Date of Award
Doctoral Dissertation - Open Access
Doctor of Philosophy
Microbiology and Immunology
The roles of UBXNs in the regulation of antiviral immune responses have not been much explored. Previous work in our lab identified UBXN1 as a negative regulator of the retinoic acid-inducible gene-I (RIG-I) like receptors (RLR) pathway and UBXN3B as a positive regulator of stimulator-of-interferon Genes (STING) -mediated immune responses. In this study, I aimed to determine the member of UBXNs as a positive regulator of ribonucleic acid (RNA) virus infection-induced innate immune responses. By using an interferon stimulated response element (ISRE)-driven luciferase reporter assay that monitors the activity of type I/III interferon (IFN)-induced janus kinase (JAK) - signal transducer and activator of transcription proteins (STAT) signaling, I found that over expressed UBXN6 synergized with RIG-I, IFN-β or IFN-λ to enhance antiviral immune responses.
I further used small interfering RNA (siRNA) and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology to abrogate UBXN6 function, aiming to establish the function of UBXN6 in viral infection and JAK-STAT signaling. By polymerase chain reaction (PCR) array I found that UBXN6-deficiency led to a reduction in type I/III IFN-induced gene expression, which was validated by quantitative reverse transcriptase polymerase chain reaction (q-RT-PCR). Also, RNA virus replication was increased in UBXN6-deficient when compared to UBXN6-sufficient cells, which was accompanied by a significant reduction in IFN-β and IFN-λ. Lastly, I decoded the mechanism by which UBXN6 regulates the JAK-STAT pathway. I observed that IFN-β-stimulated STAT1 phosphorylation was impaired in UBXN6-deficient cells. By co-immunoprecipitation techniques and mass spectrometry analysis, I identified that following IFN-β stimulation UBXN6 interacted with protein arginine methyltransferase 5 (PRMT5) that is known to interact with JAK1/2. Our results demonstrate that UBXN6 positively regulates JAK1-STAT1/2 signaling to combat viral infections.
Ketkar, Harshada and Ketkar, Harshada, "A Role of Ubiquitin Regulatory X-Domain Containing Proteins (UBXN6) in Antiviral Immunity" (2019). NYMC Student Theses and Dissertations. 24.