The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jeffery L Dangl - One of the best experts on this subject based on the ideXlab platform.
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plant intracellular innate immune receptor resistance to pseudomonas syringae pv maculicola 1 rpm1 is activated at and functions on the plasma membrane
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Eui Hwan Chung, Timothy K Eitas, Jeffery L DanglAbstract:Plants deploy intracellular innate immune receptors to recognize pathogens and initiate disease resistance. These nucleotide-binding, leucine-rich repeat (NB-LRR) proteins are activated by pathogen effector proteins that are delivered into the host cell to suppress host defense responses. Little is known about the sites and mechanisms of NB-LRR activation, but some NB-LRR proteins can function inside the plant nucleus. We demonstrate that RPM1 is activated on the plasma membrane and does not relocalize to the nucleus. An autoactive RPM1(D505V) allele that recapitulates key features of normal RPM1 activation also resides on the plasma membrane. There is no detectable relocalization of activated RPM1 to the nucleus. Hindering potential nuclear entry of RPM1-Myc did not affect either its effector-triggered hypersensitive-response (HR) cell death or its disease resistance functions, further suggesting that nuclear translocation is not required for RPM1 function. RPM1 tethered onto the plasma membrane with a dual acylated N-terminal epitope tag retained the ability to mediate HR, consistent with this RPM1 function being activated on the plasma membrane. Plant NB-LRR proteins can thus function at various locations in the cell.
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specific threonine phosphorylation of a host target by two unrelated type iii effectors activates a host innate immune receptor in plants
Cell Host & Microbe, 2011Co-Authors: Eui Hwan Chung, Luis Da Cunha, Ai Jiuan Wu, Karen Cherkis, Ahmed J Afzal, David Mackey, Jeffery L DanglAbstract:Summary The Arabidopsis NB-LRR immune receptor RPM1 recognizes the Pseudomonas syringae type III effectors AvrB or AvrRpm1 to mount an immune response. Although neither effector is itself a kinase, AvrRpm1 and AvrB are known to target Arabidopsis RIN4, a negative regulator of basal plant defense, for phosphorylation. We show that RIN4 phosphorylation activates RPM1. RIN4 142-176 is necessary and, with appropriate localization sequences, sufficient to support effector-triggered RPM1 activation, with the threonine residue at position 166 being critical. Phosphomimic substitutions at T166 cause effector-independent RPM1 activation. RIN4 T166 is phosphorylated in vivo in the presence of AvrB or AvrRpm1. RIN4 mutants that lose interaction with AvrB cannot be coimmunoprecipitated with RPM1. This defines a common interaction platform required for RPM1 activation by phosphorylated RIN4 in response to pathogenic effectors. Conservation of an analogous threonine across all RIN4-like proteins suggests a key function for this residue beyond the regulation of RPM1.
Eui Hwan Chung - One of the best experts on this subject based on the ideXlab platform.
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plant intracellular innate immune receptor resistance to pseudomonas syringae pv maculicola 1 rpm1 is activated at and functions on the plasma membrane
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Eui Hwan Chung, Timothy K Eitas, Jeffery L DanglAbstract:Plants deploy intracellular innate immune receptors to recognize pathogens and initiate disease resistance. These nucleotide-binding, leucine-rich repeat (NB-LRR) proteins are activated by pathogen effector proteins that are delivered into the host cell to suppress host defense responses. Little is known about the sites and mechanisms of NB-LRR activation, but some NB-LRR proteins can function inside the plant nucleus. We demonstrate that RPM1 is activated on the plasma membrane and does not relocalize to the nucleus. An autoactive RPM1(D505V) allele that recapitulates key features of normal RPM1 activation also resides on the plasma membrane. There is no detectable relocalization of activated RPM1 to the nucleus. Hindering potential nuclear entry of RPM1-Myc did not affect either its effector-triggered hypersensitive-response (HR) cell death or its disease resistance functions, further suggesting that nuclear translocation is not required for RPM1 function. RPM1 tethered onto the plasma membrane with a dual acylated N-terminal epitope tag retained the ability to mediate HR, consistent with this RPM1 function being activated on the plasma membrane. Plant NB-LRR proteins can thus function at various locations in the cell.
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specific threonine phosphorylation of a host target by two unrelated type iii effectors activates a host innate immune receptor in plants
Cell Host & Microbe, 2011Co-Authors: Eui Hwan Chung, Luis Da Cunha, Ai Jiuan Wu, Karen Cherkis, Ahmed J Afzal, David Mackey, Jeffery L DanglAbstract:Summary The Arabidopsis NB-LRR immune receptor RPM1 recognizes the Pseudomonas syringae type III effectors AvrB or AvrRpm1 to mount an immune response. Although neither effector is itself a kinase, AvrRpm1 and AvrB are known to target Arabidopsis RIN4, a negative regulator of basal plant defense, for phosphorylation. We show that RIN4 phosphorylation activates RPM1. RIN4 142-176 is necessary and, with appropriate localization sequences, sufficient to support effector-triggered RPM1 activation, with the threonine residue at position 166 being critical. Phosphomimic substitutions at T166 cause effector-independent RPM1 activation. RIN4 T166 is phosphorylated in vivo in the presence of AvrB or AvrRpm1. RIN4 mutants that lose interaction with AvrB cannot be coimmunoprecipitated with RPM1. This defines a common interaction platform required for RPM1 activation by phosphorylated RIN4 in response to pathogenic effectors. Conservation of an analogous threonine across all RIN4-like proteins suggests a key function for this residue beyond the regulation of RPM1.
Michael J Ackerman - One of the best experts on this subject based on the ideXlab platform.
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diastolic ventricular dysfunction as a marker for hypertrophic cardiomyopathy in a family with a novel alpha tropomyosin mutation
Journal of The American Society of Echocardiography, 2003Co-Authors: Michael G Earing, Michael J Ackerman, Patrick W OlearyAbstract:Abstract Background Early identification of familial cases of hypertrophic cardiomyopathy (HCM) depends on screening echocardiography, but hypertrophy may not be the most sensitive marker for the disease. We report the echocardiographic findings of a family with HCM and a newly reported mutation in the gene (TPM1) encoding α-tropomyosin. Methods and results An 8-year-old girl had sudden cardiac death, and was found to have HCM and a novel L185R-TPM1 mutation on postmortem examination. Screening echocardiograms and DNA analyses were performed on her family. Of the 5 remaining family members, 3 were genetically affected. Those without the TPM1 mutation had normal echocardiographic results. The only echocardiographic finding that identified all 3 of the gene-positive family members was an abnormal left ventricular diastolic filling pattern. Conclusion Abnormal left ventricular diastolic filling patterns, indicating diastolic dysfunction, may provide an early marker for the diagnosis of familial HCM in children, even in the absence of left ventricular hypertrophy.
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a novel TPM1 mutation in a family with hypertrophic cardiomyopathy and sudden cardiac death in childhood
American Journal of Cardiology, 2002Co-Authors: Sara L Van Driest, Melissa L Will, Michael J Ackerman, Dianne L AtkinsAbstract:We sought to define the pathogenic mutation in a family with hypertrophic cardiomyopathy (HC) and a markedly arrhythmogenic phenotype. The proband was an 8-year-old female with a sentinel event of sudden death. Screening echocardiograms revealed HC in 2 of her 3 siblings and her father. Her youngest male sibling was diagnosed with HC at age 2 years and died suddenly at age 6 years from ventricular fibrillation despite an implanted cardioverter defibrillator. Using DNA extracted from peripheral lymphocytes, linkage exclusion was performed by haplotype analysis of polymorphic markers for the HC genes. Genes not excluded by linkage were analyzed for mutations using denaturing high-performance liquid chromatography (DHPLC) and direct DNA sequencing. Using this strategy, a 610 T>G nucleotide substitution in the alpha-tropomyosin gene (TPM1) was identified resulting in a novel L185R (Leucine [L] to Arginine [R]) missense mutation. This mutation was a spontaneous germ-line mutation originating in the proband's father. L185R-TPM1 cosegregated with family members having clinical evidence of HC, including the proband as confirmed by molecular autopsy. The mutation was not present in 400 reference alleles. Thus, a novel missense mutation in TPM1 was discovered in a family with HC and sudden death in childhood. Unlike previously defined mutations that may disrupt the interactions between alpha-tropomyosin monomers, the L185R mutation may affect troponin-T binding. Defining the pathogenic mutation enabled definitive molecular diagnosis of 2 surviving children.
Brunangelo Falini - One of the best experts on this subject based on the ideXlab platform.
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nucleophosmin mutations in acute myeloid leukemia a tale of protein unfolding and mislocalization
Protein Science, 2013Co-Authors: Luca Federici, Brunangelo FaliniAbstract:Nucleophosmin (NPM1) is an abundant, ubiquitously expressed protein mainly localized at nucleoli but continuously shuttling between nucleus and cytoplasm. NPM1 plays a role in several cellular functions, including ribosome biogenesis and export, centrosome duplication, chromatin remodeling, DNA repair, and response to stress stimuli. Much of the interest in this protein arises from its relevance in human malignancies. NPM1 is frequently overexpressed in solid tumors and is the target of several chromosomal translocations in hematologic neoplasms. Notably, NPM1 has been characterized as the most frequently mutated gene in acute myeloid leukemia (AML). Mutations alter the C-terminal DNA-binding domain of the protein and result in its aberrant nuclear export and stable cytosolic localization. In this review, we focus on the leukemia-associated NPM1 C-terminal domain and describe its structure, function, and the effect exerted by leukemic mutations. Finally, we discuss the possibility to target NPM1 for the treatment of cancer and, in particular, of AML patients with mutated NPM1 gene.
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nucleophosmin mutations alter its nucleolar localization by impairing g quadruplex binding at ribosomal dna
Nucleic Acids Research, 2013Co-Authors: Sara Chiarella, Antonella De Cola, Giovanni Luca Scaglione, Erminia Carletti, Vincenzo Graziano, Daniela Barcaroli, Carlo Lo Sterzo, Adele Di Matteo, Carmine Di Ilio, Brunangelo FaliniAbstract:Nucleophosmin (NPM1) is an abundant nucleolar protein implicated in ribosome maturation and export, centrosome duplication and response to stress stimuli. NPM1 is the most frequently mutated gene in acute myeloid leukemia. Mutations at the C-terminal domain led to variant proteins that aberrantly and stably translocate to the cytoplasm. We have previously shown that NPM1 C-terminal domain binds with high affinity G-quadruplex DNA. Here, we investigate the structural determinants of NPM1 nucleolar localization. We show that NPM1 interacts with several G-quadruplex regions found in ribosomal DNA, both in vitro and in vivo. Furthermore, the most common leukemic NPM1 variant completely loses this activity. This is the consequence of G-quadruplex–binding domain destabilization, as mutations aimed at refolding the leukemic variant also result in rescuing the G-quadruplex–binding activity and nucleolar localization. Finally, we show that treatment of cells with a G-quadruplex selective ligand results in wild-type NPM1 dislocation from nucleoli into nucleoplasm. In conclusion, this work establishes a direct correlation between NPM1 G-quadruplex binding at rDNA and its nucleolar localization, which is impaired in the acute myeloid leukemia-associated protein variants.
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acute myeloid leukemia with mutated nucleophosmin npm1 is it a distinct entity
Blood, 2011Co-Authors: Brunangelo Falini, Maria Paola Martelli, Niccolo Bolli, Paolo Sportoletti, Arcangelo Liso, Enrico Tiacci, Torsten HaferlachAbstract:After the discovery of NPM1-mutated acute myeloid leukemia (AML) in 2005 and its subsequent inclusion as a provisional entity in the 2008 World Health Organization classification of myeloid neoplasms, several controversial issues remained to be clarified. It was unclear whether the NPM1 mutation was a primary genetic lesion and whether additional chromosomal aberrations and multilineage dysplasia had any impact on the biologic and prognostic features of NPM1-mutated AML. Moreover, it was uncertain how to classify AML patients who were double-mutated for NPM1 and CEBPA. Recent studies have shown that: (1) the NPM1 mutant perturbs hemopoiesis in experimental models; (2) leukemic stem cells from NPM1-mutated AML patients carry the mutation; and (3) the NPM1 mutation is usually mutually exclusive of biallelic CEPBA mutations. Moreover, the biologic and clinical features of NPM1-mutated AML do not seem to be significantly influenced by concomitant chromosomal aberrations or multilineage dysplasia. Altogether, these pieces of evidence point to NPM1-mutated AML as a founder genetic event that defines a distinct leukemia entity accounting for approximately one-third of all AML.
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multilineage dysplasia has no impact on biologic clinicopathologic and prognostic features of aml with mutated nucleophosmin npm1
Blood, 2010Co-Authors: Brunangelo Falini, Susanne Schnittger, Wolfgang Kern, Tamara Weiss, Katja Macijewski, Ulrike Bacher, Alexander Kohlmann, Hansulrich Klein, Marco Vignetti, Alfonso PiciocchiAbstract:NPM1-mutated acute myeloid leukemia (AML) is a provisional entity in the 2008 World Health Organization (WHO) classification of myeloid neoplasms. The significance of multilineage dysplasia (MLD) in NPM1-mutated AML is unclear. Thus, in the 2008 WHO classification, NPM1-mutated AML with MLD is classified as AML with myelodysplasia (MD)-related changes (MRCs). We evaluated morphologically 318 NPM1-mutated AML patients and found MLD in 23.3%. Except for a male predominance and a lower fms-related tyrosine kinase 3-internal tandem duplication (FLT3-ITD) incidence in the MLD(+) group, no differences were observed in age, sex, cytogenetics, and FLT3--tyrosine kinase domain between NPM1-mutated AML with and without MLD. NPM1-mutated AML with and without MLD showed overlapping immunophenotype (CD34 negativity) and gene expression profile (CD34 down-regulation, HOX genes up-regulation). Moreover, overall and event-free survival did not differ among NPM1-mutated AML patients independently of whether they were MLD(+) or MLD(-), the NPM1-mutated/FLT3-ITD negative genotype showing the better prognosis. Lack of MLD impact on survival was confirmed by multivariate analysis that highlighted FLT3-ITD as the only significant prognostic parameter in NPM1-mutated AML. Our findings indicate that NPM1 mutations rather than MLD dictate the distinctive features of NPM1-mutated AML. Thus, irrespective of MLD, NPM1-mutated AML represents one disease entity clearly distinct from AML with MRCs.
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minimal residual disease levels assessed by npm1 mutation specific rq pcr provide important prognostic information in aml
Blood, 2009Co-Authors: Susanne Schnittger, Wolfgang Kern, Claudia Tschulik, Tamara Weiss, Frank Dicker, Brunangelo Falini, Claudia Haferlach, Torsten HaferlachAbstract:Nucleophosmin (NPM1)-mutated acute myeloid leukemia (AML), which is recognized as a provisional entity in the World Health Organization 2008 classification of myeloid neoplasms, accounts for 30% of AML. We analyzed 1227 diagnostic and follow-up samples in 252 NPM1-mutated AML patients with 17 different NPM1 mutation-specific real-time quantitative polymerase chain reaction (RQ-PCR) assays. Paired diagnostic/relapse samples of 84 patients revealed stable NPM1 mutations in all cases, suggesting that they are pathogenetically early events and thus applicable for minimal residual disease detection. A total of 47 relapses were predictable because of an NPM1 mutation level (%NPM1/ABL1) increase of at least 1 log or in 15 cases because of NPM1 mutation levels not decreasing less than 3 log ranges. A high prognostic value of NPM1 levels was shown for 4 different intervals after therapy was initiated. Furthermore, thresholds of 0.1 and 0.01%NPM1/ABL1 during/after treatment discriminated between prognostic subgroups. Univariate analyses, including age, white blood cell count, blast count, CD34 positivity, FLT3 mutations status, FAB type, karyotype, NPM1 mutation type, and pretreatment NPM1 mutational level, showed that, besides NPM1 mutation level, only age and FLT3-LM mutation status were prognostically significant for EFS. Multivariate analysis, including age, FLT3-LM status, and NPM1 mutation level at different time points, demonstrated that NPM1 level was the most relevant prognostic factor during first-line treatment. Similar results were obtained in patients undergoing second-line chemotherapy or allogeneic stem cell transplantation.
Andrea Facciabene - One of the best experts on this subject based on the ideXlab platform.
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tumor endothelial marker 1 specific dna vaccination targets tumor vasculature
Journal of Clinical Investigation, 2014Co-Authors: John Facciponte, Stefano Ugel, Francesco De Sanctis, Gautham Nair, Sandy Sehgal, Efthymia Iliana Matthaiou, George Coukos, Chunsheng Li, Liping Wang, Andrea FacciabeneAbstract:Tumor endothelial marker 1 (TEM1; also known as endosialin or CD248) is a protein found on tumor vasculature and in tumor stroma. Here, we tested whether TEM1 has potential as a therapeutic target for cancer immunotherapy by immunizing immunocompetent mice with Tem1 cDNA fused to the minimal domain of the C fragment of tetanus toxoid (referred to herein as Tem1-TT vaccine). Tem1-TT vaccination elicited CD8+ and/or CD4+ T cell responses against immunodominant TEM1 protein sequences. Prophylactic immunization of animals with Tem1-TT prevented or delayed tumor formation in several murine tumor models. Therapeutic vaccination of tumor-bearing mice reduced tumor vascularity, increased infiltration of CD3+ T cells into the tumor, and controlled progression of established tumors. Tem1-TT vaccination also elicited CD8+ cytotoxic T cell responses against murine tumor-specific antigens. Effective Tem1-TT vaccination did not affect angiogenesis-dependent physiological processes, including wound healing and reproduction. Based on these data and the widespread expression of TEM1 on the vasculature of different tumor types, we conclude that targeting TEM1 has therapeutic potential in cancer immunotherapy.