Enrichment of hydroxylated C24- and C26-acyl-chain sphingolipids mediates PIN2 apical sorting at trans-Golgi network subdomains

Abstract

The post-Golgi compartment trans-Golgi Network (TGN) is a central hub divided into multiple subdomains hosting distinct trafficking pathways, including polar delivery to apical membrane. Lipids such as sphingolipids and sterols have been implicated in polar trafficking from the TGN but the underlying mechanisms linking lipid composition to functional polar sorting at TGN subdomains remain unknown. Here we demonstrate that sphingolipids with α-hydroxylated acyl-chains of at least 24 carbon atoms are enriched in secretory vesicle subdomains of the TGN and are critical for de novo polar secretory sorting of the auxin carrier PIN2 to apical membrane of Arabidopsis root epithelial cells. We show that sphingolipid acyl-chain length influences the morphology and interconnections of TGN-associated secretory vesicles. Our results uncover that the sphingolipids acyl-chain length links lipid composition of TGN subdomains with polar secretory trafficking of PIN2 to apical membrane of polarized epithelial cells.

Overexpression of trans‐Golgi network t‐SNAREs rescues vacuolar trafficking and TGN morphology defects in a putative tethering factor mutant

“…The TGN has been proposed to mature and be released from its association with the Golgi, generating an independent compartment that can deliver material to the plasma membrane (Viotti et al, 2010;Uemura et al, 2014Uemura et al, , 2019. Different coat proteins, soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), tethering factors and lipids appear to define different subdomains of the TGN (Bassham et al, 2000;Chow et al, 2008;Gendre et al, 2011;Wattelet-Boyer et al, 2016;Renna et al, 2018).…”

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

“…Two subclasses within the large A group of plant RABs, RABA2 and RABA3, identify a distinct TGN/EE membrane domain that functions in cargo delivery to the cell plate during cytokinesis (Chow et al, 2008). Whereas RABA2a defines TGN domains distinct from SYP61 vesicles, evidenced by differing lipid composition, RABA4b preferentially localizes to TGN SV sites together with SYP61, where it is involved in the transport of cell wall components (Preuss et al, 2004;Kang et al, 2011;Wattelet-Boyer et al, 2016;Jonsson et al, 2017). Another TGN domain harboring the secretory SNAREs VAMP721/722 and defined by RABA1 also has been suggested (Asaoka et al, 2013).…”

“…Importantly, the authors established a novel link between a-hydroxylated acyl chain enrichment of TGN membranes and secretory trafficking, specifically in polarized transport to the apical membrane of epidermal cells (Wattelet-Boyer et al, 2016).…”

“…Spatiotemporal image correlation spectroscopy has proven useful to characterize the dynamics of vesicle trafficking to the cell plate (Hebert et al, 2005;van Oostende-Triplet et al, 2017). Finally, lipid profiling, metabolic click labeling, and the use of oligosaccharidebased probes for high-resolution real-time imaging of glycans have recently added to the list of promising avenues to dissect the role of TGN in cargo transport (Anderson et al, 2012;Pattathil et al, 2012;Mravec et al, 2014;Wattelet-Boyer et al, 2016). Such a panoply of tools promises new exciting discoveries about the multiple functions of the plant TGN.…”

GONST2 transports GDP-Mannose for sphingolipid glycosylation in the Golgi apparatus of Arabidopsis

“…The haustorium is surrounded by host-derived membrane called the extrahaustorial membrane, which has modified endosomal characteristics . It has been shown that GIPCs are important for secretory sorting of proteins (Markham et al, 2011;Wattelet-Boyer et al, 2016), and therefore it may be that changes to a minor class of GPIC are enough to disrupt these processes, thereby negatively affecting G. orontii infection.…”