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J Cell Sci. 2013 Aug 15;126(Pt 16):3585-92. doi: 10.1242/jcs.122325. Epub 2013 May 20.

Sphingomyelin clustering is essential for the formation of microvilli.

Author information

1
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan. ikenouchi@kyushu-u.org

Abstract

Cellular architectures require regulated mechanisms to correctly localize the appropriate plasma membrane lipids and proteins. Microvilli are dynamic filamentous-actin-based protrusions of the plasma membrane that are found in the apical membrane of epithelial cells. However, it remains poorly understood how their formation is regulated. In the present study, we found that sphingomyelin clustering underlies the formation of microvilli. Clustering of sphingomyelin is required for the co-clustering of the sialomucin membrane protein podocalyxin-1 at microvilli. Podocalyxin-1 recruits ezrin/radixin/moesin (ERM)-binding phosphoprotein-50 (EBP50; also known as NHERF1), which recruits ERM proteins and phosphatidylinositol 4-phosphate 5-kinase β (PIP5Kβ). Thus, clustering of PIP5Kβ leads to local accumulation of phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2], which enhances the accumulation of ERM family proteins and induces the formation of microvilli. The present study revealed novel interactions between sphingomyelin and the cytoskeletal proteins from which microvilli are formed, and it clarified the physiological importance of the chemical properties of sphingomyelin that facilitate cluster formation.

KEYWORDS:

Apical membrane; ERM; Epithelial polarity; Lysenin; Microvilli; Sphingomyelin

PMID:
23690544
DOI:
10.1242/jcs.122325
[Indexed for MEDLINE]
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