Enhancer Binding Proteins Activate Fat Storage Cells

Researchers studying the way the body stores fat have found that primitive fat cells must undergo cell division at least twice before they can mature into full-fledged fat-storing cells. This finding, which may lead to new ways to treat obesity, was reported January 13, 2003, in the online edition of the Proceedings of the National Academy of Sciences.

In mammalian cells, certain transcription factors increase gene transcription by binding to specific DNA sequences known as enhancer sequences. These transcription factors are termed "enhancer binding proteins” (EBPs). The ability of an enhancer to mediate gene expression is dependent upon the expression of an appropriate EBP in the cell. CCAAT/enhancer binding protein (C/EBP) comprises a class of EBPs whose members are capable of preferentially recognizing and binding a specific sequence motif, or the enhancer regions of several viral promoters. CCAAT/enhancer binding proteins are a family of leucine zipper, transcription factors that bind to DNA as homodimers and heterodimers. They regulate cellular proliferation, differentiation, and apoptosis.

Investigators from Johns Hopkins School of Medicine (Baltimore, MD, USA; www.jhu.edu) working with immature fat cells in tissue culture found that at least two cell divisions were required before C/EBP became established and the primitive fat cells matured into adipocyte cells capable of storing fat.

"Fortunately or unfortunately, depending on how you look at it, food is not scarce in many parts of the world, and storing the excess calories can lead to obesity and many serious associated health problems,” explained senior author Dr. Daniel Lane, professor of biologic chemistry at Johns Hopkins University's Institute for Basic Biomedical Sciences. "Our finding may lead to new ways to tackle obesity, since we now know a crucial step in the body's ability to store additional fat, but that step would have to be targeted specifically.”



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