Fig. 2

Knockdown of MK2 by inhibited TNF-α induced cytosolic accumulation of HuR. Lysates from control cells and MK2-silenced cells were subject to Western blot analysis for HuR, the densitometric analysis showed that MK2 silencing did not influence the nuclear HuR levels (a), however, reduced cytoplasmic accumulation of HuR compared to the control cells (b). The immunofluorescent staining for HuR (green) and DAPI (blue) showed that HuR was mainly accumulated in nucleus prior to TNF-α stimulation. Cytoplasmic HuR significantly increased after 2 h of TNF-α stimulation and then decreased after 8 h, while there was no remarkable change in nuclear HuR levels. Compared to the controls, MK2 silencing reduced cytoplasmic HuR but did not greatly affect the nuclear HuR levels (c). Western blot band density data are expressed as mean ± SEM. n =3, #P <0.05 vs. negative control siRNA-transfected cells, *P <0.05 vs. cells at TNF-α 0 h. Control siRNA, negative control siRNA N-HuR, nuclear HuR; C-HuR, cytoplasmic HuR