Format

Send to

Choose Destination
See comment in PubMed Commons below
Arterioscler Thromb Vasc Biol. 2008 Nov;28(11):2056-62. doi: 10.1161/ATVBAHA.108.172478. Epub 2008 Sep 4.

Lysosomal targeting and trafficking of acid sphingomyelinase to lipid raft platforms in coronary endothelial cells.

Author information

  • 1Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA.

Abstract

OBJECTIVE:

The purpose of this study was to determine whether lysosome trafficking and targeting of acid sphingomyelinase (ASMase) to this organelle contribute to the formation of lipid raft (LR) signaling platforms in the membrane of coronary arterial endothelial cells (CAECs).

METHODS AND RESULTS:

By measurement of fluorescent resonance energy transfer (FRET), it was found that in FasL-stimulated CAECs, membrane lamp1 (a lysosome marker protein) or Fas and GM1 (a LR marker) were trafficking together. Cofocal colocalization assay showed that ceramide was enriched in these LR platforms. Further studies demonstrated that these ceramide molecules in LR platforms were colocalized with ASMase, a ceramide producing enzyme. Fluorescence imaging of living CAECs loaded with lysosomal specific dyes demonstrated that lysosomes fused with membrane on FasL stimulation. In the presence of lysosome function inhibitors, bafilomycin (Baf) or glycyl-L-phenylalanine-beta-naphthylamide (GPN), these FasL-induced changes were abolished. Moreover, this FasL-induced formation of LR platforms was also blocked in ECs transfected with siRNA of sortilin, an intracellular transporter for targeting of ASMase to lysosomes. Functionally, FasL-induced impairment of vasodilator response was reversed by lysosomal inhibitors or sortilin gene silencing.

CONCLUSIONS:

Lysosomal trafficking and targeting of ASMase are importantly involved in LRs clustering in ECs membrane, leading to the formation of signaling platforms or signalosomes.

PMID:
18772496
PMCID:
PMC2668813
DOI:
10.1161/ATVBAHA.108.172478
[PubMed - indexed for MEDLINE]
Free PMC Article

Publication Types, MeSH Terms, Substances, Grant Support

Publication Types

MeSH Terms

Substances

Grant Support

PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center