title: Characterization of the cellular action of the MSK inhibitor SB-747651A.
abstract: MSK1 (mitogen- and stress-activated kinase 1) and MSK2 are nuclear protein kinases that regulate transcription downstream of the ERK1/2 (extracellular-signal-regulated kinase 1/2) and p38α MAPKs (mitogen-activated protein kinases) via the phosphorylation of CREB (cAMP-response-element-binding protein) and histone H3. Previous studies on the function of MSKs have used two inhibitors, H89 and Ro 31-8220, both of which have multiple off-target effects. In the present study, we report the characterization of the in vitro and cellular properties of an improved MSK1 inhibitor, SB-747651A. In vitro, SB-747651A inhibits MSK1 with an IC50 value of 11 nM. Screening of an in vitro panel of 117 protein kinases revealed that, at 1 μM, SB-747651A inhibited four other kinases, PRK2 (double-stranded-RNA-dependent protein kinase 2), RSK1 (ribosomal S6 kinase 1), p70S6K (S6K is S6 kinase) (p70RSK) and ROCK-II (Rho-associated protein kinase 2), with a similar potency to MSK1. In cells, SB-747651A fully inhibited MSK activity at 5-10 μM. SB-747651A was found to inhibit the production of the anti-inflammatory cytokine IL-10 (interleukin-10) in wild-type, but not MSK1/2-knockout, macrophages following LPS (lipopolysaccharide) stimulation. Both SB-747651A and MSK1/2 knockout resulted in elevated pro-inflammatory cytokine production by macrophages in response to LPS. Comparison of the effects of SB-747651A, both in vitro and in cells, demonstrated that SB-747651A exhibited improved selectivity over H89 and Ro 31-8220 and therefore represents a useful tool to study MSK function in cells.
authors.affiliation: MRC Protein Phosphorylation Unit, Sir James Black Complex, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
authors.forename: Shaista
authors.initials: S
authors.lastname: Naqvi
authors.forename: Andrew
authors.initials: A
authors.lastname: Macdonald
authors.forename: Claire E
authors.initials: CE
authors.lastname: McCoy
authors.forename: Joanne
authors.initials: J
authors.lastname: Darragh
authors.forename: Alastair D
authors.initials: AD
authors.lastname: Reith
authors.forename: J Simon C
authors.initials: JS
authors.lastname: Arthur
mesh_terms: D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005347:Fibroblasts; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D008264:Macrophages; D051379:Mice; D015394:Molecular Structure; D010069:Oxadiazoles / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D016207:Cytokines; D004791:Enzyme Inhibitors; D007211:Indoles; D007546:Isoquinolines; D010069:Oxadiazoles; C570041:SB 747651A; D013449:Sulfonamides; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C485459:Rps6ka4 protein, mouse; C116919:mitogen and stress-activated protein kinase 1; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C064758:Ro 31-8220