Small molecule inhibitors reveal an indispensable scaffolding role of RIPK2 in NOD2 signaling
RIPK2 mediates inflammatory signaling by the bacteria-sensing receptors NOD1 and NOD2. Kinase inhibitors targeting RIPK2 are a proposed strategy to ameliorate NOD-mediated pathologies. Here, we reveal that RIPK2 kinase activity is dispensable for NOD2 inflammatory signaling and show that RIPK2 inhibitors function instead by antagonizing XIAP-binding and XIAP-mediated ubiquitination of RIPK2. We map the XIAP binding site on RIPK2 to the loop between β2 and β3 of the N-lobe of the kinase, which is in close proximity to the ATP-binding pocket. Through characterization of a new series of ATP pocket-binding RIPK2 inhi...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Hrdinka, M., Schlicher, L., Dai, B., Pinkas, D. M., Bufton, J. C., Picaud, S., Ward, J. A., Rogers, C., Suebsuwong, C., Nikhar, S., Cuny, G. D., Huber, K. V., Filippakopoulos, P., Bullock, A. N., Degterev, A., Gyrd-Hansen, M. Tags: Autophagy & Cell Death, Immunology Articles Source Type: research
ER-to-lysosome-associated degradation of proteasome-resistant ATZ polymers occurs via receptor-mediated vesicular transport
Maintenance of cellular proteostasis relies on efficient clearance of defective gene products. For misfolded secretory proteins, this involves dislocation from the endoplasmic reticulum (ER) into the cytosol followed by proteasomal degradation. However, polypeptide aggregation prevents cytosolic dislocation and instead activates ill-defined lysosomal catabolic pathways. Here, we describe an ER-to-lysosome-associated degradation pathway (ERLAD) for proteasome-resistant polymers of alpha1-antitrypsin Z (ATZ). ERLAD involves the ER-chaperone calnexin (CNX) and the engagement of the LC3 lipidation machinery by the ER-resident ...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Fregno, I., Fasana, E., Bergmann, T. J., Raimondi, A., Loi, M., Solda, T., Galli, C., D'Antuono, R., Morone, D., Danieli, A., Paganetti, P., van Anken, E., Molinari, M. Tags: Autophagy & Cell Death, Membrane & Intracellular Transport, Post-translational Modifications, Proteolysis & Proteomics Articles Source Type: research
Mitochondrial inner membrane permeabilisation enables mtDNA release during apoptosis
During apoptosis, pro-apoptotic BAX and BAK are activated, causing mitochondrial outer membrane permeabilisation (MOMP), caspase activation and cell death. However, even in the absence of caspase activity, cells usually die following MOMP. Such caspase-independent cell death is accompanied by inflammation that requires mitochondrial DNA (mtDNA) activation of cGAS-STING signalling. Because the mitochondrial inner membrane is thought to remain intact during apoptosis, we sought to address how matrix mtDNA could activate the cytosolic cGAS-STING signalling pathway. Using super-resolution imaging, we show that mtDNA is efficie...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Riley, J. S., Quarato, G., Cloix, C., Lopez, J., O'Prey, J., Pearson, M., Chapman, J., Sesaki, H., Carlin, L. M., Passos, J. F., Wheeler, A. P., Oberst, A., Ryan, K. M., Tait, S. W. Tags: Autophagy & Cell Death, Membrane & Intracellular Transport, Signal Transduction Articles Source Type: research
Rtt105 functions as a chaperone for replication protein A to preserve genome stability
Generation of single-stranded DNA (ssDNA) is required for the template strand formation during DNA replication. Replication Protein A (RPA) is an ssDNA-binding protein essential for protecting ssDNA at replication forks in eukaryotic cells. While significant progress has been made in characterizing the role of the RPA–ssDNA complex, how RPA is loaded at replication forks remains poorly explored. Here, we show that the Saccharomyces cerevisiae protein regulator of Ty1 transposition 105 (Rtt105) binds RPA and helps load it at replication forks. Cells lacking Rtt105 exhibit a dramatic reduction in RPA loading at replica...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Li, S., Xu, Z., Xu, J., Zuo, L., Yu, C., Zheng, P., Gan, H., Wang, X., Li, L., Sharma, S., Chabes, A., Li, D., Wang, S., Zheng, S., Li, J., Chen, X., Sun, Y., Xu, D., Han, J., Chan, K., Qi, Z., Feng, J., Li, Q. Tags: Chromatin, Epigenetics, Genomics & Functional Genomics, DNA Replication, Repair & Recombination Articles Source Type: research
KIF13A-regulated RhoB plasma membrane localization governs membrane blebbing and blebby amoeboid cell migration
In conclusion, KIF13A-mediated endosomal trafficking modulates RhoB plasma membrane localization to control membrane blebbing and blebby amoeboid migration. (Source: EMBO Journal)
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Gong, X., Didan, Y., Lock, J. G., Strömblad, S. Tags: Cell Adhesion, Polarity & Cytoskeleton, Membrane & Intracellular Transport Articles Source Type: research
Luteinizing hormone signaling restricts hematopoietic stem cell expansion during puberty
In this study, we identified an extrinsic mechanism by which HSC number and functions are regulated during mouse puberty. We found that the HSC number in postnatal bone marrow reached homeostasis at 4 weeks after birth. Luteinizing hormone, but not downstream sex hormones, was involved in regulating HSC homeostasis during this period. Expression of luteinizing hormone receptor (Lhcgr) is highly restricted in HSCs and multipotent progenitor cells in the hematopoietic hierarchy. When Lhcgr was deleted, HSCs continued to expand even after 4 weeks after birth, leading to abnormally elevated hematopoiesis and leukocyt...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Peng, Y. J., Yu, H., Hao, X., Dong, W., Yin, X., Lin, M., Zheng, J., Zhou, B. O. Tags: Cancer, Physiology, Stem Cells Articles Source Type: research
Neuregulin 3 promotes excitatory synapse formation on hippocampal interneurons
Hippocampal GABAergic interneurons are crucial for cortical network function and have been implicated in psychiatric disorders. We show here that Neuregulin 3 (Nrg3), a relatively little investigated low-affinity ligand, is a functionally dominant interaction partner of ErbB4 in parvalbumin-positive (PV) interneurons. Nrg3 and ErbB4 are located pre- and postsynaptically, respectively, in excitatory synapses on PV interneurons in vivo. Additionally, we show that ablation of Nrg3 results in a similar phenotype as the one described for ErbB4 ablation, including reduced excitatory synapse numbers on PV interneurons, alter...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Müller, T., Braud, S., Jüttner, R., Voigt, B. C., Paulick, K., Sheean, M. E., Klisch, C., Gueneykaya, D., Rathjen, F. G., Geiger, J. R., Poulet, J. F., Birchmeier, C. Tags: Neuroscience Articles Source Type: research
YAP-TEAD signaling promotes basal cell carcinoma development via a c-JUN/AP1 axis
The mammalian Hippo signaling pathway, through its effectors YAP and TAZ, coerces epithelial progenitor cell expansion for appropriate tissue development or regeneration upon damage. Its ability to drive rapid tissue growth explains why many oncogenic events frequently exploit this pathway to promote cancer phenotypes. Indeed, several tumor types including basal cell carcinoma (BCC) show genetic aberrations in the Hippo (or YAP/TAZ) regulators. Here, we uncover that while YAP is dispensable for homeostatic epidermal regeneration, it is required for BCC development. Our clonal analyses further demonstrate that the few emerg...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Maglic, D., Schlegelmilch, K., Dost, A. F., Panero, R., Dill, M. T., Calogero, R. A., Camargo, F. D. Tags: Cancer, Signal Transduction, Transcription Articles Source Type: research
Staphylococcus aureus virulence attenuation and immune clearance mediated by a phage lysin-derived protein
New anti-infective approaches are much needed to control multi-drug-resistant (MDR) pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA). Here, we found for the first time that a recombinant protein derived from the cell wall binding domain (CBD) of the bacteriophage lysin PlyV12, designated as V12CBD, could attenuate S. aureus virulence and enhance host immune defenses via multiple manners. After binding with V12CBD, S. aureus became less invasive to epithelial cells and more susceptible to macrophage killing. The expressions of multiple important virulence genes of S. aureus were reduced 2...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Yang, H., Xu, J., Li, W., Wang, S., Li, J., Yu, J., Li, Y., Wei, H. Tags: Immunology, Microbiology, Virology & Host Pathogen Interaction Articles Source Type: research
Seipin regulates lipid homeostasis by ensuring calcium-dependent mitochondrial metabolism
Seipin, the gene that causes Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2), is important for adipocyte differentiation and lipid homeostasis. Previous studies in Drosophila revealed that Seipin promotes ER calcium homeostasis through the Ca2+-ATPase SERCA, but little is known about the events downstream of perturbed ER calcium homeostasis that lead to decreased lipid storage in Drosophila dSeipin mutants. Here, we show that glycolytic metabolites accumulate and the downstream mitochondrial TCA cycle is impaired in dSeipin mutants. The impaired TCA cycle further leads to a decreased level of citrate, a critical ...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Ding, L., Yang, X., Tian, H., Liang, J., Zhang, F., Wang, G., Wang, Y., Ding, M., Shui, G., Huang, X. Tags: Membrane & Intracellular Transport, Metabolism Articles Source Type: research
Atypical APC/C-dependent degradation of Mcl-1 provides an apoptotic timer during mitotic arrest
The initiation of apoptosis in response to the disruption of mitosis provides surveillance against chromosome instability. Here, we show that proteolytic destruction of the key regulator Mcl-1 during an extended mitosis requires the anaphase-promoting complex or cyclosome (APC/C) and is independent of another ubiquitin E3 ligase, SCFFbw7. Using live-cell imaging, we show that the loss of Mcl-1 during mitosis is dependent on a D box motif found in other APC/C substrates, while an isoleucine-arginine (IR) C-terminal tail regulates the manner in which Mcl-1 engages with the APC/C, converting Mcl-1 from a Cdc20-dependent and c...
Source: EMBO Journal - September 3, 2018 Category: Molecular Biology Authors: Allan, L. A., Skowyra, A., Rogers, K. I., Zeller, D., Clarke, P. R. Tags: Cell Cycle, Post-translational Modifications, Proteolysis & Proteomics Articles Source Type: research
Functional patchworking at the plasma membrane
Lipids and proteins are not evenly distributed within the plasma membrane (PM), but instead segregate laterally into many specialized microdomains whose functional relevance is not clear. In this issue, Busto et al (2018) demonstrate that substrate flux through a nutrient transporter drives the lateral relocation of the transporter between specific microdomains at the yeast PM, suggesting that regulating the lateral plasma membrane compartmentalization for individual proteins could be a general process for cellular response to environmental conditions. (Source: EMBO Journal)
Source: EMBO Journal - August 15, 2018 Category: Molecular Biology Authors: Leon, S., Teis, D. Tags: Membrane & Intracellular Transport, Post-translational Modifications, Proteolysis & Proteomics News [amp ] Views Source Type: research
Astrocytic NF-{kappa}B brings the best and worst out of microglia
The role of astrocytes and microglia in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) remains incompletely understood. In this issue of The EMBO Journal, Alami et al (2018) employ a sophisticated genetic system that allows precise temporal control of NF-B activation in astrocytes to demonstrate that the timing of astrocyte activation is a key determinant of disease progression. Their results suggest that astrocyte activation drives microglia proliferation and that this can amplify not only the protective microglial effects in the presymptomatic phase of ALS, but also the detrimental microglial...
Source: EMBO Journal - August 15, 2018 Category: Molecular Biology Authors: Dokalis, N., Prinz, M. Tags: Molecular Biology of Disease, Neuroscience News [amp ] Views Source Type: research
Lateral plasma membrane compartmentalization links protein function and turnover
Biological membranes organize their proteins and lipids into nano- and microscale patterns. In the yeast plasma membrane (PM), constituents segregate into a large number of distinct domains. However, whether and how this intricate patchwork contributes to biological functions at the PM is still poorly understood. Here, we reveal an elaborate interplay between PM compartmentalization, physiological function, and endocytic turnover. Using the methionine permease Mup1 as model system, we demonstrate that this transporter segregates into PM clusters. Clustering requires sphingolipids, the tetraspanner protein Nce102, and signa...
Source: EMBO Journal - August 15, 2018 Category: Molecular Biology Authors: Busto, J. V., Elting, A., Haase, D., Spira, F., Kuhlman, J., Schäfer-Herte, M., Wedlich-Söldner, R. Tags: Membrane & Intracellular Transport, Post-translational Modifications, Proteolysis & Proteomics Articles Source Type: research
Targeting prohibitins at the cell surface prevents Th17-mediated autoimmunity
T helper (Th)17 cells represent a unique subset of CD4+ T cells and are vital for clearance of extracellular pathogens including bacteria and fungi. However, Th17 cells are also involved in orchestrating autoimmunity. By employing quantitative surface proteomics, we found that the evolutionarily conserved prohibitins (PHB1/2) are highly expressed on the surface of both murine and human Th17 cells. Increased expression of PHBs at the cell surface contributed to enhanced CRAF/MAPK activation in Th17 cells. Targeting surface-expressed PHBs on Th17 cells with ligands such as Vi polysaccharide (Typhim vaccine) inhibited CRAF-MA...
Source: EMBO Journal - August 15, 2018 Category: Molecular Biology Authors: Buehler, U., Schulenburg, K., Yurugi, H., Solman, M., Abankwa, D., Ulges, A., Tenzer, S., Bopp, T., Thiede, B., Zipp, F., Rajalingam, K. Tags: Immunology Articles Source Type: research
