Toll-like receptors (TLRs) are key innate immune receptors that recognize non-self pathogens and trigger host responses. Activation of these receptors results in the release of antimicrobial peptides, inflammatory cytokines, and co stimulatory molecules that initiate adaptive immunity for infections with gram-negative bacteria, lipopolysaccharide is the main source of inflammation, and toll-like receptor 4 (TLR4) is crucial in mediating its effects. TLR4 is expressed on cardiomyocytes, macrophages, airway epithelia, endothelial, smooth-muscle cells and in small amounts in most other tissue. But, uncontrolled activation of TLR signaling molecules may cause auto immune diseases, sepsis, and tissue damage so the activation of TLR4 should be under control. Ubiquitin¨Cdependent receptor degradation as well as stabilization was recently suggested as a novel regulatory mechanism in controlling several TLR activations. We have recently found that an ubiquitin-like protein named protein linking integrin associated protein to cytoskeleton 1 (PLIC-1) interacts with the cytoplasmic domain of TLR4. The interaction between TLR4 and PLIC-1 was verified by western blot and immunoprecipitation. Further mapping of the interacting domain was done and we observed that the N terminal fragment of PLIC-1 is interacting with TLR4. PLIC-1 has been reported to stabilize proteins by interfering with proteosomal degradation. Consistent with this finding, we observed that over expression of PLIC-1 accumulated ubiquitinated TLR4. By flow cytometric analysis we observed that over expression of PLIC-1 is stabilizing TLR4. Reporter studies show that PLIC-1 inhibits the TRIF-dependent IFN-¦Â pathway. When endogenous PLIC-1 was knocked down by RNAi, the activation of TRIF-dependent IFN-¦Â luc was further increased. The same effect was observed in J774 mouse macrophages. Taken together our results suggest that PLIC-1 is a negative regulator of TLR pathway. This knowledge may be applied in immunotherapy as a means to modulate TLR activation in diseases such as septic shock, thus provides benefit for public health.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-12082006-125251 |
| Date | 15 February 2007 |
| Creators | Biswas, Nabanita |
| Contributors | Jeremy Martinson, PhD,, Tianyi Wang, PhD,, David Hackam, MD, PhD, |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-12082006-125251/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0014 seconds