Osteopontin stimulates autophagy via integrin/CD44 and p38 MAPK signaling pathways in vascular smooth muscle cells

Osteopontin (OPN) exerts pro‐inflammatory effect and is associated with the development of abdominal aortic aneurysm (AAA). However, the molecular mechanism underlying this association remains obscure. In the present study, we compared gene expression profiles of AAA tissues using microarray assay,...

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Published in:Journal of cellular physiology 2012-01, Vol.227 (1), p.127-135
Main Authors: Zheng, Yue-Hong, Tian, Cui, Meng, Yan, Qin, Yan-Wen, Du, Ya-Hao, Du, Jie, Li, Hui-Hua
Format: Article
Language:English
Subjects:
Aortic Aneurysm, Abdominal - metabolism
Autophagy - physiology
Blotting, Western
Gene Expression
Gene Expression Profiling
Humans
Hyaluronan Receptors - metabolism
Immunohistochemistry
In Situ Nick-End Labeling
Integrins - metabolism
Muscle, Smooth, Vascular - metabolism
Oligonucleotide Array Sequence Analysis
Osteopontin - metabolism
p38 Mitogen-Activated Protein Kinases - metabolism
Reverse Transcriptase Polymerase Chain Reaction
Signal Transduction - physiology
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Summary:Osteopontin (OPN) exerts pro‐inflammatory effect and is associated with the development of abdominal aortic aneurysm (AAA). However, the molecular mechanism underlying this association remains obscure. In the present study, we compared gene expression profiles of AAA tissues using microarray assay, and found that OPN was the highest expressed gene (>125‐fold). Furthermore, the expression of LC3 protein and autophagy‐related genes including Atg4b, Beclin1/Atg6, Bnip3, and Vps34 was markedly upregulated in AAA tissues. To investigate the ability of OPN to stimulate autophagy as a potential mechanism involved in the pathogenesis of this disease, we treated vascular smooth muscle cells (SMCs) with OPN, and found that OPN significantly increased the formation of autophagosomes, expression of autophagy‐related genes and cell death, whereas blocking the signal by anti‐OPN antibody markedly inhibited OPN‐induced autophagy and SMC death. Furthermore, inhibition of integrin/CD44 and p38 MAPK signaling pathways markedly abrogated the biological effects of OPN on SMCs. These data for the first time demonstrate that OPN sitmulates autophagy directly through integrin/CD44 and p38 MAPK‐mediated pathways in SMCs. Thus, inhibition of OPN‐induced autophagy might be a potential therapeutic target in the treatment of AAA disease. J. Cell. Physiol. 227: 127–135, 2012. © 2011 Wiley Periodicals, Inc.
ISSN:0021-9541
1097-4652
DOI:10.1002/jcp.22709