RESUMO
Cytotoxic T cells produce interferon gamma (IFNγ), which plays a critical role in anti-microbial and anti-tumor responses. However, it is not clear whether T cell-derived IFNγ directly kills infected and tumor target cells, and how this may be regulated. Here, we report that target cell expression of the kinases TBK1 and IKKε regulate IFNγ cytotoxicity by suppressing the ability of T cell-derived IFNγ to kill target cells. In tumor targets lacking TBK1 and IKKε, IFNγ induces expression of TNFR1 and the Z-nucleic acid sensor, ZBP1, to trigger RIPK1-dependent apoptosis, largely in a target cell-autonomous manner. Unexpectedly, IFNγ, which is not known to signal to NFκB, induces hyperactivation of NFκB in TBK1 and IKKε double-deficient cells. TBK1 and IKKε suppress IKKα/ß activity and in their absence, IFNγ induces elevated NFκB-dependent expression of inflammatory chemokines and cytokines. Apoptosis is thought to be non-inflammatory, but our observations demonstrate that IFNγ can induce an inflammatory form of apoptosis, and this is suppressed by TBK1 and IKKε. The two kinases provide a critical connection between innate and adaptive immunological responses by regulating three key responses: (1) phosphorylation of IRF3/7 to induce type I IFN; (2) inhibition of RIPK1-dependent death; and (3) inhibition of NFκB-dependent inflammation. We propose that these kinases evolved these functions such that their inhibition by pathogens attempting to block type I IFN expression would enable IFNγ to trigger apoptosis accompanied by an alternative inflammatory response. Our findings show that loss of TBK1 and IKKε in target cells sensitizes them to inflammatory apoptosis induced by T cell-derived IFNγ.
RESUMO
Protein kinase A (PKA) holoenzyme, comprised of a cAMP-binding regulatory (R)-subunit dimer and 2 catalytic (C)-subunits, is the master switch for cAMP-mediated signaling. Of the 4 R-subunits (RIα, RIß, RIIα, RIIß), RIα is most essential for regulating PKA activity in cells. Our 2 RIα2C2 holoenzyme states, which show different conformations with and without ATP, reveal how ATP/Mg2+ functions as a negative orthosteric modulator. Biochemical studies demonstrate how the removal of ATP primes the holoenzyme for cAMP-mediated activation. The opposing competition between ATP/cAMP is unique to RIα. In RIIß, ATP serves as a substrate and facilitates cAMP-activation. The isoform-specific RI-holoenzyme dimer interface mediated by N3A-N3A' motifs defines multidomain cross-talk and an allosteric network that creates competing roles for ATP and cAMP. Comparisons to the RIIß holoenzyme demonstrate isoform-specific holoenzyme interfaces and highlights distinct allosteric mechanisms for activation in addition to the structural diversity of the isoforms.
Assuntos
Subunidade RIIbeta da Proteína Quinase Dependente de AMP Cíclico/química , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/química , Proteínas Quinases Dependentes de AMP Cíclico/química , Estrutura Quaternária de Proteína , Trifosfato de Adenosina/química , Trifosfato de Adenosina/genética , Regulação Alostérica/genética , Sequência de Aminoácidos/genética , Cristalografia por Raios X , AMP Cíclico/química , AMP Cíclico/genética , Subunidade RIIbeta da Proteína Quinase Dependente de AMP Cíclico/genética , Subunidade RIalfa da Proteína Quinase Dependente de AMP Cíclico/genética , Proteínas Quinases Dependentes de AMP Cíclico/genética , Regulação Enzimológica da Expressão Gênica/genética , Holoenzimas/química , Holoenzimas/genética , Humanos , Ligação Proteica/genética , Subunidades Proteicas/química , Subunidades Proteicas/genética , Transdução de Sinais/genéticaRESUMO
The process of mitochondrial fission-fusion has been implicated in diverse neuronal roles including neuronal survival, axon degeneration, and axon regeneration. However, whether increased fission or fusion is beneficial for neuronal health and/or axonal growth is not entirely clear, and is likely situational and cell type-dependent. In searching for mitochondrial fission-fusion regulating proteins for improving axonal growth within the visual system, we uncover that mitochondrial fission process 1,18 kDa (MTP18/MTFP1), a pro-fission protein within the CNS, is critical to maintaining mitochondrial size and volume under normal and injury conditions, in retinal ganglion cells (RGCs). We demonstrate that MTP18's expression is regulated by transcription factors involved in axonal growth, Kruppel-like factor (KLF) transcription factors-7 and -9, and that knockdown of MTP18 promotes axon growth. This investigation exposes MTP18's previously unexplored role in regulating mitochondrial fission, implicates MTP18 as a downstream component of axon regenerative signaling, and ultimately lays the groundwork for investigations on the therapeutic efficacy of MTP18 expression suppression during CNS axon degenerative events.
Assuntos
Axônios/metabolismo , Proteínas de Membrana/metabolismo , Dinâmica Mitocondrial/fisiologia , Proteínas Mitocondriais/metabolismo , Regeneração Nervosa/fisiologia , Neurônios/metabolismo , Animais , Proteínas de Membrana/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Compressão Nervosa , Crescimento Neuronal/fisiologia , Traumatismos do Nervo Óptico/metabolismo , Ratos , Ratos Sprague-Dawley , Transdução de SinaisRESUMO
BACKGROUND: Crohn's disease (CD) patients may be at increased risk for the development of Hodgkin's lymphoma (HL) or non-Hodgkin's lymphoma (NHL), either through exposure to immunosuppressive medications or due to their underlying chronic inflammatory illness. There are limited data regarding the natural history of CD following treatment of lymphoma. We present a series of CD patients who were treated for lymphoma and describe the natural history of their CD following lymphoma treatment. METHODS: Retrospective case series from three academic referral centers was used. All CD patients with a history of lymphoma were identified. Demographic data, CD medication exposure, and surgical procedures before and after lymphoma treatment were recorded. RESULTS: Nine CD patients with a history of lymphoma were identified. Eight individuals received chemotherapy, while one patient was observed without treatment. Eight patients remained free of lymphoma for a mean of 72.8 months (range 1-276 months). The ninth patient had recurrence of his HL 3 years after lymphoma diagnosis. Following lymphoma treatment, two patients had quiescent CD with no specific therapy. Three patients demonstrated significant clinical relapse of their CD and a fourth patient developed CD after treatment of her lymphoma, which ultimately required long-term immunomodulator therapy with 6-mercaptopurine or methotrexate in the first three patients, and azathioprine in the fourth. Four patients required CD surgery after lymphoma treatment. CONCLUSION: We report on the clinical course of CD in patients who develop lymphoma. Significant clinical relapse of CD following successful medical treatment of lymphoma occurred frequently in patients with a history of this neoplasm.
Assuntos
Doença de Crohn/complicações , Linfoma/complicações , Adolescente , Adulto , Antineoplásicos/uso terapêutico , Criança , Doença de Crohn/tratamento farmacológico , Feminino , Doença de Hodgkin/complicações , Doença de Hodgkin/tratamento farmacológico , Humanos , Imunossupressores/efeitos adversos , Imunossupressores/uso terapêutico , Linfoma/tratamento farmacológico , Linfoma não Hodgkin/complicações , Linfoma não Hodgkin/tratamento farmacológico , Masculino , Mercaptopurina/efeitos adversos , Mercaptopurina/uso terapêutico , Metotrexato/efeitos adversos , Metotrexato/uso terapêutico , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento , Adulto JovemRESUMO
Propofol is frequently used for sedation, induction, and maintenance of anesthesia. It is, however, associated with pain on injection. Propofol-Lipuro has an oil phase that allows a larger proportion of propofol to be dissolved in it and, thereby, apparently reduces pain. However, studies investigating this have had methodological limitations. We devised a randomized, double-blind, crossover study comparing pain on injection between two preparations of propofol, Diprivan and Propofol-Lipuro, in subanesthetic doses. Sixty healthy patients received the drugs in random order via the same injection site separated by 10 min and a 0.9% saline flush. Pain was assessed using a verbal rating score (VRS) during and at 1-min time points after injection. Differences in VRS between the two propofol preparations at different time points in each patient were analyzed. In patients who were given Diprivan first followed by Propofol-Lipuro (group D-P), pain was significantly reduced with Propofol-Lipuro compared with Diprivan during initial injection (median difference in VRS = 2 [interquartile range 0-2], P = 0.002) and at 1 min (3 [0-4], P < 0.001). In patients who were given Propofol-Lipuro first followed by Diprivan (group P-D), no significant differences in VRS were shown. Propofol-Lipuro is associated with reduced injection pain compared with Diprivan and also seems to attenuate subsequent injection pain of Diprivan when administered first. The mechanism is unknown, but may be related to a reduction in the concentration of propofol in the aqueous phase.