אסיף מאגר המחקר החקלאי

Ectopic expression of an activated RAC in Arabidopsis disrupts membrane cycling

Year:

2005

Source of publication :

Authors :

Volume :

16

Co-Authors:

Bloch, D., Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Lavy, M., Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Efrat, Y., Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Efroni, I., Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Bracha-Drori, K., Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Abu-Abied, M., Dept. of Ornamental Horticulture, Volcani Center, Bet Dagan 50250, Israel
Sadot, E., Dept. of Ornamental Horticulture, Volcani Center, Bet Dagan 50250, Israel
Yalovsky, S., Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel

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Abstract:

Rho GTPases regulate the actin cytoskeleton, exocytosis, endocytosis, and other signaling cascades. Rhos are subdivided into four subfamilies designated Rho, Racs, Cdc42, and a plant-specific group designated RACs/Rops. This research demonstrates that ectopic expression of a constitutive active Arabidopsis RAC, AtRAC10, disrupts actin cytoskeleton organization and membrane cycling. We created transgenic plants expressing either wild-type or constitutive active AtRAC10 fused to the green fluorescent protein. The activated AtRAC10 induced deformation of root hairs and leaf epidermal cells and was primarily localized in Triton X-100-insoluble fractions of the plasma membrane. Actin cytoskeleton reorganization was revealed by creating double transgenic plants expressing activated AtRAC10 and the actin marker YFP-Talin. Plants were further analyzed by membrane staining with N-[3-triethylammoniumpropyl]-4-[p- diethylaminophenylhexatrienyl] pyridinium dibromide (FM4-64) under different treatments, including the protein trafficking inhibitor brefeldin A or the actin-depolymeryzing agents latrunculin-B (Lat-B) and cytochalasin-D (CD). After drug treatments, activated AtRAC10 did not accumulate in brefeldin A compartments, but rather reduced their number and colocalized with FM4-64-labeled membranes in large intracellular vesicles. Furthermore, endocytosis was compromised in root hairs of activated AtRAC10 transgenic plants. FM4-64 was endocytosed in nontransgenic root hairs treated with the actin-stabilizing drug jasplakinolide. These findings suggest complex regulation of membrane cycling by plant RACs. © 2005 by The American Society for Cell Biology.

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