Format

Send to

Choose Destination
Arthritis Rheumatol. 2016 Aug;68(8):1887-98. doi: 10.1002/art.39618.

Aging Promotes Sirtuin 3-Dependent Cartilage Superoxide Dismutase 2 Acetylation and Osteoarthritis.

Author information

1
Oklahoma Medical Research Foundation and University of Oklahoma Health Sciences Center, Oklahoma City.
2
Oklahoma Medical Research Foundation, Oklahoma City.
3
University of Oklahoma College of Medicine and University of Oklahoma Health Sciences Center, Oklahoma City.
4
Oklahoma Medical Research Foundation, University of Oklahoma College of Medicine, and University of Oklahoma Health Sciences Center, Oklahoma City.
5
Gladstone Institutes and University of California, San Francisco.

Abstract

OBJECTIVE:

To quantify functional age-related changes in the cartilage antioxidant network in order to discover novel mediators of cartilage oxidative stress and osteoarthritis (OA) pathophysiology.

METHODS:

We evaluated histopathologic changes of knee OA in 10-, 20-, and 30-month-old male F344BN rats and analyzed cartilage oxidation according to the ratio of reduced to oxidized glutathione. Antioxidant gene expression and protein abundance were analyzed by quantitative reverse transcription-polymerase chain reaction and selected reaction-monitoring mass spectrometry, respectively. Superoxide dismutase 2 (SOD2) activity and acetylation were analyzed by colorimetric enzyme assays and Western blotting, respectively. We examined human OA cartilage to evaluate the clinical relevance of SOD2 acetylation, and we tested age-related changes in the mitochondrial deacetylase sirtuin 3 (SIRT-3) in rats and mice.

RESULTS:

Cartilage oxidation and OA severity in F344BN rats increased with age and were associated with an increase in SOD2 expression and protein abundance. However, SOD2-specific activity decreased with age due to elevated posttranslational lysine acetylation. Consistent with these findings, SIRT-3 levels decreased substantially with age, and treatment with SIRT-3 increased SOD2 activity in an age-dependent manner. SOD2 was also acetylated in human OA cartilage, and activity was increased with SIRT-3 treatment. Moreover, in C57BL/6J mice, cartilage SIRT-3 expression decreased with age, and whole-body deletion of SIRT-3 accelerated the development of knee OA.

CONCLUSION:

Our results show that SIRT-3 mediates age-related changes in cartilage redox regulation and protects against early-stage OA. These findings suggest that mitochondrial acetylation promotes OA and that restoration of SIRT-3 in aging cartilage may improve cartilage resistance to oxidative stress by rescuing acetylation-dependent inhibition of SOD2 activity.

PMID:
26866626
PMCID:
PMC5331855
DOI:
10.1002/art.39618
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center