Abstract

PURPOSE:

To investigate the role of ERK1/2 and RhoA/ROCK intracellular pathways in the modification of corneal re-epithelialization when stimulated by the diadenosine polyphosphates Ap(4)A and Ap(3)A.

METHODS:

In wounded confluent SIRC (Statens Seruminstitut rabbit cornea) cell monolayers and in the presence or absence of Ap(4)A or Ap(3)A 100 microM, a battery of P2 receptor antagonists and inhibitors of tyrosin kinases, MAPK, and cytoskeleton pathways (AG1478 100 microM, U0126 100 microM, Y27632 100 nM, and (-)-blebbistatin 10 microM; n = 8 each) were assayed. Also, the activation of ERK1/2 and ROCK-I was examined by Western blot assay after treatment with Ap(4)A and Ap(3)A (100 microM), with or without suramin, RB-2, U0126, and Y27632. The intracellular distribution of pERK and ROCK-I was examined in the presence of Ap(4)A or Ap(3)A (100 microM) with U0126 and Y27632 (100 nM).

RESULTS:

In the presence of Ap(4)A, U0126, Y27632, AG1478, and (-)-blebbistatin, reduced the migration rate compared to the effect of Ap(4)A alone (P < 0.0001, P < 0.001, P < 0.01, and P < 0.1 versus Ap(4)A, respectively). In the presence of Ap(3)A 100 microM, U0126 and Y27632 accelerated the migration rate when compared with the effect of Ap(3)A alone, whereas AG1478 and (-)-blebbistatin (P < 0.0001 versus Ap(3)A) slowed the migration rate. Western blot assays demonstrated that both dinucleotides activated the ERK1/2 pathway but only Ap(4)A activated the ROCK-I pathway. The intracellular distribution of pERK1/2 and ROCK-I reflected cross-talk between these two pathways.

CONCLUSIONS:

The activation of the Ap(4)A/P2Y(2) receptor, accelerates corneal epithelial cell migration during wound healing with the activation of MAPK and cytoskeleton pathways, whereas activation of the Ap(3)A/P2Y(6) receptor signals only the MAPK pathway.