Conserved Oligomeric Golgi and Neuronal Vesicular Trafficking

Abstract

The conserved oligomeric Golgi (COG) complex is an evolutionary conserved multi-subunit vesicle tethering complex essential for the majority of Golgi apparatus functions: protein and lipid glycosylation and protein sorting. COG is present in neuronal cells, but the repertoire of COG function in different Golgi-like compartments is an enigma. Defects in COG subunits cause alteration of Golgi morphology, protein trafficking, and glycosylation resulting in human congenital disorders of glycosylation (CDG) type II. In this review we summarize and critically analyze recent advances in the function of Golgi and Golgi-like compartments in neuronal cells and functions and dysfunctions of the COG complex and its partner proteins.

Keywords: COG; Conserved oligomeric Golgi; Glycosylation; Golgi outpost; Golgi satellite.

Fig. 1

Neuronal Golgi and Golgi-like compartments. Neuronal Golgi includes the perinuclear Golgi of the soma, and dendritic mini-stacked Golgi outposts (GO, purple) and smaller Golgi satellites (GS, blue). Insert depicts major Golgi sub-compartments and protein markers

Fig. 2

Glycosylation in neurons. N-glycosylation begins in the ER by the addition of a core glycan structure to a nascent protein. Trimming and extension take place throughout the Golgi. In COG-KO cells, N- and O-glycans are undergalactosylated and undersialylated. Neurons have an additional trafficking route that bypasses the Golgi resulting in underglycosylated structures

Fig. 3

COG structure and localization. (a) Vesicular trafficking components. (b, c) Reprinted by permission from Macmillan Publishers Ltd: [Nat Struct Mol Biol] (Ha et al. 2016), copyright (2016). (b) COG complex structure determined by class averaging of (c) EM images of purified yeast COG. (d) Endogenous COG8 in differentiated H9 human stem cell line. Co-stained for endogenous GM130 and lectin GNL-647 (high mannose-binding lectin). Arrows indicate COG8 in smaller GM130-positive compartments outside perinuclear (N) Golgi (*). Scale bar = 10 μm