Research ArticleCell Biology

Nutrient Signaling in Protein Homeostasis: An Increase in Quantity at the Expense of Quality

Sci. Signal.  16 Apr 2013:
Vol. 6, Issue 271, pp. ra24
DOI: 10.1126/scisignal.2003520

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When More Is Not Better

The mammalian target of rapamycin complex 1 (mTORC1) links nutrient availability to the activity of signaling pathways necessary for cell growth and proliferation, such as protein synthesis. The drug rapamycin, which inhibits mTORC1, increases the life span of various organisms through incompletely understood mechanisms. Conn and Qian showed that enhancing mTORC1 signaling increased the rate of protein synthesis at the expense of the quality of the synthesized proteins, an effect that was reversed by rapamycin. Because improperly synthesized proteins can induce cellular stress, these results suggest that rapamycin may exert its effects on longevity in part by enhancing the quality of protein synthesis.