It is believed that there exists some relationship between the distribution and morphology of intracellular actin and cell adherence. Cells are likely to be deteched when the quantity of actin filament decreases. Actin filaments locate in the fringe of cancer cells and cells cultured in static state, so that these filaments can stretch out and form pseudopodia to adhere to the matrix. When these cells are stimulated their pseudopodia retract so that they can easily be detached from the matrix. When external forces are exerted on cells to adhere and deadhere from the matrix, the morphology and distribution of skeleton actin will change, so as the cells' morphology. The skeleton actins in cells are changed differently to adapt to different external forces which are imposed on the cells. It is obvious that the relationship between the mechanism of cell adhering to the matrix and the morphology & distribution of actins needs more attention.
Actin Cytoskeleton ; metabolism ; Actins ; metabolism ; Cell Adhesion ; Humans ; Neoplasms ; metabolism ; pathology ; Pseudopodia ; metabolism ; Shear Strength

OBJECTIVETo investigate the role of p53 gene in serum-induced cell migration.

METHODSThe effects of p53 knockout on serum-induced formation of lamellipodia and cell migration were observed using Transwell cell migration system.

RESULTSp53(+/+) cells developed lamellipodia upon serum stimulation and showed enhanced activity of cell migration, but these effects were not observed in p53 knockout cells after serum stimulation.

CONCLUSIONp53 plays a role in serum-induced cell migration.

Animals ; Cell Line ; Cell Movement ; genetics ; Gene Expression Regulation ; Gene Knockout Techniques ; Mice ; Pseudopodia ; genetics ; metabolism ; Serum ; metabolism ; Tumor Suppressor Protein p53 ; deficiency ; genetics ; metabolism

Brain ; Cholesterol ; chemistry ; Cytoskeleton ; drug effects ; Endothelial Cells ; cytology ; metabolism ; Hemolysin Proteins ; chemistry ; pharmacology ; Humans ; Phalloidine ; pharmacology ; Pseudopodia ; drug effects ; Stress Fibers ; drug effects ; rac1 GTP-Binding Protein ; metabolism ; rhoA GTP-Binding Protein ; metabolism

Molecular mechanisms underlying the effects of Fyn on cell morphology, pseudopodium movement, and cell migration were investigated. The Fyn gene was subcloned into pEGFP-N1 to produce pEGFP-N1-Fyn. Chinese hamster ovary (CHO) cells were transfected with pEGFP-N1-Fyn. The expression of Fyn mRNA and proteins was monitored by reverse transcription-PCR and Western blotting. Additionally, transfected cells were stained with 4',6-diamidino-2-phenylindole and a series of time-lapse images was taken. Sequences of the recombinant plasmids pMD18-T-Fyn and pEGFP-N1-Fyn were confirmed by sequence identification using National Center for Biotechnology Information in USA, and Fyn expression was detected by RT-PCR and Western blotting. The morphology of CHO cells transfected with the recombinant vector was significantly altered. Fyn expression induced filopodia and lamellipodia formation. Based on these results, we concluded that overexpression of mouse Fyn induces the formation of filopodia and lamellipodia in CHO cells, and promotes cell movement.
Animals ; Blotting, Western ; CHO Cells ; Cricetinae ; Cricetulus ; Genetic Vectors ; Green Fluorescent Proteins/genetics ; Mice ; Proto-Oncogene Proteins c-fyn/genetics/*metabolism ; Pseudopodia/*metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Time-Lapse Imaging ; Transfection

The dynamic polar polymers actin filaments and microtubules are usually employed to provide the structural basis for establishing cell polarity in most eukaryotic cells. Radially round and immotile spermatids from nematodes contain almost no actin or tubulin, but still have the ability to break symmetry to extend a pseudopod and initiate the acquisition of motility powered by the dynamics of cytoskeleton composed of major sperm protein (MSP) during spermiogenesis (sperm activation). However, the signal transduction mechanism of nematode sperm activation and motility acquisition remains poorly understood. Here we show that Ca(2+) oscillations induced by the Ca(2+) release from intracellular Ca(2+) store through inositol (1,4,5)-trisphosphate receptor are required for Ascaris suum sperm activation. The chelation of cytosolic Ca(2+) suppresses the generation of a functional pseudopod, and this suppression can be relieved by introducing exogenous Ca(2+) into sperm cells. Ca(2+) promotes MSP-based sperm motility by increasing mitochondrial membrane potential and thus the energy supply required for MSP cytoskeleton assembly. On the other hand, Ca(2+) promotes MSP disassembly by activating Ca(2+)/calmodulin-dependent serine/threonine protein phosphatase calcineurin. In addition, Ca(2+)/camodulin activity is required for the fusion of sperm-specifi c membranous organelle with the plasma membrane, a regulated exocytosis required for sperm motility. Thus, Ca(2+) plays multifunctional roles during sperm activation in Ascaris suum.
Animals ; Ascaris suum ; metabolism ; Calcineurin ; metabolism ; Calcium ; metabolism ; Calmodulin ; metabolism ; Cytoskeleton ; metabolism ; Cytosol ; metabolism ; Egtazic Acid ; analogs & derivatives ; pharmacology ; Helminth Proteins ; metabolism ; Inositol 1,4,5-Trisphosphate Receptors ; metabolism ; Male ; Membrane Potential, Mitochondrial ; physiology ; Mitochondria ; metabolism ; Pseudopodia ; metabolism ; Signal Transduction ; Sperm Motility ; Spermatids ; drug effects ; physiology ; Spermatogenesis ; Type C Phospholipases ; metabolism