Golgi apparatus plays pivotal roles in vesicle transport, and is also major biosynthetic factory for cell wall polysaccharides and protein glycosylation in plant. Distinct from animal cells, the trans-Golgi network (TGN) is an essential tubular-vesicular organelle derived from the Golgi and functions as an independent sorting and trafficking hub within the cell. At the same time, TGN also acts as early endosome, receiving the vesicles of endocytosis. However, the molecular regulation of TGN biogenesis remains enigmatic.
YANG Weicai's laboratory at Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, identified an Arabidopsis protein LOT (loss of TGN) that regulates TGN biogenesis.
In lot mutant, the researchers found that pollen tube growth is inhibited in style leading to sever sterility. In mutant pollen, the Golgi cisternae is over-stacked and the number of TGN and vesicles surrounding the Golgi are significantly reduced as manifested by the dispersed cytosolic distribution of TGN-markers.
In addition, research results show that LOT affects the deposition of cell wall materials, membrane-localized receptor-like kinase and phosphoinositide species. LOT is localized on the periphery of the Golgi cisternae, but the loss of LOT function does not affect localization of the Golgi-resident protein.
Rgp1, the homolog of LOT in yeast, acts as a component of guanine nucleotide exchange factor (GEF) complex of small Rab GTPase Ypt6. Indeed, LOT can complement Rgp1 function in yeast mutant.
This study identified a Golgi-localized protein that is essential for TGN biogenesis and sheds light on the regulation of vesicle trafficking.
The paper is published online in
PNAS on November 9 2018.
This research is supported by the National Natural Science Foundation of China.
Figure. LOT regulates the TGN formation and vesicle transport in plant cell. (Image by IGDB)
