Fig. 5

Biologic validation of HIP1 as a key pathway in RA FLS. a Left: HIP1 protein expression in FLS; right: decreased HIP1 expression induced by siRNA knockdown. b HIP1 deficiency significantly reduced RA FLS invasion through Matrigel. c HIP1 and cytoskeletal rearrangement. Left three panels: morphologic differences in HIP1 deficient cells demonstrate a stellar morphology with reduced number and size of lamellipodia and reduced co-localization of phospho-FAK. Right three panels: RA FLS transfected with siRNA control (green = phospho-FAK; blue = phalloidin/actin filaments; ×600 magnification). d Altered phenotype of the HIP1-deficient FLS. Top panel: siRNA HIP1 had reduced cell elongation (E elongated; R&S round and stellar morphology; #p-value = 0.0006). Middle panel: siRNA HIP1 decreased thin central filaments and thick actin filaments. *p-value = 0.003). Bottom panel: siRNA HIP1 knockdown also reduced the number of lamellipodia and their polarized distribution. (##p-value = 0.0008). All p-values are calculated by paired t-test, and error bars indicate standard deviations