TORC1 inhibition induces lipid droplet replenishment in yeast.

Autor:	Madeira JB; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil., Masuda CA; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil., Maya-Monteiro CM; Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil., Matos GS; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil., Montero-Lomelí M; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil montero@bioqmed.ufrj.br., Bozaquel-Morais BL; Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Jazyk:	angličtina
Zdroj:	Molecular and cellular biology [Mol Cell Biol] 2015 Feb; Vol. 35 (4), pp. 737-46. Date of Electronic Publication: 2014 Dec 15.
DOI:	10.1128/MCB.01314-14
Abstrakt:	Lipid droplets (LDs) are intracellular structures that regulate neutral lipid homeostasis. In mammals, LD synthesis is inhibited by rapamycin, a known inhibitor of the mTORC1 pathway. In Saccharomyces cerevisiae, LD dynamics are modulated by the growth phase; however, the regulatory pathways involved are unknown. Therefore, we decided to study the role of the TORC1 pathway on LD metabolism in S. cerevisiae. Interestingly, rapamycin treatment resulted in a fast LD replenishment and growth inhibition. The discovery that osmotic stress (1 M sorbitol) also induced LD synthesis but not growth inhibition suggested that the induction of LDs in yeast is not a secondary response to reduced growth. The induction of LDs by rapamycin was due to increased triacylglycerol but not sterol ester synthesis. Induction was dependent on the TOR downstream effectors, the PP2A-related phosphatase Sit4p and the regulatory protein Tap42p. The TORC1-controlled transcriptional activators Gln3p, Gat1p, Rtg1p, and Rtg3p, but not Msn2p and Msn4p, were required for full induction of LDs by rapamycin. Furthermore, we show that the deletion of Gln3p and Gat1p transcription factors, which are activated in response to nitrogen availability, led to abnormal LD dynamics. These results reveal that the TORC1 pathway is involved in neutral lipid homeostasis in yeast. (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)
Databáze:	MEDLINE
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