Fig. 7. Ofs has an eIF4G-like function in S2R+ cells. (A) Growth
curves representing the average counts of GFP-(untransfected) cells from 10-13
wells with error bars representing s.e.m. (B) Western blot against
eIF4G and GFP-Ofs assessing the degree of knockdown at days 4 and 7. The major
eIF4G band is indicated with an arrow. We variably saw a second band migrating
slightly faster (asterisk); its identity is unclear. (C) Matched growth
curves for both GFP-(untransfected) and GFP+ (transfected) cells from wells
transfected with GFP alone, GFP-Ofs or GFP-eIF4G. Curves were normalized for
transfection efficiency at day 3. Key in A applies. Expression of GFP-Ofs or
GFP-eIF4G completely rescues the defects caused by eIF4G or eIF4G+Ofs
knockdown, but not by eIF4A knockdown. Each curve represents average counts
from 3-6 wells, with error bars indicating s.e.m. (D) Cell cycle
profiles for the cells represented in A showing a shift towards G1
with either eIF4G or eIF4G+Ofs knockdown. eIF4A knockdown caused an increase
in the percentage of cells with sub-G1 DNA content, normally
indicative of apoptotic cells (Oancea et
al., 2006). (E) Summary of cell cycle profiling showing
rescue by GFP-Ofs and GFP-eIF4G, but not by GFP alone. Gray bars (GFP-) and
green bars (GFP+) are paired for each experimental condition. Within each set,
from left to right: sub-G1, G1, S and G2.
Notice the relative shifts in the G1 and G2 bars:
depletion of eIF4G-like proteins caused an increase in the proportion of
G1 cells (compare G1 with G2 bars), and this
trend was reversed by transfection of either GFP-Ofs or GFP-eIF4G.