Regulation of primary cilia formation by ceramide.
The primary cilium is an important sensory organelle, the regulation of which is not fully understood. We found that in polarized Madin-Darby Canine Kidney cells, the sphingolipid ceramide is specifically distributed to a cis-Golgi compartment at the base of the primary cilium. This compartment immunostained for the centrosome marker gamma-tubulin, the Rho type GTPase cell division cycle 42 (Cdc42), and atypical protein kinase Czeta/lambda (aPKC), a kinase activated by ceramide and associated with a polarity protein complex consisting of partitioning defective (Par)6 and Cdc42. Inhibition of ceramide biosynthesis with Fumonisin B1 prevented codistribution of aPKC and Cdc42 in the centrosomal/pericentriolar compartment and severely impaired ciliogenesis. Cilium formation and codistribution of aPKC and Cdc42 were restored by incubation with N-acetyl or N-palmitoyl sphingosine (C2 or C16 ceramide), or the ceramide analog N-oleoyl serinol (S18). Cilium formation was also restored by the glycogen synthase kinase-3beta (GSK-3beta) inhibitor indirubin-3-monoxime, suggesting that regulation of ciliogenesis depends on the inhibition of GSK-3beta by ceramide-activated aPKC. Consistently, inhibition of aPKC with a pseudosubstrate inhibitor prevented restoration of ciliogenesis by C2 ceramide or S18. Our data show for the first time that ceramide is required for primary cilium formation.
Program in Developmental Neurobiology, Institute of Molecular Medicine and Genetics, School of Medicine, Medical College of Georgia, Augusta, GA 30912, USA.
Guanghu
G
Wang
Kannan
K
Krishnamurthy
Erhard
E
Bieberich
D000818:Animals; D002460:Cell Line; D002518:Ceramides / Q000378:metabolism* / Q000494:pharmacology*; D002923:Cilia / Q000187:drug effects* / Q000378:metabolism*; D004285:Dogs; D037341:Fumonisins / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D007150:Immunohistochemistry; D010088:Oxidoreductases / Q000037:antagonists & inhibitors
D002518:Ceramides; D037341:Fumonisins; C056933:fumonisin B1; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3