Cellular spelunking

The surface of fat cells contains many small pockets called caveolae (because they look like caves in an electron microscope).

Although their role is not clear, Paul F. Pilch and colleagues review in the October issue of the Journal of Lipid Research current knowledge about caveolae and conclude that one of their major functions is to regulate the movement and production of fats in fat cells. Caveolae may also help the hormone insulin bind to fat cells, but this is controversial.

Insulin binds to protein receptors on the surface of a fat cell, which activates proteins inside the cell that help lower the amount of sugar in the blood and store fats. Some scientists have shown that insulin receptors attach to caveolae, hinting at a possible role of caveolae in insulin function, but other scientists have disputed this finding. Also, scientists have suggested that caveolae can be absorbed inside the cell, forming spherical vesicles that may carry fats for storage in the cell.

Caveolae may also be involved in regulating the amount of fatty acids – the molecules resulting from the breakdown of fats – present in fat cells. When too many fatty acids are produced inside the cell, the caveolae act as small gates that modulate the release of excess fatty acids outside the cell. Conversely, the caveolae may also help produce fats and later store them in structures called lipid droplets, which are fat storage areas inside fat cells.

Paul F. Pilch and colleagues conclude that although previous and recent studies have revealed that caveolae play key roles in the regulation of fats, more research is needed to understand how they work as well as their molecular composition.

Article: “Cellular Spelunking: Exploring Adipocyte Caveolae,” by Paul F. Pilch, Ricardo P. Souto, Libin Liu, Mark P. Jedrychowski, Eric A. Berg, Catherine E. Costello, and Steven P. Gygi
(http://www.jlr.org/cgi/content/abstract/48/10/2103)

This article is the fifth in a series of reviews on “adipocyte biology” or the biology of fat tissue. The other articles in the series will appear in future issues of the journal. All thematic review articles and can be accessed at: http://www.jlr.org (under “Thematic Reviews”).

The American Society for Biochemistry and Molecular Biology is a nonprofit scientific and educational organization with over 11,900 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions and industry. The Society's student members attend undergraduate or graduate institutions.

Founded in 1906, the Society is based in Bethesda, Maryland, on the campus of the Federation of American Societies for Experimental Biology. The Society's purpose is to advance the science of biochemistry and molecular biology through publication of the Journal of Biological Chemistry, the Journal of Lipid Research, and Molecular and Cellular Proteomics, organization of scientific meetings, advocacy for funding of basic research and education, support of science education at all levels, and promoting the diversity of individuals entering the scientific work force.