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1.
J Cell Biol ; 223(10)2024 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-39150520

RESUMO

The integrated stress response (ISR) is a vital signaling pathway initiated by four kinases, PERK, GCN2, HRI and PKR, that ensure cellular resilience and protect cells from challenges. Here, we investigated whether increasing ISR signaling could rescue diabetes-like phenotypes in a mouse model of diet-induced obesity (DIO). We show that the orally available and clinically approved GCN2 activator halofuginone (HF) can activate the ISR in mouse tissues. We found that daily oral administration of HF increases glucose tolerance whilst reducing weight gain, insulin resistance, and serum insulin in DIO mice. Conversely, the ISR inhibitor GSK2656157, used at low doses to optimize its selectivity, aggravates glucose intolerance in DIO mice. Whilst loss of function mutations in mice and humans have revealed that PERK is the essential ISR kinase that protects from diabetes, our work demonstrates the therapeutic value of increasing ISR signaling by activating the related kinase GCN2 to reduce diabetes phenotypes in a DIO mouse model.


Assuntos
Obesidade , Fenótipo , Piperidinas , Proteínas Serina-Treonina Quinases , Quinazolinonas , Transdução de Sinais , eIF-2 Quinase , Animais , Quinazolinonas/farmacologia , Piperidinas/farmacologia , Camundongos , eIF-2 Quinase/metabolismo , eIF-2 Quinase/genética , Obesidade/patologia , Obesidade/metabolismo , Obesidade/prevenção & controle , Obesidade/genética , Transdução de Sinais/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Camundongos Endogâmicos C57BL , Masculino , Resistência à Insulina , Insulina/metabolismo , Insulina/sangue , Estresse Fisiológico/efeitos dos fármacos , Modelos Animais de Doenças , Dieta Hiperlipídica/efeitos adversos , Diabetes Mellitus/patologia , Diabetes Mellitus/metabolismo , Diabetes Mellitus/genética , Diabetes Mellitus/tratamento farmacológico , Diabetes Mellitus/prevenção & controle , Intolerância à Glucose/tratamento farmacológico , Adenina/análogos & derivados , Indóis
2.
EMBO J ; 43(5): 663-665, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38308018
3.
Mol Cell ; 84(3): 506-521.e11, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38159565

RESUMO

Regulated protein phosphorylation controls most cellular processes. The protein phosphatase PP1 is the catalytic subunit of many holoenzymes that dephosphorylate serine/threonine residues. How these enzymes recruit their substrates is largely unknown. Here, we integrated diverse approaches to elucidate how the PP1 non-catalytic subunit PPP1R15B (R15B) captures its full trimeric eIF2 substrate. We found that the substrate-recruitment module of R15B is largely disordered with three short helical elements, H1, H2, and H3. H1 and H2 form a clamp that grasps the substrate in a region remote from the phosphorylated residue. A homozygous N423D variant, adjacent to H1, reducing substrate binding and dephosphorylation was discovered in a rare syndrome with microcephaly, developmental delay, and intellectual disability. These findings explain how R15B captures its 125 kDa substrate by binding the far end of the complex relative to the phosphosite to present it for dephosphorylation by PP1, a paradigm of broad relevance.


Assuntos
Domínio Catalítico , Fator de Iniciação 2 em Eucariotos , Proteína Fosfatase 1 , Humanos , Fosforilação , Proteína Fosfatase 1/genética , Proteína Fosfatase 1/metabolismo
4.
Nat Commun ; 14(1): 5535, 2023 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-37684277

RESUMO

Phosphorylation of the translation initiation factor eIF2α to initiate the integrated stress response (ISR) is a vital signalling event. Protein kinases activating the ISR, including PERK and GCN2, have attracted considerable attention for drug development. Here we find that the widely used ATP-competitive inhibitors of PERK, GSK2656157, GSK2606414 and AMG44, inhibit PERK in the nanomolar range, but surprisingly activate the ISR via GCN2 at micromolar concentrations. Similarly, a PKR inhibitor, C16, also activates GCN2. Conversely, GCN2 inhibitor A92 silences its target but induces the ISR via PERK. These findings are pivotal for understanding ISR biology and its therapeutic manipulations because most preclinical studies used these inhibitors at micromolar concentrations. Reconstitution of ISR activation with recombinant proteins demonstrates that PERK and PKR inhibitors directly activate dimeric GCN2, following a Gaussian activation-inhibition curve, with activation driven by allosterically increasing GCN2 affinity for ATP. The tyrosine kinase inhibitors Neratinib and Dovitinib also activate GCN2 by increasing affinity of GCN2 for ATP. Thus, the mechanism uncovered here might be broadly relevant to ATP-competitive inhibitors and perhaps to other kinases.


Assuntos
Desenvolvimento de Medicamentos , Fator de Iniciação 2 em Eucariotos , Fosforilação , Inibição Psicológica , Trifosfato de Adenosina
5.
EMBO J ; 41(11): e109985, 2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35466425

RESUMO

Halofuginone (HF) is a phase 2 clinical compound that inhibits the glutamyl-prolyl-tRNA synthetase (EPRS) thereby inducing the integrated stress response (ISR). Here, we report that halofuginone indeed triggers the predicted canonical ISR adaptations, consisting of attenuation of protein synthesis and gene expression reprogramming. However, the former is surprisingly atypical and occurs to a similar magnitude in wild-type cells, cells lacking GCN2 and those incapable of phosphorylating eIF2α. Proline supplementation rescues the observed HF-induced changes indicating that they result from inhibition of EPRS. The failure of the GCN2-to-eIF2α pathway to elicit a measurable protective attenuation of translation initiation allows translation elongation defects to prevail upon HF treatment. Exploiting this vulnerability of the ISR, we show that cancer cells with increased proline dependency are more sensitive to halofuginone. This work reveals that the consequences of EPRS inhibition are more complex than anticipated and provides novel insights into ISR signaling, as well as a molecular framework to guide the targeted development of halofuginone as a therapeutic.


Assuntos
Piperidinas , Quinazolinonas , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/metabolismo , Fosforilação , Piperidinas/farmacologia , Prolina/metabolismo , Biossíntese de Proteínas , Quinazolinonas/farmacologia
6.
Methods Mol Biol ; 2428: 3-18, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35171470

RESUMO

Phosphorylation of the translation initiation factor eIF2α is an adaptive signaling event that is essential for cell and organismal survival from yeast to humans. It is central to the integrated stress response (ISR) that maintains cellular homeostasis in the face of threats ranging from viral infection, amino acid, oxygen, and heme deprivation to the accumulation of misfolded proteins in the endoplasmic reticulum. Phosphorylation of eIF2α has broad physiological, pathological, and therapeutic relevance. However, despite more than two decades of research and growing pharmacological interest, phosphorylation of eIF2α remains difficult to detect and quantify, because of its transient nature and because substoichiometric amounts of this modification are sufficient to profoundly reshape cellular physiology. This review aims to provide a roadmap for facilitating a robust evaluation of eIF2α phosphorylation and its downstream consequences in cells and organisms.


Assuntos
Retículo Endoplasmático , Fator de Iniciação 2 em Eucariotos , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático , Fator de Iniciação 2 em Eucariotos/metabolismo , Humanos , Fosforilação , Proteína Fosfatase 1/metabolismo , Proteínas/metabolismo
7.
Open Biol ; 11(12): 210205, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34847777

RESUMO

Phosphorylation of the translation initiation factor eIF2α is a rapid and vital cellular defence against many forms of stress. In mammals, the levels of eIF2α phosphorylation are set through the antagonistic action of four protein kinases and two heterodimeric protein phosphatases. The phosphatases are composed of the catalytic subunit PP1 and one of two related non-catalytic subunits, PPP1R15A or PPP1R15B (R15A or R15B). Here, we generated a series of R15 truncation mutants and tested their properties in mammalian cells. We show that substrate recruitment is encoded by an evolutionary conserved region in R15s, R15A325-554 and R15B340-639. G-actin, which has been proposed to confer selectivity to R15 phosphatases, does not bind these regions, indicating that it is not required for substrate binding. Fragments containing the substrate-binding regions but lacking the PP1-binding motif trapped the phospho-substrate and caused accumulation of phosphorylated eIF2α in unstressed cells. Activity assays in cells showed that R15A325-674 and R15B340-713, encompassing the substrate-binding region and the PP1-binding region, exhibit wild-type activity. This work identifies the substrate-binding region in R15s, that functions as a phospho-substrate trapping mutant, thereby defining a key region of R15s for follow up studies.


Assuntos
Mutação , Proteína Fosfatase 1/química , Proteína Fosfatase 1/metabolismo , Actinas/metabolismo , Sítios de Ligação , Clonagem Molecular , Sequência Conservada , Fator de Iniciação 2 em Eucariotos/metabolismo , Células HEK293 , Humanos , Fosforilação , Ligação Proteica , Domínios Proteicos , Proteína Fosfatase 1/genética , Especificidade por Substrato
8.
Cell Rep ; 32(11): 108154, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32937139

RESUMO

Phosphorylation of the translation initiation factor eIF2α is a rapid and vital response to many forms of stress, including protein-misfolding stress in the endoplasmic reticulum (ER stress). It is believed to cause a general reduction in protein synthesis while enabling translation of few transcripts. Such a reduction of protein synthesis comes with the threat of depleting essential proteins, a risk thought to be mitigated by its transient nature. Here, we find that translation attenuation is not uniform, with cytosolic and mitochondrial ribosomal subunits being prominently downregulated. Translation attenuation of these targets persists after translation recovery. Surprisingly, this occurs without a measurable decrease in ribosomal proteins. Explaining this conundrum, translation attenuation preferentially targets long-lived proteins, a finding not only demonstrated by ribosomal proteins but also observed at a global level. This shows that protein stability buffers the cost of translational attenuation, establishing an evolutionary principle of cellular robustness.


Assuntos
Fator de Iniciação 2 em Eucariotos/metabolismo , Biossíntese de Proteínas , Regiões 5' não Traduzidas/genética , Animais , Regulação para Baixo/genética , Estresse do Retículo Endoplasmático/genética , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Modelos Biológicos , Células NIH 3T3 , Fosforilação , Polirribossomos/metabolismo , Estabilidade Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Ribossômicas/metabolismo , Transcrição Gênica , Resposta a Proteínas não Dobradas/genética
9.
Curr Opin Neurobiol ; 61: 125-132, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32199101

RESUMO

The deposition of proteins of abnormal conformation is one of the major hallmarks of the common neurodegenerative diseases including Alzheimer's, Parkinson's, amyotrophic lateral sclerosis, frontotemporal dementia, and prion diseases. Protein quality control systems have evolved to protect cells and organisms against the harmful consequences of abnormally folded proteins that are constantly produced in small amounts. Mutations in rare inherited forms of neurodegenerative diseases have provided compelling evidence that failure of protein quality control systems can drive neurodegeneration. With extensive knowledge of these systems, and the notion that protein quality control may decline with age, many laboratories are now focussing on manipulating these evolutionarily optimized defence mechanisms to reduce the protein misfolding burden for therapeutic benefit.


Assuntos
Doenças Neurodegenerativas , Esclerose Lateral Amiotrófica , Humanos , Proteínas
10.
Biochem J ; 475(23): 3707-3723, 2018 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-30523060

RESUMO

Reversible phosphorylation of proteins is a post-translational modification that regulates all aspect of life through the antagonistic action of kinases and phosphatases. Protein kinases are well characterized, but protein phosphatases have been relatively neglected. Protein phosphatase 1 (PP1) catalyzes the dephosphorylation of a major fraction of phospho-serines and phospho-threonines in cells and thereby controls a broad range of cellular processes. In this review, I will discuss how phosphatases were discovered, how the view that they were unselective emerged and how recent findings have revealed their exquisite selectivity. Unlike kinases, PP1 phosphatases are obligatory heteromers composed of a catalytic subunit bound to one (or two) non-catalytic subunit(s). Based on an in-depth study of two holophosphatases, I propose the following: selective dephosphorylation depends on the assembly of two components, the catalytic subunit and the non-catalytic subunit, which serves as a high-affinity substrate receptor. Because functional complementation of the two modules is required to produce a selective holophosphatase, one can consider that they are split enzymes. The non-catalytic subunit was often referred to as a regulatory subunit, but it is, in fact, an essential component of the holoenzyme. In this model, a phosphatase and its array of mostly orphan substrate receptors constitute the split protein phosphatase system. The set of potentially generalizable principles outlined in this review may facilitate the study of these poorly understood enzymes and the identification of their physiological substrates.


Assuntos
Inibidores Enzimáticos/metabolismo , Fosfoproteínas Fosfatases/química , Fosfoproteínas Fosfatases/metabolismo , Multimerização Proteica , Animais , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Humanos , Fosforilação/efeitos dos fármacos , Proteína Fosfatase 1/química , Proteína Fosfatase 1/metabolismo , Proteína Fosfatase 2/química , Proteína Fosfatase 2/metabolismo , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Especificidade por Substrato
11.
Nat Rev Mol Cell Biol ; 19(11): 697-712, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30065390

RESUMO

The proteasome degrades most cellular proteins in a controlled and tightly regulated manner and thereby controls many processes, including cell cycle, transcription, signalling, trafficking and protein quality control. Proteasomal degradation is vital in all cells and organisms, and dysfunction or failure of proteasomal degradation is associated with diverse human diseases, including cancer and neurodegeneration. Target selection is an important and well-established way to control protein degradation. In addition, mounting evidence indicates that cells adjust proteasome-mediated degradation to their needs by regulating proteasome abundance through the coordinated expression of proteasome subunits and assembly chaperones. Central to the regulation of proteasome assembly is TOR complex 1 (TORC1), which is the master regulator of cell growth and stress. This Review discusses how proteasome assembly and the regulation of proteasomal degradation are integrated with cellular physiology, including the interplay between the proteasome and autophagy pathways. Understanding these mechanisms has potential implications for disease therapy, as the misregulation of proteasome function contributes to human diseases such as cancer and neurodegeneration.


Assuntos
Neoplasias/metabolismo , Neoplasias/patologia , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Complexo de Endopeptidases do Proteassoma/fisiologia , Animais , Autofagia/fisiologia , Proliferação de Células/fisiologia , Humanos , Chaperonas Moleculares/metabolismo , Proteólise , Transdução de Sinais/fisiologia
12.
Cell ; 174(5): 1216-1228.e19, 2018 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-30057111

RESUMO

Protein phosphorylation is a prevalent and ubiquitous mechanism of regulation. Kinases are popular drug targets, but identifying selective phosphatase inhibitors has been challenging. Here, we used surface plasmon resonance to design a method to enable target-based discovery of selective serine/threonine phosphatase inhibitors. The method targeted a regulatory subunit of protein phosphatase 1, PPP1R15B (R15B), a negative regulator of proteostasis. This yielded Raphin1, a selective inhibitor of R15B. In cells, Raphin1 caused a rapid and transient accumulation of its phosphorylated substrate, resulting in a transient attenuation of protein synthesis. In vitro, Raphin1 inhibits the recombinant R15B-PP1c holoenzyme, but not the closely related R15A-PP1c, by interfering with substrate recruitment. Raphin1 was orally bioavailable, crossed the blood-brain barrier, and demonstrated efficacy in a mouse model of Huntington's disease. This identifies R15B as a druggable target and provides a platform for target-based discovery of inhibitors of serine/threonine phosphatases.


Assuntos
Barreira Hematoencefálica/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Guanidinas/farmacologia , Proteína Fosfatase 1/antagonistas & inibidores , Animais , Peso Corporal , Modelos Animais de Doenças , Descoberta de Drogas , Feminino , Guanidinas/química , Células HeLa , Humanos , Doença de Huntington/metabolismo , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Proteína Fosfatase 1/metabolismo , Subunidades Proteicas/antagonistas & inibidores , Proteostase , Proteínas Recombinantes/farmacologia , Ressonância de Plasmônio de Superfície
13.
Curr Opin Neurobiol ; 51: 127-133, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29631171

RESUMO

Alzheimer's disease, Parkinson's, Huntington's, amyotrophic lateral sclerosis (ALS) and prion disorders are devastating neurodegenerative diseases of increasing prevalence in aging populations. Although clinically different, they share similar molecular features: the accumulation of one or two proteins in abnormal conformations inside or outside neurons. Enhancing protein quality control systems could be a useful strategy to neutralize the abnormal proteins causing neurodegenerative diseases. This review emphasizes the subcellular location of protein deposits in neurodegenerative diseases and the need to tailor strategies aimed at boosting protein quality control systems to the affected subcellular compartment. Inhibition of a protein phosphatase terminating the unfolded protein response will be discussed as a strategy to protect from diseases associated with misfolded proteins in the endoplasmic reticulum.


Assuntos
Retículo Endoplasmático/metabolismo , Doenças Neurodegenerativas/patologia , Neurônios/ultraestrutura , Proteínas/metabolismo , Animais , Humanos , Neurônios/metabolismo , Deficiências na Proteostase/patologia
14.
EMBO J ; 37(6)2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29496740

RESUMO

Protein aggregation is a hallmark of diverse neurodegenerative diseases. Multiple lines of evidence have revealed that protein aggregates can penetrate inside cells and spread like prions. How such aggregates enter cells remains elusive. Through a focused siRNA screen targeting genes involved in membrane trafficking, we discovered that mutant SOD1 aggregates, like viruses, exploit cofilin-1 to remodel cortical actin and enter cells. Upstream of cofilin-1, signalling from the RHO GTPase and the ROCK1 and LIMK1 kinases controls cofilin-1 activity to remodel actin and modulate aggregate entry. In the spinal cord of symptomatic SOD1G93A transgenic mice, cofilin-1 phosphorylation is increased and actin dynamics altered. Importantly, the RHO to cofilin-1 signalling pathway also modulates entry of tau and α-synuclein aggregates. Our results identify a common host cell signalling pathway that diverse protein aggregates exploit to remodel actin and enter cells.


Assuntos
Cofilina 1/metabolismo , Agregados Proteicos , Proteínas rho de Ligação ao GTP/metabolismo , Actinas/metabolismo , Animais , Linhagem Celular , Quinases Lim/metabolismo , Camundongos Transgênicos , RNA Interferente Pequeno/genética , Proteínas Recombinantes/metabolismo , Transdução de Sinais , Medula Espinal/metabolismo , Superóxido Dismutase-1/genética , Superóxido Dismutase-1/metabolismo , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo , Quinases Associadas a rho/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismo
15.
Annu Rev Cell Dev Biol ; 33: 439-465, 2017 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-28992440

RESUMO

Cells and organisms have evolved numerous mechanisms to cope with and to adapt to unexpected challenges and harsh conditions. Proteins are essential to perform the vast majority of cellular and organismal functions. To maintain a healthy proteome, cells rely on a network of factors and pathways collectively known as protein quality control (PQC) systems, which not only ensure that newly synthesized proteins reach a functional conformation but also are essential for surveillance, prevention, and rescue of protein defects. The main players of PQC systems are chaperones and protein degradation systems: the ubiquitin-proteasome system and autophagy. Here we provide an integrated overview of the diverse PQC systems in eukaryotic cells in health and diseases, with an emphasis on the key regulatory aspects and their cross talks. We also highlight how PQC regulation may be exploited for potential therapeutic benefit.


Assuntos
Proteínas/metabolismo , Aminoácidos/metabolismo , Animais , Doença , Células Eucarióticas/metabolismo , Homeostase , Humanos , Estresse Fisiológico
16.
Nat Struct Mol Biol ; 24(9): 708-716, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28759048

RESUMO

The reversible phosphorylation of proteins controls most cellular functions. Protein kinases have been popular drug targets, unlike phosphatases, which remain a drug discovery challenge. Guanabenz and Sephin1 are selective inhibitors of the phosphatase regulatory subunit PPP1R15A (R15A) that prolong the benefit of eIF2α phosphorylation, thereby protecting cells from proteostatic defects. In mice, Sephin1 prevents two neurodegenerative diseases, Charcot-Marie-Tooth 1B (CMT-1B) and SOD1-mediated amyotrophic lateral sclerosis (ALS). However, the molecular basis for R15A inhibition is unknown. Here we reconstituted human recombinant eIF2α holophosphatases, R15A-PP1 and R15B-PP1, whose activity depends on both the catalytic subunit PP1 (protein phosphatase 1) and either R15A or R15B. This system enabled the functional characterization of these holophosphatases and revealed that Guanabenz and Sephin1 induced a selective conformational change in R15A, detected by resistance to limited proteolysis. This altered the recruitment of eIF2α, preventing its dephosphorylation. This work demonstrates that regulatory subunits of phosphatases are valid drug targets and provides the molecular rationale to expand this concept to other phosphatases.


Assuntos
Fator de Iniciação 2 em Eucariotos/química , Fator de Iniciação 2 em Eucariotos/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Proteína Fosfatase 1/química , Proteína Fosfatase 1/metabolismo , Guanabenzo/análogos & derivados , Guanabenzo/metabolismo , Humanos , Ligação Proteica , Conformação Proteica/efeitos dos fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo
17.
Nat Protoc ; 12(7): 1451-1457, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28686587

RESUMO

Phenotypic analysis of mouse models of human diseases is essential to understanding the underlying disease mechanisms and to developing therapeutics. Many models of neurodegenerative diseases are associated with motor dysfunction, a powerful readout for the disease. We describe here a set of measures to quantitatively monitor early disease onset and progression. We named this set of rules qMotor because it enables sensitive, robust and quantitative measurement of motor performance in 3 d. qMotor can be used to assess early disease onset, before paralysis, as well as disease progression in diverse mouse models, and can be exploited to define robust and humane experimental end points, thereby reducing animal suffering. As an example, we apply qMotor to SOD1G93A transgenic mice. Early studies with the original transgenic SOD1G93A mice in the hybrid background (B6SJL-Tg(SOD1-G93A) have been criticized because of high noise in this mixed background and because of inadequate study designs. We applied qMotor in SOD1G93A transgenic mice in an inbred C57BL/6J background, hereafter called iSOD1G93A mice, and show a remarkably robust and consistent phenotype in this line that we use to evaluate a therapeutic approach. qMotor is a protocol generically applicable to different mouse models.


Assuntos
Atividade Motora , Doenças Neurodegenerativas/patologia , Animais , Modelos Animais de Doenças , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação de Sentido Incorreto , Superóxido Dismutase-1/genética
18.
Artigo em Inglês | MEDLINE | ID: mdl-28096265

RESUMO

Amyotrophic lateral sclerosis (ALS) is a devastating and rapidly progressive neurodegenerative disease caused by the deterioration of motor neurons. The first symptoms of ALS always begin at a focal but variable site and consistently spread to neighboring regions, suggesting that neurodegeneration in ALS is an orderly and propagating process. Like other neurodegenerative diseases, misfolding of a specific protein is central to ALS. SOD1, the major constituent of the protein deposits in some familial and sporadic forms of ALS, propagates its misfolded conformation like prions, providing a plausible molecular basis for the focality and spreading of muscle weakness in ALS. Because protein misfolding is a common cause of diverse neurodegenerative diseases, strategies aimed at boosting a cell's ability to cope with misfolded proteins could lead to therapeutics to combat these devastating age-related proteinopathies.


Assuntos
Esclerose Lateral Amiotrófica/metabolismo , Príons/metabolismo , Superóxido Dismutase-1/metabolismo , Esclerose Lateral Amiotrófica/terapia , Humanos
19.
Mol Cell ; 63(6): 915-7, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27635757

RESUMO

Proteasome degradation is essential, but the intrinsic features of a protein that signals its destruction remain incompletely understood. In this issue of Molecular Cell, Geffen et al. (2016) report an unbiased and proteome-wide method that provided insights into the protein destruction signals and pathways.


Assuntos
Complexo de Endopeptidases do Proteassoma , Proteoma
20.
Nature ; 536(7615): 184-9, 2016 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-27462806

RESUMO

The proteasome is essential for the selective degradation of most cellular proteins, but how cells maintain adequate amounts of proteasome is unclear. Here we show that there is an evolutionarily conserved signalling pathway controlling proteasome homeostasis. Central to this pathway is TORC1, the inhibition of which induced all known yeast 19S regulatory particle assembly-chaperones (RACs), as well as proteasome subunits. Downstream of TORC1 inhibition, the yeast mitogen-activated protein kinase, Mpk1, acts to increase the supply of RACs and proteasome subunits under challenging conditions in order to maintain proteasomal degradation and cell viability. This adaptive pathway was evolutionarily conserved, with mTOR and ERK5 controlling the levels of the four mammalian RACs and proteasome abundance. Thus, the central growth and stress controllers, TORC1 and Mpk1/ERK5, endow cells with a rapid and vital adaptive response to adjust proteasome abundance in response to the rising needs of cells. Enhancing this pathway may be a useful therapeutic approach for diseases resulting from impaired proteasomal degradation.


Assuntos
Evolução Molecular , Homeostase , Complexo de Endopeptidases do Proteassoma/metabolismo , Transdução de Sinais , Animais , Sobrevivência Celular , Sequência Conservada , Células HeLa , Humanos , Proteína Quinase 7 Ativada por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Chaperonas Moleculares/metabolismo , Complexo de Endopeptidases do Proteassoma/química , Subunidades Proteicas/metabolismo , Proteólise , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores , Proteínas de Saccharomyces cerevisiae/metabolismo , Estresse Fisiológico , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/metabolismo
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