Biomaterial Database

Growth factor induced activation of Rho and Rac GTPases and actin cytoskeletal reorganization in human lens epithelial cells. 2003

Rupalatha Maddala, and Venkat N Reddy, and David L Epstein, and Vasantha Rao

Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA.

OBJECTIVE To determine the involvement of the Rho GTPases-mediated signaling pathway in growth factor-stimulated actomyosin cytoskeletal organization and focal adhesion formation in lens epithelial cells. METHODS Serum starved human lens epithelial cells (SRA01/04) were treated with different growth factors including epidermal growth factor (EGF), basic-fibroblast growth factor (b-FGF), platelet derived growth factor (PDGF), transforming growth factor beta (TGF-beta), insulin-like growth factor 1 (IGF-1), lysophosphatidic acid (LPA), and thrombin. Growth factor stimulated activation of Rho and Rac GTPases were evaluated by GTP-loading pull-down assays. Changes in actin cytoskeletal organization and focal adhesions were determined by fluorescence staining using FITC-phalloidin and anti-vinculin antibody/rhodamine-conjugated secondary antibody, respectively. Fluorescence images were recorded using either confocal or fluorescence microscopy. RESULTS Rho GTPase activity was significantly augmented in human lens epithelial cells treated with EGF, b-FGF, TGF-beta, IGF-1, and LPA. Rac GTPase activation, in contrast, was significantly enhanced in response to only EGF or b-FGF. Serum starved human lens epithelial cells exhibited a strong increase in cortical actin stress fibers and integrin-mediated focal adhesions in response to b-FGF, PDGF, TGF-beta, thrombin, and LPA. While EGF induced a striking increase in membrane ruffling and a marginal increase on focal adhesion formation, IGF-1 had no effect on either. Pretreatment of lens epithelial cells with C3-exoenzyme (an irreversible inhibitor of Rho-GTPase), lovastatin (an isoprenylation inhibitor), or the Rho kinase inhibitor Y-27632 abolished the ability of the different growth factors to elicit actin stress fiber and focal adhesion formation. EGF induced membrane ruffling, however, was not suppressed by Y-27632 and C3-exoenzyme. CONCLUSIONS These results demonstrate that different growth factors induce actin cytoskeleton reorganization and formation of cell-ECM interactions in lens epithelial cells and this response of growth factors appears to be mediated, at least in part, through the Rho/Rho kinase-mediated signaling pathway. The ability of growth factors to trigger activation of Rho and Rac GTPases along with actomyosin cytoskeletal reorganization and formation of focal adhesions might well play a crucial role in lens epithelial cell proliferation, migration, elongation and survival.

UI	MeSH Term	Description	Entries
D007908	Lens, Crystalline	A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.	Eye Lens,Lens, Eye,Crystalline Lens
D008856	Microscopy, Fluorescence	Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.	Fluorescence Microscopy,Immunofluorescence Microscopy,Microscopy, Immunofluorescence,Fluorescence Microscopies,Immunofluorescence Microscopies,Microscopies, Fluorescence,Microscopies, Immunofluorescence
D002461	Cell Line, Transformed	Eukaryotic cell line obtained in a quiescent or stationary phase which undergoes conversion to a state of unregulated growth in culture, resembling an in vitro tumor. It occurs spontaneously or through interaction with viruses, oncogenes, radiation, or drugs/chemicals.	Transformed Cell Line,Cell Lines, Transformed,Transformed Cell Lines
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D003599	Cytoskeleton	The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.	Cytoplasmic Filaments,Cytoskeletal Filaments,Microtrabecular Lattice,Cytoplasmic Filament,Cytoskeletal Filament,Cytoskeletons,Filament, Cytoplasmic,Filament, Cytoskeletal,Filaments, Cytoplasmic,Filaments, Cytoskeletal,Lattice, Microtrabecular,Lattices, Microtrabecular,Microtrabecular Lattices
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D004847	Epithelial Cells	Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.	Adenomatous Epithelial Cells,Columnar Glandular Epithelial Cells,Cuboidal Glandular Epithelial Cells,Glandular Epithelial Cells,Squamous Cells,Squamous Epithelial Cells,Transitional Epithelial Cells,Adenomatous Epithelial Cell,Cell, Adenomatous Epithelial,Cell, Epithelial,Cell, Glandular Epithelial,Cell, Squamous,Cell, Squamous Epithelial,Cell, Transitional Epithelial,Cells, Adenomatous Epithelial,Cells, Epithelial,Cells, Glandular Epithelial,Cells, Squamous,Cells, Squamous Epithelial,Cells, Transitional Epithelial,Epithelial Cell,Epithelial Cell, Adenomatous,Epithelial Cell, Glandular,Epithelial Cell, Squamous,Epithelial Cell, Transitional,Epithelial Cells, Adenomatous,Epithelial Cells, Glandular,Epithelial Cells, Squamous,Epithelial Cells, Transitional,Glandular Epithelial Cell,Squamous Cell,Squamous Epithelial Cell,Transitional Epithelial Cell
D006133	Growth Substances	Signal molecules that are involved in the control of cell growth and differentiation.	Mitogens, Endogenous,Endogenous Mitogens
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man