The plasma membrane recycling pathway and cell polarity in plants: studies on PIN proteins

Abstract

Results AtPIN labelled PIN proteins in root cellsWestern blot analysis The purified AtPIN antiserum labelled one major band of approximately 68-70 kDa (Fig. 1), on western blots of wholeThe PIN-FORMED (PIN) proteins are plasma-membraneassociated facilitators of auxin transport. They are often targeted to one side of the cell only through subcellular mechanisms that remain largely unknown. Here, we have studied the potential roles of the cytoskeleton and endomembrane system in the localisation of PIN proteins. Immunocytochemistry and image analysis on root cells from Arabidopsis thaliana and maize showed that 10-30% of the intracellular PIN proteins mapped to the Golgi network, but never to prevacuolar compartments. The remaining 70-90% were associated with yet to be identified structures. The maintenance of PIN proteins at the plasma membrane depends on a BFA-sensitive machinery, but not on microtubules and actin filaments.The polar localisation of PIN proteins at the plasmamembrane was not reflected by any asymmetric distribution of cytoplasmic organelles. In addition, PIN proteins were inserted in a symmetrical manner at both sides of the cell plate during cytokinesis. Together, the data indicate that the localisation of PIN proteins is a postmitotic event, which depends on local characteristics of the plasma membrane and its direct environment. In this context, we present evidence that microtubule arrays might define essential positional information for PIN localisation. This information seems to require the presence of an intact cell wall.

ZmPIN1-Mediated Auxin Transport Is Related to Cellular Differentiation during Maize Embryogenesis and Endosperm Development

“…3) using an anti-AtPIN1 monoclonal antibody (Boutte et al, 2006). This antibody was previously tested in maize and was shown to specifically recognize all the different ZmPIN1 polypeptides ; data not shown).…”

“…Material was previously fixed in 4% paraformaldehyde in 13 phosphate-buffered saline (PBS) for 16 h at 4°C. Embedded kernels were cut with a Leica RM2135 microtome and stained overnight with the anti-AtPIN1 antibody (Boutte et al, 2006) at a 1:200 dilution in 13 PBS and 1% bovine serum albumin. Subsequently, the sections were washed twice for 10 min in 13 PBS and stained for 1 h with the secondary antibody (anti-rabbit IgG conjugated with Alexa568; Molecular Probes) diluted 1:400 in 13 PBS.…”

Rice actin-binding protein RMD is a key link in the auxin–actin regulatory loop that controls cell growth

“…S9 A and B), suggesting that RMD may regulate OsPIN protein trafficking. Because the cytoskeleton modulates protein trafficking by modifying endocytosis and exocytosis (3,4,20,(28)(29)(30), to reveal whether the OsARF23/24-RMD pathway controls endocytosis, we examined root cells using FM4-64, a tracer for endocytosis and vesicle trafficking (20,21,30). Treatment with FM4-64 for 30 min resulted in more labeled endocytic vesicles in rmd-1, osarf23, and OsARF23/24 DRi plants than WT (Fig.…”

COP1 mediates the coordination of root and shoot growth by light through modulation of PIN1- and PIN2-dependent auxin transport in Arabidopsis

“…A role for COP1 in the regulation of root growth by light, through affecting the organization of the actin cytoskeleton (Dyachok et al, 2011), has also been demonstrated. Actin is known to be essential for the intracellular trafficking of PIN proteins (Geldner et al, 2001;Boutté et al, 2006) and COP1 could affect PIN1 and PIN2 intracellular localization by modulating the activity of the actin cytoskeleton. Elucidating the mode of action of COP1 will need further experiments but our findings suggest an elegant model that explains how light regulates shoot-to-root PAT and auxin distribution over the entire plant to coordinate root and shoot development in response to light in a COP1-dependent manner (supplementary material Fig.…”