Novel compounds, '1,3-selenazine derivatives' as specific inhibitors of eukaryotic elongation factor-2 kinase.
The inhibitory activities of 5,6-dihydro-4H-1,3-selenazine derivatives on protein kinases were investigated. In a multiple protein kinase assay using a postnuclear fraction of v-src-transformed NIH3T3 cells, 4-ethyl-4-hydroxy-2-p-tolyl-5, 6-dihydro-4H-1,3-selenazine (TS-2) and 4-hydroxy-6-isopropyl-4-methyl-2-p-tolyl-5,6-dihydro-4H-1, 3-selenazine (TS-4) exhibited selective inhibitory activity against eukaryotic elongation factor-2 kinase (eEF-2K) over protein kinase A (PKA), protein kinase C (PKC) and protein tyrosine kinase (PTK). In further experiments using purified kinases, TS-2 (IC(50)=0.36 microM) and TS-4 (IC(50)=0.31 microM) inhibited eEF-2K about 25-fold more effectively than calmodulin-dependent protein kinase-I (CaMK-I), and about 6-fold (TS-2) or 33-fold (TS-4) more effectively than calmodulin-dependent protein kinase-II (CaMK-II), respectively. TS-2 and TS-4 showed much weaker inhibitory activity toward PKA and PKC, while TS-4, but not TS-2, moderately inhibited immunoprecipitated v-src kinase. TS-2 (10.7-fold) and TS-4 (12.5-fold) demonstrated more potent and more specific eEF-2K inhibitory activity than rottlerin, a previously identified eEF-2K inhibitor. TS-2 inhibited ATP or eEF-2 binding to eEF-2K in a competitive or non-competitive manner, respectively. In cultured v-src-transformed NIH3T3 cells, TS-2 also decreased phospho-eEF-2 protein level (IC(50)=4.7 microM) without changing the total eEF-2 protein level. Taken together, these results suggest that TS-2 and TS-4 are the first identified selective eEF-2K inhibitors and should be useful tools for studying the function of eEF-2K.
Cho
S I
SI
Department of Bioactive Molecules, National Institute of Infectious Diseases, Toyama, Tokyo, Japan.
Koketsu
M
M
Ishihara
H
H
Matsushita
M
M
Nairn
A C
AC
Fukazawa
H
H
Uehara
Y
Y
D016475:3T3 Cells; D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000235:genetics; D003001:Cloning, Molecular; D054736:Elongation Factor 2 Kinase; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D051379:Mice; D015394:Molecular Structure; D016566:Organoselenium Compounds / Q000494:pharmacology*
C405507:4-ethyl-4-hydroxy-2-(4-tolyl)-4H-5,6-dihydro-1,3-selenazine; D000098:Acetophenones; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D016566:Organoselenium Compounds; C085746:rottlerin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C517690:Eef2k protein, mouse; D054736:Elongation Factor 2 Kinase