PERK (IMAGE)
Caption
This image shows how the PERK-dependent arm of the UPR is thought to contribute to Myc-dependent tumorigenesis. Elevated levels of c-Myc increase the amount of synthesized proteins, including client proteins which enter the Endoplasmic reticulum (ER) to be folded by chaperones (top). An imbalance of client proteins vs. chaperones induces activation of the kinase PERK. PERK, in turn, phosphorylates the translation factor eIF2a which reduces the rates of protein synthesis. Also, phosphorylation of eIF2a increases the transcription factor ATF4 which activates the process of autophagy (bottom). Autophagy has been shown to prevent cell death. Therefore, the combined effects of PERK and eIF2a on protein synthesis and autophagy contribute to reduced cell death, thereby promoting tumor cell survival and lymphoma progression.
Credit
Constantinos Koumenis, Ph.D., Perelman School of Medicine, University of Pennsylvania
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