Poster abstracts
Poster number 57 submitted by Rocio Zaldivar
SRPK1 interacts with the HTLV-1 hbz mRNA and influences cellular proliferation
Rocio Zaldivar (Molecular, Cellular and Developmental Biology Graduate Program ), Jaideep Seth (Veterinary Biosciences ), Tasha Wilkie (Veterinary Biosciences ), Patrick Green (Veterinary Biosciences ), Amanda Panfil (Veterinary Biosciences )
Abstract:
Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus which causes persistent infection through clonal expansion of infected CD4+ T cells. Among HTLV-1 encoded genes, Hbz is critical for disease development. Hbz is encoded from the antisense strand of the integrated viral genome. Several groups have found that Hbz is multi-functional, playing significant roles in both the RNA and protein form throughout infection and establishment of latency. Hbz RNA is expressed in all virally-induced tumor cells. It was recently demonstrated that hbz RNA is predominantly nuclear in infected T cells. We hypothesize cellular protein interactions with hbz RNA secondary structure translates to cell signaling pathways important for viral persistence and cellular proliferation. Mass spectrometry was used to identify cellular proteins that differentially interact with hbz and an hbz RNA sequence containing a silent mutation (SM) that disrupts the RNA secondary structure. Our proteomics data identified an mRNA splicing factor serine/arginine protein kinase 1 (SRPK1) binding to hbz RNA. Cross-linking immunoprecipitation (CLIP) assays in HEK293T and in HTLV-1 tumor derived T-cell lines (ATL-ED) further validated this interaction. Expression vectors encoding hbz RNA only (hbzTTG) and hbz with silent mutations (hbz SM) were generated and proliferation assays in Kit-225 cells demonstrated that cells stably expressing hbzTTG showed a proliferative advantage. shRNA-mediated knockdown of SRPK1 in Kit-225 hbzTTG cells and ATL-ED cell lines was performed and localization of hbz RNA was examined using cellular fractionation and RT-qPCR. SRPK1 knockdown in Kit-225 hbzTTG cells and ATL-ED cells decreased cellular proliferation and caused redistribution of hbz from the nucleus to the cytoplasm. In conclusion, Hbz RNA proliferative abilities depend on nuclear localization and at least one cellular factor that controls this localization is SRPK1.
Keywords: HTLV-1, HBZ, SRPK1