Purchase this article with an account.
S Mohr, TS Duerler; Elevated Glucose Initiates Mitochondrial Abnormalities Involved in Apoptosis of Retinal Müller Cells . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1995.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Retinal cells undergo apoptosis, a programmed cell death that is mediated by the activation of caspases, during the development of diabetic retinopathy. We have previously shown that hyperglycemia induces caspase activation, and subsequent oxidative stress and apoptosis in the retinal Müller cell line (rMC-1). Therefore, we focused this study on the effect of elevated glucose on mitochondrial alterations known to participate in one form (Typ II) of apoptosis. Methods: Müller cells were treated with up to 25 mM glucose for 3 or 5 days. Cells treated with 5 mM glucose served as controls. Following high glucose incubation, mitochondria and cytosolic fractions were separated and probed against cytochrome c. Whole cell lysates tested for bax and bak using Western Blots. Caspase activities were measured by incubating whole cell lysates with fluorogenic substrates specific for the individual caspases. Mitochondria mediated oxidative stress was detected using MitoTrackerRed (CM-H2XRos) followed by confocal microscopy analysis. Results: High glucose treatment of retinal Müller cells induced increased mitochondrial superoxide production and the activation of caspase-8, 9, and 3 within 5 days. The amount of caspase-3 activity was strongly dependent on cell passage and was not detectable at lower passage. Starting at day 3, cytochrome c was partially released from the mitochondria into the cytosol. In addition, high glucose induced upregulation of bax, a pro-apoptotic bcl2 family member strongly associated with mitochondria-mediated apoptosis. The level of bak expression remained unchanged. Conclusion: The results indicate that hyperglycemia induces mitochondria impairment and cytochrome c release into the cytosol suggesting a Typ II apoptosis signaling pathway in retinal Müller cells.
This PDF is available to Subscribers Only