Advances in next-generation sequencing and ribosomal profiling methods highlight that the proteome is likely orders of magnitude larger than previously thought. This expansion potentially occurs through translational recoding, a process that results in the expression of multiple variations of a protein from a single messenger RNA. Our laboratory demonstrated that cyclooxygenase-3/1b (COX-3/1b), a frameshifted, intron-1-retaining, alternative splice variant from the COX-1 gene, is multiply recoded, which results in the translation of at least seven different COX-3 proteins. Two of the recoded COX-3 proteins that we identified are active prostaglandin synthases and are inhibited by non-steroidal anti-inflammatory drugs (NSAIDs). Here we show that the other non-prostaglandin-generating recoded COX-3 proteins perform new roles in innate immunity, a process in which COX are known to generally function. Our analyses determined that these recoded COX-3 proteins bind at or near the amino-terminal region of ATG9a, a critical regulator of both canonical (i.e. digestive autophagy associated with mTORc inhibition and nutrient deprivation) and non-canonical (i.e. xenophagy involved in the innate immune response to invading organisms) autophagy. We further show that this process requires mTORc signaling activity, which opposes the digestive pathway. As a final confirmation of the biological relevance of these recoded COX-3 proteins and their central role in xenophagy, we demonstrate that expression of these COX-3 proteins in an encephalomyocarditis virus infection model system differentially affects infectious virion production. These COX-3 proteins also associate with recoded cytosolic nucleobindin around large, innate immune-related, large LC3-II positive structures (LLPSs). Through mutagenizing catalytic residues of recoded COX-3 proteins and drug assays, we determine LLPS formation is dependent on oxylipin generation.
| Identifer | oai:union.ndltd.org:BGMYU2/oai:scholarsarchive.byu.edu:etd-7538 |
| Date | 01 June 2015 |
| Creators | Lee, Jonathan J. |
| Publisher | BYU ScholarsArchive |
| Source Sets | Brigham Young University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Theses and Dissertations |
| Rights | http://lib.byu.edu/about/copyright/ |
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