Research on Function of Ribosomal Protein S6 Kinases, 1α and β, Based on Molecular Cloning and siRNA-Based Interference in Juvenile Blunt Snout Bream (Megalobrama amblycephala)

The aim of this study was to investigate the effects of S6K1α and β on the expression of glycolysis- and gluconeogenesis-related genes in juvenile blunt snout bream. Two isoforms, α and β, of ribosomal protein S6 kinase 1 in blunt snout bream were cloned and characterized, and their expression patterns were examined in vivo. The sequence analysis showed that <i>s6k1α</i> and <i>s6k1β</i> contain open reading frames of 2217 and 1497 bp, encoding 738 and 498 amino acids, respectively. Both S6K1α and S6K1β consist of an S_TKc domain and an extended S_TK_X domain. <i>s6k1α</i> and <i>s6k1β</i> were abundantly expressed in the heart and gonads. siRNAs were designed, and the experiment showed that α-siRNA inhibited <i>s6k1α</i> and <i>s6k1β</i> expression, but β-siRNA exclusively inhibited <i>s6k1α</i> expression (<i>p</i> < 0.05). α-siRNA upregulated the expression levels of <i>gk</i> and <i>pk</i>, while β-siRNA upregulated <i>pepck</i> and <i>g6p</i> expression (<i>p</i> < 0.05). The expression of <i>g6pdh</i> was found to be downregulated, but the <i>gs</i> mRNA level was overexpressed after treatment with α-siRNA and β-siRNA (<i>p</i> < 0.05). In the present experiment, S6K1α was more intimately involved in the regulation of gluconeogenesis when only S6K1α was inhibited, whereas the inhibition of both S6K1α and S6K1β collectively co-regulated glycolysis.