Abstract: SA-PO242
Mitochondrial Dysfunction and Mitophagy Blockade Contribute to Renal Osteodystrophy in CKD-Mineral Bone Disorder
Session Information
- CKD-MBD: Basic and Translational
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Bone and Mineral Metabolism
- 501 Bone and Mineral Metabolism: Basic
Authors
- Hsu, Shun-Neng, Tri-Service General Hospital Department of Medicine, Taipei, Taiwan
- Hsu, Yu-Juei, Tri-Service General Hospital Department of Medicine, Taipei, Taiwan
- Farquharson, Colin, The University of Edinburgh The Roslin Institute, Roslin, Midlothian, United Kingdom
Background
Chronic kidney disease–mineral and bone disorder (CKD-MBD) presents with extra-skeletal calcification and renal osteodystrophy (ROD). The origins of ROD likely lie with elevated uremic toxins and/or an altered hormonal profile but the cellular events responsible remain unclear. Here, we report that stalled mitophagy contributes to mitochondrial dysfunction in bones of a CKD-MBD mouse model, and also human CKD-MBD patients.
Methods
C57BL/6J wild-type male mice and mito-QC mice were obtained and CKD-MBD was induced using a casein-based diet containing 0.2% adenine for five weeks. 40 wild-type mice were allocated into control and CKD-MBD groups staggered from day 0 to day 35 to assess progressive changes. RNA-seq libraries were prepared and sequenced to provide comprehensive gene expression profiles. Blood serum, μCT of tibiae, and confocal microscopy of stained cryosections assessed CKD-MBD impact.
Results
RNA-seq analysis exposed an altered expression of genes associated with mitophagy and mitochondrial function in tibia of CKD-MBD mice. The accumulation of damaged osteocyte mitochondria and the expression of mitophagy regulators, p62/SQSTM1, ATG7 and LC3 was inconsistent with functional mitophagy, and in mito-QC reporter mice with CKD-MBD, there was a 2.3-fold increase in osteocyte mitolysosomes. Altered expression of mitophagy regulators in human CKD-MBD bones was also observed. To determine if uremic toxins were possibly responsible for these observations, indoxyl sulfate treatment of osteoblasts revealed mitochondria with distorted morphology and whose membrane potential and oxidative phosphorylation were decreased, and oxygen-free radical production increased. The altered p62/SQSTM1 and LC3-II expression was consistent with impaired mitophagy machinery and the effects of indoxyl sulfate were reversible by rapamycin.
Conclusion
Mitolysosome accumulation from impaired clearance of damaged mitochondria may contribute to the skeletal complications, characteristic of ROD.
Quantification of mitophagy in osteocytes from CTL and CKD-MBD mito-QC mice.