Quantitative genetic screening reveals a Ragulator-FLCN feedback loop that regulates the mTORC1 pathway
Forward genetic screens in mammalian cell lines, such as RNAi and CRISPR-Cas9 screens, have made major contributions to the elucidation of diverse signaling pathways. Here, we exploited human haploid cells as a robust comparative screening platform and report a set of quantitative forward genetic screens for identifying regulatory mechanisms of mTORC1 signaling, a key growth control pathway that senses diverse metabolic states. Selected chemical and genetic perturbations in this screening platform, including rapamycin treatment and genetic ablation of the Ragulator subunit LAMTOR4, revealed the known core mTORC1 regulatory...
Source: Signal Transduction Knowledge Environment - September 15, 2020 Category: Science Authors: De Zan, E., van Stiphout, R., Gapp, B. V., Blomen, V. A., Brummelkamp, T. R., Nijman, S. M. B. Tags: STKE Research Resources Source Type: news

PD-1 suppresses the maintenance of cell couples between cytotoxic T cells and target tumor cells within the tumor
The killing of tumor cells by CD8+ T cells is suppressed by the tumor microenvironment, and increased expression of inhibitory receptors, including programmed cell death protein-1 (PD-1), is associated with tumor-mediated suppression of T cells. To find cellular defects triggered by tumor exposure and associated PD-1 signaling, we established an ex vivo imaging approach to investigate the response of antigen-specific, activated effector CD8+ tumor-infiltrating lymphocytes (TILs) after interaction with target tumor cells. Although TIL–tumor cell couples readily formed, couple stability deteriorated within minutes. Thi...
Source: Signal Transduction Knowledge Environment - September 15, 2020 Category: Science Authors: Ambler, R., Edmunds, G. L., Tan, S. L., Cirillo, S., Pernes, J. I., Ruan, X., Huete-Carrasco, J., Wong, C. C. W., Lu, J., Ward, J., Toti, G., Hedges, A. J., Dovedi, S. J., Murphy, R. F., Morgan, D. J., Wülfing, C. Tags: STKE Research Articles Source Type: news

COVID-19: All the wrong moves in all the wrong places
In this Editorial, Barrett and Yaffe highlight shortcomings in our collective response to the COVID-19 pandemic and underscore the need for more basic research into this new disease. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - September 15, 2020 Category: Science Authors: Barrett, C. D., Yaffe, M. B. Tags: STKE Editorial Source Type: news

Linking integrins and EVs in metastasis
Integrins mediate the uptake of extracellular vesicles into breast cancer cells. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - September 15, 2020 Category: Science Authors: Ferrarelli, L. K. Tags: STKE Editors ' Choice Source Type: news

Engineered IL-10 variants elicit potent immunomodulatory effects at low ligand doses
Interleukin-10 (IL-10) is a dimeric cytokine with both immunosuppressive and immunostimulatory activities; however, IL-10–based therapies have shown only marginal clinical benefits. Here, we explored whether the stability of the IL-10 receptor complex contributes to the immunomodulatory potency of IL-10. We generated an IL-10 mutant with enhanced affinity for its IL-10Rβ receptor using yeast surface display. Compared to the wild-type cytokine, the affinity-enhanced IL-10 variants recruited IL-10Rβ more efficiently into active cell surface signaling complexes and triggered greater STAT1 and STAT3 activation ...
Source: Signal Transduction Knowledge Environment - September 15, 2020 Category: Science Authors: Gorby, C., Sotolongo Bellon, J., Wilmes, S., Warda, W., Pohler, E., Fyfe, P. K., Cozzani, A., Ferrand, C., Walter, M. R., Mitra, S., Piehler, J., Moraga, I. Tags: STKE Research Articles Source Type: news

The hallmarks of cancer are also the hallmarks of wound healing
The Hanahan and Weinberg "hallmarks of cancer" papers provide a useful structure for considering the various mechanisms driving cancer progression, and the same might be useful for wound healing. In this Review, we highlight how tissue repair and cancer share cellular and molecular processes that are regulated in a wound but misregulated in cancer. From sustained proliferative signaling and the activation of invasion and angiogenesis to the promoting role of inflammation, there are many obvious parallels through which one process can inform the other. For some hallmarks, the parallels are more obscure. We propose...
Source: Signal Transduction Knowledge Environment - September 8, 2020 Category: Science Authors: MacCarthy-Morrogh, L., Martin, P. Tags: STKE Reviews Source Type: news

Quantitative kinase and phosphatase profiling reveal that CDK1 phosphorylates PP2Ac to promote mitotic entry
The reciprocal regulation of phosphoprotein phosphatases (PPPs) by protein kinases is essential to cell cycle progression and control, particularly during mitosis for which the role of kinases has been extensively studied. PPPs perform much of the serine/threonine dephosphorylation in eukaryotic cells and achieve substrate selectivity and specificity through the interaction of distinct regulatory subunits with conserved catalytic subunits in holoenzyme complexes. Using a mass spectrometry–based chemical proteomics approach to enrich, identify, and quantify endogenous PPP holoenzyme complexes combined with kinase prof...
Source: Signal Transduction Knowledge Environment - September 8, 2020 Category: Science Authors: Nasa, I., Cressey, L. E., Kruse, T., Hertz, E. P. T., Gui, J., Graves, L. M., Nilsson, J., Kettenbach, A. N. Tags: STKE Research Articles Source Type: news

ssRNA stimulates Piezo1 and serotonin synthesis
The gut produces serotonin upon activation of the Ca2+ channel Piezo1 by microbiome-derived ssRNA. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - September 8, 2020 Category: Science Authors: Wong, W. Tags: STKE Editors ' Choice Source Type: news

Metabolic adaptation to calorie restriction
In this study, we compared the global metabolic response to CR of mice housed at 22°C (the standard housing temperature) or at 30°C and found that thermoneutrality reverted 39 and 78% of total systemic or hypothalamic metabolic variations caused by CR, respectively. Systemic changes included pathways that control fuel use and energy expenditure during CR. Cognitive computing-assisted analysis of these metabolomics results helped to prioritize potential active metabolites that modulated the hypothermic response to CR. Last, we demonstrated with pharmacological approaches that nitric oxide (NO) produced through the c...
Source: Signal Transduction Knowledge Environment - September 8, 2020 Category: Science Authors: Guijas, C., Montenegro-Burke, J. R., Cintron-Colon, R., Domingo-Almenara, X., Sanchez-Alavez, M., Aguirre, C. A., Shankar, K., Majumder, E. L.- W., Billings, E., Conti, B., Siuzdak, G. Tags: STKE Research Resources Source Type: news

Mechanisms of autoregulation of C3G, activator of the GTPase Rap1, and its catalytic deregulation in lymphomas
C3G is a guanine nucleotide exchange factor (GEF) that regulates cell adhesion and migration by activating the GTPase Rap1. The GEF activity of C3G is stimulated by the adaptor proteins Crk and CrkL and by tyrosine phosphorylation. Here, we uncovered mechanisms of C3G autoinhibition and activation. Specifically, we found that two intramolecular interactions regulate the activity of C3G. First, an autoinhibitory region (AIR) within the central domain of C3G binds to and blocks the catalytic Cdc25H domain. Second, the binding of the protein’s N-terminal domain to its Ras exchanger motif (REM) is required for its GEF ac...
Source: Signal Transduction Knowledge Environment - September 1, 2020 Category: Science Authors: Carabias, A., Gomez-Hernandez, M., de Cima, S., Rodriguez-Blazquez, A., Moran-Vaquero, A., Gonzalez-Saenz, P., Guerrero, C., de Pereda, J. M. Tags: STKE Research Articles Source Type: news

Flipping an exosome switch
Nutrient stress changes the biogenesis and biological activity of exosomes in cancer cells. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - September 1, 2020 Category: Science Authors: VanHook, A. M. Tags: STKE Editors ' Choice Source Type: news

14-3-3 binding creates a memory of kinase action by stabilizing the modified state of phospholamban
The cardiac membrane protein phospholamban (PLN) is targeted by protein kinase A (PKA) at Ser16 and by Ca2+/calmodulin-dependent protein kinase II (CaMKII) at Thr17. β-Adrenergic stimulation and PKA-dependent phosphorylation of Ser16 acutely stimulate the sarcoplasmic reticulum calcium pump (SERCA) by relieving its inhibition by PLN. CaMKII-dependent phosphorylation may lead to longer-lasting SERCA stimulation and may sustain maladaptive Ca2+ handling. Here, we demonstrated that phosphorylation at either Ser16 or Thr17 converted PLN into a target for the phosphoadaptor protein 14-3-3 with different affinities. 14-3-3 ...
Source: Signal Transduction Knowledge Environment - September 1, 2020 Category: Science Authors: Menzel, J., Kownatzki-Danger, D., Tokar, S., Ballone, A., Unthan-Fechner, K., Kilisch, M., Lenz, C., Urlaub, H., Mori, M., Ottmann, C., Shattock, M. J., Lehnart, S. E., Schwappach, B. Tags: STKE Research Articles Source Type: news

{micro}-Opioid receptor-induced synaptic plasticity in dopamine neurons mediates the rewarding properties of anabolic androgenic steroids
Anabolic androgenic steroids (AAS) have medical utility but are often abused, and the effects of AAS on reward circuits in the brain have been suggested to lead to addiction. We investigated the previously reported correlations between AAS and the endogenous μ-opioid system in the rewarding properties of AAS in mice. We found that a single injection of a supraphysiological dose of natural or synthetic AAS strengthened excitatory synaptic transmission in putative ventral tegmental area (VTA) dopaminergic neurons. This effect was associated with the activation of μ-opioid receptors (MORs) and an increase in β-endo...
Source: Signal Transduction Knowledge Environment - September 1, 2020 Category: Science Authors: Bontempi, L., Bonci, A. Tags: STKE Research Articles Source Type: news

Growth factors and SARS-CoV-2
Phosphoproteomics analysis reveals that blocking growth factor receptor signaling inhibits SARS-CoV-replication. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - August 25, 2020 Category: Science Authors: Foley, J. F. Tags: STKE Editors ' Choice Source Type: news

Blastocyst-induced ATP release from luminal epithelial cells initiates decidualization through the P2Y2 receptor in mice
Embryo implantation involves a sterile inflammatory reaction that is required for the invasion of the blastocyst into the decidua. Adenosine triphosphate (ATP) released from stressed or injured cells acts as an important signaling molecule to regulate many key physiological events, including sterile inflammation. We found that the amount of ATP in the uterine luminal fluid of mice increased during the peri-implantation period, and this depended on the presence of an embryo. We further showed that the release of ATP from receptive epithelial cells was likely stimulated by lactate released from the blastocyst through connexi...
Source: Signal Transduction Knowledge Environment - August 25, 2020 Category: Science Authors: Gu, X.-W., Chen, Z.-C., Yang, Z.-S., Yang, Y., Yan, Y.-P., Liu, Y.-F., Pan, J.-M., Su, R.-W., Yang, Z.-M. Tags: STKE Research Articles Source Type: news

An allosteric site on MKP5 reveals a strategy for small-molecule inhibition
The mitogen-activated protein kinase (MAPK) phosphatases (MKPs) have been considered "undruggable," but their position as regulators of the MAPKs makes them promising therapeutic targets. MKP5 has been suggested as a potential target for the treatment of dystrophic muscle disease. Here, we identified an inhibitor of MKP5 using a p38α MAPK–derived, phosphopeptide-based small-molecule screen. We solved the structure of MKP5 in complex with this inhibitor, which revealed a previously undescribed allosteric binding pocket. Binding of the inhibitor to this pocket collapsed the MKP5 active site and was pred...
Source: Signal Transduction Knowledge Environment - August 25, 2020 Category: Science Authors: Gannam, Z. T. K., Min, K., Shillingford, S. R., Zhang, L., Herrington, J., Abriola, L., Gareiss, P. C., Pantouris, G., Tzouvelekis, A., Kaminski, N., Zhang, X., Yu, J., Jamali, H., Ellman, J. A., Lolis, E., Anderson, K. S., Bennett, A. M. Tags: STKE Research Articles Source Type: news

Degradation of 5hmC-marked stalled replication forks by APE1 causes genomic instability
Synthetic lethality between poly(ADP-ribose) polymerase (PARP) inhibition and BRCA deficiency is exploited to treat breast and ovarian tumors. However, resistance to PARP inhibitors (PARPis) is common. To identify potential resistance mechanisms, we performed a genome-wide RNAi screen in BRCA2-deficient mouse embryonic stem cells and validation in KB2P1.21 mouse mammary tumor cells. We found that resistance to multiple PARPi emerged with reduced expression of TET2 (ten-eleven translocation), which promotes DNA demethylation by oxidizing 5-methylcytosine (5mC) to 5-hydroxymethycytosine (5hmC) and other products. TET2 knockd...
Source: Signal Transduction Knowledge Environment - August 18, 2020 Category: Science Authors: Kharat, S. S., Ding, X., Swaminathan, D., Suresh, A., Singh, M., Sengodan, S. K., Burkett, S., Marks, H., Pamala, C., He, Y., Fox, S. D., Buehler, E. C., Muegge, K., Martin, S. E., Sharan, S. K. Tags: STKE Research Articles Source Type: news

Kinetics of receptor tyrosine kinase activation define ERK signaling dynamics
In responses to activation of receptor tyrosine kinases (RTKs), crucial cell fate decisions depend on the duration and dynamics of ERK signaling. In PC12 cells, epidermal growth factor (EGF) induces transient ERK activation that leads to cell proliferation, whereas nerve growth factor (NGF) promotes sustained ERK activation and cell differentiation. These differences have typically been assumed to reflect distinct feedback mechanisms in the Raf-MEK-ERK signaling network, with the receptors themselves acting as simple upstream inputs. We failed to confirm the expected differences in feedback type when investigating transien...
Source: Signal Transduction Knowledge Environment - August 18, 2020 Category: Science Authors: Kiyatkin, A., van Alderwerelt van Rosenburgh, I. K., Klein, D. E., Lemmon, M. A. Tags: STKE Research Articles Source Type: news

A prosocial neuroligin
NLGN3 links oxytocin signaling, protein synthesis, and social behavior in a mouse model of autism. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - August 18, 2020 Category: Science Authors: Ferrarelli, L. K. Tags: STKE Editors ' Choice Source Type: news

GULP1 regulates the NRF2-KEAP1 signaling axis in urothelial carcinoma
Disruption of the KEAP1-NRF2 pathway results in the transactivation of NRF2 target genes, consequently inducing cell proliferation and other phenotypic changes in cancer cells. Here, we demonstrated that GULP1 was a KEAP1-binding protein that maintained actin cytoskeleton architecture and helped KEAP1 to sequester NRF2 in the cytoplasm. In urothelial carcinoma of the bladder (UCB), silencing of GULP1 facilitated the nuclear accumulation of NRF2, led to constitutive activation of NRF2 signaling, and conferred resistance to the platinum drug cisplatin. Knockdown of GULP1 in UCB cells promoted tumor cell proliferation in vitr...
Source: Signal Transduction Knowledge Environment - August 18, 2020 Category: Science Authors: Hayashi, M., Guida, E., Inokawa, Y., Goldberg, R., Reis, L. O., Ooki, A., Pilli, M., Sadhukhan, P., Woo, J., Choi, W., Izumchenko, E., Gonzalez, L. M., Marchionni, L., Zhavoronkov, A., Brait, M., Bivalacqua, T., Baras, A., Netto, G. J., Koch, W., Singh, A Tags: STKE Research Articles Source Type: news

Targeting the kinase insert loop of PERK selectively modulates PERK signaling without systemic toxicity in mice
Chronic activation of the unfolded protein response (UPR), notably the branch comprising the kinase PERK and the translation initiation factor eIF2α, is a pathological feature of many neurodegenerative diseases caused by protein misfolding. Partial reduction of UPR signaling at the level of phosphorylated eIF2α is neuroprotective and avoids the pancreatic toxicity caused by full inhibition of PERK kinase activity. However, other stress pathways besides the UPR converge on phosphorylated eIF2α in the integrated stress response (ISR), which is critical to normal cellular function. We explored whether partia...
Source: Signal Transduction Knowledge Environment - August 11, 2020 Category: Science Authors: Hughes, D. T., Halliday, M., Smith, H. L., Verity, N. C., Molloy, C., Radford, H., Butcher, A. J., Mallucci, G. R. Tags: STKE Research Articles Source Type: news

Bacterial invaders drive CRC progression
The oral bacterium Fusobacterium nucleatum is often found in colorectal cancer (CRC). In the 21 July 2020 issue of Science Signaling, Casasanta et al. show that CRC cell–resident F. nucleatum promotes cytokine secretion that may potentiate tumor growth and metastatic progression in patients. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - August 11, 2020 Category: Science Authors: Meyerson, M. Tags: STKE Focus Source Type: news

Oxidative cross-linking of fibronectin confers protease resistance and inhibits cellular migration
The oxidation of tyrosine residues to generate o,o'-dityrosine cross-links in extracellular proteins is necessary for the proper function of the extracellular matrix (ECM) in various contexts in invertebrates. Tyrosine oxidation is also required for the biosynthesis of thyroid hormone in vertebrates, and there is evidence for oxidative cross-linking reactions occurring in extracellular proteins secreted by myofibroblasts. The ECM protein fibronectin circulates in the blood as a globular protein that dimerizes through disulfide bridges generated by cysteine oxidation. We found that cellular (fibrillar) fibronectin on the su...
Source: Signal Transduction Knowledge Environment - August 11, 2020 Category: Science Authors: Locy, M. L., Rangarajan, S., Yang, S., Johnson, M. R., Bernard, K., Kurundkar, A., Bone, N. B., Zmijewski, J. W., Byun, J., Pennathur, S., Zhou, Y., Thannickal, V. J. Tags: STKE Research Articles Source Type: news

A better workout without PHD3
PHD3 deficiency increases fatty acid oxidation in skeletal muscle and improves endurance exercise performance. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - August 11, 2020 Category: Science Authors: Wong, W. Tags: STKE Editors ' Choice Source Type: news

The collagen receptor glycoprotein VI promotes platelet-mediated aggregation of {beta}-amyloid
Cerebral amyloid angiopathy (CAA) and β-amyloid (Aβ) deposition in the brain parenchyma are hallmarks of Alzheimer’s disease (AD). We previously reported that platelets contribute to Aβ aggregation in cerebral vessels by secreting the factor clusterin upon binding of Aβ40 to the fibrinogen receptor integrin αIIbβ3. Here, we investigated the contribution of the collagen receptor GPVI (glycoprotein VI) in platelet-induced amyloid aggregation. Using platelets isolated from GPVI–wild type and GPVI-deficient human donors and mice, we found that Aβ40 bound to GPVI, which induced th...
Source: Signal Transduction Knowledge Environment - August 4, 2020 Category: Science Authors: Donner, L., Toska, L. M., Krüger, I., Gröniger, S., Barroso, R., Burleigh, A., Mezzano, D., Pfeiler, S., Kelm, M., Gerdes, N., Watson, S. P., Sun, Y., Elvers, M. Tags: STKE Research Articles Source Type: news

An interspecies translation model implicates integrin signaling in infliximab-resistant inflammatory bowel disease
Anti–tumor necrosis factor (anti-TNF) therapy resistance is a major clinical challenge in inflammatory bowel disease (IBD), due, in part, to insufficient understanding of disease-site, protein-level mechanisms. Although proteomics data from IBD mouse models exist, data and phenotype discrepancies contribute to confounding translation from preclinical animal models of disease to clinical cohorts. We developed an approach called translatable components regression (TransComp-R) to overcome interspecies and trans-omic discrepancies between mouse models and human subjects. TransComp-R combines mouse proteomic data with pa...
Source: Signal Transduction Knowledge Environment - August 4, 2020 Category: Science Authors: Brubaker, D. K., Kumar, M. P., Chiswick, E. L., Gregg, C., Starchenko, A., Vega, P. N., Southard-Smith, A. N., Simmons, A. J., Scoville, E. A., Coburn, L. A., Wilson, K. T., Lau, K. S., Lauffenburger, D. A. Tags: STKE Research Articles Source Type: news

Structural insights into the signal transduction mechanism of the K+-sensing two-component system KdpDE
Two-component systems (TCSs), which consist of a histidine kinase (HK) sensor and a response regulator (RR), are important for bacteria to quickly sense and respond to various environmental signals. HKs and RRs typically function as a cognate pair, interacting only with one another to transduce signaling. Precise signal transduction in a TCS depends on the specific interactions between the receiver domain (RD) of the RR and the dimerization and histidine phosphorylation domain (DHp) of the HK. Here, we determined the complex structure of KdpDE, a TCS consisting of the HK KdpD and the RR KdpE, which is responsible for K+ ho...
Source: Signal Transduction Knowledge Environment - August 4, 2020 Category: Science Authors: Xie, M., Wu, M., Han, A. Tags: STKE Research Articles Source Type: news

Coordinating a neutrophil swarm
Ca2+ and ATP signaling control the self-organized, collective behaviors of neutrophils at wound sites. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - August 4, 2020 Category: Science Authors: VanHook, A. M. Tags: STKE Editors ' Choice Source Type: news

Facilitating RSV entry
Binding of respiratory syncytial virus to the receptor IGF-1R stimulates viral entry in a PKC-dependent manner. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - July 28, 2020 Category: Science Authors: Foley, J. F. Tags: STKE Editors ' Choice Source Type: news

The mitophagy effector FUNDC1 controls mitochondrial reprogramming and cellular plasticity in cancer cells
Mitochondria are signaling hubs in eukaryotic cells. Here, we showed that the mitochondrial FUN14 domain–containing protein-1 (FUNDC1), an effector of Parkin-independent mitophagy, also participates in cellular plasticity by sustaining oxidative bioenergetics, buffering ROS production, and supporting cell proliferation. Targeting this pathway in cancer cells suppressed tumor growth but rendered transformed cells more motile and invasive in a manner dependent on ROS-mediated mitochondrial dynamics and mitochondrial repositioning to the cortical cytoskeleton. Global metabolomics and proteomics profiling identified a FU...
Source: Signal Transduction Knowledge Environment - July 28, 2020 Category: Science Authors: Li, J., Agarwal, E., Bertolini, I., Seo, J. H., Caino, M. C., Ghosh, J. C., Kossenkov, A. V., Liu, Q., Tang, H.-Y., Goldman, A. R., Languino, L. R., Speicher, D. W., Altieri, D. C. Tags: STKE Research Articles Source Type: news

A dynamic mouse peptidome landscape reveals probiotic modulation of the gut-brain axis
Certain probiotics have beneficial effects on the function of the central nervous system through modulation of the gut-brain axis. Here, we describe a dynamic landscape of the peptidome across multiple brain regions, modulated by oral administration of different probiotic species over various times. The spatiotemporal and strain-specific changes of the brain peptidome correlated with the composition of the gut microbiome. The hippocampus exhibited the most sensitive response to probiotic treatment. The administration of heat-killed probiotics altered the hippocampus peptidome but did not substantially change the gut microb...
Source: Signal Transduction Knowledge Environment - July 28, 2020 Category: Science Authors: Zhang, P., Wu, X., Liang, S., Shao, X., Wang, Q., Chen, R., Zhu, W., Shao, C., Jin, F., Jia, C. Tags: STKE Research Resources Source Type: news

Fusobacterium nucleatum host-cell binding and invasion induces IL-8 and CXCL1 secretion that drives colorectal cancer cell migration
Fusobacterium nucleatum is implicated in accelerating colorectal cancer (CRC) and is found within metastatic CRC cells in patient biopsies. Here, we found that bacterial invasion of CRC cells and cocultured immune cells induced a differential cytokine secretion that may contribute to CRC metastasis. We used a modified galactose kinase markerless gene deletion approach and found that F. nucleatum invaded cultured HCT116 CRC cells through the bacterial surface adhesin Fap2. In turn, Fap2-dependent invasion induced the secretion of the proinflammatory cytokines IL-8 and CXCL1, which are associated with CRC progression and pro...
Source: Signal Transduction Knowledge Environment - July 21, 2020 Category: Science Authors: Casasanta, M. A., Yoo, C. C., Udayasuryan, B., Sanders, B. E., Umana, A., Zhang, Y., Peng, H., Duncan, A. J., Wang, Y., Li, L., Verbridge, S. S., Slade, D. J. Tags: STKE Research Articles Source Type: news

New connections: Redox regulation of kinases
Several studies glean insight into how kinases are structurally regulated by reversible oxidation. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - July 21, 2020 Category: Science Authors: Ferrarelli, L. K. Tags: STKE Editors ' Choice Source Type: news

Redox priming promotes Aurora A activation during mitosis
In this study, x-ray crystal structures of the Aurora A kinase domain delineate redox-sensitive cysteine residues that, upon covalent modification, can allosterically regulate kinase activity and oligomerization state. We showed in both Xenopus laevis egg extracts and mammalian cells that a conserved cysteine residue within the Aurora A activation loop is crucial for Aurora A activation by autophosphorylation. We further showed that covalent disulfide adducts of this residue promote autophosphorylation of the Aurora A kinase domain. These findings reveal a potential mechanistic link between Aurora A activation and changes ...
Source: Signal Transduction Knowledge Environment - July 21, 2020 Category: Science Authors: Lim, D. C., Joukov, V., Rettenmaier, T. J., Kumagai, A., Dunphy, W. G., Wells, J. A., Yaffe, M. B. Tags: STKE Research Articles Source Type: news

Heterogeneity in human hippocampal CaMKII transcripts reveals allosteric hub-dependent regulation
Calcium/calmodulin-dependent protein kinase II (CaMKII) plays a central role in Ca2+ signaling throughout the body. In the hippocampus, CaMKII is required for learning and memory. Vertebrate genomes encode four CaMKII homologs: CaMKIIα, CaMKIIβ, CaMKII, and CaMKII. All CaMKIIs consist of a kinase domain, a regulatory segment, a variable linker region, and a hub domain, which is responsible for oligomerization. The four proteins differ primarily in linker length and composition because of extensive alternative splicing. Here, we report the heterogeneity of CaMKII transcripts in three complex samples of human hipp...
Source: Signal Transduction Knowledge Environment - July 21, 2020 Category: Science Authors: Sloutsky, R., Dziedzic, N., Dunn, M. J., Bates, R. M., Torres-Ocampo, A. P., Boopathy, S., Page, B., Weeks, J. G., Chao, L. H., Stratton, M. M. Tags: STKE Research Articles Source Type: news

Untangling the ties that bind different systemic signals in plants
Systemic signaling in plants is orchestrated by a complex network of interconnected systemic signals and cell types. In this issue of Science Signaling, Shao et al. unveil how different wound-induced signals integrate into a well-regulated systemic response. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - July 14, 2020 Category: Science Authors: Fichman, Y., Zandalinas, S. I., Mittler, R. Tags: STKE Focus Source Type: news

New connections: Flux and distance in Ca2+ signaling
Understanding ER-to-mitochondrial Ca2+ flux may provide ways to correct mitochondrial dysfunction in various diseases. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - July 14, 2020 Category: Science Authors: Wong, W. Tags: STKE Editors ' Choice Source Type: news

Functional anatomy of the full-length CXCR4-CXCL12 complex systematically dissected by quantitative model-guided mutagenesis
Because of their prominent roles in development, cancer, and HIV, the chemokine receptor CXCR4 and its ligand CXCL12 have been the subject of numerous structural and functional studies, but the determinants of ligand binding, selectivity, and signaling are still poorly understood. Here, building on our latest structural model, we used a systematic mutagenesis strategy to dissect the functional anatomy of the CXCR4-CXCL12 complex. Key charge swap mutagenesis experiments provided evidence for pairwise interactions between oppositely charged residues in the receptor and chemokine, confirming the accuracy of the predicted orie...
Source: Signal Transduction Knowledge Environment - July 14, 2020 Category: Science Authors: Stephens, B. S., Ngo, T., Kufareva, I., Handel, T. M. Tags: STKE Research Articles Source Type: news

Two glutamate- and pH-regulated Ca2+ channels are required for systemic wound signaling in Arabidopsis
Plants defend against herbivores and nematodes by rapidly sending signals from the wounded sites to the whole plant. We investigated how plants generate and transduce these rapidly moving, long-distance signals referred to as systemic wound signals. We developed a system for measuring systemic responses to root wounding in Arabidopsis thaliana. We found that root wounding or the application of glutamate to wounded roots was sufficient to trigger root-to-shoot Ca2+ waves and slow wave potentials (SWPs). Both of these systemic signals were inhibited by either disruption of both GLR3.3 and GLR3.6, which encode glutamate recep...
Source: Signal Transduction Knowledge Environment - July 14, 2020 Category: Science Authors: Shao, Q., Gao, Q., Lhamo, D., Zhang, H., Luan, S. Tags: STKE Research Articles Source Type: news

Cancer cells with defective oxidative phosphorylation require endoplasmic reticulum-to-mitochondria Ca2+ transfer for survival
Spontaneous Ca2+ signaling from the InsP3R intracellular Ca2+ release channel to mitochondria is essential for optimal oxidative phosphorylation (OXPHOS) and ATP production. In cells with defective OXPHOS, reductive carboxylation replaces oxidative metabolism to maintain amounts of reducing equivalents and metabolic precursors. To investigate the role of mitochondrial Ca2+ uptake in regulating bioenergetics in these cells, we used OXPHOS-competent and OXPHOS-defective cells. Inhibition of InsP3R activity or mitochondrial Ca2+ uptake increased α-ketoglutarate (αKG) abundance and the NAD+/NADH ratio, indicating t...
Source: Signal Transduction Knowledge Environment - July 14, 2020 Category: Science Authors: Cardenas, C., Lovy, A., Silva-Pavez, E., Urra, F., Mizzoni, C., Ahumada-Castro, U., Bustos, G., Jana, F., Cruz, P., Farias, P., Mendoza, E., Huerta, H., Murgas, P., Hunter, M., Rios, M., Cerda, O., Georgakoudi, I., Zakarian, A., Molgo, J., Foskett, J. K. Tags: STKE Research Articles Source Type: news

A redox-active switch in fructosamine-3-kinases expands the regulatory repertoire of the protein kinase superfamily
Aberrant regulation of metabolic kinases by altered redox homeostasis substantially contributes to aging and various diseases, such as diabetes. We found that the catalytic activity of a conserved family of fructosamine-3-kinases (FN3Ks), which are evolutionarily related to eukaryotic protein kinases, is regulated by redox-sensitive cysteine residues in the kinase domain. The crystal structure of the FN3K homolog from Arabidopsis thaliana revealed that it forms an unexpected strand-exchange dimer in which the ATP-binding P-loop and adjoining β strands are swapped between two chains in the dimer. This dimeric configura...
Source: Signal Transduction Knowledge Environment - July 7, 2020 Category: Science Authors: Shrestha, S., Katiyar, S., Sanz-Rodriguez, C. E., Kemppinen, N. R., Kim, H. W., Kadirvelraj, R., Panagos, C., Keyhaninejad, N., Colonna, M., Chopra, P., Byrne, D. P., Boons, G. J., van der Knaap, E., Eyers, P. A., Edison, A. S., Wood, Z. A., Kannan, N. Tags: STKE Research Articles Source Type: news

Fat cells help wounds heal
Dermal adipocytes promote wound healing by recruiting macrophages and transdifferentiating into myofibroblasts. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - July 7, 2020 Category: Science Authors: VanHook, A. M. Tags: STKE Editors ' Choice Source Type: news

BMP-1 disrupts cell adhesion and enhances TGF-{beta} activation through cleavage of the matricellular protein thrombospondin-1
Bone morphogenetic protein 1 (BMP-1) is an important metalloproteinase that synchronizes growth factor activation with extracellular matrix assembly during morphogenesis and tissue repair. The mechanisms by which BMP-1 exerts these effects are highly context dependent. Because BMP-1 overexpression induces marked phenotypic changes in two human cell lines (HT1080 and 293-EBNA cells), we investigated how BMP-1 simultaneously affects cell-matrix interactions and growth factor activity in these cells. Increasing BMP-1 led to a loss of cell adhesion that depended on the matricellular glycoprotein thrombospondin-1 (TSP-1). BMP-1...
Source: Signal Transduction Knowledge Environment - July 7, 2020 Category: Science Authors: Anastasi, C., Rousselle, P., Talantikite, M., Tessier, A., Cluzel, C., Bachmann, A., Mariano, N., Dussoyer, M., Alcaraz, L. B., Fortin, L., Aubert, A., Delolme, F., El Kholti, N., Armengaud, J., Fournie, P., Auxenfans, C., Valcourt, U., Goff, S. V.-L., Mo Tags: STKE Research Articles Source Type: news

Aurora A regulation by reversible cysteine oxidation reveals evolutionarily conserved redox control of Ser/Thr protein kinase activity
In this study, we found that the catalytic activity of the Ser/Thr kinase Aurora A was inhibited by the oxidation of a conserved cysteine residue (Cys290) that lies adjacent to Thr288, a critical phosphorylation site in the activation segment. Cys is present at the equivalent position in ~100 human Ser/Thr kinases, a residue that we found was important not only for the activity of human Aurora A but also for that of fission yeast MAPK-activated kinase (Srk1) and PKA (Pka1). Moreover, the presence of this conserved Cys predicted biochemical redox sensitivity among a cohort of human CAMK, AGC, and AGC-like kinases. Thus, we ...
Source: Signal Transduction Knowledge Environment - July 7, 2020 Category: Science Authors: Byrne, D. P., Shrestha, S., Galler, M., Cao, M., Daly, L. A., Campbell, A. E., Eyers, C. E., Veal, E. A., Kannan, N., Eyers, P. A. Tags: STKE Research Articles Source Type: news

The ER chaperone calnexin controls mitochondrial positioning and respiration
Chaperones in the endoplasmic reticulum (ER) control the flux of Ca2+ ions into mitochondria, thereby increasing or decreasing the energetic output of the oxidative phosphorylation pathway. An example is the abundant ER lectin calnexin, which interacts with sarco/endoplasmic reticulum Ca2+ ATPase (SERCA). We found that calnexin stimulated the ATPase activity of SERCA by maintaining its redox state. This function enabled calnexin to control how much ER Ca2+ was available for mitochondria, a key determinant for mitochondrial bioenergetics. Calnexin-deficient cells compensated for the loss of this function by partially shifti...
Source: Signal Transduction Knowledge Environment - June 30, 2020 Category: Science Authors: Gutierrez, T., Qi, H., Yap, M. C., Tahbaz, N., Milburn, L. A., Lucchinetti, E., Lou, P.-H., Zaugg, M., LaPointe, P. G., Mercier, P., Overduin, M., Bischof, H., Burgstaller, S., Malli, R., Ballanyi, K., Shuai, J., Simmen, T. Tags: STKE Research Articles Source Type: news

New connections: Neurodevelopmental switches
Protein modifications in neurons during early development regulate pain sensation and cognition. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - June 30, 2020 Category: Science Authors: Ferrarelli, L. K. Tags: STKE Editors ' Choice Source Type: news

Ubiquitination and functional modification of GluN2B subunit-containing NMDA receptors by Cbl-b in the spinal cord dorsal horn
N-methyl-d-aspartate (NMDA) glutamate receptors (NMDARs) containing GluN2B subunits are prevalent early after birth in most brain regions in rodents. Upon synapse maturation, GluN2B is progressively removed from synapses, which affects NMDAR function and synaptic plasticity. Aberrant recruitment of GluN2B into mature synapses has been implicated in several neuropathologies that afflict adults. We found that the E3 ubiquitin ligase Cbl-b was enriched in the spinal cord dorsal horn neurons of mice and rats and suppressed GluN2B abundance during development and inflammatory pain. Cbl-b abundance increased from postnatal day 1...
Source: Signal Transduction Knowledge Environment - June 30, 2020 Category: Science Authors: Zhang, Z.-Y., Bai, H.-H., Guo, Z., Li, H.-L., Diao, X.-T., Zhang, T.-Y., Yao, L., Ma, J.-J., Cao, Z., Li, Y.-X., Bai, X., Chen, H.-K., Suo, Z.-W., Yang, X., Hu, X.-D. Tags: STKE Research Articles Source Type: news

A PI3K- and GTPase-independent Rac1-mTOR mechanism mediates MET-driven anchorage-independent cell growth but not migration
Receptor tyrosine kinases (RTKs) are often overexpressed or mutated in cancers and drive tumor growth and metastasis. In the current model of RTK signaling, including that of MET, downstream phosphatidylinositol 3-kinase (PI3K) mediates both cell proliferation and cell migration, whereas the small guanosine triphosphatase (GTPase) Rac1 mediates cell migration. However, in cultured NIH3T3 and glioblastoma cells, we found that class I PI3K mediated oncogenic MET–induced cell migration but not anchorage-independent growth. In contrast, Rac1 regulated both processes in distinct ways. Downstream of PI3K, Rac1 mediated cel...
Source: Signal Transduction Knowledge Environment - June 23, 2020 Category: Science Authors: Hervieu, A., Heuss, S. F., Zhang, C., Barrow-McGee, R., Joffre, C., Menard, L., Clarke, P. A., Kermorgant, S. Tags: STKE Research Articles Source Type: news

Sleepless with ROS
Sleep deprivation may kill because it induces ROS accumulation and increased oxidative stress in the gut. (Source: Signal Transduction Knowledge Environment)
Source: Signal Transduction Knowledge Environment - June 23, 2020 Category: Science Authors: Wong, W. Tags: STKE Editors ' Choice Source Type: news

TRPML1 channels initiate Ca2+ sparks in vascular smooth muscle cells
TRPML1 (transient receptor potential mucolipin 1) is a Ca2+-permeable, nonselective cation channel localized to the membranes of endosomes and lysosomes and is not present or functional on the plasma membrane. Ca2+ released from endosomes and lysosomes into the cytosol through TRPML1 channels is vital for trafficking, acidification, and other basic functions of these organelles. Here, we investigated the function of TRPML1 channels in fully differentiated contractile vascular smooth muscle cells (SMCs). In live-cell confocal imaging studies, we found that most endosomes and lysosomes in freshly isolated SMCs from cerebral ...
Source: Signal Transduction Knowledge Environment - June 23, 2020 Category: Science Authors: Thakore, P., Pritchard, H. A. T., Griffin, C. S., Yamasaki, E., Drumm, B. T., Lane, C., Sanders, K. M., Feng Earley, Y., Earley, S. Tags: STKE Research Articles Source Type: news