The MK5/PRAK kinase and Myc form a negative feedback loop that is disrupted during colorectal tumorigenesis

Kress, T. R., Cannell, I. G., Brenkman, A. B., Samans, B., Gaestel, M., Roepman, P., Burgering, B. M., Bushell, M. , Rosenwald, A. and Eilers, M. (2011) The MK5/PRAK kinase and Myc form a negative feedback loop that is disrupted during colorectal tumorigenesis. Molecular Cell, 41(4), pp. 445-457. (doi: 10.1016/j.molcel.2011.01.023) (PMID:21329882)

Abstract

Expression of the Myc oncoprotein is downregulated in response to stress signals to allow cells to cease proliferation and escape apoptosis, but the mechanisms involved in this process are poorly understood. Cell cycle arrest in response to DNA damage requires downregulation of Myc via a p53-independent signaling pathway. Here we have used siRNA screening of the human kinome to identify MAPKAPK5 (MK5, PRAK) as a negative regulator of Myc expression. MK5 regulates translation of Myc, since it is required for expression of miR-34b and miR-34c that bind to the 3′UTR of MYC. MK5 activates miR-34b/c expression via phosphorylation of FoxO3a, thereby promoting nuclear localization of FoxO3a and enabling it to induce miR-34b/c expression and arrest proliferation. Expression of MK5 in turn is directly activated by Myc, forming a negative feedback loop. MK5 is downregulated in colon carcinomas, arguing that this feedback loop is disrupted during colorectal tumorigenesis.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Bushell, Professor Martin
• Authors: Kress, T. R., Cannell, I. G., Brenkman, A. B., Samans, B., Gaestel, M., Roepman, P., Burgering, B. M., Bushell, M., Rosenwald, A., and Eilers, M.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences
• Journal Name: Molecular Cell
• Publisher: Elsevier (Cell Press)
• ISSN: 1097-2765
• ISSN (Online): 1097-4164
• Published Online: 17 February 2011