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

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Abstract
The regulation of peroxisomal motility was investigated both in CHO cells and in cells derived from human umbilical vein endothelium (HUE). The cells were transfected with a construct encoding the green fluorescent protein bearing the C‐terminal peroxisomal targeting signal 1. Kinetic analysis following time‐lapse imaging revealed that CHO cells respond to simultaneous stimulation 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 Gi/Go proteins, phospholipase C, classical protein kinase C isoforms (cPKC), mitogen‐activated protein kinase kinase (MEK) or phospholipase A2 (PLA2), this signal‐mediated motility block was abolished. HUE cells grown to confluency on microporous 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 modulation from the extracellular environment and suggest a receptor‐mediated signaling cascade comprising Ca2+ influx, Gi/Go proteins, phospholipase C, cPKC isoforms, MEK and PLA2 being involved in the regulation of peroxisomal arrest.