Gaballah M, Slisz M, Hutter-Lobo D. Role of JNK-1 regulation in the protection of contact-inhibited fibroblasts from oxidative stress.
Mol Cell Biochem 2012;
359:105-13. [PMID:
21822690 PMCID:
PMC3219803 DOI:
10.1007/s11010-011-1004-1]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 07/19/2011] [Indexed: 01/04/2023]
Abstract
The molecular signaling events leading to protection from oxidative stress-induced apoptosis upon contact inhibition have not been fully investigated. Previous research has indicated a role for mitogen-activated protein kinases (MAPKs) in the regulation of contact inhibition, and these proteins have also been associated with cell cycle regulation and stress-induced apoptosis. The potential role of the MAPK JNK-1 in the stress-response of actively proliferating and contact-inhibited cells was investigated. Actively proliferating normal fibroblasts (BJ) and fibrosarcoma cells (HT-1080) were stressed with H2O2, and levels of activated JNK-1 and cleaved PARP were ascertained. Similarly, these results were compared with levels of activated JNK-1 and cleaved PARP detected in H2O2-stressed confluent fibrosarcoma or contact-inhibited fibroblast cells. Contact-inhibited fibroblasts were protected from apoptosis in comparison to subconfluent fibroblasts, concurrent with decreased JNK-1 activation. Increased culture density of fibrosarcoma cells was not protective against apoptosis, and these cells did not demonstrate density-dependent alterations in the JNK-1 stress response. This decreased activation of JNK-1 in stressed, contact-inhibited cells did not appear to be dependent upon increased expression of MKP-1; however, over-expression of MKP-1 was sufficient to result in a slight decrease in H2O2-stimulated PARP cleavage. Increasing the antioxidant capacity of fibroblasts through NAC-treatment not only lessened H2O2-stimulated JNK-1 activation, but also did not influence the expression of MKP-1. Taken together, these results suggest that regulation of negative regulation of JNK-1 upon contact inhibition is protective against apoptosis, and that this regulation is independent of MKP-1.
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