RESUMO
The Shieldin complex shields double-strand DNA breaks (DSBs) from nucleolytic resection. Curiously, the penultimate Shieldin component, SHLD1, is one of the least abundant mammalian proteins. Here, we report that the transcription factors THAP1, YY1, and HCF1 bind directly to the SHLD1 promoter, where they cooperatively maintain the low basal expression of SHLD1, thereby ensuring a proper balance between end protection and resection during DSB repair. The loss of THAP1-dependent SHLD1 expression confers cross-resistance to poly (ADP-ribose) polymerase (PARP) inhibitor and cisplatin in BRCA1-deficient cells and shorter progression-free survival in ovarian cancer patients. Moreover, the embryonic lethality and PARPi sensitivity of BRCA1-deficient mice is rescued by ablation of SHLD1. Our study uncovers a transcriptional network that directly controls DSB repair choice and suggests a potential link between DNA damage and pathogenic THAP1 mutations, found in patients with the neurodevelopmental movement disorder adult-onset torsion dystonia type 6.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Animais , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Proteínas de Ciclo Celular/genética , DNA/metabolismo , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Reparo do DNA por Junção de Extremidades/efeitos dos fármacos , Reparo do DNA/genética , Distonia/genética , Feminino , Fator C1 de Célula Hospedeira/metabolismo , Proteínas Mad2/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Poli(ADP-Ribose) Polimerase-1/metabolismo , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Reparo de DNA por Recombinação/efeitos dos fármacos , Proteínas de Ligação a Telômeros/metabolismo , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismo , Fator de Transcrição YY1/metabolismoRESUMO
Cyclolepis genistoides D. Don is a herbaceous perennial belonging to the family Asteraceae, and its vernacular name is "palo azul" (palo). Palo has been reported to exhibit many physiological effects that contribute to the prevention of metabolic syndromes, although its mechanism is unclear. Among palo's various activities, we investigated the hypothesis that palo promotes adipocytes differentiation and regulates adipokine profiles in 3T3-L1 adipocytes by modulation of peroxisome proliferator-activated receptor (PPAR) γ, a major regulator of adipose differentiation. 3T3-L1 adipocytes were cultured and differentiated in Dulbecco modified Eagle medium with 50 to 200 µg/mL palo for 7 days or were cultured with palo without differentiation protocol for 14 days. Palo down-regulated the expression of 2 types of expressed/secreted adipokines, leptin and resistin, in a concentration-dependent manner. Under a nondifferentiated condition, palo promoted the accumulation of lipid droplets in cells. Real-time polymerase chain reaction and luciferase reporter assay showed that palo up-regulated expression and transcriptional activity of PPARγ. Furthermore, palo increased the expression of insulin-sensitizing adipokine, adiponectin, which is a directly target of PPARγ, both at the messenger RNA level and at the protein level. In summary, palo demonstrated the potential to improve insulin resistance by promoting adipocyte differentiation via PPARγ activation. Results suggest an increase in adiponectin secretion and a decrease in insulin-resistant factors such as leptin and resistin.