Medical research

A new way of finding compounds that prevent aging

Researchers at Karolinska Institutet in Sweden have developed a new method for identifying compounds that prevent aging. The method is based on a new way of determining age in cultured human cells and is reported in a study ...

Oncology & Cancer

A single therapy slows multiple cancers

Targeting a single protein can help fight both breast cancers and leukemias, according to two reports published online on January 23 in the Journal of Experimental Medicine.

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Hsp90 (heat shock protein 90) is a molecular chaperone and is one of the most abundant proteins expressed in cells. It is a member of the heat shock protein family, which is upregulated in response to stress. Hsp90 is found in bacteria and all branches of eukarya, but it is apparently absent in archaea. Whereas cytoplasmic Hsp90 is essential for viability under all conditions in eukaryotes, the bacterial homologue HtpG is dispensable under non-heat stress conditions.

Heat shock proteins, as a class, are among the most highly expressed cellular proteins across all species. As their name implies, heat shock proteins protect cells when stressed by elevated temperatures. They account for 1–2% of total protein in unstressed cells. However, when cells are heated, the fraction of heat shock proteins increases to 4–6% of cellular proteins.

Heat shock protein 90 (Hsp90) is one of the most common of the heat-related proteins. The protein is named "HSP" for obvious reasons, and the "90" comes from the fact that it weighs roughly 90 kiloDaltons. A 90 kDa protein is considered fairly large for a non-fibrous protein.

The function of Hsp90 includes assisting in protein folding, cell signaling, and tumor repression. This protein was first isolated by extracting proteins from stressed cells. These cells were stressed by heating, dehydrating or by other means, all of which caused the cell’s proteins to begin to denature. As discussed in more detail below, researchers later realized that Hsp90 has other essential functions in unstressed cells.

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