Cell Biology

Splicing Limits the Damage

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Science  13 May 2011:
Vol. 332, Issue 6031, pp. 769
DOI: 10.1126/science.332.6031.769-a
CREDIT (TOP TO BOTTOM): DENG ET AL., PROC. NATL. ACAD. SCI. U.S.A. 108, 7247 (2011)

When plants encounter stresses such as extreme heat and drought, they induce signaling systems to minimize potential damage. Yeast and mammalian cells also engage similar signaling cascades in response to stress. In plant, yeast, and mammalian cells, stress-induced cellular damage is induced by the accumulation of unfolded proteins in the endoplasmic reticulum (ER), and this drives the expression of genes that promote proper protein folding or sequestration of misfolded proteins. Proteolytic processing and splicing of transcription factor mRNA are major mechanisms of generating transcription factors capable of inducing stress-related genes. In plants, two members of the bZIP family of transcription factors are activated by proteolytic processing, but bZIP60, although truncated in its active form, is not activated in this manner. Deng et al. now show that in response to stress, mRNA that encodes the transcription factor bZIP60 is spliced to exclude a transmembrane domain and to implement a putative nuclear targeting signal. After splicing and translation, the bZIP60 protein translocates to the nucleus (above; top row: unspliced bZIP60 (green) localized to the cytoplasm; bottom row: spliced bZIP60 localized to the nucleus), where it is able to activate downstream stress-response genes. These results show that stress-induced signaling mechanisms are highly conserved.

Proc. Natl. Acad. Sci. U.S.A. 108, 7247 (2011).

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