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. Author manuscript; available in PMC: 2012 Oct 18.
Published in final edited form as: Mech Ageing Dev. 2011 Jun 25;132(6-7):340–347. doi: 10.1016/j.mad.2011.06.004

Fig. 3.

Fig. 3

Proposed contribution of mitochondrial dysfunction to premature aging in Cockayne syndrome and related diseases. Upper panel: defects in CSB or other proteins involved in mtBER cause accumulation of mtDNA mutations or loss of mtDNA. Mutated or depleted mtDNA leads to altered respiration and increased production of ROS/RNS, which in turn causes more cellular damage, including even more mtDNA damage (arrows). This vicious cycle accelerates the rate of accumulating dysfunctional mitochondria. Lower panel: a single young cell contains many functional mitochondria (left). Normal aging is associated with slow accumulation of dysfunctional mitochondria. Phenotypic signs appear at high degree of mitochondrial heteroplasmy (right). Defective mtBER could increase the rate of accumulation of dysfunctional mitochondria (upper panel) in individuals with CS or other diseases characterized by accelerated aging.