Staurosporine induces ganglion cell differentiation in part by stimulating urokinase-type plasminogen activator expression and activation in the developing chick retina.
Here, we investigated whether staurosporine-mediated urokinase-type plasminogen activator (uPA) activation is involved in retinal ganglion cell (RGC) differentiation. Retinal cells were isolated from developing chick retinas at embryonic day 6 (E6). Relatively few control cells grown in serum-free medium started to form processes by 12 h. In contrast, staurosporine-treated cells had processes within 3h, and processes were evident at 8 h. Immunofluorescence staining showed that Tuj-1-positive cells with shorter neurites could be detected in control cultures at 18 h, whereas numerous Tuj-1 positive ganglion cells with longer neuritic extensions were seen in staurosporine-treated cultures. BrdU-positive proliferating cells were more numerous in control cultures than in staurosporine-treated cultures, and the BrdU staining was not detected in post-mitotic Tuj-1 positive ganglion cells. Western blotting of cell lysates showed that staurosporine induced high levels of the active form of uPA. The staurosporine-induced uPA signal was localized predominantly in the soma, neurites and axons of Tuj-1-positive ganglion cells. Amiloride, an inhibitor of uPA, markedly reduced staurosporine-induced Tuj-1 staining, neurite length, neurite number, and uPA staining versus controls. In developing retinas in ovo, amiloride administration remarkably reduced the staurosporine-induced uPA staining and RGC differentiation. Taken together, our in vitro and in vivo data collectively indicate that uPA plays a role in the staurosporine-mediated stimulation of RGC differentiation.
Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
Yeoun-Hee
YH
Kim
Yongmin
Y
Chang
Jae-Chang
JC
Jung
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D002642:Chick Embryo; D002645:Chickens; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D012160:Retina / Q000196:embryology* / Q000201:enzymology; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000201:enzymology; D019311:Staurosporine / Q000494:pharmacology*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
D047428:Protein Kinase Inhibitors; D014568:Urokinase-Type Plasminogen Activator; D019311:Staurosporine