Molecular mechanisms controlling the translation of the mrna encoding the human catalytic beta-subunit of mitochondrial h+-atp synthase in cancer an development.

Tesis doctoral de Imke María Willers

Mitochondria are essential organelles in cell physiology, playing key roles in bioenergetics, the execution of the cell death and intracellular signaling by ca2+ and reactive oxygen species (ros). mitochondrial dysfunction is associated with a large number of human pathologies, which include cancer, diabetes and neurodegeneration. It is nowadays accepted that a phenotypic trait of most human carcinomas is the reprogramming of their cellular energetic metabolism from mitochondrial oxidative phosphorylation to an enhanced aerobic glycolysis, the so-called warburg effect. In this scenario, the mitochondrial h+-atp synthase is an essential component both in the transduction of biological energy as well as in the execution of cell death. In fact, the down-regulation of the catalytic subunit of the h+-atp synthase (íY-f1-atpase) is a hallmark of many human carcinomas affording a marker of prognosis and of the response to therapy. Moreover, cancer cells and tumors over-express if1, an inhibitor of the h+-atp synthase. In the present phd thesis we have investigated the molecular mechanisms that control at post-transcriptional levels the expression of human íY-f1-atpase. We illustrate that down-regulation of íY-f1-atpase in human breast, lung, esophageal and colon cancer originates from a specific translation repression event that can be recapitulated in in vitro translation assays. We demonstrate that the human 3¿utr of íY-f1-atpase mrna (íY-mrna) is an important cis-acting element necessary for efficient translation. However, and at variance with previous findings with the rat transcript, recapitulation of translational repression requires the participation of additional cis-acting elements of the human transcript. in order to characterize the molecular mechanisms that underlie the masking of íY-mrna we have undertaken studies aimed at the identification of the rna binding proteins and mirnas that target the human transcript. Herein, we demonstrate that ras-gap sh3 binding protein 1 (g3bp1) interacts within the cellular context with the 3¿utr of íY-mrna and is part of the cytoplasmic rna granules that contain íY-mrna. Furthermore, we show that g3bp1 promotes the repression of íY-mrna translation both in vivo and in vitro. Specifically, we demonstrate that g3bp1 hampers the initiation step of íY-mrna translation, strongly supporting that the regulated binding of g3bp1 to the transcript might be involved in masking the translation of íY-mrna in human cancer. Moreover, we demonstrate in a cohort of 93 breast cancer patients that a high expression of g3bp1 affords a marker of cancer progression, specially providing a reliable indicator of developing metastatic disease within the group of breast cancer patients with a good prognosis as assessed by their metabolic phenotype. In contrast to these findings, we show that the rnabps imp1 and npm1 do not interact with íY-mrna playing no relevant role in íY-f1-atpase biology. Finally, we have developed cellular systems to analyze the role of mirnas in íY-f1-atpase expression. Using these systems we show that íY-mrna is targeted and translationally silenced by mir-127-5p, whereas mir-101, mir-103, mir-186, mir-200b, mir-423-5p and mir-581 have no apparent functional role. mir-127-5p is not expressed in human cancer cell lines. However, we observed its expression in human fetal liver strongly suggesting that it might play a relevant role controlling the translation of íY-mrna during development of the human liver.

 

Datos académicos de la tesis doctoral «Molecular mechanisms controlling the translation of the mrna encoding the human catalytic beta-subunit of mitochondrial h+-atp synthase in cancer an development.«

  • Título de la tesis:  Molecular mechanisms controlling the translation of the mrna encoding the human catalytic beta-subunit of mitochondrial h+-atp synthase in cancer an development.
  • Autor:  Imke María Willers
  • Universidad:  Autónoma de Madrid
  • Fecha de lectura de la tesis:  17/06/2011

 

Dirección y tribunal

  • Director de la tesis
    • José Manuel Cuezva Marcos
  • Tribunal
    • Presidente del tribunal: jorgina Satrústegui gil-delgado
    • José Antonio Enríquez domínguez (vocal)
    • José Luis Rodríguez peralto (vocal)
    • Alberto Muñoz terol (vocal)

 

Deja un comentario

Tu dirección de correo electrónico no será publicada. Los campos obligatorios están marcados con *

Scroll al inicio