Open AccessRibosomal S6 kinase is activated as an early event in preemergence development of encysted embryos of Artemia salina
Author(s) -
Malarkey Kevin,
Coker Kenneth J.,
Sturgill Thomas W.
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2510269.x
Subject(s) - ribosomal protein s6 , ribosomal s6 kinase , kinase , biology , p70 s6 kinase 1 , artemia salina , protein kinase a , ribosomal protein , microbiology and biotechnology , phosphorylation , biochemistry , protein kinase b , ribosome , chemistry , protein phosphorylation , rna , gene , organic chemistry , toxicity
Dormant Artemia salina cysts contain desiccated gastrulae that are metabolically inactive, and physiologically arrested. Following rehydration, embryos resume development via alterations in protein expression, in the complete absence of cell division. In mammals, activation of p70 ribosomal S6 kinase (p70 S6k ) has been implicated in translational control, in particular the selective up‐regulation of translation of mRNAs with polypyrimidine tracts at their 5′ start sites. We therefore investigated ribosomal S6 kinase activity in preemergence development. We demonstrate that an S6 kinase activity is rapidly stimulated (within < 15 min) following rehydration and coincides with the onset of ribosomal S6 subunit phosphorylation. This S6 kinase activity displays chromatographic and biochemical characteristics that are similar to those of mammalian p70 S6k . Partially purified Artemia S6 kinase was inactivated by treatment with protein phosphatase 2A. Activation of S6 kinase activity was shown to be due to an enzymatic step(s), and not simply rehydration of stored, active enzyme. The temporal profile of activation of S6 kinase activity is compatible with a regulatory function for p70 S6k in early preemergence development of encysted Artemia . These studies identify activated Artemia cysts as a system for biochemical studies of p70 S6k regulation.