Caveolin

Caveolin
Identifiers
Symbol Caveolin
Pfam PF01146
InterPro IPR001612
PROSITE PDOC00930
Caveolin 1, caveolae protein, 22kDa
Identifiers
Symbol CAV1
Alt. symbols CAV
Entrez 857
HUGO 1527
OMIM 601047
RefSeq NM_001753
UniProt Q03135
Other data
Locus Chr. 7 q31
Caveolin 2
Identifiers
Symbol CAV2
Entrez 858
HUGO 1528
OMIM 601048
RefSeq NM_001233
UniProt P51636
Other data
Locus Chr. 7 q31
Caveolin 3
Identifiers
Symbol CAV3
Entrez 859
HUGO 1529
OMIM 601253
RefSeq NM_001234
UniProt P56539
Other data
Locus Chr. 3 p25

In molecular biology Caveolins are a family of integral membrane proteins that are the principal components of caveolae membranes and involved in receptor-independent endocytosis.[1][2][3] Caveolins may act as scaffolding proteins within caveolar membranes by compartmentalizing and concentrating signaling molecules. Various classes of signaling molecules, including G-protein subunits, receptor and non-receptor tyrosine kinases, endothelial nitric oxide synthase (eNOS), and small GTPases, bind Cav-1 through its 'caveolin-scaffolding domain'.

The caveolin gene family has three members in vertebrates: CAV1, CAV2, and CAV3, coding for the proteins caveolin-1, caveolin-2, and caveolin-3, respectively. All three members are membrane proteins with similar structure. Caveolin forms oligomers and associates with cholesterol and sphingolipids in certain areas of the cell membrane, leading to the formation of caveolae.

Structure and expression

The caveolins are similar in structure. They all form hairpin loops that are inserted into the cell membrane. Both the C-terminus and the N-terminus face the cytoplasmic side of the membrane. There are two isoforms of caveolin-1: caveolin-1α and caveolin-1β, the latter lacking a part of the N-terminus.

Caveolins are found in the majority of adherent, mammalian cells.

Function

The functions of caveolins are still under intensive investigation. They are best known for their role in the formation of 50-nanometer-size invaginations of the plasma membrane, called caveolae. Oligomers of caveolin form the coat of these domains. Cells that lack caveolins also lack caveolae. Many functions are ascribed to these domains, ranging from endocytosis and transcytosis to signal transduction.

Caveolin-1 has also been shown to play a role in the integrin signaling. The tyrosine phosphorylated form of caveolin-1 colocalizes with focal adhesions, suggesting a role for caveolin-1 in migration. Indeed, downregulation of caveolin-1 leads to less efficient migration in vitro.

Genetically engineered mice that lack caveolin-1 and caveolin-2 are viable and fertile, showing that neither the caveolins nor the caveolae are essential in embryonic development or reproduction of these animals. However, knock-out animals do develop abnormal, hypertrophic lungs, and cardiac myopathy, leading to a reduction in lifespan. Mice lacking caveolins also suffer from impaired angiogenic responses as well as abnormal responses to vasoconstrictive stimuli. In zebrafish, lack of caveolins leads to embryonic lethality, suggesting that higher vertebrates (as exemplified by mice) have developed compensation or redundancy for the functions of caveolins.

Role in disease

Cancer

Caveolins have a paradoxical role in the development of this disease. They have been implicated in both tumor suppression and oncogenesis.[4] High expression of caveolins leads to inhibition of cancer-related pathways, such as growth factor signaling pathways. However, certain cancer cells that express caveolins have been shown to be more aggressive and metastatic, because of a potential for anchorage-independent growth.

Cardiovascular diseases

Caveolins are thought to play an important role during the development of atherosclerosis.[5] Furthermore, caveolin-3 has been associated with Long QT syndrome.[6]

Muscular dystrophy

Caveolin-3 has been implicated in the development of certain types of muscular dystrophy (Limb-girdle muscular dystrophy).[7]

References

  1. ↑ Tang Z, Scherer PE, Okamoto T, Song K, Chu C, Kohtz DS, Nishimoto I, Lodish HF, Lisanti MP (January 1996). "Molecular cloning of caveolin-3, a novel member of the caveolin gene family expressed predominantly in muscle". J. Biol. Chem. 271 (4): 2255–61. doi:10.1074/jbc.271.4.2255. PMID 8567687.
  2. ↑ Scherer PE, Okamoto T, Chun M, Nishimoto I, Lodish HF, Lisanti MP (January 1996). "Identification, sequence, and expression of caveolin-2 defines a caveolin gene family". Proc. Natl. Acad. Sci. U.S.A. 93 (1): 131–5. doi:10.1073/pnas.93.1.131. PMC 40192Freely accessible. PMID 8552590.
  3. ↑ Williams TM, Lisanti MP (2004). "The caveolin proteins". Genome Biol. 5 (3): 214. doi:10.1186/gb-2004-5-3-214. PMC 395759Freely accessible. PMID 15003112.
  4. ↑ Shatz M, Liscovitch M (March 2008). "Caveolin-1: a tumor-promoting role in human cancer". Int. J. Radiat. Biol. 84 (3): 177–89. doi:10.1080/09553000701745293. PMID 18300018.
  5. ↑ Williams TM, Lisanti MP (2004). "The Caveolin genes: from cell biology to medicine". Ann. Med. 36 (8): 584–95. doi:10.1080/07853890410018899. PMID 15768830.
  6. ↑ Vatta M, Ackerman MJ, Ye B, Makielski JC, Ughanze EE, Taylor EW, Tester DJ, Balijepalli RC, Foell JD, Li Z, Kamp TJ, Towbin JA (November 2006). "Mutant caveolin-3 induces persistent late sodium current and is associated with long-QT syndrome". Circulation. 114 (20): 2104–12. doi:10.1161/CIRCULATIONAHA.106.635268. PMID 17060380.
  7. ↑ Galbiati F, Razani B, Lisanti MP (October 2001). "Caveolae and caveolin-3 in muscular dystrophy". Trends Mol Med. 7 (10): 435–41. doi:10.1016/S1471-4914(01)02105-0. PMID 11597517.

External links

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