A clickable inhibitor reveals context-dependent autoactivation of p90 RSK

Michael S. Cohen; Haralambos Hadjivassiliou; Jack Taunton

doi:10.1038/nchembio859

A clickable inhibitor reveals context-dependent autoactivation of p90 RSK

Michael S. Cohen
, Haralambos Hadjivassiliou
, Jack Taunton

Research output: Contribution to journal › Article › peer-review

142 Scopus citations

Abstract

p90 ribosomal protein S6 kinases (RSKs) integrate upstream signals through two catalytic domains. Autophosphorylation of Ser386 by the regulatory C-terminal kinase domain (CTD) is thought to be essential for activation of the N-terminal kinase domain (NTD), which phosphorylates multiple downstream targets. We recently reported fmk, an irreversible inhibitor of the CTD of RSK1 and RSK2. Here we describe fmk-pa, a propargylamine variant that has improved cellular potency and a 'clickable' tag for assessing the extent and selectivity of covalent RSK modification. Copper-catalyzed conjugation of an azidoalkyl reporter (the click reaction) revealed that fmk-pa achieves selective and saturable modification of endogenous RSK1 and RSK2 in mammalian cells. Saturating concentrations of fmk-pa inhibited Ser386 phosphorylation and downstream signaling in response to phorbol ester stimulation, but had no effect on RSK activation by lipopolysaccharide. RSK autoactivation by the CTD is therefore context dependent, which suggests that NTD and CTD inhibitors should have distinct physiological effects.

Original language	English (US)
Pages (from-to)	156-160
Number of pages	5
Journal	Nature Chemical Biology
Volume	3
Issue number	3
DOIs	https://doi.org/10.1038/nchembio859
State	Published - Mar 2007
Externally published	Yes

Funding

This work was supported by the US National Institutes of Health (GM71434) and a University of California at San Francisco President’s Dissertation-Year Fellowship to M.S.C. We thank M. Pak and E. Brown (University of California at San Francisco) for the primary mouse macrophages. We thank H. Luecke, M. Simon and members of the Taunton laboratory for many helpful discussions and for critical reading of the manuscript.

Funders	Funder number
US National Institutes of Health
National Institute of General Medical Sciences	R01GM071434
University of California-Berkeley, Berkeley California

ASJC Scopus subject areas

Molecular Biology
Cell Biology

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10.1038/nchembio859

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title = "A clickable inhibitor reveals context-dependent autoactivation of p90 RSK",

abstract = "p90 ribosomal protein S6 kinases (RSKs) integrate upstream signals through two catalytic domains. Autophosphorylation of Ser386 by the regulatory C-terminal kinase domain (CTD) is thought to be essential for activation of the N-terminal kinase domain (NTD), which phosphorylates multiple downstream targets. We recently reported fmk, an irreversible inhibitor of the CTD of RSK1 and RSK2. Here we describe fmk-pa, a propargylamine variant that has improved cellular potency and a 'clickable' tag for assessing the extent and selectivity of covalent RSK modification. Copper-catalyzed conjugation of an azidoalkyl reporter (the click reaction) revealed that fmk-pa achieves selective and saturable modification of endogenous RSK1 and RSK2 in mammalian cells. Saturating concentrations of fmk-pa inhibited Ser386 phosphorylation and downstream signaling in response to phorbol ester stimulation, but had no effect on RSK activation by lipopolysaccharide. RSK autoactivation by the CTD is therefore context dependent, which suggests that NTD and CTD inhibitors should have distinct physiological effects.",

author = "Cohen, \{Michael S.\} and Haralambos Hadjivassiliou and Jack Taunton",

note = "Funding Information: This work was supported by the US National Institutes of Health (GM71434) and a University of California at San Francisco President{\textquoteright}s Dissertation-Year Fellowship to M.S.C. We thank M. Pak and E. Brown (University of California at San Francisco) for the primary mouse macrophages. We thank H. Luecke, M. Simon and members of the Taunton laboratory for many helpful discussions and for critical reading of the manuscript.",

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N2 - p90 ribosomal protein S6 kinases (RSKs) integrate upstream signals through two catalytic domains. Autophosphorylation of Ser386 by the regulatory C-terminal kinase domain (CTD) is thought to be essential for activation of the N-terminal kinase domain (NTD), which phosphorylates multiple downstream targets. We recently reported fmk, an irreversible inhibitor of the CTD of RSK1 and RSK2. Here we describe fmk-pa, a propargylamine variant that has improved cellular potency and a 'clickable' tag for assessing the extent and selectivity of covalent RSK modification. Copper-catalyzed conjugation of an azidoalkyl reporter (the click reaction) revealed that fmk-pa achieves selective and saturable modification of endogenous RSK1 and RSK2 in mammalian cells. Saturating concentrations of fmk-pa inhibited Ser386 phosphorylation and downstream signaling in response to phorbol ester stimulation, but had no effect on RSK activation by lipopolysaccharide. RSK autoactivation by the CTD is therefore context dependent, which suggests that NTD and CTD inhibitors should have distinct physiological effects.

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A clickable inhibitor reveals context-dependent autoactivation of p90 RSK

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