関: caveola、caveolar、foveolar、lacunar

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/05/26 01:02:14」(JST)

wiki en

In biology, caveolae (Latin for "little caves"; singular, caveola), which are a special type of lipid raft, are small (50–100 nanometer) invaginations of the plasma membrane in many vertebrate cell types, especially in endothelial cells and adipocytes.

These flask-shaped structures are rich in proteins as well as lipids such as cholesterol and sphingolipids and have several functions in signal transduction.^[1] They are also believed to play a role in endocytosis, oncogenesis, and the uptake of pathogenic bacteria and certain viruses.^[2]^[3]^[4]

Caveolins

Formation and maintenance of caveolae is primarily due to the protein caveolin,^[5] a 21 kD protein. There are three homologous genes of caveolin expressed in mammalian cells: Cav1, Cav2 and Cav3. These proteins have a common topology: cytoplasmic N-terminus with scaffolding domain, long hairpin transmembrane domain and cytoplasmic C-terminus. Caveolins are synthesized as monomers and transported to the Golgi apparatus. During their subsequent transport through the secretory pathway, caveolins associate with lipid rafts and form oligomers (14-16 molecules). These oligomerized caveolins form the caveolae. The presence of caveolin leads to a local change in morphology of the membrane. ^[6]

Caveolar endocytosis

Caveolae are one source of clathrin-independent raft-dependent endocytosis. The ability of caveolins to oligomerize due to their oligomerization domains is necessary for formation of caveolar endocytic vesicles. The oligomerization leads to formation of caveolin-rich microdomains in the plasma membrane. Increased levels of cholesterol and insertion of scaffolding domain of caveolins to the plasma membrane then lead to expansion of the caveolar invagination and to formation of endocytic vesicle. Fission of the vesicle from the plasma membrane is then mediated by GTPase dynamin II which is localized at the neck of the budding vesicle. The released caveolar vesicle can fuse with early endosome or caveosome. The caveosome is an endosomal compartment with neutral pH which does not have early endosomal markers, however, contains molecules internalized by the caveolar endocytosis. ^[6] ^[7]

This type of endocytosis is used for example for transcytosis of albumin in endothelial cells or for internalization of the insulin receptor in primary adipocytes. ^[6]

Other roles of caveolae

Caveolae can be used for entry to the cell by some pathogens and so they avoid degradation in lysosomes. However, some bacteria do not use typical caveolae but only caveolin-rich areas of the plasma membrane. The pathogens exploiting this endocytic pathway include viruses such as SV40 and polyoma virus and bacteria such as some strains of Escherichia coli, Pseudomonas aeruginosa and Porphyromonas gingivalis. ^[7]
Caveolae have a role in the cell signaling, too. Caveolins associate with some signaling molecules (e.g. eNOS) through their scaffolding domain and so they can regulate their signaling. Caveolae are also involved in regulation of channels and in calcium signaling. ^[7]
Caveolae also participate in lipid regulation. High levels of caveolin Cav1 are expressed in adipocytes. Caveolin associates with cholesterol, fatty acids and lipid droplets and is involved in its regulation. ^[7]
Caveolae can also serve as mechanosensors in various cell types. In endothelial cells, caveolae are involved in flow sensation. Chronic exposure to the flow stimulus leads to increased levels of caveolin Cav1 in plasma membrane, its phosphorylation, activation of eNOS signaling enzyme and to remodeling of blood vessels. In smooth-muscle cells, caveolin Cav1 has a role in stretch sensing which triggers cell-cycle progression. ^[7]

Inhibitors

Some known inhibitors of the caveolae pathway are Filipin III, Genistein and Nystatin. ^[6]

References

^ Anderson RG (1998). "The caveolae membrane system". Annu. Rev. Biochem. 67: 199–225. doi:10.1146/annurev.biochem.67.1.199. PMID 9759488.
^ Frank P, Lisanti M (2004). "Caveolin-1 and caveolae in atherosclerosis: differential roles in fatty streak formation and neointimal hyperplasia". Current Opinion in Lipidology 15 (5): 523–9. doi:10.1097/00041433-200410000-00005. PMID 15361787.
^ Li X, Everson W, Smart E (2005). "Caveolae, lipid rafts, and vascular disease". Trends Cardiovasc Med 15 (3): 92–6. doi:10.1016/j.tcm.2005.04.001. PMID 16039968.
^ Pelkmans L (2005). "Secrets of caveolae- and lipid raft-mediated endocytosis revealed by mammalian viruses". Biochim Biophys Acta 1746 (3): 295–304. doi:10.1016/j.bbamcr.2005.06.009. PMID 16126288.
^ Caveolae at the US National Library of Medicine Medical Subject Headings (MeSH)
^ ^a ^b ^c ^d Lajoie, P. and I.R. Nabi, Lipid rafts, caveolae, and their endocytosis. Int Rev Cell Mol Biol, 2010. 282: p. 135-63.
^ ^a ^b ^c ^d ^e Parton, R.G. and K. Simons, The multiple faces of caveolae. Nature Reviews Molecular Cell Biology, 2007. 8(3): p. 185-94.

External links

Histology image: 21402loa – Histology Learning System at Boston University

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

1. JCおよびBKウイルス感染の疫学 epidemiology of jc and bk virus infection
2. 脂肪異栄養症症候群 lipodystrophic syndromes
3. プリオンの生物学および遺伝学 biology and genetics of prions
4. 魚油と海洋由来オメガ3脂肪酸 fish oil and marine omega 3 fatty acids
5. 肢帯型筋ジストロフィー limb girdle muscular dystrophy

English Journal

Caveolin-1 overexpression is associated with simultaneous abnormal expression of the E-cadherin/α-β catenins complex and multiple erbb receptors and with lymph nodes metastasis in head and neck squamous cell carcinomas.

Masuelli L, Budillon A, Marzocchella L, Mrozek MA, Vitolo D, Di Gennaro E, Losito S, Sale P, Longo F, Ionna F, Lista F, Muraro R, Modesti A, Bei R.SourceDepartment of Experimental Medicine, University "Sapienza," Rome, Italy.
Journal of cellular physiology.J Cell Physiol.2012 Sep;227(9):3344-53. doi: 10.1002/jcp.24034.
The presence of lymph node metastases is one of the most important prognostic indicators in head and neck squamous cell carcinomas (HNSCCs). An alteration of the E-cadherin-catenins complex and EGFR is essential for the invasiveness of cancer cells. Caveolin-1, the major structural protein of the ca
PMID 22213373

Fibronectin attachment protein from bacillus Calmette-Guerin as targeting agent for bladder tumor cells.

Coon BG, Crist S, González-Bonet AM, Kim HK, Sowa J, Thompson DH, Ratliff TL, Aguilar RC.SourceDepartment of Biological Sciences, Purdue University, West Lafayette, IN; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN.
International journal of cancer. Journal international du cancer.Int J Cancer.2012 Aug 1;131(3):591-600. doi: 10.1002/ijc.26413. Epub 2011 Oct 20.
The adjuvant therapy of choice for superficial bladder cancer is the intravesical instillation of live Mycobacterium bovis bacillus Calmette-Guerin (BCG). Despite the fact that this therapy is the most effective treatment for superficial bladder cancer, intravesical administration of BCG is associat
PMID 21901746

Japanese Journal

Dual-ligand modification of PEGylated liposomes shows better cell selectivity and efficient gene delivery

Kibria Golam,Hatakeyama Hiroto,Ohga Noritaka,Hida Kyoko,Harashima Hideyoshi
Journal of Controlled Release 153(2), 141-148, 2011-07-30
… RGD-PEG-LP and R8/RGD-PEG-LP were preferentially taken up by caveolae-mediated and clathrin-mediated endocytosis pathways, respectively. …
NAID 120003660586

肺胞上皮細胞におけるタンパク質・ペプチドの輸送とその制御

高野幹久,湯元良子
膜 36(4), 145-153, 2011-07-01
… Functional and siRNA studies suggest that albumin is taken up by clathrin-mediated endocytosis in type II cells, while clathrin- and caveolae-independent but dynamin-dependent pathway is involved in insulin endocytosis. …
NAID 10029602000