RESUMO
The literary critic and NRF editor Jean Paulhan devised a way of thinking about fluctuating historical and psychological attitudes toward language, organizing them into a dialectic of "Rhetoric" and "Terror." In this article, I focus on Paulhan and Sartre's response to the interwar crisis of Terror and explore Rhetoric and Terror as a heuristic in the intellectual history of France.
Assuntos
Linguística , FrançaRESUMO
The Stac3 gene is exclusively expressed in skeletal muscle, and Stac3 knockout is perinatal lethal in mice. Previous data from Stac3-deleted diaphragms indicated that Stac3-deleted skeletal muscle could not contract because of defective excitation-contraction (EC) coupling. In this study, we determined the contractility of Stac3-deleted hindlimb muscle. In response to frequent electrostimulation, Stac3-deleted hindlimb muscle contracted but the maximal tension generated was only 20% of that in control (wild type or heterozygous) muscle (P < 0.05). In response to high [K(+)], caffeine, and 4-chloro-m-cresol (4-CMC), the maximal tensions generated in Stac3-deleted muscle were 29% (P < 0.05), 58% (P = 0.08), and 55% (P < 0.05) of those in control muscle, respectively. In response to 4-CMC or caffeine, over 90% of myotubes formed from control myoblasts contracted, but only 60% of myotubes formed from Stac3-deleted myoblasts contracted (P = 0.05). However, in response to 4-CMC or caffeine, similar increases in intracellular calcium concentration were observed in Stac3-deleted and control myotubes. Gene expression and histological analyses revealed that Stac3-deleted hindlimb muscle contained more slow type-like fibers than control muscle. These data together confirm a critical role of STAC3 in EC coupling but also suggest that STAC3 may have additional functions in skeletal muscle, at least in the hindlimb muscle.
Assuntos
Acoplamento Excitação-Contração , Membro Posterior/patologia , Membro Posterior/fisiopatologia , Músculos/patologia , Músculos/fisiopatologia , Proteínas do Tecido Nervoso/deficiência , Proteínas Adaptadoras de Transdução de Sinal , Animais , Histocitoquímica , Camundongos KnockoutRESUMO
BACKGROUND: The SH3 and cysteine-rich domain 3 (Stac3) gene is specifically expressed in the skeletal muscle. Stac3 knockout mice die perinatally. In this study, we determined the potential role of Stac3 in postnatal skeletal muscle growth, fiber composition, and contraction by generating conditional Stac3 knockout mice. METHODS: We disrupted the Stac3 gene in 4-week-old male mice using the Flp-FRT and tamoxifen-inducible Cre-loxP systems. RESULTS: RT-qPCR and western blotting analyses of the limb muscles of target mice indicated that nearly all Stac3 mRNA and more than 70 % of STAC3 protein were deleted 4 weeks after tamoxifen injection. Postnatal Stac3 deletion inhibited body and limb muscle mass gains. Histological staining and gene expression analyses revealed that postnatal Stac3 deletion decreased the size of myofibers and increased the percentage of myofibers containing centralized nuclei, with no effect on the total myofiber number. Grip strength and grip time tests indicated that postnatal Stac3 deletion decreased limb muscle strength in mice. Muscle contractile tests revealed that postnatal Stac3 deletion reduced electrostimulation-induced but not the ryanodine receptor agonist caffeine-induced maximal force output in the limb muscles. Calcium imaging analysis of single flexor digitorum brevis myofibers indicated that postnatal Stac3 deletion reduced electrostimulation- but not caffeine-induced calcium release from the sarcoplasmic reticulum. CONCLUSIONS: This study demonstrates that STAC3 is important to myofiber hypertrophy, myofiber-type composition, contraction, and excitation-induced calcium release from the sarcoplasmic reticulum in the postnatal skeletal muscle.
Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Desenvolvimento Muscular , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Retículo Sarcoplasmático/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Fatores Etários , Animais , Cafeína/farmacologia , Canais de Cálcio Tipo L/genética , Canais de Cálcio Tipo L/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Estimulação Elétrica , Regulação da Expressão Gênica no Desenvolvimento , Genótipo , Hipertrofia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Contração Muscular , Desenvolvimento Muscular/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/patologia , Força Muscular , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/crescimento & desenvolvimento , Músculo Esquelético/fisiopatologia , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Fenótipo , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/patologiaRESUMO
Nemaline myopathy (NM) is a congenital myopathy that can result in lethal muscle dysfunction and is thought to be a disease of the sarcomere thin filament. Recently, several proteins of unknown function have been implicated in NM, but the mechanistic basis of their contribution to disease remains unresolved. Here, we demonstrated that loss of a muscle-specific protein, kelch-like family member 40 (KLHL40), results in a nemaline-like myopathy in mice that closely phenocopies muscle abnormalities observed in KLHL40-deficient patients. We determined that KLHL40 localizes to the sarcomere I band and A band and binds to nebulin (NEB), a protein frequently implicated in NM, as well as a putative thin filament protein, leiomodin 3 (LMOD3). KLHL40 belongs to the BTB-BACK-kelch (BBK) family of proteins, some of which have been shown to promote degradation of their substrates. In contrast, we found that KLHL40 promotes stability of NEB and LMOD3 and blocks LMOD3 ubiquitination. Accordingly, NEB and LMOD3 were reduced in skeletal muscle of both Klhl40-/- mice and KLHL40-deficient patients. Loss of sarcomere thin filament proteins is a frequent cause of NM; therefore, our data that KLHL40 stabilizes NEB and LMOD3 provide a potential basis for the development of NM in KLHL40-deficient patients.
Assuntos
Proteínas Musculares/deficiência , Miopatias da Nemalina/etiologia , Miopatias da Nemalina/metabolismo , Animais , Animais Recém-Nascidos , Proteínas do Citoesqueleto/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Musculares/química , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Miopatias da Nemalina/patologia , Domínios e Motivos de Interação entre Proteínas , Estabilidade Proteica , Proteólise , Sarcômeros/metabolismo , Sarcômeros/patologia , UbiquitinaçãoRESUMO
Loss-of-function mutations in the myotubularin gene (MTM1) cause X-linked myotubular myopathy (XLMTM), a fatal, congenital pediatric disease that affects the entire skeletal musculature. Systemic administration of a single dose of a recombinant serotype 8 adeno-associated virus (AAV8) vector expressing murine myotubularin to Mtm1-deficient knockout mice at the onset or at late stages of the disease resulted in robust improvement in motor activity and contractile force, corrected muscle pathology, and prolonged survival throughout a 6-month study. Similarly, single-dose intravascular delivery of a canine AAV8-MTM1 vector in XLMTM dogs markedly improved severe muscle weakness and respiratory impairment, and prolonged life span to more than 1 year in the absence of toxicity or a humoral or cell-mediated immune response. These results demonstrate the therapeutic efficacy of AAV-mediated gene therapy for myotubular myopathy in small- and large-animal models, and provide proof of concept for future clinical trials in XLMTM patients.
Assuntos
Modelos Animais de Doenças , Terapia Genética/métodos , Miopatias Congênitas Estruturais/genética , Miopatias Congênitas Estruturais/terapia , Animais , Dependovirus/genética , Diafragma , Cães , Vetores Genéticos , Genótipo , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Knockout , Contração Muscular , Debilidade Muscular , Mutação , Miopatias Congênitas Estruturais/mortalidade , Proteínas Tirosina Fosfatases não Receptoras/genéticaRESUMO
Polybrominated diphenyl ethers (PBDEs) and their methoxylated- (MeO-) and hydroxylated- (OH-) analogs are ubiquitously distributed in the environment worldwide. The OH-BDEs have greater potency than PBDEs and can be produced from the transformation of MeO-BDEs. The objectives of the current study were to (1) identify the enzyme(s) that catalyze biotransformation of 6-MeO-BDE-47 to 6-OH-BDE-47 in livers from rainbow trout, and (2) compare biotransformation of 6-MeO-BDE-47 to 6-OH-BDE-47 among rainbow trout, white sturgeon and goldfish. Cytochrome P450 1A (CYP1A) enzymes did not catalyze the biotransformation reaction. However, biotransformation was significantly inhibited by the CYP inhibitors clotrimazole and 1-benzylimidazole but not gestodene. Therefore, the reaction is likely catalyzed by CYP2 enzymes. When biotransformation was compared among species, concentrations of 6-OH-BDE-47 were significantly 3.4- and 9.1-fold greater in microsomes from rainbow trout compared to goldfish or white sturgeon, respectively. Concentrations of 6-OH-BDE-47 in microsomes from goldfish were non-significantly 2.7-fold greater than in sturgeon. The initial rate of biotransformation in microsomes from livers of rainbow trout was significantly 2.0- and 6.2-fold greater than the initial rate of biotransformation in microsomes from livers of goldfish or sturgeon, respectively, while the initial rate in goldfish was significantly 3.1-fold greater than in sturgeon. It is hypothesized that differences in CYP-mediated biotransformation of MeO-BDEs to OH-BDEs could influence concentrations of OH-BDEs in different species of fish.