title: Mislocalization of large ARF-GEFs as a potential mechanism for BFA resistance in COG-deficient cells.
abstract: Defects in subunits of the conserved oligomeric Golgi (COG) complex represent a growing subset of congenital disorders of glycosylation (CDGs). In addition to altered protein glycosylation and vesicular trafficking, Cog-deficient patient fibroblasts exhibit a striking delay in the Golgi-disrupting effects of brefeldin A (BFA). Despite the diagnostic value of this BFA resistance, the molecular basis of this response is not known. To investigate potential mechanisms of resistance, we analyzed the localization of the large ARF-GEF, GBF1, in several Cog-deficient cell lines. Our results revealed mislocalization of GBF1 to non-Golgi compartments, in particular the ERGIC, within these cells. Biochemical analysis of GBF1 in control and BFA-treated fibroblasts demonstrated that the steady-state level and membrane recruitment is not substantially affected by COG deficiency, supporting a role for the COG complex in the localization but not membrane association of GBF1. We also showed that pretreatment of fibroblasts with bafilomycin resulted in a GBF1-independent BFA resistance that appears additive with the resistance associated with COG deficiency. These data provide new insight into the mechanism of BFA resistance in Cog-deficient cells by suggesting a role for impaired ARF-GEF localization.
authors: Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA. rsteet@ccrc.uga.edu
authors: Heather
authors: H
authors: Flanagan-Steet
authors: Steven
authors: S
authors: Johnson
authors: Richard D
authors: RD
authors: Smith
authors: Julia
authors: J
authors: Bangiyeva
authors: Vladimir
authors: V
authors: Lupashin
authors: Richard
authors: R
authors: Steet
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003593:Cytoplasm / Q000378:metabolism; D004351:Drug Resistance / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D000077614:Golgi Matrix Proteins; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D037241:Mannose-Binding Lectins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D011799:Quinazolines; D011804:Quinolines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: C119087:ARFGEF1 protein, human; D033942:Adaptor Proteins, Vesicular Transport; C498528:COG3 protein, human; C553748:COG6 protein, human; C512294:COG7 protein, human; C491738:ERP29 protein, human; C120445:GBF1 protein, human; D000077614:Golgi Matrix Proteins; D020662:Guanine Nucleotide Exchange Factors; D006360:Heat-Shock Proteins; C084004:LMAN1 protein, human; D018942:Macrolides; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D011725:Pyridines; D011799:Quinazolines; D011804:Quinolines; D034741:RNA, Small Interfering; D020032:Tyrphostins; C539165:golgicide A; C087574:macrogolgin; C057620:bafilomycin A; C101044:RTKI cpd; D020126:Brefeldin A; D006180:Proton-Translocating ATPases