Dopamine-induced translocation of protein kinase C isoforms visualized in renal epithelial cells

• Short-term regulation of sodium metabolism is dependent on the modulation of the activity of sodium transporters by first and second messengers. In understanding diseases associated with sodium retention, it is necessary to identify the coupling between these messengers. We have examined whether dopamine, an important first messenger in tubular cells, activates and translocates various protein kinase C (PKC) isoforms. We used a proximal tubular-like cell line, LLCPK-1 cells, in which dopamine was found to inhibit Na+-K(+)ATPase in a PKC-dependent manner. Translocation of PKC isoforms was studied with both subcellular fractionation and confocal microscopy. Both techniques revealed a dopamine-induced translocation from cytosol to plasma membrane of PKC-alpha and -epsilon, but not of PKC-delta,-gamma, and -zeta. The process of subcellular fractionation resulted in partial translocation of PKC-epsilon. This artifact was eliminated in confocal studies. Confocal imaging permitted detection of translocation within 20 s. Translocation was abolished by a phospholipase C inhibitor and by an antagonist against the dopamine 1 subtype (D-1) but not the 2 subtype of receptor (D-2). In conclusion, this study visualizes in renal epithelial cells a very rapid activation of the PKC-alpha and -epsilon isoforms by the D-1 receptor subtype.

Keyword

kidney

Na+-K+-ATPase

phospholipase C

dopamine

spontaneously hypertensive rats

phospholipase-c

induced activation

proximal tubule

phosphorylation

receptors

na+,k+-atpase

na,k-atpase

alpha-1

subunit

Publication and Content Type

ref (subject category)

art (subject category)