MicroRNA expression and its implications for diagnosis and therapy of tongue squamous cell carcinoma

Tongue squamous cell carcinoma (TSCC) is the most common type of oral squamous cell carcinomas and is well known for its high rate of lymph nodal metastasis. Despite the identification of many molecular mechanisms in TSCC, the number of deaths associated with TSCC increased during the past 5 years. MicroRNAs (miRNAs) are a family of small non‐coding RNA molecules, which regulate gene expression by either translational inhibition or mRNA degradation. miRNAs have been proven to be key regulators of various biological and pathological processes including cell proliferation, development and tumourigenesis. Increasing evidence has demonstrated that the deregulated miRNAs are implicated in the diagnosis and treatment of TSCC. In this review, we summarized the expressions and roles of miRNAs in TSCC and comment on the potential roles of miRNAs in diagnosis, prognosis and treatment of this malignancy.     

Myosin VI,an actin motor for membrane traffic and cell migration

The actin cytoskeleton and associated myosin motor proteins are essential for the transport and steady-state localization of vesicles and organelles and for the dynamic remodeling of the plasma membrane as well as for the maintenance of differentiated cell-surface structures. Myosin VI may be expected to have unique cellular functions, because it moves, unlike almost all other myosins, towards the minus end of actin filaments. Localization and functional studies indicate that myosin VI plays a role in a variety of different intracellular processes, such as endocytosis and secretion as well as cell migration. These diverse functions of myosin VI are mediated by interaction with a range of different binding partners .     

Pulsatile contractions promote apoptotic cell extrusion in epithelial tissues

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Patterns in Space: Coordinating Adhesion and Actomyosin Contractility at E-cadherin Junctions

Abstract

Cadherin adhesion receptors are fundamental determinants of tissue organization in health and disease. Increasingly, we have come to appreciate that classical cadherins exert their biological actions through active cooperation with the contractile actin cytoskeleton. Rather than being passive resistors of detachment forces, cadherins can regulate the assembly and mechanics of the contractile apparatus itself. Moreover, coordinate spatial patterning of adhesion and contractility is emerging as a determinant of morphogenesis. Here we review recent developments in cadherins and actin cytoskeleton cooperativity, by focusing on E-cadherin adhesive patterning in the epithelia. Next, we discuss the underlying principles of cellular rearrangement during Drosophila germband extension and epithelial cell extrusion, as models of how planar and apical–lateral patterns of contractility organize tissue architecture.     

Patterns of expression of muscle-specific markers of differentiation in satellite cell cultures: determination by enzyme-linked immunoculture assay and confocal immunofluorescent assay

Equine satellite cell clone SE-11 and ovine satellite cell clone I(1)were evaluated for expression of myosin heavy chain, myogenin, desmin, and muscle-specific actin over a 240 h period in culture. An enzyme-linked immunoculture assay (ELICA) was capable of detecting these proteins at all time points evaluated. A linear relationship was demonstrated between the natural logarithm of the absorbance values (corrected for cell number) from the ELICA and percent fusion in both SE-11 and I(1)cultures. The r(2)values for SE-11 cultures were: desmin 0.82, muscle actin 0.81, myogenin 0.78, and myosin 0.70. The r(2)values for I(1)cultures were: desmin 0.77, muscle actin 0.72, myogenin 0.70, and myosin 0.61. Our confocal results support the idea that differences exist between species in the differentiation dynamics of satellite cells. Further, these data suggest that the ELICA may be applied to previously conducted experiments, enabling additional data to be obtained with relation to muscle protein expression.     

Emerging role for nuclear rotation and orientation in cell migration

Nucleus movement, positioning, and orientation is precisely specified and actively regulated within cells, and it plays a critical role in many cellular and developmental processes. Mutation of proteins that regulate the nucleus anchoring and movement lead to diverse pathologies, laminopathies in particular, suggesting that the nucleus correct positioning and movement is essential for proper cellular function. In motile cells that polarize toward the direction of migration, the nucleus undergoes controlled rotation promoting the alignment of the nucleus with the axis of migration. Such spatial organization of the cell appears to be optimal for the cell migration. Nuclear reorientation requires the cytoskeleton to be anchored to the nuclear envelope, which exerts pulling or pushing torque on the nucleus. Here we discuss the possible molecular mechanisms regulating the nuclear rotation and reorientation and the significance of this type of nuclear movement for cell migration.     

Emerging role for nuclear rotation and orientation in cell migration

Nucleus movement, positioning, and orientation is precisely specified and actively regulated within cells, and it plays a critical role in many cellular and developmental processes. Mutation of proteins that regulate the nucleus anchoring and movement lead to diverse pathologies, laminopathies in particular, suggesting that the nucleus correct positioning and movement is essential for proper cellular function. In motile cells that polarize toward the direction of migration, the nucleus undergoes controlled rotation promoting the alignment of the nucleus with the axis of migration. Such spatial organization of the cell appears to be optimal for the cell migration. Nuclear reorientation requires the cytoskeleton to be anchored to the nuclear envelope, which exerts pulling or pushing torque on the nucleus. Here we discuss the possible molecular mechanisms regulating the nuclear rotation and reorientation and the significance of this type of nuclear movement for cell migration.     

Extracellular matrix- and cytoskeleton-dependent changes in cell shape and stiffness

Cell spreading is correlated with changes in important cell functions including DNA synthesis, motility, and differentiation. Spreading is accompanied by a complex reorganization of the cytoskeleton that can be related to changes in cell stiffness. While cytoskeletal organization and the resulting cell stiffness have been studied in motile cells such as fibroblasts, less is known of these events in nonmigratory, epithelial cells. Hence, we examined the relationship between cell function, spreading, and stiffness, as measured by atomic force microscopy. Cell stiffness increased with spreading on a high density of fibronectin (1000 ng/cm(2)) but remained low in cells that stayed rounded on a low fibronectin density (1 ng/cm(2)). Disrupting actin or myosin had the same effect of inhibiting spreading, but had different effects on stiffness. Disrupting f-actin assembly lowered both stiffness and spreading, while inhibiting myosin light chain kinase inhibited spreading but increased cell stiffness. However, disrupting either actin or myosin inhibited DNA synthesis. These results demonstrate the relationship between cell stiffness and spreading in hepatocytes. They specifically show that normal actin and myosin function is required for hepatocyte spreading and DNA synthesis and demonstrate opposing effects on cell stiffness upon disruption of actin and myosin.     

Maintaining epithelial integrity: a function for gigantic spectraplakin isoforms in adherens junctions

The Short stop (Shot/Kakapo) spectraplakin is a giant cytoskeletal protein, which exists in multiple isoforms with characteristics of both spectrin and plakin superfamilies. Previously characterized Shot isoforms are similar to spectrin and dystrophin, with an actin-binding domain followed by spectrin repeats. We describe a new large exon within the shot locus, which encodes a series of plakin repeats similar to the COOH terminus of plakins such as plectin and BPAG1e. We find that the plakin repeats are inserted between the actin-binding domain and spectrin repeats, generating isoforms as large as 8,846 residues, which could span 400 nm. These novel isoforms localized to adherens junctions of embryonic and follicular epithelia. Loss of Shot within the follicle epithelium leads to double layering and accumulation of actin and ZO-1 in between, and a reduction of Armadillo and Discs lost within, mutant cells, indicative of a disruption of adherens junction integrity. Thus, we identify a new role for spectraplakins in mediating cell-cell adhesion.     

Myosin-II reorganization during mitosis is controlled temporally by its dephosphorylation and spatially by Mid1 in fission yeast

Cytokinesis in many eukaryotes requires an actomyosin contractile ring. Here, we show that in fission yeast the myosin-II heavy chain Myo2 initially accumulates at the division site via its COOH-terminal 134 amino acids independently of F-actin. The COOH-terminal region can access to the division site at early G2, whereas intact Myo2 does so at early mitosis. Ser1444 in the Myo2 COOH-terminal region is a phosphorylation site that is dephosphorylated during early mitosis. Myo2 S1444A prematurely accumulates at the future division site and promotes formation of an F-actin ring even during interphase. The accumulation of Myo2 requires the anillin homologue Mid1 that functions in proper ring placement. Myo2 interacts with Mid1 in cell lysates, and this interaction is inhibited by an S1444D mutation in Myo2. Our results suggest that dephosphorylation of Myo2 liberates the COOH-terminal region from an intramolecular inhibition. Subsequently, dephosphorylated Myo2 is anchored by Mid1 at the medial cortex and promotes the ring assembly in cooperation with F-actin.     

MARCKS phosphorylation by PKC strongly impairs cell polarity in the chick neural plate

Neurulation involves a complex coordination of cellular movements that are in great part based on the modulation of the actin cytoskeleton. MARCKS, an F‐actin‐binding protein and the major substrate for PKC, is necessary for gastrulation and neurulation morphogenetic movements in mice, frogs, and fish. We previously showed that this protein accumulates at the apical region of the closing neural plate in chick embryos, and here further explore its role in this process and how it is regulated by PKC phosphorylation. PKC activation by PMA caused extensive neural tube closure defects in cultured chick embryos, together with MARCKS phosphorylation and redistribution to the cytoplasm. This was concomitant with an evident disruption of neural plate cell polarity and extensive apical cell extrusion. This effect was not due to actomyosin hypercontractility, but it was reproduced upon MARCKS knockdown. Interestingly, the overexpression of a nonphosphorylatable form of MARCKS was able to revert the cellular defects observed in the neural plate after PKC activation. Altogether, these results suggest that MARCKS function during neurulation would be to maintain neuroepithelial polarity through the stabilization of subapical F‐actin, a function that appears to be counteracted by PKC activation.     

Fission yeast cytoskeletons and cell polarity factors: connecting at the cortex

Cell polarity is a fundamental property of cells from unicellular to multicellular organisms. Most of the time, it is essential so that the cells can achieve their function. The fission yeast Schizosaccharomyces pombe is a powerful genetic model organism for studying the molecular mechanisms of the cell polarity process. Indeed, S. pombe cells are rod-shaped and cell growth is restricted at the poles. The accurate localization of the cell growth machinery at the cell cortex, which involves the actin cytoskeleton, depends on cell polarity pathways that are temporally and spatially regulated. The importance of interphase microtubules and cell polarity factors acting at the cortex of cell ends in this process has been shown. Here, we review recent advances in knowledge of molecular pathways leading to the establishment of a cellular axis in fission yeast. We also describe the role of cortical proteins and mitotic cytoskeletal rearrangements that control the symmetry of cell division.     

Current approaches in dendritic cell generation and future implications for cancer immunotherapy

The discovery of tumor-associated antigens, which are either selectively or preferentially expressed by tumors, together with an improved insight in dendritic cell biology illustrating their key function in the immune system, have provided a rationale to initiate dendritic cell-based cancer immunotherapy trials. Nevertheless, dendritic cell vaccination is in an early stage, as methods for preparing tumor antigen presenting dendritic cells and improving their immunostimulatory function are continuously being optimized. In addition, recent improvements in immunomonitoring have emphasized the need for careful design of this part of the trials. Still, valuable proofs-of-principle have been obtained, which favor the use of dendritic cells in subsequent, more standardized clinical trials. Here, we review the recent developments in clinical DC generation, antigen loading methods and immunomonitoring approaches for DC-based trials.     

Cell competition and its implications for development and cancer

Cell competition is a struggle for existence between cells in heterogeneous tissues of multicellular organisms.Loser cells,which die during cell competition,are normally viable when grown only with other loser cells,but when mixed with winner cells,they are at a growth disadvantage and undergo apoptosis.Intriguingly,several recent studies have revealed that cells bearing mutant tumor-suppressor genes,which show overgrowth and tumorigenesis in a homotypic situation,are frequently eliminated,through cell competition,from tissues in which they are surrounded by wild-type cells.Here,we focus on the regulation of cellular competitiveness and the mechanism of cell competition as inferred from two different categories of mutant cells:(1) slower-growing cells and (2) structurally defective cells.We also discuss the possible role of cell competition as an intrinsic homeostasis system through which normal cells sense and remove aberrant cells,such as precancerous cells,to maintain the integrity and normal development of tissues and organs.     

Hepatic stellate cell activation in vitro: cell cycle arrest at G2/M and modification of cell motility

Hepatic fibrosis is a common response to chronic liver injury and is characterized by increased production of extracellular matrix components, whose major part is produced by hepatic stellate cells activated by inflammatory mediators to proliferate and migrate into the injured regions. GRX cells are a model of hepatic stellate cells characterized as myofibroblasts by morphological and biochemical criteria. We have recently shown that they respond to inflammatory mediators and cytokines present in the concanavalin A-activated spleen cell supernatant (SCS) by quantitative changes in the expression of intermediate filaments. The present study investigated the effects of SCS and TNF-alpha on the GRX cell proliferation and on the organization of the actin cytoskeleton. SCS and TNF-alpha diminished the culture cell density, with an increase of cell [(3)H]thymidine incorporation and of cellular protein content, indicating an arrest in the G2/M phase of the cell cycle, which was reversible 48 h after removal of SCS. This effect was abrogated by dibutiryl-cAMP. Actin cytoskeleton reorganization was observed after 24 h treatment, indicating increased cell motility. Our results suggest that inflammation-dependent activation of stellate cells occurs in ordered interaction and coordination of proinflammatory agents. The increase of cAMP levels activates the conversion of lipocytes into myofibroblasts and increases the number of cells that can participate in repair. Since cAMP retains cells in the G1 phase, cytokines of the TNF-alpha group are required for cell proliferation inducing the entry into the S phase. The progression through the G2/M checkpoint is mediated again by increased cAMP levels.     

Organization of GPI-anchored proteins at the cell surface and its physiopathological relevance

Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) are a class of proteins attached to the extracellular leaflet of the plasma membrane via a post-translational modification, the glycolipid anchor. The presence of both glycolipid anchor and protein portion confers them unique features. GPI-APs are expressed in all eukaryotes, from fungi to plants and animals. They display very diverse functions ranging from enzymatic activity, signaling, cell adhesion, cell wall metabolism, neuritogenesis, and immune response. Likewise other plasma membrane proteins, the spatio-temporal organization of GPI-APs is critical for their biological activities in physiological conditions. In this review, we will summarize the latest findings on plasma membrane organization of GPI-APs and the mechanism of its regulation in different cell types. We will also examine the involvement of specific GPI-APs namely the prion protein PrP^C, the Folate Receptor alpha and the urokinase plasminogen activator receptor in human diseases focusing on neurodegenerative diseases and cancer.