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1.
Cell ; 184(3): 655-674.e27, 2021 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-33497611

RESUMO

Ras GTPase-activating protein-binding proteins 1 and 2 (G3BP1 and G3BP2, respectively) are widely recognized as core components of stress granules (SGs). We report that G3BPs reside at the cytoplasmic surface of lysosomes. They act in a non-redundant manner to anchor the tuberous sclerosis complex (TSC) protein complex to lysosomes and suppress activation of the metabolic master regulator mechanistic target of rapamycin complex 1 (mTORC1) by amino acids and insulin. Like the TSC complex, G3BP1 deficiency elicits phenotypes related to mTORC1 hyperactivity. In the context of tumors, low G3BP1 levels enhance mTORC1-driven breast cancer cell motility and correlate with adverse outcomes in patients. Furthermore, G3bp1 inhibition in zebrafish disturbs neuronal development and function, leading to white matter heterotopia and neuronal hyperactivity. Thus, G3BPs are not only core components of SGs but also a key element of lysosomal TSC-mTORC1 signaling.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , DNA Helicases/metabolismo , Lisossomos/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , RNA Helicases/metabolismo , Proteínas com Motivo de Reconhecimento de RNA/metabolismo , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais , Esclerose Tuberosa/metabolismo , Sequência de Aminoácidos , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Grânulos Citoplasmáticos/efeitos dos fármacos , Grânulos Citoplasmáticos/metabolismo , DNA Helicases/química , Evolução Molecular , Feminino , Humanos , Insulina/farmacologia , Proteínas de Membrana Lisossomal/metabolismo , Lisossomos/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fenótipo , Proteínas de Ligação a Poli-ADP-Ribose/química , RNA Helicases/química , Proteínas com Motivo de Reconhecimento de RNA/química , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Peixe-Zebra/metabolismo
2.
Elife ; 82019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31411562

RESUMO

Target of rapamycin complex 1 (TORC1) and AMP-activated protein kinase (AMPK) antagonistically modulate metabolism and aging. However, how they coordinate to determine longevity and if they act via separable mechanisms is unclear. Here, we show that neuronal AMPK is essential for lifespan extension from TORC1 inhibition, and that TORC1 suppression increases lifespan cell non autonomously via distinct mechanisms from global AMPK activation. Lifespan extension by null mutations in genes encoding raga-1 (RagA) or rsks-1 (S6K) is fully suppressed by neuronal-specific rescues. Loss of RAGA-1 increases lifespan via maintaining mitochondrial fusion. Neuronal RAGA-1 abrogation of raga-1 mutant longevity requires UNC-64/syntaxin, and promotes mitochondrial fission cell nonautonomously. Finally, deleting the mitochondrial fission factor DRP-1 renders the animal refractory to the pro-aging effects of neuronal RAGA-1. Our results highlight a new role for neuronal TORC1 in cell nonautonomous regulation of longevity, and suggest TORC1 in the central nervous system might be targeted to promote healthy aging.


Assuntos
Caenorhabditis elegans/enzimologia , Caenorhabditis elegans/fisiologia , Longevidade , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Dinâmica Mitocondrial , Proteínas Quinases/metabolismo , Quinases Proteína-Quinases Ativadas por AMP , Animais
3.
NPJ Genom Med ; 3: 25, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30210807

RESUMO

Human herpesvirus 6A and 6B frequently acquires latency. HHV-6 activation has been associated with various human diseases. Germ line inheritance of chromosomally integrated HHV-6 makes viral DNA-based analysis difficult for determination of early stages of viral activation. We characterized early stages of HHV-6 activation using high throughput transcriptomics studies and applied the results to understand virus activation under clinical conditions. Using a latent HHV-6A cell culture model in U2OS cells, we identified an early stage of viral reactivation, which we define as transactivation that is marked by transcription of several viral small non-coding RNAs (sncRNAs) in the absence of detectable increase in viral replication and proteome. Using deep sequencing approaches, we detected previously known as well as a new viral sncRNAs that characterized viral transactivation and differentiated it from latency. Here we show changes in human transcriptome upon viral transactivation that reflect multiple alterations in mitochondria-associated pathways, which was supported by observation of increased mitochondrial fragmentation in virus reactivated cells. Furthermore, we present here a unique clinical case of DIHS/DRESS associated death where HHV-6 sncRNA-U14 was abundantly detected throughout the body of the patient in the presence of low viral DNA. In this study, we have identified a unique and early stage of viral activation that is characterized by abundant transcription of viral sncRNAs, which can serve as an ideal biomarker under clinical conditions.

4.
Cell Host Microbe ; 22(3): 255-257, 2017 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-28910630

RESUMO

The replication vacuole of Legionella pneumophila makes contact with host mitochondria. In this issue of Cell Host & Microbe, Escoll et al. (2017) dissect the mechanisms of this interaction, the effect of the T4SS effector MitF on mitochondrial function, and the resultant metabolic reprogramming of infected cells to benefit the bacteria.


Assuntos
Legionella pneumophila , Vacúolos , Proteínas de Bactérias , Humanos , Mitocôndrias
5.
J Cell Biol ; 216(4): 1071-1089, 2017 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-28330939

RESUMO

Obligate intracellular bacteria such as Chlamydia trachomatis depend on metabolites of the host cell and thus protect their sole replication niche by interfering with the host cells' stress response. Here, we investigated the involvement of host microRNAs (miRNAs) in maintaining the viability of C. trachomatis-infected primary human cells. We identified miR-30c-5p as a prominently up-regulated miRNA required for the stable down-regulation of p53, a major suppressor of metabolite supply in C. trachomatis-infected cells. Loss of miR-30c-5p led to the up-regulation of Drp1, a mitochondrial fission regulator and a target gene of p53, which, in turn, severely affected chlamydial growth and had a marked effect on the mitochondrial network. Drp1-induced mitochondrial fragmentation prevented replication of C. trachomatis even in p53-deficient cells. Additionally, Chlamydia maintain mitochondrial integrity during reactive oxygen species-induced stress that occurs naturally during infection. We show that C. trachomatis require mitochondrial ATP for normal development and hence postulate that they preserve mitochondrial integrity through a miR-30c-5p-dependent inhibition of Drp1-mediated mitochondrial fission.


Assuntos
Infecções por Chlamydia/microbiologia , Chlamydia trachomatis/genética , Replicação do DNA/genética , MicroRNAs/genética , Mitocôndrias/microbiologia , Dinâmica Mitocondrial/genética , Linhagem Celular Tumoral , Células Cultivadas , Regulação para Baixo/genética , Células HeLa , Células Endoteliais da Veia Umbilical Humana , Humanos , Regulação para Cima/genética
6.
Elife ; 62017 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-28347402

RESUMO

Obligate intracellular Chlamydia trachomatis replicate in a membrane-bound vacuole called inclusion, which serves as a signaling interface with the host cell. Here, we show that the chlamydial deubiquitinating enzyme (Cdu) 1 localizes in the inclusion membrane and faces the cytosol with the active deubiquitinating enzyme domain. The structure of this domain revealed high similarity to mammalian deubiquitinases with a unique α-helix close to the substrate-binding pocket. We identified the apoptosis regulator Mcl-1 as a target that interacts with Cdu1 and is stabilized by deubiquitination at the chlamydial inclusion. A chlamydial transposon insertion mutant in the Cdu1-encoding gene exhibited increased Mcl-1 and inclusion ubiquitination and reduced Mcl-1 stabilization. Additionally, inactivation of Cdu1 led to increased sensitivity of C. trachomatis for IFNγ and impaired infection in mice. Thus, the chlamydial inclusion serves as an enriched site for a deubiquitinating activity exerting a function in selective stabilization of host proteins and protection from host defense.


Assuntos
Proteínas de Bactérias/metabolismo , Chlamydia trachomatis/imunologia , Chlamydia trachomatis/fisiologia , Enzimas Desubiquitinantes/metabolismo , Evasão da Resposta Imune , Proteína de Sequência 1 de Leucemia de Células Mieloides/metabolismo , Vacúolos/microbiologia , Células HEK293 , Células HeLa , Interações Hospedeiro-Patógeno , Humanos , Processamento de Proteína Pós-Traducional
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