of the irisin receptor should greatly facilitate our understanding of irisin’s function in exercise and human health.
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•The αV class of integrins are irisin receptors in osteocytes and adipose tissues•Irisin increases sclerostin expression in osteocytes to induce bone resorption•Genetic deletion of FNDC5 (or Irisin) completely blocks OVX-induced trabecular bone loss
Irisin, through its integrin receptor, promotes skeletal remodeling with implications for stemming bone loss.
G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent ...pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
•Introductory bases and equations of HDX-MS.•Protein dynamics explored by HDX-MS.•Representative case studies that measured by HDX-MS.•Future directions of HDX-MS.
Proteins are not rigid bodies under ...their physiological conditions. Here we discuss a solution-phase structural proteomics technique, hydrogen deuterium exchange coupled with mass spectrometry (HDX-MS), as a means to study protein dynamics, which can complement other structural approaches. We outline the background theory and highlight the utility of HDX-MS measurements in two case studies involving a nuclear receptor and an innate immunity receptor. We also discuss emerging software advances for improving data analysis and three-dimensional visualization.
Despite the growing evidence suggesting that long noncoding RNAs (lncRNAs) are critical regulators of several biological processes, their functions in the nervous system remain elusive. We have ...identified an lncRNA, GM12371, in hippocampal neurons that is enriched in the nucleus and necessary for synaptic communication, synapse density, synapse morphology, and dendritic tree complexity. Mechanistically, GM12371 regulates the expression of several genes involved in neuronal development and differentiation, as well as expression of specific lncRNAs and their cognate mRNA targets. Furthermore, we find that cAMP-PKA signaling upregulates the expression of GM12371 and that its expression is essential for the activity-dependent changes in synaptic transmission in hippocampal neurons. Taken together, our data establish a key role for GM12371 in regulating synapse function.
Hydrogen deuterium exchange mass spectrometry (HDX-MS) is a powerful biophysical technique being increasingly applied to a wide variety of problems. As the HDX-MS community continues to grow, ...adoption of best practices in data collection, analysis, presentation and interpretation will greatly enhance the accessibility of this technique to nonspecialists. Here we provide recommendations arising from community discussions emerging out of the first International Conference on Hydrogen-Exchange Mass Spectrometry (IC-HDX; 2017). It is meant to represent both a consensus viewpoint and an opportunity to stimulate further additions and refinements as the field advances.
Nuclear receptors (NRs) play central roles in metabolic syndrome, making them attractive drug targets despite the challenge of achieving functional selectivity. For instance, members of the ...thiazolidinedione class of insulin sensitizers offer robust efficacy but have been limited due to adverse effects linked to activation of genes not involved in insulin sensitization. Studies reviewed here provide strategies for targeting subsets of PPARγ target genes, enabling development of next-generation modulators with improved therapeutic index. Additionally, emerging evidence suggests that targeting the NRs ROR and Rev-erb holds promise for treating metabolic syndrome based on their involvement in circadian rhythm and metabolism.
The vitamin D receptor (VDR) functions as an obligate heterodimer in complex with the retinoid X receptor (RXR). These nuclear receptors are multidomain proteins, and it is unclear how various ...domains interact with one another within the nuclear receptor heterodimer. Here, we show that binding of intact heterodimer to DNA alters the receptor dynamics in regions remote from the DNA-binding domains (DBDs), including the coactivator binding surfaces of both co-receptors, and that the sequence of the DNA response element can determine these dynamics. Furthermore, agonist binding to the heterodimer results in changes in the stability of the VDR DBD, indicating that the ligand itself may play a role in DNA recognition. These data suggest a mechanism by which nuclear receptors show promoter specificity and have differential effects on various target genes, providing insight into the function of selective nuclear receptor modulators.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The RNA sensor MDA5 recruits the signaling adaptor MAVS to initiate type I interferon signaling and downstream antiviral responses, a process that requires K63-linked polyubiquitin chains. Here, we ...examined the mechanisms whereby K63-polyUb chain regulate MDA5 activation. Only long unanchored K63-polyUbn (n ≥ 8) could mediate tetramerization of the caspase activation and recruitment domains of MDA5 (MDA5CARDs). Cryoelectron microscopy structures of a polyUb13-bound MDA5CARDs tetramer and a polyUb11-bound MDA5CARDs-MAVSCARD assembly revealed a tower-like formation, wherein eight Ubs tethered along the outer rim of the helical shell, bridging MDA5CARDs and MAVSCARD tetramers into proximity. ATP binding and hydrolysis promoted the stabilization of RNA-bound MDA5 prior to MAVS activation via allosteric effects on CARDs-polyUb complex. Abundant ATP prevented basal activation of apo MDA5. Our findings reveal the ordered assembly of a MDA5 signaling complex competent to recruit and activate MAVS and highlight differences with RIG-I in terms of CARD orientation and Ub sensing that suggest different abilities to induce antiviral responses.
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•MDA5-MAVS signaling complex formation requires longer K63-polyUb chain than RIG-I•Cryo-EM structure of the MDA5CARDs-MAVSCARD-K63-polyUb signaling cascade•HDX-MS detects global receptor dynamics of MDA5 signaling in solution•MDA5-RNA fiber upon ATP stimuli promotes stabilization of the CARDs-polyUb complex
The RNA sensor MDA5 recruits the signaling adaptor MAVS to initiate type I interferon signaling and downstream antiviral responses. Through structural and biochemical studies, Song, Chen et al. reveal the ordered assembly of a MDA5 signaling complex mediated via a long K63-polyUb chain tethering mechanism and highlight differences with RIG-I that suggest different abilities to induce antiviral responses.
Retinoic acid inducible gene-I (RIG-I) ensures immune surveillance of viral RNAs bearing a 5'-triphosphate (5'ppp) moiety. Mutations in RIG-I (C268F and E373A) lead to impaired ATPase activity, ...thereby driving hyperactive signaling associated with autoimmune diseases. Here we report, using hydrogen/deuterium exchange, mechanistic models for dysregulated RIG-I proofreading that ultimately result in the improper recognition of cellular RNAs bearing 7-methylguanosine and N
-2'-O-methylation (Cap1) on the 5' end. Cap1-RNA compromises its ability to stabilize RIG-I helicase and blunts caspase activation and recruitment domains (CARD) partial opening by threefold. RIG-I H830A mutation restores Cap1-helicase engagement as well as CARDs partial opening event to a level comparable to that of 5'ppp. However, E373A RIG-I locks the receptor in an ATP-bound state, resulting in enhanced Cap1-helicase engagement and a sequential CARDs stimulation. C268F mutation renders a more tethered ring architecture and results in constitutive CARDs signaling in an ATP-independent manner.
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