Dynamic Behavior of the trans-Golgi Network in Root Tissues of Arabidopsis Revealed by Super-Resolution Live Imaging

Abstract

The trans-Golgi network (TGN) is an important organelle for protein transport at the post-Golgi network, which functions as a sorting station that directs cargo proteins to a variety of destinations including post-Golgi compartments and the extracellular space. However, the functions and dynamics of the TGN in plant cells have not been well understood yet. To elucidate the dynamics of the plant TGN, we established transgenic plants expressing green fluorescent protein (GFP)-SYP43, the ortholog of Tlg2/syntaxin16, which is localized to the TGN in yeast and mammalian cells, under the control of the native promoter as a TGN marker. Observation by confocal laser scanning microscopy and super-resolution confocal live imaging microscopy revealed two types of TGN in Arabidopsis root: the GA-TGNs (Golgi-associated TGNs), located on the trans-side of the Golgi apparatus, and the GI-TGNs (Golgi-released independent TGNs), located away from the Golgi apparatus and behaving independently. The GI-TGNs is derived from a population of GA-TGNs by segregation, although the core of the GA-TGN remains even after the generation of the GI-TGN. We further found that the abundance of the GI-TGNs differs between observed tissues. Our results indicate that the dynamic features of the TGN in plant cells differ from those of animal and yeast cells.

Basolateral sorting and transcytosis define the Cu+-regulated translocation of ATP7B to the bile canaliculus

“…The Cu + -induced release of ATP7B from the TGN was found to be a rapid process that begins within 5 min of the addition of 40 µM Cu + and is completed within 20-25 min. Treatment with bafilomycin A1 delayed the detachment of the cisterna carrying ATP7B from the TGN, demonstrating that cisterna detachment is a prerequisite to the generation of transport vesicles, as has previously been described in plants (Uemura et al, 2014). This process is pH dependent, and the rapidity of this occurrence in mammalian cells is probably why it has not been previously observed in organisms other than plants.…”

Danger-associated peptide signaling in Arabidopsis requires clathrin

“…To better understand the endocytic route of PEPR with its ligand, we incubated various fluorescencetagged endomembrane markers with TAMRA-pep1 and assessed their colocalization after a 40-min chase by counting as positive only the vesicles with colocalization values >0.5 calculated by Pearson's correlation coefficient. TAMRA-pep1 colocalized only partially (18-37%) with all tested TGN markers, including VHA-a1, SYP61, SYP42, clathrin, and YFP-RabA1e (13)(14)(15)(16)(17) (Fig. S7A).…”

The Plant Trans-Golgi Network: Not Just a Matter of Distinction

“…Superresolution live imaging of the TGN-localized soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein SYP43 was used recently to characterize the dynamic behavior of the GA-TGN and Golgi-independent TGN (GI-TGN) populations (Uemura et al, 2014), corroborating the Golgi cisternal maturation model (Kang et al, 2011). The GA-TGNs localized on the trans-side of the Golgi apparatus, while the GI-TGNs (Golgi-released independent TGNs) were located away from the Golgi apparatus and behaved independently (Uemura et al, 2014).…”

“…The GA-TGNs localized on the trans-side of the Golgi apparatus, while the GI-TGNs (Golgi-released independent TGNs) were located away from the Golgi apparatus and behaved independently (Uemura et al, 2014). The authors proposed that segregation of GA-TGNs gives rise to the GI-TGNs with a core of the GA-TGN remaining after the process.…”