Functional characterization of porcine LSm14A in IFN-β induction.

Human LSm14A has recently been found as a processing body-associated sensor of intracellular viral nucleic acids and triggers signaling for type I IFN expression. Here porcine LSm14A (pLSm14A) was cloned from the PK-15 cells. The pLSm14A ORF is 1392 bp in length, encoding 463 amino acids. The putative pLSm14A contains a Sm-like domain and two arginine-glycine-glycine (RGG) boxes. The pLSm14A has high identity at the amino acid level to those of bovine, human and mouse (93.5-97.4%) and is transcribed in different tissues of pigs. In HEK293 or Marc-145 cells, pLSm14A was localized in the cytosol as P-body-like dots. Expression of pLSm14A in HEK293 or Marc-145 cells enhanced activities of IFN-β and NF-κB promoters, induced IFN-β transcription, and potentiated poly(I:C)-induced IFN-β promoter activation, indicating that pLSm14A is a potential signal molecule in the IFN-β pathway of pigs. We also found that pLSm14A-induced IFN-β promoter activity was down-regulated by porcine reproductive and respiratory syndrome virus infection in Marc-145 cells. Since pLSm14A is constitutively expressed in virtually all tissues, more research is needed to explore its role in initial phase of viral infections of pigs and its relationship with RIG-I in sensing PAMPs for type I IFN induction.