Stress-induced ER to Golgi translocation of ceramide synthase 1 is dependent on proteasomal processing.
The ceramide synthase (CerS) enzymes are key regulators of ceramide homeostasis. CerS1 is central to regulating C18 ceramide which has been shown to be important in cancer and the response to chemotherapeutic drugs. Previous work indicated that some drugs induced a novel and specific translocation of CerS1 from the endoplasmic reticulum to the Golgi apparatus. We now show that diverse stresses such as UV light, DTT, as well as drugs with different mechanisms of action induce CerS1 translocation. The stresses cause a specific cleavage of the CerS1 enzyme, and the cleavage is dependent on the action of the proteasome. Inhibition of proteasome function inhibits stress-induced CerS1 translocation, indicating that this proteolytic cleavage precedes the translocation. Modulation of protein kinase C activity shows that it plays a central role in regulating CerS1 translocation. Analysis of the C-terminus of the CerS1 protein shows that several KxKxx motifs are not involved in regulating stress induced translocation. The study suggests that diverse stresses initiate responses through different signaling pathways, which ultimately converge to regulate CerS1 localization. The data provide an increasingly detailed understanding of the regulation of this important enzyme in normal and stressed cells and support the idea that it is uniquely regulated with respect to the other CerS enzymes.
Sridevi
Priya
P
Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA.
Alexander
Hannah
H
Laviad
Elad L
EL
Min
Junxia
J
Mesika
Adi
A
Hannink
Mark
M
Futerman
Anthony H
AH
Alexander
Stephen
S
D019943:Amino Acid Substitution / Q000502:physiology; D002460:Cell Line; D002945:Cisplatin / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D004229:Dithiothreitol / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D006388:Hemagglutinins / Q000235:genetics; D007976:Leupeptins / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009842:Oligopeptides; D010455:Peptides / Q000235:genetics; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D051049:Sphingosine N-Acyltransferase / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014466:Ultraviolet Rays; D056811:Unfolded Protein Response / Q000187:drug effects / Q000502:physiology*
D015853:Cysteine Proteinase Inhibitors; D006388:Hemagglutinins; D007976:Leupeptins; D008565:Membrane Proteins; D009842:Oligopeptides; D010455:Peptides; D061988:Proteasome Inhibitors; D011993:Recombinant Fusion Proteins; D004317:Doxorubicin; C085706:FLAG peptide; C493790:CERS1 protein, human; D051049:Sphingosine N-Acyltransferase; D011493:Protein Kinase C; D046988:Proteasome Endopeptidase Complex; D002945:Cisplatin; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D004229:Dithiothreitol