Regulation of Chlamydomonas flagella and ependymal cell motile cilia by ceramide-mediated translocation of GSK3.

Abstract

Cilia are important organelles formed by cell membrane protrusions; however, little is known about their regulation by membrane lipids. We characterize a novel activation mechanism for glycogen synthase kinase-3 (GSK3) by the sphingolipids phytoceramide and ceramide that is critical for ciliogenesis in Chlamydomonas and murine ependymal cells, respectively. We show for the first time that Chlamydomonas expresses serine palmitoyl transferase (SPT), the first enzyme in (phyto)ceramide biosynthesis. Inhibition of SPT in Chlamydomonas by myriocin led to loss of flagella and reduced tubulin acetylation, which was prevented by supplementation with the precursor dihydrosphingosine. Immunocytochemistry showed that (phyto)ceramide was colocalized with phospho-Tyr-216-GSK3 (pYGSK3) at the base and tip of Chlamydomonas flagella and motile cilia in ependymal cells. The (phyto)ceramide distribution was consistent with that of a bifunctional ceramide analogue UV cross-linked and visualized by click-chemistry-mediated fluorescent labeling. Ceramide depletion, by myriocin or neutral sphingomyelinase deficiency (fro/fro mouse), led to GSK3 dephosphorylation and defective flagella and cilia. Motile cilia were rescued and pYGSK3 localization restored by incubation of fro/fro ependymal cells with exogenous C24:1 ceramide, which directly bound to pYGSK3. Our findings suggest that (phyto)ceramide-mediated translocation of pYGSK into flagella and cilia is an evolutionarily conserved mechanism fundamental to the regulation of ciliogenesis.

• Authors: Ji Na Kong, Kara Hardin, Michael Dinkins, Guanghu Wang, Qian He, Tarik Mujadzic, Gu Zhu, Jacek Bielawski, Stefka Spassieva, Erhard Bieberich
• Journal: Molecular biology of the cell (Mol Biol Cell) Vol. 26 Issue 24 Pg. 4451-65 (Dec 01 2015) ISSN: 1939-4586 [Electronic] United States
• PMID: 26446842 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: © 2015 Kong et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Chemical References

• Ceramides
• Tubulin
• Serine C-Palmitoyltransferase
• Glycogen Synthase Kinase 3

Topics

• Acetylation
• Animals
• Cells, Cultured
• Ceramides (metabolism)
• Chlamydomonas (enzymology, metabolism)
• Cilia (enzymology, metabolism)
• Ependyma (cytology, metabolism)
• Flagella (enzymology, metabolism)
• Glycogen Synthase Kinase 3 (metabolism)
• Humans
• Mice
• Mice, Inbred C57BL
• Serine C-Palmitoyltransferase (metabolism)
• Tubulin (metabolism)