Ceramide-dependent release of ceramide kinase from cultured cells.
Ceramide kinase (CERK) and its product, ceramide-1-phosphate (Cer-1-P), are implicated in signaling processes, but the action mechanisms are not fully elucidated. When checking for intracellular effects of Cer-1-P by exposing CERK-expressing CHO cells to truncated ceramides, an unexpected decrease in CERK activity and protein level was observed. This decrease appeared dose-dependent and specific for the d-erythro-ceramide configuration and the presence of the double bond. At early time points, CERK clustered near the plasma membrane, followed later by its appearance in the culture medium. In cells expressing CERK lacking the pleckstrin domain or an inactive CERK mutant, this ceramide effect was not observed, indicating that clustering and release of CERK may be mediated by Cer-1-P. Presumably, high local Cer-1-P concentrations will increase the plasma membrane curvature and lead to release of CERK by vesicle shedding. This could be a potential regulatory mechanism in CERK/Cer-1-P signaling so far not investigated.
Van Overloop
Helena
H
Katholieke Universiteit Leuven, Faculteit Geneeskunde, Departement Moleculaire Celbiologie, LIPIT, Campus Gasthuisberg, Herestraat, Box 601, B-3000 Leuven, Belgium.
Van Veldhoven
Paul P
PP
D000818:Animals; D016466:CHO Cells; D002518:Ceramides / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D014162:Transfection
D002518:Ceramides; C065576:ceramide 1-phosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C066324:ceramide kinase