Résumé
Mitochondria play a key role in cell metabolism. In addition to synthesizing ATP, they also participate in many physiological and pathological processes, including apoptosis, inflammation, oxidative stress, neuronal disease, tumor development, and aging. Most gene transcription of mitochondrial proteins occurs in the nucleus, so the biogenesis of mitochondria and the maintenance of mitochondrial homeostasis mainly depend on the expression of nuclear genes (nDNA) and mitochondria-nucleus interactions. Conversely, mitochondria can affect the expression of nuclear genes through nuclear transcription factors, a process called mitochondrial retrograde signaling. This review summarizes the research progress on mitochondria-nucleus retrograde signaling and its regulation, including the ways by which mitochondria regulate nuclear genes and affect biological processes, and discusses new strategies for the treatment of diseases that involve mitochondrial retrograde signaling in disease pathology.
Résumé
Mitochondrial dysfunctions play major roles in ageing. How mitochondrial stresses invoke downstream responses and how specificity of the signaling is achieved, however, remains unclear. We have previously discovered that the RNA component of Telomerase TERC is imported into mitochondria, processed to a shorter form TERC-53, and then exported back to the cytosol. Cytosolic TERC-53 levels respond to mitochondrial functions, but have no direct effect on these functions, suggesting that cytosolic TERC-53 functions downstream of mitochondria as a signal of mitochondrial functions. Here, we show that cytosolic TERC-53 plays a regulatory role on cellular senescence and is involved in cognition decline in 10 months old mice, independent of its telomerase function. Manipulation of cytosolic TERC-53 levels affects cellular senescence and cognition decline in 10 months old mouse hippocampi without affecting telomerase activity, and most importantly, affects cellular senescence in terc cells. These findings uncover a senescence-related regulatory pathway with a non-coding RNA as the signal in mammals.