The role of mitochondrial reactive oxygen species in pH regulation in articular chondrocytes.
Abstract: To examine the effect of O(2) and the role, and source, of reactive oxygen species (ROS) on pH regulation in articular chondrocytes. Methods: Cartilage from equine metacarpo/tarsophalangeal joints was digested (collagenase) to isolate chondrocytes and loaded with 2',7'-bis-2-(carboxyethyl)-5(6)-carboxylfluorescein, a pH-sensitive fluorophore. O(2) tension was maintained using Eschweiler tonometers and a Wosthoff gas mixer. Cells were exposed to agents which alter ROS levels, mitochondrial inhibitors and/or inhibitors of protein phosphorylation. ROS levels were determined by dichlorofluorescein and mitochondrial membrane potential measured using JC-1. Results: pH homeostasis was dependent on ROS. Na(+)/H(+) exchanger (NHE) activity was inhibited at low O(2) tension (acid efflux reducing from 2.30+/-0.05 to 1.27+/-0.11mMmin(-1) at 1%). NHE activity correlated with ROS levels (r(2)=0.65). ROS levels were increased by antimycin A (with levels at 1% O(2) tension increasing from 59+/-9% of the value at 20% to 87+/-7%), but reduced by rotenone, myxothiazol and diphenyleneiodonium. Hypoxia induced depolarisation of the mitochondrial membrane potential (with JC-1 red-green fluorescence ratio at 1% O(2) tension decreasing to 40+/-10% of the value at 20%). The response to changes in O(2) and to antimycin A was inhibited by staurosporine, wortmanin and calyculin A. Conclusions: The fall in ROS levels in hypoxia reduces the ability of articular chondrocytes to regulate pH, inhibiting NHE activity via changes in protein phosphorylation. The site of ROS generation is likely to be mitochondrial electron transport chain complex III. These effects are important to understanding normal chondrocyte function and response to altered O(2) tension.
Publication Date: 2007-02-15 PubMed ID: 17306992DOI: 10.1016/j.joca.2007.01.008Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research article investigates the effect of oxygen and reactive oxygen species (ROS) on the regulation of pH in articular chondrocytes, the cells that produce and maintain cartilage. The researchers conclude that a decrease in ROS levels under low oxygen conditions reduces the cell’s ability to maintain pH, inhibiting an essential cellular process through changes in protein phosphorylation.
Methodology
- The team used cartilage from equine metacarpo/tarsophalangeal joints to extract chondrocytes, which were then loaded with a pH-sensitive fluorophore.
- Eschweiler tonometers and a Wosthoff gas mixer were used to control and maintain the concentration of oxygen.
- The cells were treated with various agents known to affect ROS levels, such as mitochondrial inhibitors and protein phosphorylation inhibitors.
- ROS levels in the cells were measured using dichlorofluorescein while the mitochondrial membrane potential was assessed using a dye known as JC-1.
Results
- The research found that the regulation of pH in articular chondrocytes is dependent on ROS levels.
- Under low oxygen tension, the activity of the Na(+)/H(+) exchanger (NHE), important for maintaining cellular pH, was inhibited.
- There was a correlation observed between NHE activity and ROS levels.
- Agents such as antimycin A increased ROS levels, whereas others like rotenone, myxothiazol, and diphenyleneiodonium decreased them.
- Under hypoxic or low oxygen conditions, there was a depolarization or reduction in the mitochondrial membrane potential.
- The changes in ROS levels with alterations in oxygen availability and the application of agents like antimycin A were blocked by proteins inhibitors such as staurosporine, wortmanin, and calyculin A.
Conclusions
- The observed decrease in ROS levels under low oxygen conditions results in reduced pH regulation ability of articular chondrocytes by inhibiting the activity of NHE through changes in protein phosphorylation.
- It is suggested that mitochondrial electron transport chain complex III might be the site of ROS generation.
- These findings form an important basis for understanding the normal function of chondrocytes and their response to changes in oxygen tension, which has implications on health and diseases, particularly those affecting the joints.
Cite This Article
APA
Milner PI, Wilkins RJ, Gibson JS.
(2007).
The role of mitochondrial reactive oxygen species in pH regulation in articular chondrocytes.
Osteoarthritis Cartilage, 15(7), 735-742.
https://doi.org/10.1016/j.joca.2007.01.008 Publication
Researcher Affiliations
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
MeSH Terms
- Animals
- Cartilage, Articular / metabolism
- Chondrocytes / metabolism
- Homeostasis / physiology
- Horses
- Hydrogen-Ion Concentration
- Mitochondria
- Oxygen / metabolism
- Reactive Oxygen Species / metabolism
- Sodium-Hydrogen Exchangers / metabolism
Citations
This article has been cited 17 times.- Ji ML, Jiang H, Li Z, Geng R, Hu JZ, Lin YC, Lu J. Sirt6 attenuates chondrocyte senescence and osteoarthritis progression.. Nat Commun 2022 Dec 10;13(1):7658.
- Li Y, Lin R, Peng X, Wang X, Liu X, Li L, Bai R, Wen S, Ruan Y, Chang X, Tang R, Liu N. The Role of Mitochondrial Quality Control in Anthracycline-Induced Cardiotoxicity: From Bench to Bedside.. Oxid Med Cell Longev 2022;2022:3659278.
- Yari D, Ebrahimzadeh MH, Movaffagh J, Shahroodi A, Shirzad M, Qujeq D, Moradi A. Biochemical Aspects of Scaffolds for Cartilage Tissue Engineering; from Basic Science to Regenerative Medicine.. Arch Bone Jt Surg 2022 Mar;10(3):229-244.
- Zhou F, Mei J, Yuan K, Han X, Qiao H, Tang T. Isorhamnetin attenuates osteoarthritis by inhibiting osteoclastogenesis and protecting chondrocytes through modulating reactive oxygen species homeostasis.. J Cell Mol Med 2019 Jun;23(6):4395-4407.
- Zhang K, Jiang D. RhoA inhibits the hypoxia-induced apoptosis and mitochondrial dysfunction in chondrocytes via positively regulating the CREB phosphorylation.. Biosci Rep 2017 Apr 30;37(2).
- Li J, Dong S. The Signaling Pathways Involved in Chondrocyte Differentiation and Hypertrophic Differentiation.. Stem Cells Int 2016;2016:2470351.
- Heywood HK, Lee DA. Bioenergetic reprogramming of articular chondrocytes by exposure to exogenous and endogenous reactive oxygen species and its role in the anabolic response to low oxygen.. J Tissue Eng Regen Med 2017 Aug;11(8):2286-2294.
- Collins JA, Moots RJ, Clegg PD, Milner PI. Resveratrol and N-acetylcysteine influence redox balance in equine articular chondrocytes under acidic and very low oxygen conditions.. Free Radic Biol Med 2015 Sep;86:57-64.
- Collins JA, Moots RJ, Winstanley R, Clegg PD, Milner PI. Oxygen and pH-sensitivity of human osteoarthritic chondrocytes in 3-D alginate bead culture system.. Osteoarthritis Cartilage 2013 Nov;21(11):1790-8.
- Martin JA, Martini A, Molinari A, Morgan W, Ramalingam W, Buckwalter JA, McKinley TO. Mitochondrial electron transport and glycolysis are coupled in articular cartilage.. Osteoarthritis Cartilage 2012 Apr;20(4):323-9.
- Kolling J, Wyse AT. Creatine prevents the inhibition of energy metabolism and lipid peroxidation in rats subjected to GAA administration.. Metab Brain Dis 2010 Sep;25(3):331-8.
- White R, Gibson JS. The effect of oxygen tension on calcium homeostasis in bovine articular chondrocytes.. J Orthop Surg Res 2010 Apr 26;5:27.
- Sarafian TA, Montes C, Imura T, Qi J, Coppola G, Geschwind DH, Sofroniew MV. Disruption of astrocyte STAT3 signaling decreases mitochondrial function and increases oxidative stress in vitro.. PLoS One 2010 Mar 10;5(3):e9532.
- Goodwin W, McCabe D, Sauter E, Reese E, Walter M, Buckwalter JA, Martin JA. Rotenone prevents impact-induced chondrocyte death.. J Orthop Res 2010 Aug;28(8):1057-63.
- Chiche J, Brahimi-Horn MC, Pouysségur J. Tumour hypoxia induces a metabolic shift causing acidosis: a common feature in cancer.. J Cell Mol Med 2010 Apr;14(4):771-94.
- Gibson JS, McCartney D, Sumpter J, Fairfax TP, Milner PI, Edwards HL, Wilkins RJ. Rapid effects of hypoxia on H+ homeostasis in articular chondrocytes.. Pflugers Arch 2009 Oct;458(6):1085-92.
- Gibson JS, Milner PI, White R, Fairfax TP, Wilkins RJ. Oxygen and reactive oxygen species in articular cartilage: modulators of ionic homeostasis.. Pflugers Arch 2008 Jan;455(4):563-73.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
