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Brassinosteroid nuclear signaling recruits HSP 90 activity
Author(s) -
Samakovli Despina,
Margaritopoulou Theoni,
Prassinos Constantinos,
Milioni Dimitra,
Hatzopoulos Polydefkis
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12843
Subject(s) - hsp90 , geldanamycin , brassinosteroid , microbiology and biotechnology , cytoplasm , biology , arabidopsis , heat shock protein , hsp90 inhibitor , signal transduction , brassinolide , nuclear transport , genetics , gene , cell nucleus , botany , mutant , plant growth
Summary Heat shock protein 90 ( HSP 90) controls a number of developmental circuits, and serves a sophisticated and highly regulatory function in signaling pathways. Brassinosteroids ( BR s) control many aspects of plant development. Genetic, physiological, cytological, gene expression, live cell imaging, and pharmacological approaches provide conclusive evidence for HSP 90 involvement in A rabidopsis thaliana BR signaling. Nuclear‐localized HSP 90s translocate to cytoplasm when their activity is blocked by the HSP 90 inhibitor geldanamycin ( GDA ). GDA treatment promoted the export of BIN 2, a regulator of BR signaling, from the nucleus into the cytoplasm, indicating that active HSP 90 is required to sustain BIN 2 in the nucleus. HSP 90 nuclear localization was inhibited by brassinolide ( BL ). HSP 90s interact with BIN 2 in the nucleus of untreated cells and in the cytoplasm of BL ‐treated cells, showing that the site‐specific action of HSP 90 on BIN 2 is controlled by BR s. GDA and BL treatments change the expression of a common set of previously identified BR ‐responsive genes. This highlights the effect of active HSP 90s on the regulation of BR ‐responsive genes. Our observations reveal that HSP 90s have a central role in sustaining BIN 2 nuclear function. We propose that BR signaling is mediated by HSP 90 activity and via trafficking of BIN 2– HSP 90 complexes into the cytoplasm.

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