Figure 3: ROCK1 activity is essential for metabolic stress-induced autophagy.
(a) The effect of ROCK1 depletion on autophagy marker, LC3II. MEF ROCK1flox/flox cells were generated and treated with Con or Ad-Cre for 72 h. Cells were then incubated in nutrient-rich (+Glucose) or HBSS media for 2 h. Cell extracts were resolved by SDS–PAGE and ROCK1 KO was confirmed by western blotting (left panel). The same blot was used for LC3 and β-actin expression. Cells from the same experiment were fixed with chilled acetone and immunofluroscence was performed against endogenous LC3 (red). Blue represents nuclear DAPI staining. Scale bar, 20 μm. (b) EJ cells (left) with a stable knockdown using shCont. or shROCK1#1 were incubated in control (+glucose) or nutrient-free (HBSS) medium (−glucose) for 24 h and lysed. Lysates were subjected to western blotting with antibodies indicated. HeLa cells (right) with a transient knockdown using siCont. and siROCK1#2 for 30 h were further incubated in control or HBSS media for 8 h. Whole cell extracts were prepared, resolved by SDS–PAGE and analysed for ROCK1, LC3 and β-actin. Relative ratios of LC3II/LC3I are shown. (c) HeLa cells were treated with H2O or 10 μM ROCK1 inhibitor, Y27632, for 8 h. Cells were then cultured in high glucose (0 h) or starved for in HBSS nutrient-free media for 6 h. One hour before collection, cells were incubated in dimethylsulphoxide (control) or 0.1 μM bafilomycin-A1. Whole cell lysates were resolved by SDS–PAGE and were analysed by western blotting with indicated antibodies. (d) HeLa cells incubated with H2O or 10 μM Y27632 for 8 h were washed with PBS and cultured in control (+Glu) or HBSS media (−Glu) for an additional 8 h. Cells were fixed in acetone and immunofluorescence was performed against endogenous LC3 antibody (green). Scale bar, 20 μm. Graph represents % of LC3 punctae/cell (mean±s.d.), n=25 cells; (Student’s t-test) **P=0.00041. (e) Transmission electron micrographs of EJ cells with stable shCont. or shROCK1#1 knockdown, cultured in control or HBSS medium for 16 h. Arrow bars indicate autophagic vacuoles. Scale bar, 500 nm.
