scholarly journals DRG2 Accelerates Senescence via Negative Regulation of SIRT1 in Human Diploid Fibroblasts

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Bing Si Li ◽  
Ai Lin Jin ◽  
ZiQi Zhou ◽  
Jae Ho Seo ◽  
Byung-Min Choi
Keyword(s):  
Oxidative Stress ◽  
Cell Growth ◽  
Binding Protein ◽  
Ectopic Expression ◽  
Sirtuin 1 ◽  
Premature Senescence ◽  
Gtp Binding Protein ◽  
Human Diploid Fibroblasts ◽  
Gtp Binding ◽  
Stress Induced Premature Senescence

Accumulating evidence suggests that developmentally regulated GTP-binding protein 2 (DRG2), an evolutionarily conserved GTP-binding protein, plays an important role in regulating cell growth, inflammation, and mitochondria dynamics. However, the effect of DRG2 in aging remains unclear. In this study, we found that endogenous DRG2 protein expression is upregulated in oxidative stress-induced premature senescence models and tissues of aged mice. Ectopic expression of DRG2 significantly promoted senescence-associated β-galactosidase (SA-β-gal) activity and inhibited cell growth, concomitant with increase in levels of acetyl (ac)-p53 (Lys382), ac-nuclear factor-kB (NF-κB) p65 (Lys310), p21Waf1/Cip1, and p16Ink4a and a decrease in cyclin D1. In this process, reactive oxygen species (ROS) and phosphorylation of H2A histone family member X (H2A.X), forming γ-H2A.X, were enhanced. Mechanistically, ectopic expression of DRG2 downregulated Sirtuin-1 (SIRT1), resulting in augmented acetylation of p53 and NF-κB p65. Additionally, DRG2 knockdown significantly abolished oxidative stress-induced premature senescence. Our results provide a possible molecular mechanism for investigation of cellular senescence and aging regulated by DRG2.

A Role for the Common GTP-Binding Protein in Coupling of Chromosome Replication to Cell Growth and Cell Division

2002 ◽  
Vol 292 (2) ◽  
pp. 333-338 ◽  
Author(s):  
Aleksandra Sikora-Borgula ◽  
Monika Słomińska ◽  
Piotr Trzonkowski ◽  
Ryszard Zielke ◽  
Andrzej Myśliwski ◽  
...  
Keyword(s):  
Cell Division ◽  
Cell Growth ◽  
Binding Protein ◽  
Chromosome Replication ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
The Common

scholarly journals The hydroxyurea-induced small GTP-binding protein SAR modulates γ-globin gene expression in human erythroid cells

Blood ◽  
2005 ◽  
Vol 106 (9) ◽  
pp. 3256-3263 ◽  
Author(s):  
Delia C. Tang ◽  
Jianqiong Zhu ◽  
Wenli Liu ◽  
Kyung Chin ◽  
Jun Sun ◽  
...  
Keyword(s):  
Cell Growth ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Globin Gene ◽  
K562 Cells ◽  
Pi3 Kinase ◽  
Erythroid Cell ◽  
Erythroid Cells ◽  
Gtp Binding Protein ◽  
Gtp Binding

AbstractHydroxyurea (HU), a drug effective in the treatment of sickle cell disease, is thought to indirectly promote fetal hemoglobin (Hb F) production by perturbing the maturation of erythroid precursors. The molecular mechanisms involved in HU-mediated regulation of γ-globin expression are currently unclear. We identified an HU-induced small guanosine triphosphate (GTP)–binding protein, secretion-associated and RAS-related (SAR) protein, in adult erythroid cells using differential display. Stable SAR expression in K562 cells increased γ-globin mRNA expression and resulted in macrocytosis. The cells appeared immature. SAR-mediated induction of γ-globin also inhibited K562 cell growth by causing arrest in G1/S, apoptosis, and delay of maturation, cellular changes consistent with the previously known effects of HU on erythroid cells. SAR also enhanced both γ- and β-globin transcription in primary bone marrow CD34+ cells, with a greater effect on γ-globin than on β-globin. Although up-regulation of GATA-2 and p21 was observed both in SAR-expressing cells and HU-treated K562 cells, phosphatidylinositol 3 (PI3) kinase and phosphorylated ERK were inhibited specifically in SAR-expressing cells. These data reveal a novel role of SAR distinct from its previously known protein-trafficking function. We suggest that SAR may participate in both erythroid cell growth and γ-globin production by regulating PI3 kinase/extracellular protein–related kinase (ERK) and GATA-2/p21-dependent signal transduction pathways.

scholarly journals Identification and Characterization of Putative Tumor Suppressor NGB, a GTP-Binding Protein That Interacts with the Neurofibromatosis 2 Protein

2007 ◽  
Vol 27 (6) ◽  
pp. 2103-2119 ◽  
Author(s):  
Hansoo Lee ◽  
Donghwa Kim ◽  
Han C. Dan ◽  
Eric L. Wu ◽  
Tatiana M. Gritsko ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Tumor Suppressor ◽  
Malignant Tumors ◽  
Binding Protein ◽  
Ectopic Expression ◽  
Cell Aggregation ◽  
Gtp Binding Protein ◽  
Neurofibromatosis 2 ◽  
Primary Tumors ◽  
Gtp Binding

ABSTRACT Mutations of the neurofibromatosis 2 (NF2) tumor suppressor gene have frequently been detected not only in schwannomas and other central nervous system tumors of NF2 patients but also in their sporadic counterparts and malignant tumors unrelated to the NF2 syndrome such as malignant mesothelioma, indicating a broader role for the NF2 gene in human tumorigenesis. However, the mechanisms by which the NF2 product, merlin or schwannomin, is regulated and controls cell proliferation remain elusive. Here, we identify a novel GTP-binding protein, dubbed NGB (referring to NF2-associated GTP binding protein), which binds to merlin. NGB is highly conserved between Saccharomyces cerevisiae, Caenorhabditis elegans, and human cells, and its GTP-binding region is very similar to those found in R-ras and Rap2. However, ectopic expression of NGB inhibits cell growth, cell aggregation, and tumorigenicity in tumorigenic schwanomma cells. Down-regulation and infrequent mutation of NGB were detected in human glioma cell lines and primary tumors. The interaction of NGB with merlin impairs the turnover of merlin, yet merlin does not affect the GTPase nor GTP-binding activity of NGB. Finally, the tumor suppressor functions of NGB require merlin and are linked to its ability to suppress cyclin D1 expression. Collectively, these findings indicate that NGB is a tumor suppressor that regulates and requires merlin to suppress cell proliferation.

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.

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.

Rap1b Association with the Platelet Cytoskeleton Occurs in the Absence of Glycoproteins IIb/IIIa

1998 ◽  
Vol 79 (04) ◽  
pp. 832-836 ◽  
Author(s):  
Thomas Fischer ◽  
Christina Duffy ◽  
Gilbert White
Keyword(s):  
Molecular Weight ◽  
Divalent Cation ◽  
Binding Proteins ◽  
Binding Protein ◽  
Platelet Membrane ◽  
Low Molecular Weight ◽  
Membrane Glycoproteins ◽  
Gtp Binding Protein ◽  
Gtp Binding Proteins ◽  
Gtp Binding

SummaryPlatelet membrane glycoproteins (GP) IIb/IIIa and rap1b, a 21 kDa GTP binding protein, associate with the triton-insoluble, activation-dependent platelet cytoskeleton with similar rates and divalent cation requirement. To examine the possibility that GPIIb/IIIa was required for rap1b association with the cytoskeleton, experiments were performed to determine if the two proteins were linked under various conditions. Chromatography of lysates from resting platelets on Sephacryl S-300 showed that GPIIb/IIIa and rap1b were well separated and distinct proteins. Immunoprecipitation of GPIIb/IIIa from lysates of resting platelets did not produce rap1b or other low molecular weight GTP binding proteins and immunoprecipitation of rap1b from lysates of resting platelets did not produce GPIIb/IIIa. Finally, rap1b was associated with the activation-dependent cytoskeleton of platelets from a patient with Glanzmann’s thrombasthenia who lacks surface expressed glycoproteins IIb and IIIa. Based on these findings, we conclude that no association between GPIIb/IIIa and rap1b is found in resting platelets and that rap1b association with the activation-dependent cytoskeleton is at least partly independent of GPIIb/IIIa.

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