E-Cadherin Transport from the trans-Golgi Network in Tubulovesicular Carriers is Selectively Regulated by Golgin-97

Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
Traffic (Impact Factor: 4.35). 01/2006; 6(12):1142-56. DOI: 10.1111/j.1600-0854.2005.00349.x
Source: PubMed

ABSTRACT E-cadherin is a cell-cell adhesion protein that is trafficked and delivered to the basolateral cell surface. Membrane-bound carriers for the post-Golgi exocytosis of E-cadherin have not been characterized. Green fluorescent protein (GFP)-tagged E-cadherin (Ecad-GFP) is transported from the trans-Golgi network (TGN) to the recycling endosome on its way to the cell surface in tubulovesicular carriers that resemble TGN tubules labeled by members of the golgin family of tethering proteins. Here, we examine the association of golgins with tubular carriers containing E-cadherin as cargo. Fluorescent GRIP domains from golgin proteins replicate the membrane binding of the full-length proteins and were coexpressed with Ecad-GFP. The GRIP domains of p230/golgin-245 and golgin-97 had overlapping but nonidentical distributions on the TGN; both domains were on TGN-derived tubules but only the golgin-97 GRIP domain coincided with Ecad-GFP tubules in live cells. When the Arl1-binding endogenous golgins, p230/golgin-245 and golgin-97 were displaced from Golgi membranes by overexpression of the p230 GRIP domain, trafficking of Ecad-GFP was inhibited. siRNA knockdown of golgin-97 also inhibited trafficking of Ecad-GFP. Thus, the GRIP domains of p230/golgin-245 and golgin-97 bind discriminately to distinct membrane subdomains of the TGN. Golgin-97 is identified as a selective and essential component of the tubulovesicular carriers transporting E-cadherin out of the TGN.

Download full-text


Available from: John G Lock, Apr 01, 2015
22 Reads
  • Source
    • "Golgins are a large family loosely characterized by their Golgi localization and extended coiled coil motifs and have traditionally been associated with maintenance of Golgi structure and assisting bulk flow of proteins through the organelle [16]. Golgin-160 is a vertebrate-specific golgin that is one of only three golgins implicated in trafficking of specific cargoes [15,17–20]. Hicks et al. demonstrated in vitro that the third intracellular loop of β1AR can interact with the N-terminal head domain of golgin-160 in a PIST-independent manner, and that depletion of golgin-160 from HeLa cells decreases the steady state surface levels of exogenously expressed β1AR without affecting internalization rates. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Golgin-160 is a member of the golgin family of proteins, which have been implicated in the maintenance of Golgi structure and in vesicle tethering. Golgin-160 is atypical; it promotes post-Golgi trafficking of specific cargo proteins, including the β-1 adrenergic receptor (β1AR), a G protein-coupled receptor. Here we show that golgin-160 binds directly to the third intracellular loop of β1AR and that this binding depends on three basic residues in this loop. Mutation of the basic residues does not affect trafficking of β1AR from the endoplasmic reticulum through the Golgi complex, but results in reduced steady-state levels at the plasma membrane. We hypothesize that golgin-160 promotes incorporation of β1AR into specific transport carriers at the trans-Golgi network to ensure efficient delivery to the cell surface. These results add to our understanding of the biogenesis of β1AR, and suggest a novel point of regulation for its delivery to the plasma membrane.
    International Journal of Molecular Sciences 02/2014; 15(2):2929-45. DOI:10.3390/ijms15022929 · 2.86 Impact Factor
  • Source
    • "We next sought to investigate the specific transport step affected by Rab6 disruption. We have previously shown that TNF exits the TGN in dynamic tubular carriers demarked by the trans-golgin p230/golgin-245/GOLGA4 (hereafter p230) [8]. LPS up-regulates the formation of these carriers and depletion of p230 in vitro and in vivo impairs TNF trafficking out of the TGN, blocking its secretion [9]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Lipopolysaccharide (LPS)-activated macrophages secrete pro-inflammatory cytokines, including tumor necrosis factor (TNF) to elicit innate immune responses. Secretion of these cytokines is also a major contributing factor in chronic inflammatory disease. In previous studies we have begun to elucidate the pathways and molecules that mediate the intracellular trafficking and secretion of TNF. Rab6a and Rab6a' (collectively Rab6) are trans-Golgi-localized GTPases known for roles in maintaining Golgi structure and Golgi-associated trafficking. We found that induction of TNF secretion by LPS promoted the selective increase of Rab6 expression. Depletion of Rab6 (via siRNA and shRNA) resulted in reorganization of the Golgi ribbon into more compact structures that at the resolution of electron microcopy consisted of elongated Golgi stacks that likely arose from fusion of smaller Golgi elements. Concomitantly, the delivery of TNF to the cell surface and subsequent release into the media was reduced. Dominant negative mutants of Rab6 had similar effects in disrupting TNF secretion. In live cells, Rab6-GFP were localized on trans-Golgi network (TGN)-derived tubular carriers demarked by the golgin p230. Rab6 depletion and inactive mutants altered carrier egress and partially reduced p230 membrane association. Our results show that Rab6 acts on TNF trafficking at the level of TGN exit in tubular carriers and our findings suggest Rab6 may stabilize p230 on the tubules to facilitate TNF transport. Both Rab6 isoforms are needed in macrophages for Golgi stack organization and for the efficient post-Golgi transport of TNF. This work provides new insights into Rab6 function and into the role of the Golgi complex in cytokine secretion in inflammatory macrophages.
    PLoS ONE 02/2013; 8(2):e57034. DOI:10.1371/journal.pone.0057034 · 3.23 Impact Factor
  • Source
    • "In addition, the GRIP domains of both Golgin-245 and Golgin-97 associate with tubular membrane extensions of the trans-Golgi [48]. Moreover, Lock et al. [48] reported that Golgin-97 is involved in trafficking of E-cadherin containing vesicles out of the trans-Golgi. Golgin-97 was shown to play an important role in vesicular transport between the trans-Golgi and the endosome in vitro [49]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Lipid droplets carrying triglycerides and cholesteryl esters are emerging as dynamic cellular organelles that are generated in nearly every cell. They play a key role in lipid and membrane homeostasis. Abnormal lipid droplet dynamics are associated with the pathophysiology of many metabolic diseases, such as obesity, diabetes, atherosclerosis, fatty liver, and even cancer. Chylomicrons, stable droplets also consisting of triglycerides and cholesterol are generated in the intestinal epithelium to transport exogenous (dietary) lipids after meals from the small intestine to tissues for degradation. Defective chylomicron formation is responsible for inherited lipoprotein deficiencies, including abetalipoproteinemia, hypobetalipoproteinemia and chylo-micron retention disease. These are disorders sharing characteristics like fat malabsorption, low levels of circulating lipids and fat-soluble vitamins, failure to thrive in early childhood, ataxic neuropathy and visual impairment. Thus, understanding the molecular mechanisms governing the dynamics of lipid droplets and chylomicrons, namely, their biogenesis, growth, maintenance, and degradation, will not only clarify their molecular role, but might provide additional indications to treatment of metabolic diseases. In this review we highlight the role of two small GTPases (ARFRP1 and ARL1) and their downstream targets acting on the trans-Golgi (Golgins and Rab proteins) on lipid droplet and chylomicron formation.
    Bioscience Reports 10/2012; 33(1). DOI:10.1042/BSR20120082 · 2.64 Impact Factor
Show more