Myosin Motors and Not Actin Comets Are Mediators of the Actin-based Golgi-to-Endoplasmic Reticulum Protein Transport

Durán, Juan M.; Valderrama, Ferran; Castel, Susanna; Magdalena, Juana; Tomàs, Mariona; Hosoya, Hiroshi; Renau‐Piqueras, Jaime; Malhotra, Vivek; Egea, Gustavo

doi:10.1091/mbc.e02-04-0214

Cited by 86 publications

(74 citation statements)

References 79 publications

(107 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, our finding that ␤COP and the trans-Golgi network adaptor protein AP-1 were released at the same rate in control and patient cells (Figure 2) suggests an alternate mechanism. Because BFA-induced tubulation has been shown to occur along microtubules Sciaky et al, 1997;Duran et al, 2003), the COG complex may facilitate Golgi-to-ER transport by tethering retrograde-bound tubules to the cytoskeleton. If this is the mechanism of action, it is notable that the COG complex would be acting independently of COPI.…”

Section: Discussionmentioning

confidence: 99%

COG-7-deficient Human Fibroblasts Exhibit Altered Recycling of Golgi Proteins

Steet

Kornfeld

2006

MBoC

View full text Add to dashboard Cite

Recently, we reported that two siblings presenting with the clinical syndrome congenital disorders of glycosylation (CDG) have mutations in the gene encoding Cog7p, a member of the conserved oligomeric Golgi (COG) complex. In this study, we analyzed the localization and trafficking of multiple Golgi proteins in patient fibroblasts under a variety of conditions. Although the immunofluorescent staining pattern of several Golgi proteins was indistinguishable from normal, the staining of endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC)-53 and the vesicularsoluble N-ethylmaleimide-sensitive factor attachment protein receptors GS15 and GS28 was abnormal, and the steadystate level of GS15 was greatly decreased. Retrograde transport of multiple Golgi proteins to the ER in patient fibroblasts via brefeldin A-induced tubules was significantly slower than occurs in normal fibroblasts, whereas anterograde protein trafficking was much less affected. After prolonged treatment with brefeldin A, several Golgi proteins were detected in clusters that colocalize with the microtubule-organizing center in patient cells. All of these abnormalities were normalized in COG7-corrected patient fibroblasts. These results serve to better define the role of the COG complex in facilitating protein trafficking between the Golgi and ER and provide a diagnostic framework for the identification of CDG defects involving trafficking proteins. INTRODUCTIONThe congenital disorders of glycosylation (CDG) are a group of autosomal recessive multisystem disorders typically defined by defects in proteins directly involved in the N-linked glycosylation pathway (Freeze, 2001;Marquardt and Denecke, 2003). The molecular defects resulting in CDG were recently expanded to include proteins involved in overall Golgi function. Specifically, two siblings were described with a fatal form of CDG (classified as CDG-IIe) caused by mutation in the gene encoding Cog7p, a member of the conserved oligomeric Golgi (COG) complex (Wu et al., 2004). Fibroblasts from these patients are deficient in COG subunits 5-8 that compromise lobe B of the complex and exhibit subtle decreases in the sialylation of both N-and O-linked oligosaccharides (Wu et al., 2004;. The glycosylation defects were COG dependent because they were effectively rescued by transduction of CDG-IIe fibroblasts with wild-type COG7 cDNA.The vesicle tethering COG complex is thought to mediate numerous steps in anterograde and retrograde transport within the secretory apparatus (reviewed in . A role for the COG complex in maintaining the fidelity of retrograde transport within the Golgi has been supported by recent evidence indicating that acute depletion of COG3 prevents tethering of retrograde vesicles within the Golgi resulting in the accumulation of Golgi proteins, including the soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) GS15 and GS28 in COG complex-dependent (CCD) vesicles (Zolov and Lupashin, 2005). Because resident Golgi proteins such as glycosylation enz...

show abstract

Section: Discussionmentioning

confidence: 99%

COG-7-deficient Human Fibroblasts Exhibit Altered Recycling of Golgi Proteins

Steet

Kornfeld

2006

MBoC

View full text Add to dashboard Cite

show abstract

“…Although myosin II in mammalian systems is most widely associated with cortical cytoskeletal functions such as cell migration and cytokinesis, it is intriguing that several reports have implicated myosin II in Golgi function and trafficking in higher systems (DeGiorgis et al, 2002;Duran et al, 2003;Wollert et al, 2003). Further studies to determine whether myosin II in Dictyostelium may have more direct roles in vesicle trafficking, Golgi organization, or membrane dynamics in other settings would be worthwhile.…”

Section: Discussionmentioning

confidence: 99%

Identification and Characterization of a Novel α-Kinase with a von Willebrand Factor A-like Motif Localized to the Contractile Vacuole and Golgi Complex inDictyostelium discoideum

Betapudi

Mason

Licate

et al. 2005

MBoC

View full text Add to dashboard Cite

We have identified a new protein kinase in Dictyostelium discoideum that carries the same conserved class of "␣-kinase" catalytic domain as reported previously in myosin heavy chain kinases (MHCKs) in this amoeba but that has a completely novel domain organization. The protein contains an N-terminal von Willebrand factor A (vWFA)-like motif and is therefore named VwkA. Manipulation of VwkA expression level via high copy number plasmids (VwkA ؉؉ cells) or gene disruption (vwkA null cells) results in an array of cellular defects, including impaired growth and multinucleation in suspension culture, impaired development, and alterations in myosin II abundance and assembly. Despite sequence similarity to MHCKs, the purified protein failed to phosphorylate myosin II in vitro. Autophosphorylation activity, however, was enhanced by calcium/calmodulin, and the enzyme can be precipitated from cellular lysates with calmodulin-agarose, suggesting that VwkA may directly bind calmodulin. VwkA is cytosolic in distribution but enriched on the membranes of the contractile vacuole and Golgi-like structures in the cell. We propose that VwkA likely acts indirectly to influence myosin II abundance and assembly behavior and possibly has broader roles than previously characterized ␣ kinases in this organism, which all seem to be MHCKs. INTRODUCTIONNearly all aspects of cell life are regulated by protein phosphorylation involving a large number of biochemical reactions and distinct signaling pathways. Existence of ϳ500 genes encoding various protein kinases in the human genome further underscores their importance in cell life (Manning et al., 2002). Most of these conventional protein kinases belong to serine/threonine/tyrosine, a kinase superfamily whose members carry a conserved catalytic domain with recognizable sequence similarity in spite of having different targets in the cell (Hardie, 1994;Hanks and Hunter, 1995). In recent years, however, biochemical and molecular approaches have led to the identification of more divergent classes of eukaryotic protein kinases carrying a catalytic domain sequence with no sequence similarity with conventional protein kinase catalytic domains (Manning et al., 2002). One major class of unconventional protein kinases was first identified via representatives of myosin heavy chain kinases (MHCKs) in Dictyostelium discoideum (Futey et al., 1995;Côté et al., 1997) and via identification of mammalian eEF-2 kinase (eEF-2K) as an unconventional protein kinase (Ryazanov et al., 1997). This novel, conserved group of unconventional eukaryotic protein kinases has been termed the ␣-kinase family (Ryazanov et al., 1999;Drennan and Ryazanov, 2004).Molecular cloning and biochemical characterization studies demonstrated that at least three Dictyostelium ␣-kinases genes encode enzymes that can specifically phosphorylate myosin II heavy chain (MHC) in vitro and in vivo, and were thus named as MHC kinase A (MHCK A), MHC kinase B (MHCK B) and MHC kinase C (MHCK C) (Futey et al., 1995;Clancy et al., 1997;Luo et al., 200...

show abstract

“…In addition, there is evidence that further components such as clathrin, dynamin-2, epsinR, and syntaxins 6 and 16 play a role. The dependence on actin and microtubules shows that the cytoskeleton is also important (Valderrama et al 2001;Luna et al 2002;Duran et al 2003). A small fraction (5% -10%) of the STX has been shown to escape already at the endosomal level (McKenzie et al 2009).…”

Section: Sorting In Endosomesmentioning

confidence: 99%