[HTML][HTML] Regulation of TORC1 in response to amino acid starvation via lysosomal recruitment of TSC2

C Demetriades, N Doumpas, AA Teleman - Cell, 2014 - cell.com
Cell, 2014cell.com
Summary TOR complex 1 (TORC1) is a potent anabolic regulator of cellular growth and
metabolism. When cells have sufficient amino acids, TORC1 is active due to its lysosomal
localization mediated via the Rag GTPases. Upon amino acid removal, the Rag GTPases
release TORC1, causing it to become cytoplasmic and inactive. We show here that, upon
amino acid removal, the Rag GTPases also recruit TSC2 to the lysosome, where it can act
on Rheb. Only when both the Rag GTPases and Rheb are inactive is TORC1 fully released …
Summary
TOR complex 1 (TORC1) is a potent anabolic regulator of cellular growth and metabolism. When cells have sufficient amino acids, TORC1 is active due to its lysosomal localization mediated via the Rag GTPases. Upon amino acid removal, the Rag GTPases release TORC1, causing it to become cytoplasmic and inactive. We show here that, upon amino acid removal, the Rag GTPases also recruit TSC2 to the lysosome, where it can act on Rheb. Only when both the Rag GTPases and Rheb are inactive is TORC1 fully released from the lysosome. Upon amino acid withdrawal, cells lacking TSC2 fail to completely release TORC1 from the lysosome, fail to completely inactivate TORC1, and fail to adjust physiologically to amino acid starvation. These data suggest that regulation of TSC2 subcellular localization may be a general mechanism to control its activity and place TSC2 in the amino-acid-sensing pathway to TORC1.
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