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Proc Natl Acad Sci U S A. 2013 Feb 19;110(8):E613-22. doi: 10.1073/pnas.1216585110. Epub 2013 Jan 28.

Direct chemical evidence for sphingolipid domains in the plasma membranes of fibroblasts.

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1
School of Chemical Sciences, University of Illinois, Urbana, IL 61801, USA.

Abstract

Sphingolipids play important roles in plasma membrane structure and cell signaling. However, their lateral distribution in the plasma membrane is poorly understood. Here we quantitatively analyzed the sphingolipid organization on the entire dorsal surface of intact cells by mapping the distribution of (15)N-enriched ions from metabolically labeled (15)N-sphingolipids in the plasma membrane, using high-resolution imaging mass spectrometry. Many types of control experiments (internal, positive, negative, and fixation temperature), along with parallel experiments involving the imaging of fluorescent sphingolipids--both in living cells and during fixation of living cells--exclude potential artifacts. Micrometer-scale sphingolipid patches consisting of numerous (15)N-sphingolipid microdomains with mean diameters of ∼200 nm are always present in the plasma membrane. Depletion of 30% of the cellular cholesterol did not eliminate the sphingolipid domains, but did reduce their abundance and long-range organization in the plasma membrane. In contrast, disruption of the cytoskeleton eliminated the sphingolipid domains. These results indicate that these sphingolipid assemblages are not lipid rafts and are instead a distinctly different type of sphingolipid-enriched plasma membrane domain that depends upon cortical actin.

PMID:
23359681
PMCID:
PMC3581929
DOI:
10.1073/pnas.1216585110
[Indexed for MEDLINE]
Free PMC Article
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