The cytoskeleton consists of 3 filamentous components: intermediate filaments, microtubules, and actin filaments. Actin filaments continuously assemble and disassemble far out of equilibrium to adapt cells in response to external stimuli. Actin filaments organization and dynamic are controlled by a multitude of actin-binding proteins including actin-bundling proteins. L-plastin, expressed abundantly in lymphocytes and monocytes, is an actin-bundling protein that roles in immune defense and in metastatic invasion of cancer cells. The actin-bundling activity of L-plastin is regulated not only by intracellular calcium concentration, but by phosphorylation of Ser5. The actin-bundling activity of L-pastin decreases by increased calcium concentration but is promoted by phosphorylation of Ser5. The morphology changes and motility of cells requires continuous remodeling of actin filaments which demands the sensitive nature of L-plastin to Ca2+-signal, phosphorylation of Ser5, and probably additional regulation. This review briefly describes the structure and regulation of L-plastin, and roles for L-plastin in cancer invasion and in macrophages.
Actin Cytoskeleton ; Calcium ; Cytoskeleton ; Intermediate Filaments ; Lymphocytes ; Macrophages* ; Microfilament Proteins ; Microtubules ; Monocytes ; Phosphorylation

BACKGROUND: Intermediate filaments as well as microtubule and microfilament are major components of cytoskeleton of human cells. Melanocytes have vimentin intermediate filament, which have not been well investigated as other cytoskeletons, especially in their function. OBJECTIVE: The purpose of this study was to observe the motile characteristics of vimentin intermediate filament in living B16 melanoma cells. METHODS: The motile properties of vimentin intermediate filament have been studied in living B16 melanoma cells using green fluorescent protein(GFP). cDNA expressing GFP-vimentin fusion protein was cloned and transfected into living B16 melanoma cells. Living cells were observed under fluorescent microscope and confocal microscope. Time-lapse images were collected and analysed. RESULTS: GFP-vimentin is incorporated into the endogenous vimentin networks. Time-lapse observations of vimentin fibrils demonstrate that they are constantly changing their configurations. Intersecting points of vimentin fibrils, or foci, frequently move towards or away from each other, indicating that the fibrils can lengthen or shorten. Fluorescence recovery after photobleaching shows that bleach zones across fibrils rapidly recover their fluorescence. During this recovery, bleached zones frequently move, indicating translocation of fibrils. Short filamentous structures('squiggle') are also seen actively translocating. Melanosomes also are changing their position back-and-pro constantly. They are co-localized very well with kinesin molecules in B16 melanoma cells. CONCLUSION: The vimentin intermediate filament and melanosomes in B16 melanoma cells have very active movement, which seem to have close relation with kinesin motor proteins.
Actin Cytoskeleton ; Clone Cells ; Cytoskeleton ; DNA, Complementary ; Fluorescence ; Fluorescence Recovery After Photobleaching ; Humans ; Intermediate Filaments* ; Kinesin ; Melanocytes ; Melanoma, Experimental* ; Melanosomes ; Microtubules ; Vimentin*

Microtubules are the prime component of the cytoskeleton along with microfilaments. Being vital for organelle transport and cellular divisions during spermatogenesis and sperm motility process, microtubules ascertain functional capacity of sperm. Also, microtubule based structures such as axoneme and manchette are crucial for sperm head and tail formation. This review (a) presents a concise, yet detailed structural overview of the microtubules, (b) analyses the role of microtubule structures in various male reproductive functions, and (c) presents the association of microtubular dysfunctions with male infertility. Considering the immense importance of microtubule structures in the formation and maintenance of physiological functions of sperm cells, this review serves as a scientific trigger in stimulating further male infertility research in this direction.]]>
Actin Cytoskeleton ; Axoneme ; Cytoskeleton ; Humans ; Infertility, Male ; Kartagener Syndrome ; Male ; Male ; Microtubule-Associated Proteins ; Microtubules ; Organelles ; Sperm Head ; Sperm Motility ; Spermatogenesis ; Spermatozoa ; Tail

Bile canaliculi is closely related to the cytoskeleton; actin filament web, microtubules and cytokeratin intermediate filaments. To understand how cytoskeletal alteration affects bile canalicular structure, the investigators injected cytochalasin B and colchicine into mice intraperitoneally to inhibit the polymerization of actin filaments and microtubules respectively, and observed the structural changes of bile canaliculi and hepatocytes with transmission and scanning electron microscopes. Bile canaliculi were dilatated and microvilli were decreased in number and length after injection of cytochalasin B and colchicine. Some bile canaliculi branched irregularly after colchicine treatment. Actin filament web in the canalicular ectoplasm was disrupted leaving granular zone after cytochalasin B treatment, but was intact after colchicine treatment. Intermediate filament bundles located at angles to the canalicular membrane appeared after colchicine treatment. Intercellular junctions delimiting bile canaliculi were intact after colchicine treatment, however were disrupted after cytochalsin B treatment. Focal junctions resembling desmosome were formed between microvilli after colchicine treatment. In both cytochalasin B and colchicine treated groups, lumen of rough endoplasmic reticulum were dilated, Golgi apparatus became prominent, and lipid droplets were appeared in the cytoplasm. These results suggest that both intact actin filaments and microtubules are necessary to keep the structural integrity of bile canaliculi.
Actin Cytoskeleton ; Animals ; Bile Canaliculi* ; Bile* ; Colchicine* ; Cytochalasin B* ; Cytoplasm ; Cytoskeleton ; Desmosomes ; Endoplasmic Reticulum, Rough ; Golgi Apparatus ; Hepatocytes* ; Humans ; Intercellular Junctions ; Intermediate Filaments ; Keratins ; Liver* ; Membranes ; Mice* ; Microtubules ; Microvilli ; Polymerization ; Polymers ; Research Personnel

The Kingdom fungus has a unique structure and organization. Recent advances in electron microscopy and use of specific cytochemical technique enable the ultrastructures to be visualized. The hypha is a tube-like structure with a rigid wall, containing a moving slug of protoplasm. Hypha grows only at the tapered apical tip region, which is called extension zone. Extreme tip area has apical vesicle cluster which is responsible for tip growth. Unique fungal structure, Spitzenk rper, is thought to be a central region of the apical vesicle cluster. Most hyphal structures except the species belong to Zygomycetes have septa. But the septum is not completely blocked and it has different types of opening pores. The simple septal pores with Woronin bodies, which are found in Ascomycetes and Deuteromycetes, can be plugged in two different mechanisms. During normal differentiation the pores become occluded by a gradual deposition of plugged material. Loss of cytoplasm from damaged hyphae can be reduced and blocked by the rapid occlusion of septal pores by Woronin bodies or hexagonal crystal bodies. Septal sealing in Basidiomycetes which have dolipore septum is made by the rapid formation of electron-dense pore plugs. The shape of the fungal cell is the shape of fungal wall. Fungal walls appear to be composed of layers, which are thought to merge into one another to form one structure. The cytoskeleton consists of microtubules and microfilaments with motor proteins, and they seems to act together in the fungal cells.
Actin Cytoskeleton ; Ascomycota ; Basidiomycota ; Cytoplasm ; Cytoskeleton ; Fungal Structures ; Fungi ; Gastropoda ; Hyphae ; Microscopy, Electron ; Microtubules ; Mitosporic Fungi

OBJECTIVE: The purpose of this study was to evaluate the effect of Cytochalasin B (CCB) on the cytoskeletal stability of mouse oocyte frozen by vitrification. METHODS: Mouse oocytes retrieved from cycle stimulated by PMSG and hCG were treated by CCB and then vitrified in EFS-30. These oocytes were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing of the oocytes was carried out at room temperature for 5 seconds, then the EM grid was placed into 0.75 M, 0.5 M and 0.25 M sucrose at 37degress C for 3 minutes, each. These oocytes were fixed in 4% formaldehyde for an hour and then washed in PPB for 15 minutes 3 times, then incubated in PPB containing anti-tubulin monoclonal antibody at 4degress C overnight. And then, the oocytes were incubated with FITC-conjugated anti-mouse IgG and propidium iodide (PI) for 45 minutes. Pattern of microtubules and microfilaments of oocytes were evaluated with a confocal microscope. RESULTS: The rate of oocytes containing normal microtubules and microfilaments was significantly decreased after vitrification. The rate of oocyte containing normal microtubules in CCB treated group was higher than those in non-treated group (53.7% vs. 48.9%), but the difference was not significant. The rate of oocyte containing normal microfilaments in CCB treated group was significantly higher than those in non-treated group (64.5% vs. 38.3%, p<0.05).CONCLUSION: Microfilaments stability could be improved by CCB treatment prior to vitrification. It is suggested that CCB treatment prior to vitrification improve stability of cytoskeleton and then increase success rate in IVF-ET program using vitrification and thawing oocyte.
Actin Cytoskeleton ; Animals ; Cytochalasin B* ; Cytoskeleton ; Formaldehyde ; Immunoglobulin G ; Mice* ; Microtubules ; Nitrogen ; Oocytes* ; Propidium ; Sucrose ; Vitrification*

OBJECTIVE: The purpose of this study was to evaluate the effect of Cytochalasin B (CCB) on the cytoskeletal stability of mouse oocyte frozen by vitrification. METHODS: Mouse oocytes retrieved from cycle stimulated by PMSG and hCG were treated by CCB and then vitrified in EFS-30. These oocytes were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing of the oocytes was carried out at room temperature for 5 seconds, then the EM grid was placed into 0.75 M, 0.5 M and 0.25 M sucrose at 37degress C for 3 minutes, each. These oocytes were fixed in 4% formaldehyde for an hour and then washed in PPB for 15 minutes 3 times, then incubated in PPB containing anti-tubulin monoclonal antibody at 4degress C overnight. And then, the oocytes were incubated with FITC-conjugated anti-mouse IgG and propidium iodide (PI) for 45 minutes. Pattern of microtubules and microfilaments of oocytes were evaluated with a confocal microscope. RESULTS: The rate of oocytes containing normal microtubules and microfilaments was significantly decreased after vitrification. The rate of oocyte containing normal microtubules in CCB treated group was higher than those in non-treated group (53.7% vs. 48.9%), but the difference was not significant. The rate of oocyte containing normal microfilaments in CCB treated group was significantly higher than those in non-treated group (64.5% vs. 38.3%, p<0.05).CONCLUSION: Microfilaments stability could be improved by CCB treatment prior to vitrification. It is suggested that CCB treatment prior to vitrification improve stability of cytoskeleton and then increase success rate in IVF-ET program using vitrification and thawing oocyte.
Actin Cytoskeleton ; Animals ; Cytochalasin B* ; Cytoskeleton ; Formaldehyde ; Immunoglobulin G ; Mice* ; Microtubules ; Nitrogen ; Oocytes* ; Propidium ; Sucrose ; Vitrification*

UNLABELLEDOBJECTIVE To evaluate the effects of grooved, alkali- and heat-treated, acid-etched and TiO2 blasted surfaces of titanium substrates on F-actin cytoskeleton of osteoblasts in vitro.

METHODSOsteoblasts derived from fetal rat calvarial were cultured on 6 different commercially pure titanium discs-grooved(G), sandblasted (SB), sand-blasted and acid-etching (SLA) surfaces and alkali- and heat-treated (AH1, AH2, AH3) surfaces. For F-actin cytoskeleton measurement, osteoblasts whose filamentous actin was stained with phalloidin-TRITC were cultured for 1, 2, 4, 12 h, evaluated by CLSM observation.

RESULTSOsteoblasts attached to the different types of surfaces after 1 hour culture were similar. The actin cytoskeleton formed a ring of cortical filaments around the nucleus after 1 hour on SB, AH2, AH3, SLA surfaces. Actin filaments condensed along edges of pits. The actin filaments of seeded cells were spread after 2 h. The actin filaments on G formed bundles around the nucleus. The filaments began to parallel to the grooves. On AH1, the fibres formed a ring of cortical filaments around the nucleus with some cytoplasmic fibres radially oriented. On AH2, AH3, SB, the fibres orignised in a cytoplasmic meshwork with fibres which terminate at the ridge of depressions. The cell were suspending itself over the depressed areas. Actin filaments on SB were distinct and well formed that were oriented paralled to one another and the long axis of cells. After 4 h, actin filaments appeared organised in a parallel to one another and the long axis of cells. After 12 h, the actin filaments on all surfaces were well spread and were oriented paralled to another and to the long axis of the cell. The filaments formed bundles which reached to holes or adhered to the ridge of raised points, suspending cells over depressed areas.

CONCLUSIONAfter 12 h, the actin filaments on all surfaces were well spread and were oriented parallel to another and to the long axis of the cell. It was concluded that F-actin cytoskeleton of osteoblasts were spread best on SB surfaces among all surfaces.

Actin Cytoskeleton ; Actins ; Animals ; Cytoskeleton ; Microtubules ; Osteoblasts ; Prostheses and Implants ; Rats ; Surface Properties ; Titanium

OBJECTIVETo investigate the relationship between c-fos gene and filamentous actin (F-actin) in MG-63 osteoblasts under cyclic tensile stress.

METHODSMG-63 osteoblasts were subjected to cyclic tensile stress (0.5 Hz, 2 000 microstrain) for 3, 6, and 12 h. The changes of c-fos gene were investigated by fluorescent quantitation polymerase chain reaction. Then the best loading time group was screened as the experimental group compared with 0 h group. The changes of F-actin and c-fos were investigated with or without cytochalasin D treatment.

RESULTSCyclic tensile stress induced high expression of c-fos mRNA, and peaked at 3 h. After loading, F-actin had a structure reorganization, but had no change in expression. After cytochalasin D treatment, the formation of stress fibers and the fluorescence intensity of F-actin cytoskeleton significantly reduced, meanwhile the c-fos mRNA expression was inhibited.

CONCLUSIONAfter loading, there is only structure reorganization for F-actin, and the expression has not any change. That means the remodeling F-actin is the existing one. F-actin reorganization is an important part in c-fos gene expression induced by stress.

Actin Cytoskeleton ; Actins ; Cytochalasin D ; Cytoskeleton ; Genes, fos ; Humans ; Microtubules ; Osteoblasts ; RNA, Messenger ; Stress, Mechanical

OBJECTIVETo explore the response of rat bone marrow mesenchymal stem cells (MSCs and calvarial osteoblasts to mechanical strain and the consequent changes of cytoskeleton F-actin.

METHODSBone marrow MSCs and calvarial osteoblasts were isolated from SD rats and cultured in vitro. Mechanical stretch was performed on passage 3 cells at 2 000 microepsilon for 0, 2, 6 and 12 hours using four-point bending system. The response of cells and the distribution of F-actin were observed using fluorescent staining under laser scanning confocal microscope and the morphological parameters were quantified using image analysis software Laserpix.

RESULTSUnder mechanical stretch, the fluorescent staining decreased obviously at both MSCs and osteoblasts, and F-actin filaments were rearranged and became tenuous, thinner, and abnormally distributed. The outline of nucleus became unclear and apoptotic changes were observed at some of both cells. Cellular size decreased more significantly in MSCs than in osteoblasts. Quantity analysis showed that total area of cells, total fluorescent density and green fluorescent density (F-actin) were all significantly decreased in MSCs (P < 0.05 or P < 0.01), and total fluorescent density, green fluorescent density and red fluorescent density (nuclei) did also in osteoblasts (P < 0.05 or P < 0.01).

CONCLUSIONMechanical stretch caused extensive response on both MSCs and osteoblasts which led to the rearrangement of F-actin filament and apoptosis in some of these cells. MSCs were more sensitive to mechanical strain than osteoblasts.

Actin Cytoskeleton ; metabolism ; Actins ; metabolism ; Animals ; Bone Marrow Cells ; Cells, Cultured ; Cytoskeleton ; Mesenchymal Stromal Cells ; Microtubules ; Osteoblasts ; Rats ; Stress, Mechanical