Tuberous sclerosis complex 2 loss-of-function mutation regulates reactive oxygen species production through Rac1 activation.
The products of the TSC1 (hamartin) and TCS2 (tuberin) tumor suppressor genes negatively regulate cell growth by inhibiting mTOR signaling. Recent research has led to the postulation that tuberin and/or hamartin are involved in tumor migration, presumably through Rho activation. Here we show that LEF-8 cells, which contain a Y1571 missense mutation in tuberin, express higher Rac1 activity than tuberin negative and positive cells. We also provide evidence of obvious lamellipodia formation in LEF-8 cells. Since the production of TSC2(Y1571H) cannot form a hetero-complex with hamartin, we further analyzed another mutant, TSC2(R611Q), which also lacks the ability to form a complex with hamartin. Introducing both forms of mutated TSC2 into COS-1 cells increased Rac1 activity as well as cell motility. We also found these two mutants interacted with Rac1. We further demonstrated that the introduction of mutated TSC2 into COS-1 cells can generate higher reactive oxygen species (ROS). These results indicate that loss-of-function mutated tuberin can activate Rac1 and thereby increase ROS production.
Suzuki
Tsukasa
T
Department of Applied Biology and Chemistry, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
Das
Swadesh K
SK
Inoue
Hirohumi
H
Kazami
Machiko
M
Hino
Okio
O
Kobayashi
Toshiyuki
T
Yeung
Raymond S
RS
Kobayashi
Ken-Ichi
K
Tadokoro
Tadahiro
T
Yamamoto
Yuji
Y
D000818:Animals; D002460:Cell Line; D002465:Cell Movement; D002522:Chlorocebus aethiops; D004789:Enzyme Activation; D051379:Mice; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D017382:Reactive Oxygen Species; C000624654:Tsc2 protein, mouse; C000624655:Tsc2 protein, rat; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D020830:rac1 GTP-Binding Protein