iScience (Nov 2021)

The fission yeast FLCN/FNIP complex augments TORC1 repression or activation in response to amino acid (AA) availability

  • Isabel A. Calvo,
  • Shalini Sharma,
  • Joao A. Paulo,
  • Alexander O.D. Gulka,
  • Andras Boeszoermenyi,
  • Jingyu Zhang,
  • Jose M. Lombana,
  • Christina M. Palmieri,
  • Laura A. Laviolette,
  • Haribabu Arthanari,
  • Othon Iliopoulos,
  • Steven P. Gygi,
  • Mo Motamedi

Journal volume & issue
Vol. 24, no. 11
p. 103338

Abstract

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Summary: The target of Rapamycin complex1 (TORC1) senses and integrates several environmental signals, including amino acid (AA) availability, to regulate cell growth. Folliculin (FLCN) is a tumor suppressor (TS) protein in renal cell carcinoma, which paradoxically activates TORC1 in response to AA supplementation. Few tractable systems for modeling FLCN as a TS are available. Here, we characterize the FLCN-containing complex in Schizosaccharomyces pombe (called BFC) and show that BFC augments TORC1 repression and activation in response to AA starvation and supplementation, respectively. BFC co-immunoprecipitates V-ATPase, a TORC1 modulator, and regulates its activity in an AA-dependent manner. BFC genetic and proteomic networks identify the conserved peptide transmembrane transporter Ptr2 and the phosphoribosylformylglycinamidine synthase Ade3 as new AA-dependent regulators of TORC1. Overall, these data ascribe an additional repressive function to Folliculin in TORC1 regulation and reveal S. pombe as an excellent system for modeling the AA-dependent, FLCN-mediated repression of TORC1 in eukaryotes.

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