Protective role of mitochondrial uncoupling protein UCP3 and the transcription factor Nrf2 against cardiac ischemia-reperfusion injury and their involvement in ischemic preconditioning

• Autores: Patricia Sánchez Pérez
• Directores de la Tesis: Susana Cadenas Álvarez (dir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2019
• Idioma: español
• Tribunal Calificador de la Tesis: Carmen Aragón Rueda (presid.), Eduardo Rial Zueco (secret.), Laura Beatriz Valdez (voc.)
• Programa de doctorado: Programa de Doctorado en Biociencias Moleculares por la Universidad Autónoma de Madrid
• Materias:
  • Química
    • Bioquímica
      • Biología molecular
  • Ciencias de la vida
    • Biología celular
    • Fisiología humana
      • Fisiología cardiovascular
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Mitochondria are a main source of reactive oxygen species (ROS) in cells, particularly in pathological conditions such as ischemia-reperfusion (IR). Mitochondrial uncoupling proteins UCP2 and UCP3 play an important role in the control of ROS production by the electron transport chain. Besides, the transcription factor Nrf2 (nuclear factor-erythroid 2-related factor 2) is a master regulator of the cellular redox homeostasis. In this thesis, we aimed at analysing the regulation of UCP3 and Nrf2 in response to hypoxia and their protective effect against cardiac IR injury. We have found that hypoxia induces UCP3 expression and Nrf2 nuclear accumulation in C2C12 myotubes and HL-1 cardiomyocytes. These effects are mediated by the activation of p38 MAPK that in turn phosphorylates and activates ATF-1. Moreover, hypoxia/reoxygenation increases mitochondrial superoxide production and induces UCP3 expression and Nrf2 nuclear accumulation to a greater extent than hypoxia alone. Likewise, simulated ischemia and simulated ischemia-reperfusion (SIR) increase UCP3 expression and the activation of both Nrf2 and ATF-1 in HL-1 cells. Consistent with enhanced superoxide production after hypoxia/reoxygenation, SIR augments HNE-protein adducts, indicating increased oxidative stress. Nrf2 activation and ATF-1 phosphorylation also increase in isolated perfused hearts subjected to IR or ischemic preconditioning (IPC), from both UCP3-KO and wild-type mice, although this increase is higher in hearts lacking UCP3. Similarly, active caspase-3 expression is enhanced in these conditions, particularly in UCP3-KO hearts, which reflects increased damage. UCP3 plays a cardioprotective role against IR injury, since isolated perfused hearts from mice lacking this protein present larger infarct size than those from wild-type mice. Consistent with this result, creatine kinase activity in the coronary effluent is higher in UCP3-KO than in wild-type mice at reperfusion. The cardioprotective effect of UCP3 against IR injury is even more relevant in aged than in adult mice and is also evident after left anterior descending (LAD) coronary artery ligation followed by reperfusion, as the histological analysis showed that UCP3 knockout hearts present larger infarct size than wild-type hearts. Moreover, UCP3-KO mice have a tendency to exhibit increased signs of cardiac damage as evaluated by echocardiography. A metabolomics analysis showed that, in ischemic conditions, UCP3 affects on the accumulation of the Krebs cycle intermediates. The data suggest that lipid and energy metabolism are the pathways more likely to be modulated by UCP3.

    The transcription factor Nrf2 plays a cardioprotective role against IR injury, since isolated perfused hearts from mice lacking Nrf2 present larger infarct size than those from wild-type mice.

    Accordingly, creatine kinase activity in the coronary effluent is higher in Nrf2-KO than in wildtype mice at reperfusion. Our results indicate that Nrf2 is involved in IPC, since the absence of this factor abolishes IPC protective effects.