PDGF receptor-[beta] modulates metanephric mesenchyme chemotaxis induced by PDGF AA

PDGF B chain or PDGF receptor (PDGFR)-[beta]-deficient (-/-) mice lack mesangial cells. To study responses of [alpha]- and [beta]-receptor activation to PDGF ligands, metanephric mesenchymal cells (MMCs) were established from embryonic day E11.5 wild-type (+/+) and -/- mouse embryos. PDGF BB stimulated cell migration in +/+ cells, whereas PDGF AA did not. Conversely, PDGF AA was chemotactic for -/- MMCs. The mechanism by which PDGFR-[beta] inhibited AA-induced migration was investigated. PDGF BB, but not PDGF AA, increased intracellular [Ca.sup.2+] and the production of reactive oxygen species (ROS) in +/+ cells. Transfection of -/- MMCs with the wild-type [beta]-receptor restored cell migration and ROS generation in response to PDGF BB and inhibited AA-induced migration. Inhibition of [Ca.sup.2+] signaling facilitated PDGF AA-induced chemotaxis in the wild-type cells. The antioxidant N-acetyl-L-cysteine (NAC) or the NADPH oxidase inhibitor diphenyleneiodonium (DPI) abolished the BB-induced increase in intracellular [Ca.sup.2+] concentration, suggesting that ROS act as upstream mediators of [Ca.sup.2+] in suppressing PDGF AA-induced migration. These data indicate that ROS and [Ca.sup.2+] generated by active PDGFR-[beta] play an essential role in suppressing PDGF AA-induced migration in +/+ MMCs During kidney development, PDGFR [beta]-mediated ROS generation and [Ca.sup.2+] influx suppress PDGF AA-induced chemotaxis in metanephric mesenchyme. reactive oxygen species; calcium