PKC-Mediated USP Phosphorylation at Ser35 Modulates 20-Hydroxyecdysone Signaling in Drosophila
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- 作者：Sheng Wang ; Jiawan Wang ; Yaning Sun ; Qisheng Song ; Sheng Li
- 刊名：Journal of Proteome Research
- 出版年：2012
- 出版时间：December 7, 2012
- 年：2012
- 卷：11
- 期：12
- 页码：6187-6196
- 全文大小：418K
- 年卷期：v.11,no.12(December 7, 2012)
- ISSN：1535-3907
文摘
The nuclear receptor complex of the steroid hormone, 20-hydroxyecdysone (20E), is a heterodimer composed of EcR and USP. Our previous studies in Drosophila suggest that PKC modulates 20E signaling by phosphorylating EcR-USP. However, the exact phosphorylation sites in EcR and USP have not been identified. Using LC鈥揗S/MS analysis, we first identified Ser35 of USP as a PKC phosphorylation site. Mutation of USP Ser35 to Ala35 in S2 cells not only eliminated USP phosphorylation, but also attenuated the 20E-induced luciferase activity, mimicking the treatment with a PKC-specific inhibitor chelerythrine chloride in Kc cells. In the larval salivary glands (SG), inhibition of PKC activity with the binary GAL4/UAS system reduced USP phosphorylation and down-regulated the 20E primary-response genes, E75B and Br-C, and RNAi knockdown of Rack1 had stronger inhibitory effects than overexpression of PKCi. Moreover, RNAi knockdown of four PKC isozyme genes expressed in the SG exhibited a variety of inhibitory effects on USP phosphorylation and expression of E75B and Br-C, with the strongest inhibitory effects occurring when aPKC was knocked down by RNAi. Taken together, we conclude that PKC-mediated USP phosphorylation at Ser35 modulates 20E signaling in Drosophila.