Cell Biology

New Actions for Actin

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Science  20 May 2011:
Vol. 332, Issue 6032, pp. 897
DOI: 10.1126/science.332.6032.897-a

Actin is a major component of the cytoskeleton and regulates fundamental cellular processes such as cell motility, cell division, and organelle movement. Actin is also present in the nucleus, participating in transcription, chromatin remodeling, and nuclear export, although additional roles for nuclear actin are still being defined. In a search for factors that regulate cellular reprogramming of differentiated cells into pluripotent cells, Miyamoto et al. identified nuclear actin as a candidate cell reprogramming factor. When somatic nuclei were transplanted into amphibian oocytes, filamentous actin localized to the nuclear envelope. One day after nuclear transfer, filamentous actin was detected in the transplanted nucleus. Polymerized nuclear actin was required for the transcriptional reactivation of Oct4, which is critical for cellular reprogramming. The actin signaling protein Toca-1 enhanced polymerization of actin and stimulated Oct4 reactivation. Actin bound to RNA polymerase and the chromatin complex BAF, suggesting that it may regulate gene expression by promoting transcription and chromatin remodeling.

Genes Dev. 25, 946 (2011).

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