Characterization and expression analysis in the developing embryonic brain of the porcine FET family: FUS, EWS, and TAF15

The FET protein family consists of FUS (TLS), EWS (EWSR1), and TAF15. The FET proteins bind DNA and RNA and are involved in transcriptional regulation and RNA processing. Translocations involving the FET genes have been identified in human sarcomas, and mutations in the FUS and TAF15 genes are associated with Amyotrophic Lateral Sclerosis. We here describe the characterization of the porcine FET proteins and an expression analysis during embryonic brain development. The FET proteins are well conserved between pig and human. FET protein mutations associated with Amyotrophic Lateral Sclerosis affect evolutionary conserved amino acids. In cultured cells the porcine FET proteins have a nuclear localization with some specific cytoplasmic aggregation of TAF15 in neuronal progenitor cells. Immunohistochemical analyses supported a predominant nuclear localization, but also faint cytoplasmic localization. The FET proteins have similar expression profiles throughout the development of the embryonic porcine brain and most cell types appeared positive for expression. Quantitative RT-PCR analyses showed that the FET mRNA expression decreased during embryonic development of hippocampus and for FUS and EWS during embryonic development of cortex. FET mRNA expression was relatively constant in brain stem, basal ganglia, and cerebellum. Overall the FET protein localization and mRNA and protein expression analyses were concordant with previous analysis from the human brain. The presented results indicate that the porcine brain could be an alternative model for the future examination of the normal functions as well as neurological disease associated functions of the FET proteins.