HuR expression and proportion of full length HuR and cleavage products in monocytic U937 cells.

Full length HuR (36 kDa) and HuR cleavage products (CP1; 24 kDa and CP2; 8 kDa) in LPS-stimulated (A and B) and Salmonella enteritidis-infected (C) cells. The cells were transfected with vector (Mock) or genomic clone of HLA-B27 (B27g) or the HLA-B27 mutants B27.E45M (E45M) and B27.H9F (H9F). In all infection experiments, time ‘0′ refers to the time point where cells are infected with bacteria, incubated for 1 h and washed to remove the extracellular bacteria. In LPS experiments, time ‘0′ refers to the time of LPS stimulation. Expression of HuR was determined by FACS analysis (A) and SDS-PAGE and Western blotting (B, C). In A, a representative data is shown at 5 h time point together with analysis of a total of four independent experiments. In B and C, heat shock 70 kDa protein 8, HSPA8 was used as a loading control. Results from densitometric analysis of five independent experiments are shown in diagram. See Materials and Methods for details. * = P-value <0.05 for HuR, ^† = P-value <0.05 for CP2 and ^‡ = P-value <0.06 for CP1 versus Mock at the respective time point.