Response to Comment on "A Dynamic Network Model of mTOR Signaling Reveals TSC-Independent mTORC2 Regulation": Building a Model of the mTOR Signaling Network with a Potentially Faulty Tool.
10.07.2012
Dalle Pezze P, Sonntag AG, Shanley DP, Thedieck K.
Sci Signal. 2012;5(232):lc4.
We modeled the mammalian or mechanistic target of rapamycin (mTOR) network and proposed a previously unknown mode of activation of the mTOR-containing complex mTORC2 through a phosphoinositide 3-kinase–dependent, and tuberous sclerosis complex–independent mechanism. In this letter we respond to concerns raised by Dr. B. D. Manning, Harvard University, Boston, US. Manning questions the validity of using the phosphorylation of Ser2481 of mTOR as a specific readout of mTORC2 activity and suggests an in vitro mTORC2 kinase assay as a more appropriate method to parameterize a dynamic mTOR model. We confirm with new data the validity of Ser2481 of mTOR as mTORC2 readout in HeLa cells; we also show that in contrast to mTORC1, mTORC2 is not regulated by the TSC1-TSC2 complex. Thus, we maintain that our computational-experimental approach in combination with careful selection of the readout and cell system is appropriate for studying mTORC2 regulation by insulin.
