Abstract 191: Ras GTPase-activating Protein SH3 Domain Binding Protein 1 (G3BP1) Regulates The Induction Of Stress Granules During Cardiac Hypertrophy

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Danish Sayed
Keyword(s):  
Cardiac Hypertrophy ◽  
Cardiac Myocytes ◽  
Posttranscriptional Regulation ◽  
Binding Protein ◽  
Stress Granules ◽  
Sh3 Domain ◽  
Gtpase Activating Protein ◽  
Ras Gtpase ◽  
Mrna Binding

Stress granules (SGs) are dynamic, microscopically visible, cytoplasmic bodies that play a major role in mRNA metabolism (e.g. sorting, storage, decay) and induced in cells during stress conditions like starvation, oxidative strain or growth. With substantial role in cancer and neurodegenerative diseases, these granules have never been studied during cardiac hypertrophy, or in the heart in general. Several studies have identified independent proteins, mostly mRNA binding proteins that are part of these granules, some of which are sufficient to nucleate the assembly in quiescent cells even without stress. One such mRNA binding protein is Ras GTPase-activating protein SH3 domain binding protein 1 (G3BP1), which increases during cardiac hypertrophy via posttranscriptional regulation. Thus, we hypothesized that G3BP1 might be involved in the induction of SGs during hypertrophy and hence in regulating mRNA processing and gene expression. Our aim was to investigate, 1) if these SGs appear in hypertrophied hearts and 2) if G3BP1 is necessary and sufficient to induce them during hypertrophic stimuli. In vivo staining of TIA-1/TIAR (SG marker) in mouse hearts subjected to sham or transaortic coarctation (TAC) surgeries showed accumulation of these granules with cardiac hypertrophy. Similar induction was seen in isolated, cultured, rat neonatal cardiac myocytes with hypertrophic stimulation (Endothelin1) or overexpression of G3BP1 alone (>60% of myocytes stained for SG). Conversely, switch to growth-inhibited conditions or knockdown of G3BP1 in hypertrophying myocytes was sufficient to prevent the assembly of these structures. Co-staining with other components of these granules like TIA-1/TIAR or proteins specific to P bodies, like decapping enzyme 1 validated these structures as SGs in cardiac myocytes. Interestingly, a long non-coding RNA, Gas5 (Growth Arrest Specific 5) that is validated binding partner of G3BP1 sequestered to perinuclear focal locations in myocytes stimulated with ET1, suggesting growth-induced recruitment to SGs. While we are still in process of examining G3BP1 targets that are recruited to SGs and their role in hypertrophy development, we have concluded that G3BP1 is required for the induction of SGs during cardiac hypertrophy

scholarly journals Identification of the Ras GTPase-activating protein GAP1m as a phosphatidylinositol-3,4,5-trisphosphate-binding protein in vivo

1999 ◽  
Vol 9 (5) ◽  
pp. 265-269 ◽  
Author(s):  
Peter J. Lockyer ◽  
Stefan Wennström ◽  
Sabine Kupzig ◽  
Kanamarlapudi Venkateswarlu ◽  
Julian Downward ◽  
...  
Keyword(s):  
Binding Protein ◽  
Gtpase Activating Protein ◽  
Ras Gtpase

scholarly journals Vaccinia Virus Intermediate Stage Transcription Is Complemented by Ras-GTPase-activating Protein SH3 Domain-binding Protein (G3BP) and Cytoplasmic Activation/Proliferation-associated Protein (p137) Individually or as a Heterodimer

2004 ◽  
Vol 279 (50) ◽  
pp. 52210-52217 ◽  
Author(s):  
George C. Katsafanas ◽  
Bernard Moss
Keyword(s):  
Transcription Factors ◽  
Rna Polymerase ◽  
Hela Cell ◽  
Vaccinia Virus ◽  
Binding Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Intermediate Stage ◽  
Sh3 Domain ◽  
Gtpase Activating Protein ◽  
Ras Gtpase

Transcription of the DNA genome of vaccinia virus occurs in the cytoplasm and is temporally programmed by early, intermediate, and late stage-specific transcription factors in conjunction with a viral multisubunit RNA polymerase. The RNA polymerase, capping enzyme, and three factors (VITF-1, VITF-2, and VITF-3) are sufficient forin vitrotranscription of a DNA template containing an intermediate stage promoter. Vaccinia virus intermediate transcription factor (VITF)-1 and -3 are virus-encoded, whereas VITF-2 was partially purified from extracts of uninfected HeLa cells. Using purified and recombinant viral proteins, we showed that the HeLa cell factor was required for transcription of linear or nicked circular templates but not of super coiled DNA. HeLa cell polypeptides of ∼110 and 66 kDa copurified with VITF-2 activity through multiple chromatographic steps. The polypeptides were separated by SDS-polyacrylamide gel electrophoresis and identified by mass spectrometry as Ras-GTPase-activating protein SH3 domain-binding protein (G3BP) and p137, recently named cytoplasmic activation/proliferation-associated protein-1. The co-purification of the two polypeptides with transcription-complementing activity was confirmed with specific antibodies, and their association with each other was demonstrated by affinity chromatography of tagged recombinant forms. Furthermore, recombinant G3BP and p137 expressed individually or together in mammalian or bacterial cells complemented the activity of the viral RNA polymerase and transcription factors. The involvement of cellular proteins in transcription of intermediate stage genes may regulate the transition between early and late phases of vaccinia virus replication.

scholarly journals Novel Role of Ras-GTPase Activating Protein SH3 Domain-Binding Protein G3BP in Adhesion and Migration of 32D Myeloid Progenitor Cells

2012 ◽  
Vol 6 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Kerstin Schwarz ◽  
Frank Aschenbrenner ◽  
Brigitte Ruster ◽  
Manuela Kampfmann ◽  
Martina Komor ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Rho Gtpases ◽  
Stromal Cell ◽  
Cell Model ◽  
Binding Protein ◽  
Three Dimensional ◽  
Sh3 Domain ◽  
Gtpase Activating Protein ◽  
Ras Gtpase ◽  
And Migration

Rho GTPases are involved in homing and mobilization of hematopoietic stem and progenitor cells due to their impact on cytoskeleton remodeling. We have previously shown that inhibition of Rho, Rac and Cdc42 clearly impairs adhesion of normal and leukemic hematopoietic progenitor cells (HPC) to fibronectin and migration in a three-dimensional stromal cell model. Here, we identified the Ras GTPase-Activating Protein SH3 Domain-Binding Protein (G3BP) as a target gene of Rho GTPases and analysed its role in regulating HPC motility. Overexpression of G3BP significantly enhanced adhesion of murine 32D HPC to fibronectin and human umbilical vein endothelial cells, increased the proportion of adherent cells in a flow chamber assay and promoted cell migration in a transwell assay and a three-dimensional stromal cell model suggesting a strong impact on the cytoskeleton. Immunofluorescent staining of G3BP-overexpressing fibroblasts revealed a Rho-like phenotype characterized by formation of actin stress fibers in contrast to the Rac-like phenotype of control fibroblasts. This is the first report implicating a role for G3BP in Rho GTPase-mediated signalling towards adhesion and migration of HPC. Our results may be of clinical importance, since G3BP was found overexpressed in human cancers.

scholarly journals A Ras-GTPase-activating protein SH3-domain-binding protein.

1996 ◽  
Vol 16 (6) ◽  
pp. 2561-2569 ◽  
Author(s):  
F Parker ◽  
F Maurier ◽  
I Delumeau ◽  
M Duchesne ◽  
D Faucher ◽  
...  
Keyword(s):  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Sh3 Domain ◽  
Ras Signaling ◽  
Gtpase Activating Protein ◽  
Ras Gtpase ◽  
Rich Domain ◽  
Acid Protein ◽  
Amino Acid Protein

We report the purification of a Ras-GTPase-activating protein (GAP)-binding protein, G3BP, a ubiquitously expressed cytosolic 68-kDa protein that coimmunoprecipitates with GAP. G3BP physically associates with the SH3 domain of GAP, which previously had been shown to be essential for Ras signaling. The G3BP cDNA revealed that G3BP is a novel 466-amino-acid protein that shares several features with heterogeneous nuclear RNA-binding proteins, including ribonucleoprotein (RNP) motifs RNP1 and RNP2, an RG-rich domain, and acidic sequences. Recombinant G3BP binds effectively to the GAP SH3 domain G3BP coimmunoprecipitates with GAP only when cells are in a proliferating state, suggesting a recruitment of a GAP-G3BP complex when Ras is in its activated conformation.

scholarly journals The Ras GTPase-activating Protein (GAP) Is an SH3 Domain-binding Protein and Substrate for the Src-related Tyrosine Kinase, Hck

1995 ◽  
Vol 270 (24) ◽  
pp. 14718-14724 ◽  
Author(s):  
Scott D. Briggs ◽  
Sophia S. Bryant ◽  
Richard Jove ◽  
Sam D. Sanderson ◽  
Thomas E. Smithgall
Keyword(s):  
Tyrosine Kinase ◽  
Binding Protein ◽  
Sh3 Domain ◽  
Gtpase Activating Protein ◽  
Ras Gtpase
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