scholarly journals rho, a Small GTP-Binding Protein, Is Essential for Shigella Invasion of Epithelial Cells

1997 ◽  
Vol 185 (2) ◽  
pp. 281-292 ◽  
Author(s):  
Masahisa Watarai ◽  
Yoichi Kamata ◽  
Shunji Kozaki ◽  
Chihiro Sasakawa
Keyword(s):  
Epithelial Cells ◽  
Cho Cells ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Shigella Flexneri ◽  
Chinese Hamster ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Causative Agents ◽  
Invasive Capacity

Shigella, the causative agents of bacillary dysentery, are capable of invading mammalian cells that are not normally phagocytic. Uptake of bacteria by the mammalian cells is directed by bacterial factors named IpaB, IpaC, and IpaD invasins, in which Ipa invasins secreted into the bacterial environment can interact with α5β1 integrin. We report here that Shigella invasion of epithelial cells requires rho activity, a ras-related GTP-binding protein. The invasive capacity of Shigella flexneri for Chinese hamster ovary (CHO) cells and other epithelial cells were greatly reduced when treated with Clostridium botulinum exoenzyme C3 transferase. Conversely, uptake of bacteria by CHO cells was promoted upon microinjection of an activated rho variant, Val14RhoA. Attachment of S. flexneri to CHO cells can elicit tyrosine phosphorylation of pp125FAK and paxillin, localized accumulation of F-actin, vinculin, and talin, and activation of protein kinase C, which were all blocked by the treatment with C3 transferase. Our results indicate that cellular signal transduction regulated by rho is essential for Shigella invasion of epithelial cells.

scholarly journals Interaction of Ipa proteins of Shigella flexneri with alpha5beta1 integrin promotes entry of the bacteria into mammalian cells.

1996 ◽  
Vol 183 (3) ◽  
pp. 991-999 ◽  
Author(s):  
M Watarai ◽  
S Funato ◽  
C Sasakawa
Keyword(s):  
Epithelial Cells ◽  
Cho Cells ◽  
Mammalian Cells ◽  
Shigella Flexneri ◽  
Chinese Hamster ◽  
Invasive Capacity ◽  
Beta 1 Integrin ◽  
Cellular Components

Shigella is a genus of highly adapted bacterial pathogens that cause bacillary dysentery in humans. Bacteria reaching the colon invade intestinal epithelial cells by a process of bacterial-directed endocytosis mediated by the Ipa proteins: IpaB, IpaC, and IpaD of Shigella. The invasion of epithelial cells is thought to be a receptor-mediated phenomenon, although the cellular components of the host that interact with the Ipa proteins have not yet been identified. We report here that in a Shigella flexneri invasive system and Chinese hamster ovary (CHO) cell monolayers, the Ipa proteins were capable of interacting directly with alpha5beta1 integrin. The invasive capacity of S. flexneri for CHO cells increased as levels of alpha5beta1 integrin were elevated. When CHO cells were infected with S. flexneri, the tyrosine phosphorylation both of pp 125FAK, an integrin-regulated 125 K focal adhesion kinase, and of paxillin was stimulated. In contrast, an isogenic strain of S. flexneri that was defective in invasion owing to a mutation in its spa32 gene failed to induce such phosphorylation. Under in vitro and in vivo conditions, the released IpaB, IpaC, and IpaD proteins bound to alpha 5 beta 1 integrin in a manner different from that of soluble fibronectin but similar to that of the tissue form of fibronectin. At the site of attachment of S. flexneri to CHO cells, alpha5beta1 integrin converged with polymerization of actin. These data thus suggest that the capacity of Ipa proteins to interact with alpha5beta1 integrin may be an important Shigella factor in triggering the reorganization of actin cytoskeletons.

scholarly journals Rab1b regulates vesicular transport between the endoplasmic reticulum and successive Golgi compartments.

1991 ◽  
Vol 115 (1) ◽  
pp. 31-43 ◽  
Author(s):  
H Plutner ◽  
A D Cox ◽  
S Pind ◽  
R Khosravi-Far ◽  
J R Bourne ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Essential Role ◽  
Secretory Pathway ◽  
Binding Protein ◽  
Vesicular Transport ◽  
Initial Step ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Golgi Compartment

We report an essential role for the ras-related small GTP-binding protein rab1b in vesicular transport in mammalian cells. mAbs detect rab1b in both the ER and Golgi compartments. Using an assay which reconstitutes transport between the ER and the cis-Golgi compartment, we find that rab1b is required during an initial step in export of protein from the ER. In addition, it is also required for transport of protein between successive cis- and medial-Golgi compartments. We suggest that rab1b may provide a common link between upstream and downstream components of the vesicular fission and fusion machinery functioning in early compartments of the secretory pathway.

The small GTP-binding protein Rho regulates a phosphatidylinositol 4-phosphate 5-kinase in mammalian cells

Cell ◽  
1994 ◽  
Vol 79 (3) ◽  
pp. 507-513 ◽  
Author(s):  
Lisa D. Chong ◽  
Alexis Traynor-Kaplan ◽  
Gary M. Bokoch ◽  
Martin Alexander Schwartz
Keyword(s):  
Mammalian Cells ◽  
Binding Protein ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Phosphatidylinositol 4

scholarly journals A mammalian inhibitory GDP/GTP exchange protein (GDP dissociation inhibitor) for smg p25A is active on the yeast SEC4 protein.

1991 ◽  
Vol 11 (5) ◽  
pp. 2909-2912 ◽  
Author(s):  
T Sasaki ◽  
K Kaibuchi ◽  
A K Kabcenell ◽  
P J Novick ◽  
Y Takai
Keyword(s):  
Exchange Reaction ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Yeast Cells ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Constitutive Secretion ◽  
Gdp Dissociation Inhibitor ◽  
Exchange Protein

Evidence is accumulating that smg p25A, a small GTP-binding protein, may be involved in the regulated secretory processes of mammalian cells. The SEC4 protein is known to be required for constitutive secretion in yeast cells. We show here that the mammalian GDP dissociation inhibitor (GDI), which was identified by its action on smg p25A, is active on the yeast SEC4 protein in inhibiting the GDP/GTP exchange reaction and is capable of forming a complex with the GDP-bound form of the SEC4 protein but not with the GTP-bound form. These results together with our previous findings that smg p25A GDI is found in mammalian cells with both regulated and constitutive secretion types suggest that smg p25A GDI plays a role in both regulated and constitutive secretory processes, although smg p25A itself may be involved only in regulated secretory processes. These results also suggest that a GDI for the SEC4 protein is present in yeast cells.

scholarly journals The Small GTP-binding Protein R-Ras Can Influence Integrin Activation by Antagonizing a Ras/Raf-initiated Integrin Suppression Pathway

1999 ◽  
Vol 10 (6) ◽  
pp. 1799-1809 ◽  
Author(s):  
Tariq Sethi ◽  
Mark H. Ginsberg ◽  
Julian Downward ◽  
Paul E. Hughes
Keyword(s):  
Binding Protein ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Integrin Activation ◽  
Gtp Binding Protein ◽  
Ovary Cells ◽  
Downstream Effector ◽  
Gtp Binding ◽  
Downstream Effectors ◽  
Rapid Modulation

The rapid modulation of ligand-binding affinity (“activation”) is a central property of the integrin family of cell adhesion receptors. The small GTP-binding protein Ras and its downstream effector kinase Raf-1 suppress integrin activation. In this study we explored the relationship between Ras and the closely related small GTP-binding protein R-Ras in modulating the integrin affinity state. We found that R-Ras does not seem to be a direct activator of integrins in Chinese hamster ovary cells. However, we observed that GTP-bound R-Ras strongly antagonizes the Ras/Raf-initiated integrin suppression pathway. Furthermore, this reversal of the Ras/Raf suppressor pathway does not seem to be via a competition between Ras and R-Ras for common downstream effectors or via an inhibition of Ras/Raf-induced MAP kinase activation. Thus, R-Ras and Ras may act in concert to regulate integrin affinity via the activation of distinct downstream effectors.

A mammalian inhibitory GDP/GTP exchange protein (GDP dissociation inhibitor) for smg p25A is active on the yeast SEC4 protein

1991 ◽  
Vol 11 (5) ◽  
pp. 2909-2912
Author(s):  
T Sasaki ◽  
K Kaibuchi ◽  
A K Kabcenell ◽  
P J Novick ◽  
Y Takai
Keyword(s):  
Exchange Reaction ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Yeast Cells ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Constitutive Secretion ◽  
Gdp Dissociation Inhibitor ◽  
Exchange Protein

Evidence is accumulating that smg p25A, a small GTP-binding protein, may be involved in the regulated secretory processes of mammalian cells. The SEC4 protein is known to be required for constitutive secretion in yeast cells. We show here that the mammalian GDP dissociation inhibitor (GDI), which was identified by its action on smg p25A, is active on the yeast SEC4 protein in inhibiting the GDP/GTP exchange reaction and is capable of forming a complex with the GDP-bound form of the SEC4 protein but not with the GTP-bound form. These results together with our previous findings that smg p25A GDI is found in mammalian cells with both regulated and constitutive secretion types suggest that smg p25A GDI plays a role in both regulated and constitutive secretory processes, although smg p25A itself may be involved only in regulated secretory processes. These results also suggest that a GDI for the SEC4 protein is present in yeast cells.

scholarly journals A human homologue of the yeast GST1 gene codes for a GTP-binding protein and is expressed in a proliferation-dependent manner in mammalian cells.

1989 ◽  
Vol 8 (12) ◽  
pp. 3807-3814 ◽  
Author(s):  
S. Hoshino ◽  
H. Miyazawa ◽  
T. Enomoto ◽  
F. Hanaoka ◽  
Y. Kikuchi ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Binding Protein ◽  
Dependent Manner ◽  
Human Homologue ◽  
Gtp Binding Protein ◽  
Gtp Binding
Sign in / Sign up

Export Citation Format

Share Document