Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 24
Filter
1.
Nat Cell Biol ; 9(3): 299-309, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17310241

ABSTRACT

Non-muscle myosin II has diverse functions in cell contractility, cytokinesis and locomotion, but the specific contributions of its different isoforms have yet to be clarified. Here, we report that ablation of the myosin IIA isoform results in pronounced defects in cellular contractility, focal adhesions, actin stress fibre organization and tail retraction. Nevertheless, myosin IIA-deficient cells display substantially increased cell migration and exaggerated membrane ruffling, which was dependent on the small G-protein Rac1, its activator Tiam1 and the microtubule moter kinesin Eg5. Myosin IIA deficiency stabilized microtubules, shifting the balance between actomyosin and microtubules with increased microtubules in active membrane ruffles. When microtubule polymerization was suppressed, myosin IIB could partially compensate for the absence of the IIA isoform in cellular contractility, but not in cell migration. We conclude that myosin IIA negatively regulates cell migration and suggest that it maintains a balance between the actomyosin and microtubule systems by regulating microtubule dynamics.


Subject(s)
Actomyosin/metabolism , Cell Movement/physiology , Microtubules/metabolism , Nonmuscle Myosin Type IIA/physiology , Aminoquinolines/pharmacology , Animals , Azepines/pharmacology , COS Cells , Cell Adhesion/physiology , Cell Movement/drug effects , Chlorocebus aethiops , Embryonic Stem Cells/cytology , Embryonic Stem Cells/drug effects , Embryonic Stem Cells/metabolism , Enzyme Inhibitors/pharmacology , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/metabolism , Guanine Nucleotide Exchange Factors/genetics , Guanine Nucleotide Exchange Factors/metabolism , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , Kinesins/antagonists & inhibitors , Kinesins/genetics , Kinesins/metabolism , Mice , Microtubules/drug effects , Naphthalenes/pharmacology , Nocodazole/pharmacology , Nonmuscle Myosin Type IIA/antagonists & inhibitors , Nonmuscle Myosin Type IIA/genetics , Nonmuscle Myosin Type IIB/antagonists & inhibitors , Nonmuscle Myosin Type IIB/genetics , Nonmuscle Myosin Type IIB/physiology , Pyrimidines/pharmacology , RNA, Small Interfering/genetics , T-Lymphoma Invasion and Metastasis-inducing Protein 1 , Thiones/pharmacology , Transfection , Vinblastine/pharmacology , rac1 GTP-Binding Protein/antagonists & inhibitors , rac1 GTP-Binding Protein/genetics , rac1 GTP-Binding Protein/metabolism
2.
J Immunol ; 188(3): 1234-44, 2012 Feb 01.
Article in English | MEDLINE | ID: mdl-22219328

ABSTRACT

The innate immune system responds to endogenous molecules released during cellular stress or those that have undergone modifications normally absent in healthy tissue. These structures are detected by pattern-recognition receptors, alerting the immune system to "danger." In this study, we looked for early signals that direct immune cells to cells undergoing stress before irreversible damage takes place. To avoid detecting signals emanating from apoptotic or necrotic cells we exposed fibroblasts to sublethal oxidative stress. Our results indicate that both nonenzymatic chemical reactions and aldehyde dehydrogenase-2-mediated enzymatic activity released signals from fibroblasts that selectively attracted CD14(+) monocytes but not T, NK, and NKT cells or granulocytes. Splenocytes from MyD88(-/-) mice did not migrate, and treatment with an inhibitory peptide that blocks MyD88 dimerization abrogated human monocyte migration. Monocyte migration was accompanied by downmodulation of CD14 expression and by the phosphorylation of IL-1R-associated kinase 1, a well-known MyD88-dependent signaling molecule. The scavenger receptor inhibitors, dextran sulfate and fucoidan, attenuated monocyte migration toward stressed cells and IL-1R-associated kinase 1 phosphorylation. Surprisingly, although monocyte migration was MyD88 dependent, it was not accompanied by inflammatory cytokine secretion. Taken together, these results establish a novel link between scavenger receptors and MyD88 that together function as sensors of oxidation-associated molecular patterns and induce monocyte motility. Furthermore, the data indicate that MyD88 independently regulates monocyte activation and motility.


Subject(s)
Cell Movement , Fibroblasts/physiology , Monocytes/physiology , Myeloid Differentiation Factor 88/physiology , Oxidative Stress/physiology , Receptors, Scavenger/physiology , Aldehyde Dehydrogenase , Animals , Fibroblasts/metabolism , Humans , Lipopolysaccharide Receptors , Macrophages , Mice , Myeloid Differentiation Factor 88/metabolism , Receptors, Scavenger/metabolism , Signal Transduction
3.
Curr Opin Cell Biol ; 17(5): 524-32, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16112853

ABSTRACT

The ability of cells to migrate within the extracellular matrix and to remodel it depends as much on the physical and biochemical characteristics of a particular matrix as on cellular properties. Analyzing the different modes of migration of cells in matrices, and how cells switch between these modes, is vital for understanding a variety of physiological and pathological processes. Recent work provides new insights, but also raises some debates about the mechanisms and regulation of cell migration in three-dimensional matrices.


Subject(s)
Cell Movement/physiology , Extracellular Matrix/physiology , Models, Biological , Animals , Basement Membrane/metabolism , Basement Membrane/physiology , Extracellular Matrix/metabolism , Humans , Monomeric GTP-Binding Proteins/metabolism , Monomeric GTP-Binding Proteins/physiology , Signal Transduction/physiology
4.
J Immunol ; 184(3): 1300-8, 2010 Feb 01.
Article in English | MEDLINE | ID: mdl-20032293

ABSTRACT

Human embryonic stem cells (hESCs) can proliferate extensively in culture and give rise to progeny of the three germ layers. Several reports suggested that mouse and hESCs may attenuate immune responses. In this study, we focused on the mechanism by which hESCs inhibit T cell responses. Using coculture experiments, we demonstrate that hESCs inhibit cytokine secretion and T cell proliferation in response to potent T cell activators. Furthermore, we show that hESCs downmodulate the TCR-associated CD3-zeta chain. These effects are maintained when hESCs are replaced by their conditioned media and can be restored by the addition of L-arginine to hESC-conditioned media or by treatment of hESCs with a specific arginase inhibitor. Moreover, we show arginase-I expression and activity in hESCs. We further demonstrate that mouse ESCs (mESCs) similarly inhibit T cell activation via arginase I, suggesting an evolutionary conserved mechanism of T cell suppression by ESCs. In addition, we demonstrate that arginase I expression is not limited to ESCs in culture, but can also be detected in the inner cell mass and the trophectoderm of preimplantation mouse embryos and hESC-derived trophectoderm cells. Finally, T cells infiltrating ESC-derived teratomas have significantly lower levels of CD3-zeta chain. Collectively, the data indicate a role for ESC-arginase I activity in the attenuation of T cell activation.


Subject(s)
Arginase/physiology , Cytokines/antagonists & inhibitors , Embryonic Stem Cells/enzymology , Embryonic Stem Cells/immunology , Lymphocyte Activation/immunology , T-Lymphocyte Subsets/enzymology , T-Lymphocyte Subsets/immunology , Adult , Animals , Arginine/metabolism , CD3 Complex/immunology , CD3 Complex/metabolism , Cell Line , Cell Movement/genetics , Cell Movement/immunology , Cells, Cultured , Coculture Techniques , Cytokines/metabolism , Embryonic Stem Cells/transplantation , Gene Expression Regulation, Enzymologic/immunology , Humans , Leukocytes, Mononuclear/cytology , Leukocytes, Mononuclear/enzymology , Leukocytes, Mononuclear/immunology , Mice , Receptors, Antigen, T-Cell/antagonists & inhibitors , Receptors, Antigen, T-Cell/biosynthesis , T-Lymphocyte Subsets/cytology , Teratoma/enzymology , Teratoma/immunology , Teratoma/pathology
5.
Stem Cell Reports ; 17(12): 2643-2660, 2022 12 13.
Article in English | MEDLINE | ID: mdl-36368331

ABSTRACT

In the mammalian embryo, a formative pluripotent phase is proposed to exist at the early post-implantation period, during the transition from the pre-implantation naive-to the post-implantation primed-epiblast. By recapitulating a laminin component of the extracellular matrix niche during embryonic formative transition, and defined culture conditions, we generated cultures highly enriched for self-renewing human pluripotent stem cells (hPSCs), exhibiting properties of early post-implantation epiblast cells. These hPSCs display post-implantation-epiblast gene expression profiles. FGF and TGF-ß signaling maintain their self-renewal for multiple passages. They have inactive canonical Wnt signaling, do not express primitive streak markers, and are competent to initiate differentiation toward germline and somatic fates. hPSCs exhibiting early post-implantation epiblast properties may shed light on human embryonic PSCs development and may serve for initiating somatic and germ cell specification.


Subject(s)
Germ Layers , Pluripotent Stem Cells , Animals , Humans , Pluripotent Stem Cells/metabolism , Embryo, Mammalian , Primitive Streak , Cell Differentiation , Wnt Signaling Pathway , Mammals
6.
J Cell Biol ; 170(5): 793-802, 2005 Aug 29.
Article in English | MEDLINE | ID: mdl-16129786

ABSTRACT

Directional migration moves cells rapidly between points, whereas random migration allows cells to explore their local environments. We describe a Rac1 mechanism for determining whether cell patterns of migration are intrinsically random or directionally persistent. Rac activity promoted the formation of peripheral lamellae that mediated random migration. Decreasing Rac activity suppressed peripheral lamellae and switched the cell migration patterns of fibroblasts and epithelial cells from random to directionally persistent. In three-dimensional rather than traditional two-dimensional cell culture, cells had a lower level of Rac activity that was associated with rapid, directional migration. In contrast to the directed migration of chemotaxis, this intrinsic directional persistence of migration was not mediated by phosphatidylinositol 3'-kinase lipid signaling. Total Rac1 activity can therefore provide a regulatory switch between patterns of cell migration by a mechanism distinct from chemotaxis.


Subject(s)
Cell Movement/physiology , rac GTP-Binding Proteins/metabolism , Cell Culture Techniques , Cell Surface Extensions/metabolism , Cells, Cultured , Epithelial Cells/cytology , Epithelial Cells/metabolism , Fibroblasts/cytology , Fibroblasts/metabolism , Fibronectins/metabolism , Guanosine Triphosphate/metabolism , Humans , Integrins/genetics , Integrins/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Phosphoinositide-3 Kinase Inhibitors , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Random Allocation , Signal Transduction/physiology , cdc42 GTP-Binding Protein/genetics , cdc42 GTP-Binding Protein/metabolism , rac GTP-Binding Proteins/genetics , rho GTP-Binding Proteins/genetics , rho GTP-Binding Proteins/metabolism
7.
Methods Mol Biol ; 522: 251-9, 2009.
Article in English | MEDLINE | ID: mdl-19247613

ABSTRACT

Multiple cell types have an inherent ability to contract the extracellular matrix to which they are attached and grow on. Cells exert contractile forces on a compliant substrate, increase the tension, and deform it. Numerous intracellular as well as environmental factors are involved in determination of cellular contractility, which can be precisely measured by atomic force microscopy, laser tweezers, or other complex apparatus. These, however, are far from being standard equipment in most cell biology labs. Fibrin gels provide a simple and affordable alternative for evaluation of changes in cell contractility by either quantitation of end-point gel contraction or in a dynamic mode by time-lapse imaging. They also provide a flexible system in which the physical properties, such as density and compliance, as well as their biochemical composition can easily be altered to suit the special requirements of various cell types and experimental models.


Subject(s)
Fibrin/chemistry , Gels , Models, Biological , Humans , Microscopy, Atomic Force
8.
Methods Enzymol ; 406: 345-61, 2006.
Article in English | MEDLINE | ID: mdl-16472669

ABSTRACT

Selective down-modulation or silencing of individual members of the Rho-GTPase family is now practical using RNA interference. Transfection of mammalian cells with an individual siRNA duplex or siRNA pools can suppress expression of a specific isoform to understand its function. By adjusting the dose of siRNA, intermediate levels of suppression can be attained to test the biological role of different levels of a GTPase such as Rac. Nevertheless, there are significant potential pitfalls, including "off-target" effects of the siRNA on other genes. Besides demonstrating successful, noncytotoxic suppression of protein and activity levels of a specific GTPase, controls are essential to establish specificity. In this chapter, we provide methods for selective knockdown of expression by siRNA and confirmation of the effectiveness of Rho GTPase silencing, as well as descriptions and some examples of controls for specificity that include evaluations of dose-response, negative and positive controls, GTPase specificity, confirmation by using more than one siRNA for the same gene, rescue by a mutated siRNA-resistant cDNA encoding the target gene, and complementary supporting evidence. Selective silencing of specific Rho family GTPases should provide increasing insight into the regulatory and functional roles of each isoform in a wide variety of biological processes.


Subject(s)
RNA Interference/physiology , rho GTP-Binding Proteins/antagonists & inhibitors , Cell Line , DNA, Complementary/genetics , Humans , RNA, Small Interfering/physiology , Transfection/methods , rho GTP-Binding Proteins/genetics
10.
FASEB J ; 17(2): 163-74, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12554695

ABSTRACT

The formation of new blood vessels is a critical determinant of tumor progression. We find that Par1 gene expression plays a central role in blood vessel recruitment in animal models. By in vivo injection of either Matrigel plugs containing Par1-expressing cells or of rat prostatic carcinoma cells transfected with tetracycline-inducible Par1 expression vectors, we show that Par1 significantly enhances both angiogenesis and tumor growth. Several vascular endothelial growth factor (VEGF) splice forms are induced in cells expressing Par1. Activation of PAR1 markedly augments the expression of VEGF mRNAs and of functional VEGFs as determined by in vitro assays for endothelial tube alignment and bovine aortic endothelial cell proliferation. Because neutralizing anti-VEGF antibodies potently inhibited Par1-induced endothelial cell proliferation, we conclude that Par1-induced angiogenesis requires VEGF. Specific inhibitors of protein kinase C (PKC), Src, and phosphatidylinositol 3-kinase (PI3K) inhibit Par1-induced VEGF expression, suggesting the participation of these kinases in the process. We also show that oncogenic transformation by genes known to be part of PAR1 signaling machinery is sufficient to increase VEGF expression in NIH 3T3 cells. These data support the novel notion that initiation of cell signaling either by activating PAR1 or by the activated forms of oncogenes is sufficient to induce VEGF and hence angiogenesis.


Subject(s)
Cell Transformation, Neoplastic , Neoplasms/blood supply , Neovascularization, Pathologic/physiopathology , Receptors, Thrombin/physiology , 3T3 Cells , Animals , Blotting, Northern , Endothelial Growth Factors/genetics , Endothelial Growth Factors/metabolism , Gene Expression , Genes, ras/genetics , Genes, src/genetics , Humans , Intercellular Signaling Peptides and Proteins/genetics , Intercellular Signaling Peptides and Proteins/metabolism , Lymphokines/genetics , Lymphokines/metabolism , Male , Mice , Mice, Inbred BALB C , Neoplasm Transplantation , Neoplasms/genetics , Neoplasms, Experimental/genetics , Neoplasms, Experimental/pathology , Oncogenes/genetics , Phosphatidylinositol 3-Kinases/metabolism , Protein Kinase C/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Receptor, PAR-1 , Receptors, Thrombin/genetics , Transfection , Transplantation, Heterologous , Tumor Cells, Cultured , Vascular Endothelial Growth Factor A , Vascular Endothelial Growth Factors , src-Family Kinases/metabolism
11.
Arterioscler Thromb Vasc Biol ; 23(6): 940-4, 2003 Jun 01.
Article in English | MEDLINE | ID: mdl-12637343

ABSTRACT

While protease-activated receptors (PARs) play a traditional role in vascular biology, they emerge with surprisingly new assignments in tumor biology. PAR1 expression correlates with the invasion properties of breast carcinoma, whereas human PAR1 antisense reduces their ability to migrate through Matrigel. Part of the molecular mechanism of PAR1 invasion involves the formation of focal contact complexes on PAR1 activation. PAR1 induces angiogenesis in animal models in vivo and exhibits an oncogenic phenotype of enhanced ductal complexity when overexpressed in mouse mammary glands.


Subject(s)
Epithelial Cells/metabolism , Neoplasm Invasiveness/physiopathology , Neoplasm Metastasis/physiopathology , Receptor, PAR-1/physiology , Animals , Breast/blood supply , Breast/growth & development , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Division , Cytoskeleton/ultrastructure , Epithelial Cells/pathology , Female , Humans , Integrins/physiology , Mice , Mice, Knockout , Morphogenesis , Neovascularization, Pathologic/physiopathology , Oligonucleotides, Antisense/pharmacology , Placenta/blood supply , Pregnancy , Receptors, Vitronectin/physiology , Thrombin/physiology , Vascular Endothelial Growth Factor A/biosynthesis , Vascular Endothelial Growth Factor A/genetics
12.
Cancer Res ; 75(13): 2663-73, 2015 Jul 01.
Article in English | MEDLINE | ID: mdl-25977329

ABSTRACT

The DNA damage response (DDR) is a comprehensive and complex network of phosphorylation-mediated signaling pathways that originates endogenously from the DNA lesion and activates intrinsic DNA repair mechanisms. Here we describe a macrophage-dependent mechanism that regulates the response to DNA damage. We demonstrate that human monocytes, by releasing macrophage-derived HB-EGF, enhance DDR in neighboring cells suffering from DNA damage. Consequently, HB-EGF-treated cells exhibit higher double-strand break (DSB) rejoining and display lower levels of residual DSBs. Diethylnitrosamine (DEN) injection induce DSBs along with elevation in the number of macrophages and HB-EGF expression. Significantly, macrophage depletion or blocking HB-EGF activity results in higher levels of nonrepairable DSBs, suggesting that macrophages play a role in the resolution of DNA damage via HB-EGF. This study establishes that macrophages, acting through the activation of the EGFR cascade, constitute an important cell nonautonomous physiologic component of the DDR and points to a unique role played by immune cells in maintaining genome integrity.


Subject(s)
DNA Damage/immunology , Macrophages/immunology , Animals , Cells, Cultured , DNA Breaks, Double-Stranded , DNA End-Joining Repair/immunology , ErbB Receptors/immunology , ErbB Receptors/pharmacology , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/immunology , Heparin-binding EGF-like Growth Factor/immunology , Heparin-binding EGF-like Growth Factor/pharmacology , Humans , Liver/drug effects , Liver/immunology , Liver/physiology , Macrophages/drug effects , Male , Mice , Mice, Inbred C57BL , Monocytes/drug effects , Monocytes/immunology , Oxidation-Reduction , Signal Transduction/immunology
13.
Oncotarget ; 6(33): 34691-703, 2015 Oct 27.
Article in English | MEDLINE | ID: mdl-26415227

ABSTRACT

The function of imprinted H19 long non-coding RNA is still controversial. It is highly expressed in early embryogenesis and decreases after birth and re-expressed in cancer. To study the role of H19 in oncogenesis and pluripotency, we down-regulated H19 expression in vitro and in vivo in pluripotent human embryonic carcinoma (hEC) and embryonic stem (hES) cells. H19 knockdown resulted in a decrease in the expression of the pluripotency markers Oct4, Nanog, TRA-1-60 and TRA-1-81, and in the up-regulation of SSEA1; it further attenuated cell proliferation, decreased cell-matrix attachment, and up-regulated E-Cadherin expression. SCID-Beige mice transplanted with H19 down-regulated hEC cells exhibited slower kinetics of tumor formation, resulting in an increased animal survival. Tumors derived from H19 down-regulated cells showed a decrease in the expression of pluripotency markers and up-regulation of SSEA-1 and E-cadherin. Our results suggest that H19 oncogenicity in hEC cells is mediated through the regulation of the pluripotency state.


Subject(s)
Cell Transformation, Neoplastic/genetics , Embryonic Stem Cells , Pluripotent Stem Cells , RNA, Long Noncoding/genetics , Animals , Blotting, Western , Cell Line, Tumor , Gene Knockdown Techniques , Heterografts , Humans , Immunohistochemistry , Mice , Mice, SCID , Microscopy, Fluorescence , Polymerase Chain Reaction , RNA, Small Interfering , Transfection
14.
PLoS One ; 10(10): e0138807, 2015.
Article in English | MEDLINE | ID: mdl-26437462

ABSTRACT

A splicing mutation in the IKBKAP gene causes Familial Dysautonomia (FD), affecting the IKAP protein expression levels and proper development and function of the peripheral nervous system (PNS). Here we found new molecular insights for the IKAP role and the impact of the FD mutation in the human PNS lineage by using a novel and unique human embryonic stem cell (hESC) line homozygous to the FD mutation originated by pre implantation genetic diagnosis (PGD) analysis. We found that IKBKAP downregulation during PNS differentiation affects normal migration in FD-hESC derived neural crest cells (NCC) while at later stages the PNS neurons show reduced intracellular colocalization between vesicular proteins and IKAP. Comparative wide transcriptome analysis of FD and WT hESC-derived neurons together with the analysis of human brains from FD and WT 12 weeks old embryos and experimental validation of the results confirmed that synaptic vesicular and neuronal transport genes are directly or indirectly affected by IKBKAP downregulation in FD neurons. Moreover we show that kinetin (a drug that corrects IKBKAP alternative splicing) promotes the recovery of IKAP expression and these IKAP functional associated genes identified in the study. Altogether, these results support the view that IKAP might be a vesicular like protein that might be involved in neuronal transport in hESC derived PNS neurons. This function seems to be mostly affected in FD-hESC derived PNS neurons probably reflecting some PNS neuronal dysfunction observed in FD.


Subject(s)
Carrier Proteins/metabolism , Down-Regulation , Dysautonomia, Familial/genetics , Human Embryonic Stem Cells/pathology , Neurons/metabolism , Peripheral Nervous System/pathology , Synaptic Vesicles/metabolism , Biological Transport/drug effects , Biological Transport/genetics , Carrier Proteins/genetics , Cell Differentiation/drug effects , Down-Regulation/drug effects , Dysautonomia, Familial/metabolism , Dysautonomia, Familial/pathology , Fetus , Human Embryonic Stem Cells/drug effects , Humans , Kinetin/pharmacology , Male , Mutation , Neural Crest/drug effects , Neural Crest/pathology , Neurons/drug effects , Peripheral Nervous System/drug effects , Phenotype , Synaptic Vesicles/drug effects , Transcriptional Elongation Factors
15.
Nat Biotechnol ; 28(4): 361-4, 2010 Apr.
Article in English | MEDLINE | ID: mdl-20351691

ABSTRACT

Undifferentiated human embryonic stem cells (hESCs) are currently propagated on a relatively small scale as monolayer colonies. Culture of hESCs as floating aggregates is widely used for induction of differentiation into embryoid bodies. Here we show that hESC lines can be derived from floating inner cell masses in suspension culture conditions that do not involve feeder cells or microcarriers. This culture system supports prolonged propagation of the pluripotent stem cells as floating clusters without their differentiation into embryoid bodies. HESCs cultivated as aggregates in suspension maintain the expression of pluripotency markers and can differentiate into progeny of the three germ layers both in vitro and in vivo. We further show the controlled differentiation of hESC clusters in suspension into neural spheres. These results pave the way for large-scale expansion and controlled differentiation of hESCs in suspension, which would be valuable in basic and applied research.


Subject(s)
Cell Culture Techniques/methods , Embryonic Stem Cells/cytology , Embryonic Stem Cells/physiology , Tissue Engineering/methods , Cell Differentiation , Cell Proliferation , Cells, Cultured , Humans
16.
Cell Stem Cell ; 5(4): 396-408, 2009 Oct 02.
Article in English | MEDLINE | ID: mdl-19796620

ABSTRACT

Dysfunction and loss of retinal pigment epithelium (RPE) leads to degeneration of photoreceptors in age-related macular degeneration and subtypes of retinitis pigmentosa. Human embryonic stem cells (hESCs) may serve as an unlimited source of RPE cells for transplantation in these blinding conditions. Here we show the directed differentiation of hESCs toward an RPE fate under defined culture conditions. We demonstrate that nicotinamide promotes the differentiation of hESCs to neural and subsequently to RPE fate. In the presence of nicotinamide, factors from the TGF-beta superfamily, which presumably pattern RPE development during embryogenesis, further direct RPE differentiation. The hESC-derived pigmented cells exhibit the morphology, marker expression, and function of authentic RPE and rescue retinal structure and function after transplantation to an animal model of retinal degeneration caused by RPE dysfunction. These results are an important step toward the future use of hESCs to replenish RPE in blinding diseases.


Subject(s)
Embryonic Stem Cells/cytology , Epithelial Cells/cytology , Retinal Pigment Epithelium/cytology , Activin Receptors, Type I/pharmacology , Activin Receptors, Type II/pharmacology , Activins/pharmacology , Animals , Cell Differentiation/drug effects , Cell Line , Cell Transplantation , Embryonic Stem Cells/drug effects , Embryonic Stem Cells/ultrastructure , Epithelial Cells/drug effects , Epithelial Cells/ultrastructure , Fibroblast Growth Factor 2/pharmacology , Flow Cytometry , Humans , Immunophenotyping , Microscopy, Electron, Transmission , Microscopy, Phase-Contrast , Polymerase Chain Reaction , Rats , Transforming Growth Factor beta/pharmacology
17.
Cell Adh Migr ; 1(3): 152-5, 2007.
Article in English | MEDLINE | ID: mdl-19262128

ABSTRACT

Non-muscle myosin II has diverse functions in cell contractility, morphology, cytokinesis and migration. Mammalian cells have three isoforms of non-muscle myosin II, termed IIA, IIB and IIC, encoded by three different genes. These isoforms share considerable homology and some overlapping functions, yet they exhibit differences in enzymatic properties, subcellular localization, molecular interaction and tissue distribution.(1-6) Our studies have focused on the IIA isoform, and they reveal unique regulatory roles in cell-cell adhesion and cell migration that are associated with cross-talk of the actomyosin system with microtubules. In humans, various mutations in the MYH9 gene that encodes the myosin IIA heavy chain cause autosomal dominant disease, whereas in mice, the complete deficiency is embryonic lethal but heterozygous mice are nearly normal. We discuss here the differences between mouse and human phenotypes and how the wealth of mechanistic knowledge about myosin II based on in vitro studies and mouse models can help us understand the molecular and cellular pathophysiology of myosin IIA deficiency in humans.


Subject(s)
Cell Movement , Genetic Diseases, Inborn/metabolism , Molecular Motor Proteins/metabolism , Myosin Heavy Chains/metabolism , Nonmuscle Myosin Type IIA/metabolism , Animals , Cell Adhesion/genetics , Embryo Loss/genetics , Embryo Loss/metabolism , Genetic Diseases, Inborn/genetics , Humans , Isoenzymes/genetics , Isoenzymes/metabolism , Mice , Molecular Motor Proteins/genetics , Myosin Heavy Chains/genetics , Nonmuscle Myosin Type IIA/genetics
18.
Cell ; 126(4): 645-7, 2006 Aug 25.
Article in English | MEDLINE | ID: mdl-16923382

ABSTRACT

A key challenge in stem cell research is to learn how to direct the differentiation of stem cells toward specific fates. In this issue of Cell, Engler et al. (2006) identify a new factor regulating stem cell fate: the elasticity of the matrix microenvironment. By changing the stiffness of the substrate, human mesenchymal stem cells could be directed along neuronal, muscle, or bone lineages.


Subject(s)
Cell Differentiation/physiology , Extracellular Matrix , Mesenchymal Stem Cells/metabolism , Cell Culture Techniques , Cell Lineage , Elasticity , Extracellular Matrix/chemistry , Extracellular Matrix/metabolism , Humans
19.
Exp Cell Res ; 312(17): 3425-31, 2006 Oct 15.
Article in English | MEDLINE | ID: mdl-16956606

ABSTRACT

Thymosin beta4 is a 43-amino acid actin-binding protein that promotes cell migration and is important in angiogenesis, wound healing, and tumor metastasis. We searched for genes upregulated by thymosin beta4 and identified zyxin as increased in SiHa cells in the presence of exogenously added thymosin beta4 and when thymosin beta4 is overexpressed using adenoviral vectors. Both zyxin and thymosin beta4 show increased localization in the nucleus. We conclude that thymosin beta4 may exert some of its migration promoting activity via increased zyxin expression.


Subject(s)
Cell Nucleus/metabolism , Cytoskeletal Proteins/metabolism , Glycoproteins/metabolism , Thymosin/metabolism , Active Transport, Cell Nucleus , Cell Line, Tumor , Cytoskeletal Proteins/analysis , Glycoproteins/analysis , Humans , Peptides , Protein Transport , Thymosin/genetics , Zyxin
SELECTION OF CITATIONS
SEARCH DETAIL