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Abstract: TH-PO520

The Role of Mitochondrial Dysfunction in Matrix Vesicles (MV)-Induced Calcification of Recipient Vascular Smooth Muscle Cells (VSMC)

Session Information

Category: Bone and Mineral Metabolism

  • 401 Bone and Mineral Metabolism: Basic

Authors

  • Chen, Neal X., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • O'Neill, Kalisha, Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Dominguez, James M., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Moe, Sharon M., Indiana University School of Medicine, Indianapolis, Indiana, United States
Background

Oxidative stress is increased in patients with CKD and associated with vascular calcification. We have previously demonstrated that cellular derived MV, but not media derived MV, increase calcification of recipient normal rat VSMC in association with activation of mitogen activated protein kinase (MAPK), increased intracellular calcium [Ca]i derived from the endoplasmic reticulum (ER), and increased NADPH oxidase (NOX) 1 expression. We hypothesized that cellular MV induced generation of reactive oxygen species (ROS) from mitochondrial dysfunction in the recipient VSMC.

Methods

Ten ug of MV were co-cultured with recipient VSMC in calcification media (high phosphorus) for up to 7 days and alteration of ROS production examined by CellRox using confocal microscopy. Mitochondrial superoxide generation was determined by MitoROS. Direct mitochondrial respiration was measured by Seahorse XF Analyses. Mitochondrial contents of respiratory complexes was determined using total OXPHOS by Western blot. Some cultures were incubated with the NOX1/4 inhibitor GKT137831.

Results

MV increased ROS production by 146% at 24 h and continued to increase by 106% at day 7 in recipient VSMC during calcification. Incubation with GKT137831 reduced ROS production and decreased [Ca]i in recipient VSMC. We then determined if mitochondria dysregulation was the source of the increased ROS production in recipient VSMC. Adding MV had no effect on mitochondrial superoxide production or mitochondrial contents in recipient VSMC. Seahorse experiments demonstrated that there was no effect of MV on basal oxygen consumption (OCR), ATP production, maximal respiratory capacity or reserve respiratory capacity in recipient VSMC. These results suggest that MV-induced cytosolic ROS production is not due to mitochondrial dysfunction in recipient VSMC.

Conclusion

Cellular MV induce ROS production in recipient VSMC during calcification. However, this increased ROS is not mediated via mitochondrial dysfunction and thus likely represents a response to increased [Ca]i release from the ER and/or other cell signaling pathways. Further understanding the mechanism by which MV induce calcification of normal VSMC to propagate calcification is needed to facilitate the development of targeted therapies.

Funding

  • Other NIH Support