Figure 7. Effect of inhibition of
transforming growth factor (TGF)-β receptor I or Smad3 phosphorylation
on Smad and non-Smad signaling pathways. Optic nerve head (ONH)
astrocytes and lamina cribrosa (LC) cells were pre-incubated with
SB431542 (10 uM) or SIS3 (25 uM), 1h before treatment with TGF-β2. ONH
astrocytes and LC cells were then treated with recombinant TGF-β2 for 1
h and total cell lysates were subjected to western blot analysis for
phosphorylation of Smad and non-Smad signaling pathways. A:
western blot analysis of pSmad3, Smad3, pSmad2, and Smad2 in ONH
astrocytes and LC cells. B: western blot analysis of
phosphorylated extracellular signal-regulated kinases (ERK)1/2, total
ERK1/2, phosphorylated p38, total p38, phosphorylated c-Jun N-terminal
kinases (JNK)1/2, and total JNK1/2 in ONH astrocytes and LC cells.
Samples were run in the same gel but not in the order presented.
SB431542 inhibited TGF-β2 induced phosphorylation of Smad2/3, whereas
SIS3 selectively inhibited phosphorylation of Smad3. The inhibitors had
no effect on members of the non-Smad pathway.