Cell Biology

Hidden Change

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Science  12 Dec 2008:
Vol. 322, Issue 5908, pp. 1611
DOI: 10.1126/science.322.5908.1611c

Biological systems are buffered against variation by proteins termed phenotypic capacitors, of which heat shock protein 90 (Hsp90) is the founding member. This protein chaperone reveals diverse phenotypic variation when its level falls, exposing previously silenced genotypes. Given that species advancement requires genetic diversity and phenotypic change, phenotypic capacitors have been suggested to support evolution; the reduction of Hsp90, which occurs under stressful conditions, would release phenotypes that can be acted on by natural selection to drive evolution. Whether other cellular proteins harbor capacitor function is unclear. Levy and Siegel used high-throughput morphological phenotyping and found that more than 5% of yeast genes act as capacitors by buffering environmental variation and suppressing phenotypic diversity. These capacitors were found to control cellular processes, such as cell cycle regulation and stress responses. Beyond a role in natural selection, phenotypic capacitors may also support the evolution of cancer cells, which are notoriously resilient to many environmental stresses and exhibit widespread genetic instability. Hsp90 is thought to buffer these tumorigenic properties and promote survival, and Hsp90 inhibitors may have potential as cancer chemotherapeutics. — HP*

PLoS Biol. 6, e264 (2008).

  • * Helen Pickersgill is a locum editor in Science's editorial department.

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