p38 MAP kinase inhibitor suppresses transforming growth factor-β2-induced type 1 collagen production in trabecular meshwork cells.

Glaucoma is an age-related neurodegenerative disease of retinal ganglion cells, and appropriate turnover of the extracellular matrix in the trabecular meshwork is important in its pathology. Here, we report the effects of Rho-associated kinase (ROCK) and p38 MAP kinase on transforming growth factor (TGF)-β2-induced type I collagen production in human trabecular meshwork cells. TGF-β2 increased RhoA activity, actin polymerization, and myosin light chain 2 phosphorylation. These effects were significantly inhibited by Y-27632, but not SB203580. TGF-β2 also increased promoter activity, mRNA synthesis, and protein expression of COL1A2. These effects were significantly inhibited by SB203580, but not Y-27632. Additionally, Y-27632 did not significantly inhibit TGF-β2-induced promoter activation, or phosphorylation or nuclear translocation of Smad2/3, whereas SB203580 partially suppressed these processes. Collectively, TGF-β2-induced production of type 1 collagen is suppressed by p38 inhibition and accompanied by partial inactivation of Smad2/3, in human trabecular meshwork cells.