Gene Expression

TOR Signals Alter Chromatin

Science's STKE  07 Jan 2003:
Vol. 2003, Issue 164, pp. tw4-TW4
DOI: 10.1126/stke.2003.164.tw4

The signaling pathway controlled by the kinase TOR (target of rapamycin) governs cell growth in response to nutrient availability. It accomplishes this in part by inducing the expression of genes encoding ribosomal proteins (RP genes). Rohde and Cardenas report that TOR signaling maintains the presence of a histone acetylase called Esa1 at RP gene promoters. In the absence of TOR signaling, either by nutrient depletion or inhibition of TOR by rapamycin, Esa1 is released from promoters. A deacetylating complex called Rpd3-Sin3, which is already present at RP gene promoters, is then able to inhibit transcription of RP genes. Thus, TOR signaling can regulate growth by altering ribosome biogenesis through modification of chromatin conformation.

J. R. Rohde, M. E. Cardenas, The Tor pathway regulates gene expression by linking nutrient sensing to histone acetylation. Mol. Cell. Biol. 23, 629-635 (2003). [Abstract] [Full Text]