Receptor-mediated regulation of peroxisomal motility in CHO and endothelial cells

The regulation of peroxisomal motility was investigated both in CHO cells a nd in cells derived from human umbilical vein endothelium (HUE). The cells were transfected with a construct encoding the green fluorescent protein be aring the C-terminal peroxisomal targeting signal 1, Kinetic analysis follo wing time-lapse imaging revealed that CHO cells respond to simultaneous sti mulation with ATP and lysophosphatidic acid (LPA) by reducing: peroxisomal movements. When Ca2+ was omitted from the extracellular medium or the cells were incubated with inhibitors for heterotrimeric G(i)/G(o) proteins, phos pholipase C, classical protein kinase C isoforms (cPKC), mitogen-activated protein kinase kinase (MEK) or phospholipase A(2) (PLA(2)), this signal-med iated motility block was abolished. HUE cells grown to confluency on microp orous membranes responded similarly to ATP-LPA receptor co-stimulation, but only when the ligands had access to the basolateral membrane region. These data demonstrate that peroxisomal motility is subject to specific modulati on from the extracellular environment and suggest a receptor-mediated signa ling cascade comprising Ca2+ influx, G(i)/G(o) proteins, phospholipase C, c PKC isoforms, MEK and PLA(2) being involved in the regulation of peroxisoma l arrest.