Abstract: FR-PO215
Diabetic Milieu-Induced Mitochondrial Oxidative Damage and Loss of Mitochondrial Proteostasis in Glomerular Endothelial Cells
Session Information
- Diabetic Kidney Disease: Basic - II
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Diabetic Kidney Disease
- 601 Diabetic Kidney Disease: Basic
Authors
- Casalena, Gabriella, Icahn school of medicine at mount sinai, New York, New York, United States
- Yu, Liping, Mount Sinai School of Medicine, New York, New York, United States
- Daehn, Ilse S., Mount Sinai School of Medicine, New York, New York, United States
Background
Oxidative stress and mitochondrial dysfunction are considered central mediators in the pathogenesis of diabetic complications including diabetic kidney disease (DKD). We have demonstrated that mitochondrial stress and dysfunction in glomerular endothelial cells precede and mediate in part albuminuria, podocyte defects and depletion, and glomerulosclerosis in DKD susceptible DBA/2J mice. We hypothesize that DKD-susceptibility is characterized by glomerular endothelial mitochondrial stress-dependent endothelial dysfunction and secretion of crosstalk factors required for podocyte injury and depletion.
Aim: To examine mitochondrial oxidative stress and quality control mechanisms in glomerular endothelial cells exposed to a diabetic milieu and assess the impact of endothelial cell dysfunction on podocytes in co-culture.
Methods
We treated murine glomerular endothelial cells (mGECs) with high glucose media (HG) and 2.5% v/v of sera from non-diabetic control (CS) and diabetic (DS) DBA/2J mice. We measured mitochondrial function (oxygen consumption), fragmentation (mitotracker), mitochondrial ROS (mtROS; mitoSOX), accumulation of oxidized products (DNA lesion frequency, γ-H2AX, 8-oxoG, 3-Nitrotyrosine), mitochondrial unfolded protein response (UPRmt), endothelial function (NOS activity) and cell death (Annexin/PI).
Results
Treatment of mGECs with HG or DS resulted in increased mtROS, oxidative mtDNA damage, mitochondria fission and reduced mitochondrial function compared to controls, this in turn impaired the synthesis of electron transport chain components. mtROS specific scavenger (mitoTEMPO) prevented these changes. Chronic exposure of mGECs to the diabetic milieu (up to 72h) resulted in accumulation of oxidized products due to inadequate clearance and loss of mitochondrial proteostasis, leading to cellular dysfunction. Co-incubation of podocytes with conditioned media from stressed mGECs resulted podocytes cell death.
Conclusion
Our results demonstrate that the diabetic environment can mediate GEC dysfunction by triggering mitochondria stress. Furthermore the inability to restore mitochondrial function and proteostasis, suggests a maladaptive response under chronic exposure to diabetic milieu and in turn the secretion of pro-apoptotic factors affecting podocytes in co-cultures.
Funding
- NIDDK Support