Chemical genetics screen for enhancers of rapamycin identifies a specific inhibitor of an SCF family E3 ubiquitin ligase.
The target of rapamycin (TOR) plays a central role in eukaryotic cell growth control. With prevalent hyperactivation of the mammalian TOR (mTOR) pathway in human cancers, strategies to enhance TOR pathway inhibition are needed. We used a yeast-based screen to identify small-molecule enhancers of rapamycin (SMERs) and discovered an inhibitor (SMER3) of the Skp1-Cullin-F-box (SCF)(Met30) ubiquitin ligase, a member of the SCF E3-ligase family, which regulates diverse cellular processes including transcription, cell-cycle control and immune response. We show here that SMER3 inhibits SCF(Met30) in vivo and in vitro, but not the closely related SCF(Cdc4). Furthermore, we demonstrate that SMER3 diminishes binding of the F-box subunit Met30 to the SCF core complex in vivo and show evidence for SMER3 directly binding to Met30. Our results show that there is no fundamental barrier to obtaining specific inhibitors to modulate function of individual SCF complexes.
Aghajan
Mariam
M
Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, and the Molecular Biology Institute, University of California, Los Angeles, California, USA.
Jonai
Nao
N
Flick
Karin
K
Fu
Fei
F
Luo
Manlin
M
Cai
Xiaolu
X
Ouni
Ikram
I
Pierce
Nathan
N
Tang
Xiaobo
X
Lomenick
Brett
B
Damoiseaux
Robert
R
Hao
Rui
R
Del Moral
Pierre M
PM
Verma
Rati
R
Li
Ying
Y
Li
Cheng
C
Houk
Kendall N
KN
Jung
Michael E
ME
Zheng
Ning
N
Huang
Lan
L
Deshaies
Raymond J
RJ
Kaiser
Peter
P
Huang
Jing
J
D002453:Cell Cycle; D002478:Cells, Cultured; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D058570:TOR Serine-Threonine Kinases; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D047908:Intracellular Signaling Peptides and Proteins; D044767:Ubiquitin-Protein Ligases; C546842:MTOR protein, human; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases