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Cell Sep 2020Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most frequent cause of familial Parkinson's disease. LRRK2 is a multi-domain protein containing a kinase and...
Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most frequent cause of familial Parkinson's disease. LRRK2 is a multi-domain protein containing a kinase and GTPase. Using correlative light and electron microscopy, in situ cryo-electron tomography, and subtomogram analysis, we reveal a 14-Å structure of LRRK2 bearing a pathogenic mutation that oligomerizes as a right-handed double helix around microtubules, which are left-handed. Using integrative modeling, we determine the architecture of LRRK2, showing that the GTPase and kinase are in close proximity, with the GTPase closer to the microtubule surface, whereas the kinase is exposed to the cytoplasm. We identify two oligomerization interfaces mediated by non-catalytic domains. Mutation of one of these abolishes LRRK2 microtubule-association. Our work demonstrates the power of cryo-electron tomography to generate models of previously unsolved structures in their cellular environment.
Topics: Cryoelectron Microscopy; Cytoplasm; Electron Microscope Tomography; GTP Phosphohydrolases; HEK293 Cells; Humans; Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; Microscopy, Electron, Transmission; Microtubules; Models, Chemical; Mutation; Parkinson Disease; Phosphotransferases; Protein Domains; WD40 Repeats
PubMed: 32783917
DOI: 10.1016/j.cell.2020.08.004 -
Nature Communications Feb 2022Aging and mechanical overload are prominent risk factors for osteoarthritis (OA), which lead to an imbalance in redox homeostasis. The resulting state of oxidative...
Aging and mechanical overload are prominent risk factors for osteoarthritis (OA), which lead to an imbalance in redox homeostasis. The resulting state of oxidative stress drives the pathological transition of chondrocytes during OA development. However, the specific molecular pathways involved in disrupting chondrocyte redox homeostasis remain unclear. Here, we show that selenophosphate synthetase 1 (SEPHS1) expression is downregulated in human and mouse OA cartilage. SEPHS1 downregulation impairs the cellular capacity to synthesize a class of selenoproteins with oxidoreductase functions in chondrocytes, thereby elevating the level of reactive oxygen species (ROS) and facilitating chondrocyte senescence. Cartilage-specific Sephs1 knockout in adult mice causes aging-associated OA, and augments post-traumatic OA, which is rescued by supplementation of N-acetylcysteine (NAC). Selenium-deficient feeding and Sephs1 knockout have synergistic effects in exacerbating OA pathogenesis in mice. Therefore, we propose that SEPHS1 is an essential regulator of selenium metabolism and redox homeostasis, and its dysregulation governs the progression of OA.
Topics: Aging; Animals; Cartilage, Articular; Chondrocytes; Disease Models, Animal; Homeostasis; Male; Mice; Mice, Knockout; Osteoarthritis; Oxidation-Reduction; Oxidative Stress; Phosphotransferases; Reactive Oxygen Species; Selenium; Selenoproteins; Transcriptome
PubMed: 35140209
DOI: 10.1038/s41467-022-28385-7 -
Science (New York, N.Y.) Jan 2017In plants, perception of invading pathogens involves cell-surface immune receptor kinases. Here, we report that the Arabidopsis SITE-1 PROTEASE (S1P) cleaves endogenous...
In plants, perception of invading pathogens involves cell-surface immune receptor kinases. Here, we report that the Arabidopsis SITE-1 PROTEASE (S1P) cleaves endogenous RAPID ALKALINIZATION FACTOR (RALF) propeptides to inhibit plant immunity. This inhibition is mediated by the malectin-like receptor kinase FERONIA (FER), which otherwise facilitates the ligand-induced complex formation of the immune receptor kinases EF-TU RECEPTOR (EFR) and FLAGELLIN-SENSING 2 (FLS2) with their co-receptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1 (BAK1) to initiate immune signaling. We show that FER acts as a RALF-regulated scaffold that modulates receptor kinase complex assembly. A similar scaffolding mechanism may underlie FER function in other signaling pathways.
Topics: Arabidopsis; Arabidopsis Proteins; Peptide Hormones; Phosphotransferases; Plant Immunity; Proprotein Convertases; Protein Kinases; Protein Serine-Threonine Kinases; Proteolysis; Receptors, Pattern Recognition; Serine Endopeptidases; Signal Transduction
PubMed: 28104890
DOI: 10.1126/science.aal2541 -
Nature Dec 2021The liberation of energy stores from adipocytes is critical to support survival in times of energy deficit; however, uncontrolled or chronic lipolysis associated with...
The liberation of energy stores from adipocytes is critical to support survival in times of energy deficit; however, uncontrolled or chronic lipolysis associated with insulin resistance and/or insulin insufficiency disrupts metabolic homeostasis. Coupled to lipolysis is the release of a recently identified hormone, fatty-acid-binding protein 4 (FABP4). Although circulating FABP4 levels have been strongly associated with cardiometabolic diseases in both preclinical models and humans, no mechanism of action has yet been described. Here we show that hormonal FABP4 forms a functional hormone complex with adenosine kinase (ADK) and nucleoside diphosphate kinase (NDPK) to regulate extracellular ATP and ADP levels. We identify a substantial effect of this hormone on beta cells and given the central role of beta-cell function in both the control of lipolysis and development of diabetes, postulate that hormonal FABP4 is a key regulator of an adipose-beta-cell endocrine axis. Antibody-mediated targeting of this hormone complex improves metabolic outcomes, enhances beta-cell function and preserves beta-cell integrity to prevent both type 1 and type 2 diabetes. Thus, the FABP4-ADK-NDPK complex, Fabkin, represents a previously unknown hormone and mechanism of action that integrates energy status with the function of metabolic organs, and represents a promising target against metabolic disease.
Topics: Adipocytes; Diabetes Mellitus; Fatty Acid-Binding Proteins; Humans; Insulin; Islets of Langerhans; Lipolysis; Nucleosides; Phosphotransferases
PubMed: 34880500
DOI: 10.1038/s41586-021-04137-3 -
Nature Communications Sep 2014Human cancer genomes harbour a variety of alterations leading to the deregulation of key pathways in tumour cells. The genomic characterization of tumours has uncovered...
Human cancer genomes harbour a variety of alterations leading to the deregulation of key pathways in tumour cells. The genomic characterization of tumours has uncovered numerous genes recurrently mutated, deleted or amplified, but gene fusions have not been characterized as extensively. Here we develop heuristics for reliably detecting gene fusion events in RNA-seq data and apply them to nearly 7,000 samples from The Cancer Genome Atlas. We thereby are able to discover several novel and recurrent fusions involving kinases. These findings have immediate clinical implications and expand the therapeutic options for cancer patients, as approved or exploratory drugs exist for many of these kinases.
Topics: Gene Expression Profiling; Gene Fusion; Genome, Human; Humans; Molecular Targeted Therapy; Neoplasms; Phosphotransferases; Sequence Analysis, RNA
PubMed: 25204415
DOI: 10.1038/ncomms5846 -
Molecular Genetics and Metabolism Nov 2022Studies aimed at supporting different treatment approaches for pantothenate kinase-associated neurodegeneration (PKAN) have revealed the complexity of coenzyme A (CoA)... (Review)
Review
Studies aimed at supporting different treatment approaches for pantothenate kinase-associated neurodegeneration (PKAN) have revealed the complexity of coenzyme A (CoA) metabolism and the limits of our current knowledge about disease pathogenesis. Here we offer a foundation for critically evaluating the myriad approaches, argue for the importance of unbiased disease models, and highlight some of the outstanding questions that are central to our understanding and treating PKAN.
Topics: Humans; Pantothenate Kinase-Associated Neurodegeneration; Coenzyme A; Phosphotransferases (Alcohol Group Acceptor)
PubMed: 36240582
DOI: 10.1016/j.ymgme.2022.09.011 -
Current Biology : CB Mar 2018Cells maintain integrity despite changes in their mechanical properties elicited during growth and environmental stress. How cells sense their physical state and...
Cells maintain integrity despite changes in their mechanical properties elicited during growth and environmental stress. How cells sense their physical state and compensate for cell-wall damage is poorly understood, particularly in plants. Here we report that FERONIA (FER), a plasma-membrane-localized receptor kinase from Arabidopsis, is necessary for the recovery of root growth after exposure to high salinity, a widespread soil stress. The extracellular domain of FER displays tandem regions of homology with malectin, an animal protein known to bind di-glucose in vitro and important for protein quality control in the endoplasmic reticulum. The presence of malectin-like domains in FER and related receptor kinases has led to widespread speculation that they interact with cell-wall polysaccharides and can potentially serve a wall-sensing function. Results reported here show that salinity causes softening of the cell wall and that FER is necessary to sense these defects. When this function is disrupted in the fer mutant, root cells explode dramatically during growth recovery. Similar defects are observed in the mur1 mutant, which disrupts pectin cross-linking. Furthermore, fer cell-wall integrity defects can be rescued by treatment with calcium and borate, which also facilitate pectin cross-linking. Sensing of these salinity-induced wall defects might therefore be a direct consequence of physical interaction between the extracellular domain of FER and pectin. FER-dependent signaling elicits cell-specific calcium transients that maintain cell-wall integrity during salt stress. These results reveal a novel extracellular toxicity of salinity, and identify FER as a sensor of damage to the pectin-associated wall.
Topics: Arabidopsis; Arabidopsis Proteins; Calcium Signaling; Cell Wall; Phosphotransferases; Salt Stress
PubMed: 29456142
DOI: 10.1016/j.cub.2018.01.023 -
The Journal of Biological Chemistry Apr 2023The cytidine diphosphate-choline (Kennedy) pathway culminates with the synthesis of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) by choline/ethanolamine...
The cytidine diphosphate-choline (Kennedy) pathway culminates with the synthesis of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) by choline/ethanolamine phosphotransferase 1 (CEPT1) in the endoplasmic reticulum (ER), and PC synthesis by choline phosphotransferase 1 (CHPT1) in the Golgi apparatus. Whether the PC and PE synthesized by CEPT1 and CHPT1 in the ER and Golgi apparatus has different cellular functions has not been formally addressed. Here, we used CRISPR editing to generate CEPT1-and CHPT1-KO U2OS cells to assess the differential contribution of the enzymes to feedback regulation of nuclear CTP:phosphocholine cytidylyltransferase (CCT)α, the rate-limiting enzyme in PC synthesis, and lipid droplet (LD) biogenesis. We found that CEPT1-KO cells had a 50 and 80% reduction in PC and PE synthesis, respectively, while PC synthesis in CHPT1-KO cells was also reduced by 50%. CEPT1 KO caused the posttranscriptional induction of CCTα protein expression as well as its dephosphorylation and constitutive localization on the inner nuclear membrane and nucleoplasmic reticulum. This activated CCTα phenotype was prevented by incubating CEPT1-KO cells with PC liposomes to restore end-product inhibition. Additionally, we determined that CEPT1 was in close proximity to cytoplasmic LDs and CEPT1 KO resulted in the accumulation of small cytoplasmic LDs, as well as increased nuclear LDs enriched in CCTα. In contrast, CHPT1 KO had no effect on CCTα regulation or LD biogenesis. Thus, CEPT1 and CHPT1 contribute equally to PC synthesis; however, only PC synthesized by CEPT1 in the ER regulates CCTα and the biogenesis of cytoplasmic and nuclear LDs.
Topics: Phosphatidylcholines; Lipid Droplets; Phosphotransferases; Homeostasis; Choline; Choline-Phosphate Cytidylyltransferase
PubMed: 36871755
DOI: 10.1016/j.jbc.2023.104578 -
Cell Chemical Biology Jan 2018New opportunities to advance small-molecule kinase ligands that downregulate their cognate target binding proteins are discussed. Rationally designed heterobifunctional... (Review)
Review
New opportunities to advance small-molecule kinase ligands that downregulate their cognate target binding proteins are discussed. Rationally designed heterobifunctional kinase degraders are compared with ATP site ligands that were serendipitously found to cause kinase downregulation. These approaches could be particularly useful in the treatment of cancers since many kinases are known to remodel pro-oncogenic protein-protein interactions, which could be destroyed by small-molecule-mediated kinase depletion.
Topics: Down-Regulation; Humans; Ligands; Phosphotransferases; Protein Kinase Inhibitors
PubMed: 29174540
DOI: 10.1016/j.chembiol.2017.10.011 -
ELife Dec 2023Why does protein kinase A respond to purine nucleosides in certain pathogens, but not to the cyclic nucleotides that activate this kinase in most other organisms?
Why does protein kinase A respond to purine nucleosides in certain pathogens, but not to the cyclic nucleotides that activate this kinase in most other organisms?
Topics: Leishmania donovani; Ligands; Phosphotransferases; Cyclic AMP-Dependent Protein Kinases; Purine Nucleosides; Trypanosoma brucei brucei
PubMed: 38126364
DOI: 10.7554/eLife.94720