ARTERIAL INJURY AND SMOOTH MUSCLE CELL SIGNALING

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DESCRIPTION (Adapted from Investigator's Abstract): This proposal will determine the intracellular signaling pathways that are important for the replication of SMC after arterial injury. The first group of experiments will document the activation of the MAP kinase pathways, namely p42/44erk in the ballooned injured rat carotid arteries. Activation of this pathway will be inhibited in vivo with a topically applied MEK1 inhibitor and the effect on SMC replication quantitated. Furthermore, the effect of activation of the p46sapk on SMC growth by transfecting cells with the upstream activator of p46sapk and measuring their ability to replicate in response to known mitogens. The second specific aim will determine the role of mitogen-activated protein kinase phosphatases (MKP-1) on SMC replication in rat carotid arteries. Initially MKP1/2 expression will be documented at various times after injury. MKP-1 will be inhibited with pervanadate and its expression blocked with an antisense oligonucleotide. The replication of carotid artery SMC to known agonists will then be quantitated. The third aim will determine if the MAP kinases, p42/44erk are activated by FGF2 and PDGF. Rat arteries will be denuded of endothelium in a manner known to induce a minimal SMC replication, and then FGF2 and PDGF will be administered. The activity of p42/44erk and the expression of MKP-1 will be measured in the SMC of these arteries. The final group of experiments will document the time course of cyclin D and E activity and the presence of cyclin inhibitors, p21 and p27 at times after carotid injury. Further studies will evaluate the effect of p27 on SMC replication in vivo by inhibiting its expression with an antisense oligonucleotide and then measuring the ability of intimal SMC to respond to known mitogens. In other studies the inhibitor, p27 will be over expressed in SMC and its role in suppressing SMC replication, when challenged with a mitogenic stimulus, quantitated. These studies will provide important data on the signaling pathways thought to be active in SMC and determine if their activation is critical for SMC replication.