The Ras Signaling Inhibitor LOX-PP Interacts with Hsp70 and c-Raf To Reduce Erk Activation and Transformed Phenotype of Breast Cancer Cells ▿
American Society for Microbiology, 2011
academicJournal
Zugriff:
The lysyl oxidase gene (LOX) inhibits Ras signaling in transformed fibroblasts and breast cancer cells. Its activity was mapped to the 162-amino-acid propeptide domain (LOX-PP) of the lysyl oxidase precursor protein. LOX-PP inhibits Erk signaling, motility, and tumor formation in a breast cancer xenograft model; however, its mechanism of action is largely unknown. Here, a copurification-mass spectrometry approach was taken using ectopically expressed LOX-PP in HEK293T cells and the heat shock/chaperone protein Hsp70 identified. Hsp70 interaction with LOX-PP was confirmed using coimmunoprecipitation of intracellularly and bacterially expressed and endogenous proteins. The interaction was mapped to the Hsp70 peptide-binding domain and to LOX-PP amino acids 26 to 100. LOX-PP association reduced Hsp70 chaperone activities of protein refolding and survival after heat shock. LOX-PP interacted with the Hsp70 chaperoned protein c-Raf. With the use of ectopic expression of LOX-PP wild-type and deletion proteins, small interfering RNA (siRNA) knockdown, and Lox−/− mouse embryo fibroblasts, LOX-PP interaction with c-Raf was shown to decrease downstream activation of MEK and NF-κB, migration, and anchorage-independent growth and reduce its mitochondrial localization. Thus, the interaction of LOX-PP with Hsp70 and c-Raf inhibits a critical intermediate in Ras-induced MEK signaling and plays an important role in the function of this tumor suppressor.
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The Ras Signaling Inhibitor LOX-PP Interacts with Hsp70 and c-Raf To Reduce Erk Activation and Transformed Phenotype of Breast Cancer Cells ▿
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Autor/in / Beteiligte Person: | Sato, Seiichi ; Trackman, Philip C. ; Mäki, Joni M. ; Myllyharju, Johanna ; Kirsch, Kathrin H. ; Sonenshein, Gail E. |
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Veröffentlichung: | American Society for Microbiology, 2011 |
Medientyp: | academicJournal |
DOI: | 10.1128/MCB.01148-10 |
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