scholarly journals Developmentally regulated GTP-binding protein 2 coordinates Rab5 activity and transferrin recycling

2016 ◽  
Vol 27 (2) ◽  
pp. 334-348 ◽  
Author(s):  
Muralidharan Mani ◽  
Unn Hwa Lee ◽  
Nal Ae Yoon ◽  
Hyo Jeong Kim ◽  
Myoung Seok Ko ◽  
...  
Keyword(s):  
Binding Protein ◽  
Ectopic Expression ◽  
Small Gtpase ◽  
Endocytic Pathway ◽  
Dependent Manner ◽  
Phosphatidylinositol 3 Kinase ◽  
Gtp Binding Protein ◽  
Developmentally Regulated ◽  
Gtp Binding ◽  
Phosphatidylinositol 3

The small GTPase Rab5 regulates the early endocytic pathway of transferrin (Tfn), and Rab5 deactivation is required for Tfn recycling. Rab5 deactivation is achieved by RabGAP5, a GTPase-activating protein, on the endosomes. Here we report that recruitment of RabGAP5 is insufficient to deactivate Rab5 and that developmentally regulated GTP-binding protein 2 (DRG2) is required for Rab5 deactivation and Tfn recycling. DRG2 was associated with phosphatidylinositol 3-phosphate–containing endosomes. It colocalized and interacted with EEA1 and Rab5 on endosomes in a phosphatidylinositol 3-kinase–dependent manner. DRG2 depletion did not affect Tfn uptake and recruitment of RabGAP5 and Rac1 to Rab5 endosomes. However, it resulted in impairment of interaction between Rab5 and RabGAP5, Rab5 deactivation on endosomes, and Tfn recycling. Ectopic expression of shRNA-resistant DRG2 rescued Tfn recycling in DRG2-depleted cells. Our results demonstrate that DRG2 is an endosomal protein and a key regulator of Rab5 deactivation and Tfn recycling.

Overexpression of developmentally regulated GTP-binding protein-2 increases bone loss

2013 ◽  
Vol 304 (7) ◽  
pp. E703-E710 ◽  
Author(s):  
Ke Ke ◽  
Ok-Joo Sul ◽  
Woon-Ki Kim ◽  
Mi-Hyun Lee ◽  
Myung-Seok Ko ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Mass ◽  
Binding Protein ◽  
Small Gtpases ◽  
Dependent Manner ◽  
Gtp Binding Protein ◽  
Developmentally Regulated ◽  
Gtp Binding ◽  
Actin Rings

The developmentally regulated GTP-binding protein-2 (DRG2) is a novel subclass of GTP-binding proteins. Many functional characteristics of osteoclasts (OC) are associated with small GTPases. We hypothesized that DRG2 affects bone mass via modulating OC activity. Using DRG2 transgenic mice, we investigated the role of DRG2 in bone remodeling. DRG2 overexpression caused a decrease in bone mass and an increase in the number and activity of OC in vivo. DRG2 overexpression increased fusion, spreading, survival, and resorption activity of OC in vitro . Downregulation of DRG2 by siRNA decreased fusion, spreading, and survival of OC, supporting the observations found in DRG2 transgenic OC. Transgenic mature OCs were larger, with actin rings and higher ERK, Akt, Rac1 and Rho activities than wild-type OCs. Inhibition of these proteins abolished the effects of DRG2 on formation of large OCs with actin rings, implying that DRG2 affects cytoskeleton reorganization in a Rac1/Rho/ERK/Akt-dependent manner. In summary, DRG2 is associated with survival and cytoskeleton organization of OC under influence of macrophage colony-stimulating factor, and its overexpression leads to elevated bone resorptive activity of OC, resulting in bone loss.

Small GTP-binding Protein RalA Associates with Weibel-Palade Bodies in Endothelial Cells

1999 ◽  
Vol 82 (09) ◽  
pp. 1177-1181 ◽  
Author(s):  
Hubert de Leeuw ◽  
Pauline Wijers-Koster ◽  
Jan van Mourik ◽  
Jan Voorberg
Keyword(s):  
Endothelial Cells ◽  
Binding Proteins ◽  
Binding Protein ◽  
Control Release ◽  
Small Gtpase ◽  
Gtp Binding Protein ◽  
Two Dimensional Gel Electrophoresis ◽  
Gtp Binding Proteins ◽  
Dense Granules ◽  
Gtp Binding

SummaryIn endothelial cells von Willebrand factor (vWF) and P-selectin are stored in dense granules, so-called Weibel-Palade bodies. Upon stimulation of endothelial cells with a variety of agents including thrombin, these organelles fuse with the plasma membrane and release their content. Small GTP-binding proteins have been shown to control release from intracellular storage pools in a number of cells. In this study we have investigated whether small GTP-binding proteins are associated with Weibel-Palade bodies. We isolated Weibel-Palade bodies by centrifugation on two consecutive density gradients of Percoll. The dense fraction in which these subcellular organelles were highly enriched, was analysed by SDS-PAGE followed by GTP overlay. A distinct band with an apparent molecular weight of 28,000 was observed. Two-dimensional gel electrophoresis followed by GTP overlay revealed the presence of a single small GTP-binding protein with an isoelectric point of 7.1. A monoclonal antibody directed against RalA showed reactivity with the small GTP-binding protein present in subcellular fractions that contain Weibel-Palade bodies. The small GTPase RalA was previously identified on dense granules of platelets and on synaptic vesicles in nerve terminals. Our observations suggest that RalA serves a role in regulated exocytosis of Weibel-Palade bodies in endothelial cells.

Developmentally regulated GTP-binding protein-2 regulates adipocyte differentiation

2021 ◽  
Author(s):  
Byong Seo Park ◽  
Hye Li Im ◽  
Nal Ae Yoon ◽  
Thai Hien Tu ◽  
Jeong Woo Park ◽  
...  
Keyword(s):  
Adipocyte Differentiation ◽  
Binding Protein ◽  
Gtp Binding Protein ◽  
Developmentally Regulated ◽  
Gtp Binding

Rabphilin-3A, a putative target protein for smg p25A/rab3A p25 small GTP-binding protein related to synaptotagmin

1993 ◽  
Vol 13 (4) ◽  
pp. 2061-2068
Author(s):  
H Shirataki ◽  
K Kaibuchi ◽  
T Sakoda ◽  
S Kishida ◽  
T Yamaguchi ◽  
...  
Keyword(s):  
Binding Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Bovine Brain ◽  
Target Protein ◽  
Dependent Manner ◽  
Gtp Binding Protein ◽  
Reading Frame ◽  
Gtp Binding ◽  
Putative Target

In a previous study (H. Shirataki, K. Kaibuchi, T. Yamaguchi, K. Wada, H. Horiuchi, and Y. Takai, J. Biol. Chem. 267:10946-10949, 1992), we highly purified from bovine brain crude membranes the putative target protein for smg p25A/rab3A p25, a ras p21-related small GTP-binding protein implicated in neurotransmitter release. In this study, we have isolated and sequenced the cDNA of this protein from a bovine brain cDNA library. The cDNA had an open reading frame encoding a protein of 704 amino acids with a calculated M(r) of 77,976. We tentatively refer to this protein as rabphilin-3A. Structural analysis of rabphilin-3A revealed the existence of two copies of an internal repeat that were homologous to the C2 domain of protein kinase C as described for synaptotagmin, which is known to be localized in the membrane of the synaptic vesicle and to bind to membrane phospholipid in a Ca(2+)-dependent manner. The isolated cDNA was expressed in COS7 cells, and the encoded protein was recognized with an anti-rabphilin-3A polyclonal antibody and was identical in size with rabphilin-3A purified from bovine brain by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Moreover, both rabphilin-3A purified from bovine brain and recombinant rabphilin-3A made a complex with the GTP gamma S-bound form of rab3A p25 but not with the GDP-bound form of rab3A p25. Immunoblot and Northern (RNA) blot analyses showed that rabphilin-3A was highly expressed in bovine and rat brains. These results indicate that rabphilin-3A is a novel protein that has C2 domains and selectively interacts with the GTP-bound form of rab3A p25.

scholarly journals Developmentally Regulated GTP binding protein 1 (DRG1) controls microtubule dynamics

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Anna Katharina Schellhaus ◽  
Daniel Moreno-Andrés ◽  
Mayank Chugh ◽  
Hideki Yokoyama ◽  
Athina Moschopoulou ◽  
...  
Keyword(s):  
Binding Protein ◽  
Microtubule Dynamics ◽  
Gtp Binding Protein ◽  
Developmentally Regulated ◽  
Gtp Binding

scholarly journals Developmentally regulated GTP-binding protein 1 modulates ciliogenesis via an interaction with Dishevelled

2019 ◽  
Vol 218 (8) ◽  
pp. 2659-2676 ◽  
Author(s):  
Moonsup Lee ◽  
Yoo-Seok Hwang ◽  
Jaeho Yoon ◽  
Jian Sun ◽  
Adam Harned ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Binding Protein ◽  
Basal Bodies ◽  
Apical Surface ◽  
Gtp Binding Protein ◽  
Developmentally Regulated ◽  
Rhoa Activity ◽  
Gtp Binding ◽  
Xenopus Laevis Embryo ◽  
Multiciliated Cells

Cilia are critical for proper embryonic development and maintaining homeostasis. Although extensively studied, there are still significant gaps regarding the proteins involved in regulating ciliogenesis. Using the Xenopus laevis embryo, we show that Dishevelled (Dvl), a key Wnt signaling scaffold that is critical to proper ciliogenesis, interacts with Drg1 (developmentally regulated GTP-binding protein 1). The loss of Drg1 or disruption of the interaction with Dvl reduces the length and number of cilia and displays defects in basal body migration and docking to the apical surface of multiciliated cells (MCCs). Moreover, Drg1 morphants display abnormal rotational polarity of basal bodies and a decrease in apical actin and RhoA activity that can be attributed to disruption of the protein complex between Dvl and Daam1, as well as between Daam1 and RhoA. These results support the concept that the Drg1–Dvl interaction regulates apical actin polymerization and stability in MCCs. Thus, Drg1 is a newly identified partner of Dvl in regulating ciliogenesis.

Mechanism of phospholipase D activation induced by extracellular ATP in osteoblast-like cells

1995 ◽  
Vol 145 (1) ◽  
pp. 81-86 ◽  
Author(s):  
A Suzuki ◽  
J Shinoda ◽  
Y Oiso ◽  
O Kozawa
Keyword(s):  
Phospholipase D ◽  
Inositol Phosphates ◽  
Binding Protein ◽  
Extracellular Atp ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Gtp Binding Protein ◽  
Proliferative Effect ◽  
Gtp Binding ◽  
Pkc Activation

Abstract We have previously reported that extracellular ATP stimulates Ca2+ influx from extracellular space, resulting in the production of prostaglandin E2 which mediates, at least in part, its proliferative effect on osteoblast-like MC3T3-E1 cells, and that the activation of protein kinase C (PKC) stimulates phospholipase D in these cells. In the present study, we examined the effect of extracellular ATP on phosphatidylcholine-hydrolysing phospholipase D activity in MC3T3-E1 cells. ATP stimulated the formation of both choline and inositol phosphates dose-dependently in the range between 0·1 and 1 mm. The formation of choline by a combination of ATP and NaF, an activator of GTP-binding protein, was synergistic, whereas that of inositol phosphates was not. A combination of ATP and 12-O-tetradecanoylphorbol-13-acetate, a PKC activating phorbol ester, additively stimulated the formation of choline. Staurosporine, an inhibitor of PKC, had little effect on ATP-stimulated formation of choline. Choline formation was significantly reduced by chelating extracellular Ca2+ with EGTA, while being inhibited by W-7, an antagonist of calmodulin. These results suggest that extracellular ATP stimulates phospholipase D in a Ca2+/calmodulin-dependent manner in osteoblast-like cells, and that neither PKC activation nor GTP-binding protein is involved in this mechanism. Journal of Endocrinology (1995) 145, 81–86

DRG: A novel developmentally regulated GTP-binding protein

1992 ◽  
Vol 189 (1) ◽  
pp. 363-370 ◽  
Author(s):  
Takashi Sazuka ◽  
Yasuhiro Tomooka ◽  
Yoji Ikawa ◽  
Makoto Noda ◽  
Sharad Kumar
Keyword(s):  
Binding Protein ◽  
Gtp Binding Protein ◽  
Developmentally Regulated ◽  
Gtp Binding
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