WALTON, L J; TUNNACLIFFE, A; University of Cambridge, UK; University of Cambridge, UK: Expression of a nematode LEA protein in mammalian cells improves tolerance to hyperosmotic shock

The late embryogenesis abundant (LEA) proteins are expressed in a number of anhydrobiotic organisms in response to dehydration stress. They are postulated to play a role in desiccation tolerance but as yet their precise function remains unclear. In this study, a nematode Group 3 LEA like protein was expressed in a mammalian cell line. The human embryonic kidney cell line T-REx 293 was transfected with the gene Aav-lea-1 from the anhydrobiotic nematode Aphelenchus avenae; expression was controlled using a tetracycline-inducible promoter. Several stable clonal cell lines were generated and production of the LEA protein was confirmed by Western blot. The LEA protein was found to accumulate in the cytoplasm at a concentration of up to 1.4% of the total soluble protein, comparable to the levels of LEA proteins found in desiccation-tolerant plant seeds. Stress tolerance experiments demonstrated that the presence of LEA protein improves the cells’ tolerance to hypertonic concentrations of sodium chloride, but no effect on desiccation tolerance was observed when the cells were dried at 98% or 90% relative humidity. Our results suggest that LEA proteins alone are unlikely to confer desiccation tolerance on mammalian cells but that multiple modifications are required.