Clathrin‐independent endocytosis contributes to uptake of glucose into BY‐2 protoplasts

Abstract

SUMMARYIn eukaryotic cells, several pathways exist for the internalization of plasma membrane proteins and extracellular cargo molecules. These endocytic pathways can be divided into clathrin-dependent and clathrin-independent pathways. While clathrin-dependent pathways are known to be involved in a variety of cellular processes in plants, clathrin-independent pathways have so far only been identified in animal and yeast cells. Here we show that internalization of fluorescent glucose into BY-2 cells leads to accumulation of the sugar in compartments of the endocytic pathway. This endocytic uptake of glucose was not blocked by ikarugamycin, an inhibitor of clathrin-dependent endocytosis, suggesting a role for clathrin-independent endocytosis in glucose uptake. Investigations of fusion and fission of single vesicles by membrane capacitance measurements revealed stimulation of endocytic activity by extracellular glucose. Glucose-stimulated fission of vesicles was not affected by addition of ikarugamycin or blocking of clathrin coat formation by transient over-expression of HUB1 (the C-terminal part of the clathrin heavy chain). These data demonstrate that clathrin-independent endocytosis does occur in plant cells. This pathway may represent a common mechanism for the uptake of external nutrients.

Rapid endocytosis is triggered upon imbibition in Arabidopsis seeds

“…Taking into account that the major endocytic mechanism in plants depends on the coat protein clathrin 2,43 and the fact that inhibitors known to affect clathrin-dependent endocytosis provoked a remarkable delay in the rate of seed germination, the early endocytosis reported here seems to be mediated, at least in part, by chlatrin-dependent endocytosis. However, nonclathrin endocytosis has recently been reported for the internalization of glucose into BY-2 protoplasts 44 and our earlier study reported on myosin VIII-dependent fluid phase endocytosis in root cells. 11 Therefore, further studies are needed on the further analysis of the nature of plant endocytosis supporting the plant embryo germination.…”

Populus euphratica APYRASE2 Enhances Cold Tolerance by Modulating Vesicular Trafficking and Extracellular ATP in Arabidopsis Plants

“…To determine whether NGXT191 could suppress PeAPY2 in vivo, PeAPY2-transgenic lines were subjected to 0, 1.5, 3, or 6 mg mL 21 for 1.5 h followed by FM4-64 staining. The uptake of FM4-64 was calculated as the ratio of intracellular fluorescence to whole-cell fluorescence (Bandmann and Homann, 2012), and values were standardized to the wild-type control treated without NGXT191 (Kitakura et al, 2011). Wild-type and transgenic plants were examined for differences in exocytosis with BFA.…”

Functional Analysis of the Hydrophilic Loop in Intracellular Trafficking of Arabidopsis PIN-FORMED Proteins

“…In plants, the mechanism and components for clathrin-dependent endocytosis have been relatively well studied (Chen et al, 2011) compared with clathrinindependent endocytosis. However, several recent studies have strongly indicated the existence of clathrin-independent pathways for endocytosis (Moscatelli et al, 2007;Onelli et al, 2008;Bandmann and Homann, 2012;Li et al, 2012). It is worth noting that the YXXФ motif does not guarantee that the protein undergoes endocytosis only by the clathrin-dependent process (Doré et al, 2001).…”