Nature Cell Biology1, 98 - 105 (1999)
Published online: 15 May 1999; | doi:10.1038/10067
Dominant-negative caveolin inhibits H-Ras function by disrupting cholesterol-rich
plasma membrane domains
Sandrine Roy1, Robert Luetterforst2, Angus Harding1, Ann Apolloni1, Maria Etheridge1, Espen Stang2, 3, Barbara Rolls2, John F. Hancock1
& Robert G. Parton2
1
Queensland Cancer Fund Laboratory of Experimental Oncology,
Department of Pathology, University of Queensland Medical School,
Herston Road, Brisbane 4006, Australia
2
Centre for Microscopy and Microanalysis, Centre for
Molecular and Cellular Biology, Department of Physiology and Pharmacology,
University of Queensland, Brisbane 4072,
Australia
3
Current address: Institute of Pathology, The National
Hospital, Oslo
0027, Norway
The plasma membrane pits known as caveolae have been implicated both in
cholesterol homeostasis and in signal transduction. CavDGV
and CavKSY, two dominant-negative amino-terminal truncation
mutants of caveolin, the major structural protein of caveolae, significantly
inhibited caveola-mediated SV40 infection, and were assayed for effects on
Ras function. We find that CavDGV completely blocked Raf activation
mediated by H-Ras, but not that mediated by K-Ras. Strikingly, the inhibitory
effect of CavDGV on H-Ras signalling was completely reversed
by replenishing cell membranes with cholesterol and was mimicked by cyclodextrin
treatment, which depletes membrane cholesterol. These results provide a crucial
link between the cholesterol-trafficking role of caveolin and its postulated
role in signal transduction through cholesterol-rich surface domains. They
also provide direct evidence that H-Ras and K-Ras, which are targeted to the
plasma membrane by different carboxy-terminal anchors, operate in functionally
distinct microdomains of the plasma membrane.
