Effects of Caenorhabditis elegans sgk-1 mutations on lifespan, stress resistance, and DAF-16/FoxO regulation
Article first published online: 19 JUL 2013
© 2013 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Volume 12, Issue 5, pages 932–940, October 2013
How to Cite
Chen, A. T.-Y., Guo, C., Dumas, K. J., Ashrafi, K. and Hu, P. J. (2013), Effects of Caenorhabditis elegans sgk-1 mutations on lifespan, stress resistance, and DAF-16/FoxO regulation. Aging Cell, 12: 932–940. doi: 10.1111/acel.12120
- Issue published online: 11 SEP 2013
- Article first published online: 19 JUL 2013
- Accepted manuscript online: 20 JUN 2013 08:24AM EST
- Manuscript Accepted: 12 JUN 2013
- NIH Office of Research Infrastructure Programs. Grant Number: P40 OD010440
- University of Michigan Medical Scientist Training Program. Grant Number: T32-GM786332
- National Institute on Aging Biology of Aging Training. Grant Number: T32-AG000114
- Sidney Kimmel Foundation for Cancer Research and R01. Grant Number: AG041177
- National Institutes of Health
- C. elegans ;
- insulin-like growth factor signaling;
The AGC family serine–threonine kinases Akt and Sgk are similar in primary amino acid sequence and in vitro substrate specificity, and both kinases are thought to directly phosphorylate and inhibit FoxO transcription factors. In the nematode Caenorhabditis elegans, it is well established that AKT-1 controls dauer arrest and lifespan by regulating the subcellular localization of the FoxO transcription factor DAF-16. SGK-1 is thought to act similarly to AKT-1 in lifespan control by phosphorylating and inhibiting the nuclear translocation of DAF-16/FoxO. Using sgk-1 null and gain-of-function mutants, we now provide multiple lines of evidence indicating that AKT-1 and SGK-1 influence C. elegans lifespan, stress resistance, and DAF-16/FoxO activity in fundamentally different ways. Whereas AKT-1 shortens lifespan, SGK-1 promotes longevity in a DAF-16-/FoxO-dependent manner. In contrast to AKT-1, which reduces resistance to multiple stresses, SGK-1 promotes resistance to oxidative stress and ultraviolet radiation but inhibits thermotolerance. Analysis of several DAF-16/FoxO target genes that are repressed by AKT-1 reveals that SGK-1 represses a subset of these genes while having little influence on the expression of others. Accordingly, unlike AKT-1, which promotes the cytoplasmic sequestration of DAF-16/FoxO, SGK-1 does not influence DAF-16/FoxO subcellular localization. Thus, in spite of their similar in vitro substrate specificities, Akt and Sgk influence longevity, stress resistance, and FoxO activity through distinct mechanisms in vivo. Our findings highlight the need for a re-evaluation of current paradigms of FoxO regulation by Sgk.