Expression of Caveolin-1 Is Required for the Transport of Caveolin-2 to the Plasma Membrane
RETENTION OF CAVEOLIN-2 AT THE LEVEL OF THE GOLGI COMPLEX*
- Isabella ParolinitOatOb,
- Massimo SargiacomotOb,
- Ferruccio GalbiatitOa,
- Giovanni RizzotOb,
- Francesco GrignanitObtOc,
- Jeffrey A. EngelmantOaFNd,
- Takashi OkamototOeFNf,
- Tsuneya IkezutOeFNf,
- Philipp E. ScherertOgFNh,
- Rosalia Morai,
- Enrique Rodriguez-Boulani,FNj,
- Cesare PeschletObtOk and
- Michael P. LisantitOaFNl
- From the Departments of tOaMolecular Pharmacology andtOgCell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, the tObDepartment of Hematology-Oncology, Istituto Superiore di Sanità, 00161 Rome, Italy, the tOcIstituto di Medicina Interna e Scienze Oncologiche, Perugina University, 06100 Perugina, Italy, the tOeDepartment of Neurosciences, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195,iDyson Vision Research Institute, Weill Medical College of Cornell University, New York, New York 10021, and the tOkKimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
Abstract
Caveolins-1 and -2 are normally co-expressed, and they form a hetero-oligomeric complex in many cell types. These caveolin hetero-oligomers are thought to represent the assembly units that drive caveolae formation in vivo. However, the functional significance of the interaction between caveolins-1 and -2 remains unknown. Here, we show that caveolin-1 co-expression is required for the transport of caveolin-2 from the Golgi complex to the plasma membrane. We identified a human erythroleukemic cell line, K562, that expresses caveolin-2 but fails to express detectable levels of caveolin-1. This allowed us to stringently assess the effects of recombinant caveolin-1 expression on the behavior of endogenous caveolin-2. We show that expression of caveolin-1 in K562 cells is sufficient to reconstitute the de novo formation of caveolae in these cells. In addition, recombinant expression of caveolin-1 allows caveolin-2 to form high molecular mass oligomers that are targeted to caveolae-enriched membrane fractions. In striking contrast, in the absence of caveolin-1 expression, caveolin-2 forms low molecular mass oligomers that are retained at the level of the Golgi complex. Interestingly, we also show that expression of caveolin-1 in K562 cells dramatically up-regulates the expression of endogenous caveolin-2. Northern blot analysis reveals that caveolin-2 mRNA levels remain constant under these conditions, suggesting that the expression of caveolin-1 stabilizes the caveolin-2 protein. Conversely, transient expression of caveolin-2 in CHO cells is sufficient to up-regulate endogenous caveolin-1 expression. Thus, the formation of a hetero-oligomeric complex between caveolins-1 and -2 stabilizes the caveolin-2 protein product and allows caveolin-2 to be transported from the Golgi complex to the plasma membrane.
Footnotes
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↵* This work was supported by an NCI, National Institutes of Health Grant R01-CA-80250 (to M. P. L.) and by grants from the Charles E. Culpeper Foundation (to M. P. L.), the G. Harold and Leila Y. Mathers Charitable Foundation (to M. P. L. and P. E. S.), and the Sidney Kimmel Foundation for Cancer Research (to M. P. L.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵FNd Supported by National Institutes of Health Medical Scientist Training Program Grant T32-GM07288.
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↵FNf Supported by National Institutes of Health FIRST Award MH-56036 (to T. O.).
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↵FNh Supported by a grant from Pfizer Corp., a pilot grant from the AECOM DRTC, and by a research grant from the American Diabetes Association.
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↵FNj Supported by National Institutes of Health Grant GM-34107 and a Jules and Doris Stein Professorship from the Research to Prevent Blindness Foundation.
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↵FNl To whom correspondence should be addressed. Tel.: 718-430-8828; Fax: 718-430-8830; E-mail: lisanti@aecom.yu.edu.
- Abbreviations:
- Cav
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caveolin
- FACS
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fluorescence-activated cell sorter
- GFP
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green fluorescent protein
- mAb
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monoclonal antibody
- PAGE
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polyacrylamide gel electrophoresis
- PBS
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phosphate-buffered saline
- CHO
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Chinese hamster ovary
- Mes
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4-morpholinoethanesulfonic acid
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- Received April 1, 1999.
- Revision received May 25, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
