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Redistribution of actin, profilin and phosphatidylinositol-4,5-bisphosphate in growing and maturing root hairs

Redistribution of actin, profilin and phosphatidylinositol-4,5-bisphosphate in growing and... The continuously changing polar cytoplasmic organization during initiation and tip growth of root hairs is reflected by a dynamic redistribution of cytoskeletal elements. The small G-actin binding protein, profilin, which is known to be a widely expressed, potent regulator of actin dynamics, was specifically localized at the tip of root hairs and co-distributed with a diffusely fluorescing apical cap of actin, but not with subapical actin microfilament (MF) bundles. Profilin and actin caps were present exclusively in the bulge of outgrowing root hairs and at the apex of elongating root hairs; both disappeared when tip growth terminated, indicating a tip-growth mechanism that involves profilin-actin interactions for the delivery and localized exocytosis of secretory vesicles. Phosphatidylinositol-4,5-bisphosphate (PIP2), a ligand of profilin, was localized almost exclusively in the bulge and, subsequently, formed a weak tip-to-base gradient in the elongating root hairs. When tip growth was eliminated by the MF-disrupting inhibitor cytochalasin D, the apical profilin and the actin fluorescence were lost. Mastoparan, which is known to affect the PIP2 cycle, probably by stimulating phospholipases, caused the formation of a meshwork of distinct actin MFs replacing the diffuse apical actin cap and, concomittantly, tip growth stopped. This suggests that mastoparan interferes with the PIP2-regulated profilin-actin interactions and hence disturbs conditions indispensable for the maintenance of tip growth in root hairs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Planta Springer Journals

Redistribution of actin, profilin and phosphatidylinositol-4,5-bisphosphate in growing and maturing root hairs

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References (47)

Publisher
Springer Journals
Copyright
Copyright © 1999 by Springer-Verlag Berlin Heidelberg
Subject
Life Sciences; Plant Sciences; Agriculture; Ecology; Forestry
ISSN
0032-0935
eISSN
1432-2048
DOI
10.1007/s004250050746
Publisher site
See Article on Publisher Site

Abstract

The continuously changing polar cytoplasmic organization during initiation and tip growth of root hairs is reflected by a dynamic redistribution of cytoskeletal elements. The small G-actin binding protein, profilin, which is known to be a widely expressed, potent regulator of actin dynamics, was specifically localized at the tip of root hairs and co-distributed with a diffusely fluorescing apical cap of actin, but not with subapical actin microfilament (MF) bundles. Profilin and actin caps were present exclusively in the bulge of outgrowing root hairs and at the apex of elongating root hairs; both disappeared when tip growth terminated, indicating a tip-growth mechanism that involves profilin-actin interactions for the delivery and localized exocytosis of secretory vesicles. Phosphatidylinositol-4,5-bisphosphate (PIP2), a ligand of profilin, was localized almost exclusively in the bulge and, subsequently, formed a weak tip-to-base gradient in the elongating root hairs. When tip growth was eliminated by the MF-disrupting inhibitor cytochalasin D, the apical profilin and the actin fluorescence were lost. Mastoparan, which is known to affect the PIP2 cycle, probably by stimulating phospholipases, caused the formation of a meshwork of distinct actin MFs replacing the diffuse apical actin cap and, concomittantly, tip growth stopped. This suggests that mastoparan interferes with the PIP2-regulated profilin-actin interactions and hence disturbs conditions indispensable for the maintenance of tip growth in root hairs.

Journal

Planta – Springer Journals

Published: Oct 21, 1999

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