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Jonathan G. Crowston, Leo Sheck, Nicole J. Van Bergen, Shanjean Lee, Vicki Chrysostomou, Andrea L. Vincent, Ian A. Trounce; Defects In Whole Cell Respiration In POAG Lymphoblasts. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6947.
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Increased rates of mtDNA mutations have been reported in POAG patients. Last year we demonstrated a complex I-driven ATP synthesis defect in lymphoblast mitochondria isolated from a cohort of POAG patients compared to age-matched controls. The current study investigated whether this manifests in a whole cell respiration defect in POAG-patient derived lymphoblasts
Whole cell respiration was measured by high-resolution respirometry. Adenosine triphosphate (ATP) synthesis rates were measured in whole cells. Oxidative phosphorylation (OXPHOS) protein expression, as well as response to mitochondrial toxins, lymphoblast growth rates in galactose media and mitochondrial morphology were assessed in transformed lymphocytes from POAG patients (n=15) and a group of age- and gender-matched controls (n=14).
POAG lymphoblasts had significantly lower endogenous (-30%, 0.016)) and complex I driven (-17.5%, P<0.046)) maximum respiration rates and reduced complex I-driven ATP (0.38±0.03 fmoles ATP/sec/106 cells in controls and 0.252±0.032 fmoles ATP/sec/106 cells(p=0.001)/ Complex II-driven ATP synthesis was preserved. Other measures of mitochondrial function, such as OXPHOS protein expression, response to mitochondrial toxins, growth rates in galactose media and gross mitochondrial morphology revealed no significant differences between the control and POAG cohort.
POAG lymphoblasts in our cohort exhibited a defect in whole cell respiration which appears to involve complex I of the OXPHOS pathway, leading to decreased rates of ATP production. In the presence of a multitude of cellular stressors as seen in the early stages of POAG, this defect may lead to bioenergetic deficiency in retinal ganglion cells and an increased susceptibility to cell death.
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