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Involvement of the mitogen‐activated protein kinase SIMK in regulation of root hair tip growth
Author(s) -
Šamaj Jozef,
Ovecka Miroslav,
Hlavacka Andrej,
Lecourieux Fatma,
Meskiene Irute,
Lichtscheidl Irene,
Lenart Peter,
Salaj Ján,
Volkmann Dieter,
Bögre László,
Baluška František,
Hirt Heribert
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf349
Subject(s) - root hair , biology , microbiology and biotechnology , kinase , actin cytoskeleton , actin , protein kinase a , cytoplasm , cytoskeleton , mapk/erk pathway , biochemistry , cell , gene
Mitogen‐activated protein kinases (MAPKs) are involved in stress signaling to the actin cytoskeleton in yeast and animals. We have analyzed the function of the stress‐activated alfalfa MAP kinase SIMK in root hairs. In epidermal cells, SIMK is predominantly nuclear. During root hair formation, SIMK was activated and redistributed from the nucleus into growing tips of root hairs possessing dense F‐actin meshworks. Actin depolymerization by latrunculin B resulted in SIMK relocation to the nucleus. Conversely, upon actin stabilization with jasplakinolide, SIMK co‐localized with thick actin cables in the cytoplasm. Importantly, latrunculin B and jasplakinolide were both found to activate SIMK in a root‐derived cell culture. Loss of tip‐focused SIMK and actin was induced by the MAPK kinase inhibitor UO 126 and resulted in aberrant root hairs. UO 126 inhibited targeted vesicle trafficking and polarized growth of root hairs. In contrast, overexpression of gain‐of‐function SIMK induced rapid tip growth of root hairs and could bypass growth inhibition by UO 126. These data indicate that SIMK plays a crucial role in root hair tip growth.