RESUMEN
Dysferlinopathy is a progressive muscle disorder that includes limb-girdle muscular dystrophy type 2B and Miyoshi myopathy (MM). It is caused by mutations in the dysferlin (DYSF) gene, whose function is to reseal the muscular membrane. Treatment with proteasome inhibitor MG-132 has been shown to increase misfolded dysferlin in fibroblasts, allowing them to recover their membrane resealing function. Here, we developed a screening system based on myocytes from MM patient-derived induced pluripotent stem cells. According to the screening, nocodazole was found to effectively increase the level of dysferlin in cells, which, in turn, enhanced membrane resealing following injury by laser irradiation. Moreover, the increase was due to microtubule disorganization and involved autophagy rather than the proteasome degradation pathway. These findings suggest that increasing the amount of misfolded dysferlin using small molecules could represent an effective future clinical treatment for dysferlinopathy. Stem Cells Translational Medicine 2019;8:1017-1029.
Asunto(s)
Evaluación Preclínica de Medicamentos/métodos , Células Madre Pluripotentes Inducidas/trasplante , Células Musculares/metabolismo , Distrofia Muscular de Cinturas/tratamiento farmacológico , Adulto , Femenino , Humanos , Persona de Mediana Edad , FenotipoRESUMEN
Dysferlinopathies, which are muscular diseases caused by mutations in the dysferlin gene, remain serious medical problems due to the lack of therapeutic agents. Herein, we report the design, synthesis, and structure-activity relationships of a 2,6-disubstituted 3H-imidazo[4,5-b]pyridine series, which was identified from the phenotypic screening of chemicals that increase the level of dysferlin in myocytes differentiated from patient-derived induced pluripotent stem cells (iPSCs). Optimization studies with cell-based phenotypic assay led to the identification of a highly potent compound, 19, with dysferlin elevation effects at double-digit nanomolar concentrations. In addition, the molecular target of our chemical series was identified as tubulin, through a tubulin polymerization assay and a competitive binding assay using a photoaffinity labeling probe.
Asunto(s)
Imidazoles/química , Distrofia Muscular de Cinturas/tratamiento farmacológico , Piridinas/química , Moduladores de Tubulina/uso terapéutico , Sitios de Unión , Diferenciación Celular , Proliferación Celular/efectos de los fármacos , Diseño de Fármacos , Disferlina/metabolismo , Células Hep G2 , Humanos , Imidazoles/farmacología , Imidazoles/uso terapéutico , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Simulación del Acoplamiento Molecular , Distrofia Muscular de Cinturas/patología , Proteína MioD/metabolismo , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Estructura Terciaria de Proteína , Piridinas/farmacología , Piridinas/uso terapéutico , Relación Estructura-Actividad , Tubulina (Proteína)/química , Tubulina (Proteína)/metabolismo , Moduladores de Tubulina/química , Moduladores de Tubulina/farmacologíaRESUMEN
Here we show a novel pathway of transcriptional regulation of a DNA-binding transcription factor by coupled interaction and modification (e.g., acetylation) through the DNA-binding domain (DBD). The oncogenic regulator SET was isolated by affinity purification of factors interacting with the DBD of the cardiovascular transcription factor KLF5. SET negatively regulated KLF5 DNA binding, transactivation, and cell-proliferative activities. Down-regulation of the negative regulator SET was seen in response to KLF5-mediated gene activation. The coactivator/acetylase p300, on the other hand, interacted with and acetylated KLF5 DBD, and activated its transcription. Interestingly, SET inhibited KLF5 acetylation, and a nonacetylated mutant of KLF5 showed reduced transcriptional activation and cell growth complementary to the actions of SET. These findings suggest a new pathway for regulation of a DNA-binding transcription factor on the DBD through interaction and coupled acetylation by two opposing regulatory factors of a coactivator/acetylase and a negative cofactor harboring activity to inhibit acetylation.
Asunto(s)
Proteínas Nucleares/metabolismo , Proteínas/metabolismo , Transactivadores/metabolismo , Acetilación , Animales , Sitios de Unión , Línea Celular , Proteínas Cromosómicas no Histona , ADN Complementario/genética , Proteínas de Unión al ADN , Regulación hacia Abajo , Proteína p300 Asociada a E1A , Células HeLa , Chaperonas de Histonas , Humanos , Técnicas In Vitro , Factores de Transcripción de Tipo Kruppel , Ratones , Modelos Biológicos , Mutagénesis Sitio-Dirigida , Estructura Terciaria de Proteína , Conejos , Ratas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transactivadores/química , Transactivadores/genética , Factores de Transcripción , Regulación hacia ArribaRESUMEN
Krüppel-like factor 5 (KLF5) is a transcription factor important in regulation of the cardiovascular response to external stress. KLF5 regulates pathological cell growth, and its acetylation is important for this effect. Its mechanisms of action, however, are still unclear. Analysis in KLF5-deficient mice showed that KLF5 confers apoptotic resistance in vascular lesions. Mechanistic analysis further showed that it specifically interacts with poly(ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme important in DNA repair and apoptosis. KLF5 interacted with a proteolytic fragment of PARP-1, and acetylation of KLF5 under apoptotic conditions increased their affinity. Moreover, KLF5 wild-type (but not a non-acetylatable point mutant) inhibited apoptosis as induced by the PARP-1 fragment. Collectively, we have found that KLF5 regulates apoptosis and targets PARP-1, and further, for acetylation to regulate these effects. Our findings thus implicate functional interaction between the transcription factor KLF5 and PARP-1 in cardiovascular apoptosis.