Optical control of MAP kinase kinase 6 (MKK6) reveals that it has divergent roles in pro-apoptotic and anti-proliferative signaling

• Published in: The Journal of biological chemistry 2020-06, Vol.295 (25), p.8494-8504
• Main Authors: Rahman, Shah Md. Toufiqur, Zhou, Wenyuan, Deiters, Alexander, Haugh, Jason M.
• Format: Article
• Language: English
• Subjects: Animals; apoptosis; Apoptosis - radiation effects; Cell Biology; cell death; Cell Line; Cell Proliferation - radiation effects; cell signaling; cell stress; Fibroblasts - cytology; Fibroblasts - metabolism; Humans; MAP Kinase Kinase 6 - genetics; MAP Kinase Kinase 6 - metabolism; Mice; mitogen-activated protein kinase (MAPK); Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; mitogen-activated protein kinase kinase 6 (MAP2K6); mitogen-activated protein kinases; Mutagenesis; optogenetics; p38 Mitogen-Activated Protein Kinases - antagonists & inhibitors; p38 Mitogen-Activated Protein Kinases - metabolism; Protein Isoforms - antagonists & inhibitors; Protein Isoforms - metabolism; Proto-Oncogene Proteins B-raf - genetics; Proto-Oncogene Proteins B-raf - metabolism; signal transduction; Signal Transduction - radiation effects; Ultraviolet Rays
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.RA119.012079

The selective pressure imposed by extrinsic death signals and stressors adds to the challenge of isolating and interpreting the roles of proteins in stress-activated signaling networks. By expressing a kinase with activating mutations and a caged lysine blocking the active site, we can rapidly switch on catalytic activity with light and monitor the ensuing dynamics. Applying this approach to MAP kinase 6 (MKK6), which activates the p38 subfamily of MAPKs, we found that decaging active MKK6 in fibroblasts is sufficient to trigger apoptosis in a p38-dependent manner. Both in fibroblasts and in a murine melanoma cell line expressing mutant B-Raf, MKK6 activation rapidly and potently inhibited the pro-proliferative extracellular signal–regulated kinase (ERK) pathway; to our surprise, this negative cross-regulation was equally robust when all p38 isoforms were inhibited. These results position MKK6 as a new pleiotropic signal transducer that promotes both pro-apoptotic and anti-proliferative signaling, and they highlight the utility of caged, light-activated kinases for dissecting stress-activated signaling networks.