博士 / 國立中興大學 / 生物科技學研究所 / 104 / Proper regulation of immune signaling is critical in preventing overreacted responses. One mechanism is to limit the extent or duration of immune responses by producing inhibitory alternatively spliced isoform. We previously demonstrated that the debilitation of grouper Toll-like receptor (gTLR9) signaling is achieved by an inhibitory isoform, gTLR9B (9B). The 9B isoform is identical to full-length gTLR9A (9A) except truncation in the C-terminal signaling transducing TIR domain. Previous study showed fluctuated expression of 9A and 9B, where 9A precedes 9B. Furthermore, overexpression of 9B suppresses ligand-induced IL-1? expression. In this study, the responsiveness of 9B to ligand was further confirmed by the mobilization of 9B to the endosome, where it co-localizes with the ligand. The result suggests 9B functions as a molecular sink to compete ligand with 9A. In addition, the gTlr9 alternative splicing was shown to be regulated through ligand-induced phosphorylation of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II). The ligand-activated NF-?B pathway biased toward the production of the 9B isoform. Because NF-?B is known to recruit p-TEFb kinase, which phosphorylates the Pol II CTD at Ser2 residues, the p-TEFb’s role in alternative splicing was further examined. Promoting p-TEFb kinase activity significantly favored the production of the 9B isoform, whereas inhibiting p-TEFb yielded an opposite result. The biological significance of this feedback alternative splicing regulatory event was further demonstrated in both cell lines and enriched grouper macrophage. Taken together, data presented here provide a mechanistic insight into the feedback regulatory loop in gTLR9 signaling pathway.
| Identifer | oai:union.ndltd.org:TW/104NCHU5111005 |
| Date | January 2016 |
| Creators | Fang-Yao Lee, 李方堯 |
| Contributors | , 張典顯, 邱品文 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 84 |
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