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Characterization of an apical ceramide-enriched compartment regulating ciliogenesis
Qian He1, Guanghu Wang, Somsankar Dasgupta
1Program in Developmental Neurobiology, Institute of Molecular Medicine and Genetics, School of Medicine, Georgia Health Sciences University, Augusta, GA 30912, USA.
Molecular Biology of the Cell
|June 22, 2012
Summary
A novel apical compartment (ACEC) enriched in ceramide and Rab11a proteins is crucial for primary cilia formation. This ceramide-sphingomyelin pathway supports ciliogenesis by promoting tubulin acetylation.
Area of Science:
- Cell Biology
- Lipid Biology
Background:
- Primary cilia are essential cellular organelles involved in various signaling pathways.
- The biogenesis and maintenance of primary cilia are complex processes involving specific protein and lipid components.
Purpose of the Study:
- To investigate the role of ceramide and associated proteins in the formation of primary cilia in Madin-Darby canine kidney (MDCK) cells.
- To identify novel cellular compartments and molecular mechanisms regulating ciliogenesis.
Main Methods:
- Utilized magnetic sorting to isolate ceramide and Rab11a vesicles.
- Employed dominant-negative mutants of atypical protein kinase C (aPKC) to study protein complex formation.
- Inhibited acid sphingomyelinase with imipramine to assess the impact on ACEC formation and ciliogenesis.
- Used histone deacetylase (HDAC) inhibitor trichostatin A to evaluate rescue effects on ciliogenesis.
Main Results:
- Identified an apical ceramide-enriched compartment (ACEC) colocalized with Rab11a at the base of primary cilia.
- Isolated vesicles containing ceramide and Rab11a showed similar protein profiles, including aPKC, Cdc42, Sec8, Rab11a, and Rab8, suggesting a ciliogenic complex.
- Demonstrated that ceramide derived from endocytosed sphingomyelin (SM) is essential for ACEC formation and ciliogenesis.
- Showed that ceramide promotes tubulin acetylation in cilia, which is critical for primary cilia stability.
Conclusions:
- The ACEC is a novel compartment where SM-derived ceramide drives the formation of a lipid-protein complex essential for primary cilia.
- This complex sustains primary cilia by preventing microtubule deacetylation, highlighting a new regulatory mechanism in ciliogenesis.
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