RESUMO
The muscular dystrophies are broadly classified as muscle wasting diseases with myofiber dropout due to cellular necrosis, inflammation, alterations in extracellular matrix composition, and fatty cell replacement. These events transpire and progress despite ongoing myofiber regeneration from endogenous satellite cells. The degeneration/regeneration response to muscle injury/disease is modulated by the proinflammatory cytokine transforming growth factor-ß (TGF-ß), which can also profoundly influence extracellular matrix composition through increased secretion of profibrotic proteins, such as the matricellular protein periostin. Here we show that up-regulation and secretion of periostin is pathological and enhances disease in the δ-sarcoglycan null (Sgcd(-/-)) mouse model of muscular dystrophy (MD). Indeed, MD mice lacking the Postn gene showed dramatic improvement in skeletal muscle structure and function. Mechanistically, Postn gene deletion altered TGF-ß signaling so that it now enhanced tissue regeneration with reduced levels of fibrosis. Systemic antagonism of TGF-ß with a neutralizing monoclonal antibody mitigated the beneficial effects of Postn deletion in vivo. These data suggest that periostin functions as a disease determinant in MD by promoting/allowing the pathological effects of TGF-ß, suggesting that inhibition of periostin could represent a unique treatment approach.
Assuntos
Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Distrofia Muscular Animal/fisiopatologia , Transdução de Sinais/fisiologia , Fator de Crescimento Transformador beta/metabolismo , Animais , Anticorpos Neutralizantes/farmacologia , Colágeno/metabolismo , Modelos Animais de Doenças , Fibrose/metabolismo , Fibrose/patologia , Fibrose/fisiopatologia , Camundongos , Camundongos Knockout , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Distrofia Muscular Animal/metabolismo , Distrofia Muscular Animal/patologia , Comunicação Parácrina/fisiologia , Sarcoglicanas/genética , Fator de Crescimento Transformador beta/imunologiaRESUMO
Recent studies have placed an increasing amount of emphasis on the cardiovascular system and understanding how the heart and its vasculature can be regenerated following pathological stresses, such as hypertension and myocardial infarction. The remodeling process involves the permanent cellular constituents of the heart including myocytes, fibroblasts, endothelial cells, pericytes, smooth muscle cells and stem cells. It also includes transient cell populations, such as immune cells (e.g. lymphocytes, mast cells and macrophages) and circulating stem cells. Following injury, there are dramatic shifts in the various cardiac cell populations that can affect cell-cell and cell-extracellular matrix interactions and cardiac function. Cardiac fibroblasts are a key component in normal heart function, as well as during the remodeling process through dynamic cell-cell interactions and synthesis and degradation of the extracellular matrix. Fibroblasts dynamically interact with the various cardiac cell populations through mechanical, chemical (autocrine and/or paracrine) and electrophysiological means to alter gene and protein expression, cellular processes and ultimately cardiac function. Better understanding these cell-cell and cell-extracellular matrix interactions and their biological consequences should provide novel therapeutic targets for the treatment of heart disease. In this review we discuss the nature of these interactions and the importance of these interactions in maintaining normal heart function, as well as their role in the cardiac remodeling process. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium."
Assuntos
Células Endoteliais/citologia , Matriz Extracelular/metabolismo , Fibroblastos/citologia , Miócitos Cardíacos/citologia , Comunicação Celular/fisiologia , Células Endoteliais/metabolismo , Matriz Extracelular/química , Fibroblastos/metabolismo , Coração/fisiologia , Coração/fisiopatologia , Traumatismos Cardíacos/metabolismo , Traumatismos Cardíacos/patologia , Humanos , Mecanotransdução Celular , MicroRNAs/metabolismo , Miócitos Cardíacos/metabolismo , Recuperação de Função Fisiológica/fisiologiaRESUMO
Cardiac hypertrophy, whether pathological or physiological, induces a variety of additional morphological and physiological changes in the heart, including altered contractility and hemodynamics. Events exacerbating these changes are documented during later stages of hypertrophy (usually termed pathological hypertrophy). Few studies document the morphological and physiological changes during early physiological hypertrophy. We define acute cardiac remodeling events in response to transverse aortic constriction (TAC), including temporal changes in hypertrophy, collagen deposition, capillary density, and the cell populations responsible for these changes. Cardiac hypertrophy induced by TAC in mice was detected 2 days after surgery (as measured by heart weight, myocyte width, and wall thickness) and peaked by day 7. Picrosirius staining revealed increased collagen deposition 7 days after TAC; immunostaining and flow cytometry indicated a concurrent increase in fibroblasts. The findings correlated with angiogenesis in TAC hearts; a decrease in capillary density was observed at day 2, with recovery to sham-surgery levels by day 7. Increased pericyte levels, which were observed 2 days after TAC, may mediate this angiogenic transition. Gene expression suggests a coordinated response in growth, extracellular matrix, and angiogenic factors to mediate the observed morphological changes. Our data demonstrate that morphological changes in response to cardiovascular injury occur rapidly, and the present findings allow correlation of specific events that facilitate these changes.
Assuntos
Cardiomegalia/patologia , Miocárdio/patologia , Animais , Aorta Torácica/metabolismo , Aorta Torácica/patologia , Aorta Torácica/fisiopatologia , Aorta Torácica/cirurgia , Cardiomegalia/fisiopatologia , Proliferação de Células , Colágeno/metabolismo , Constrição Patológica , Modelos Animais de Doenças , Matriz Extracelular/metabolismo , Imunofluorescência , Regulação da Expressão Gênica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Miocárdio/ultraestrutura , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Coloração e Rotulagem , Remodelação VentricularRESUMO
OBJECTIVE: Although significant research has detailed angiogenesis during development and cancer, little is known about cardiac angiogenesis, yet it is critical for survival following pathological insult. The transcription factor c-Myc is a target of anticancer therapies because of its mitogenic and proangiogenic induction. In the current study, we investigate its role in cardiac angiogenesis in a cell-dependent and gene-specific context. METHODS AND RESULTS: Angiogenesis assays using c-Myc-deficient cardiac endothelial cells and fibroblasts demonstrate that c-Myc is essential to vessel formation, and fibroblast-mediated vessel formation is dependent on c-Myc expression in fibroblasts. Gene analyses revealed that c-Myc-mediated gene expression is unique in cardiac angiogenesis and varies in a cell-dependent manner. In vitro 3-dimensional cultures demonstrated c-Myc's role in the expression of secreted angiogenic factors, while also providing evidence for c-Myc-mediated cell-cell interactions. Additional in vivo vascular analyses support c-Myc's critical role in capillary formation and vessel patterning during development and also in response to a pathological stimulus where its expression in myocytes is required for angiogenic remodeling. CONCLUSIONS: These data demonstrate that proper c-Myc expression in cardiac fibroblasts and myocytes is essential to cardiac angiogenesis. These results have the potential for novel therapeutic applications involving the angiogenic response during cardiac remodeling.
Assuntos
Vasos Coronários/citologia , Neovascularização Fisiológica/genética , Proteínas Proto-Oncogênicas c-myc/biossíntese , RNA/genética , Transdução de Sinais , Animais , Comunicação Celular , Células Cultivadas , Vasos Coronários/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Reação em Cadeia da Polimerase , Proteínas Proto-Oncogênicas c-myc/genéticaRESUMO
Checkpoints that control Myc-mediated proliferation and apoptosis are bypassed during tumorigenesis. Genes encoding polyamine biosynthetic enzymes are overexpressed in B cells from E mu-Myc transgenic mice. Here, we report that disabling one of these Myc targets, Ornithine decarboxylase (Odc), abolishes Myc-induced suppression of the Cdk inhibitors p21(Cip1) and p27(Kip1), thereby impairing Myc's proliferative, but not apoptotic, response. Moreover, lymphoma development was markedly delayed in E mu-Myc;Odc(+/-) transgenic mice and in E mu-Myc mice treated with the Odc inhibitor difluoromethylornithine (DFMO). Strikingly, tumors ultimately arising in E mu-Myc;Odc(+/-) transgenics lacked deletions of Arf, suggesting that targeting Odc forces other routes of transformation. Therefore, Odc is a critical Myc transcription target that regulates checkpoints that guard against tumorigenesis and is an effective target for cancer chemoprevention.
Assuntos
Linfoma/metabolismo , Ornitina Descarboxilase/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Animais , Apoptose/efeitos dos fármacos , Linfócitos B/química , Linfócitos B/efeitos dos fármacos , Linfócitos B/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proliferação de Células/efeitos dos fármacos , Inibidor p16 de Quinase Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p21 , Inibidor de Quinase Dependente de Ciclina p27 , Eflornitina/farmacologia , Expressão Gênica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Heterozigoto , Linfoma/tratamento farmacológico , Linfoma/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes , Camundongos Transgênicos , Tamanho do Órgão/efeitos dos fármacos , Ornitina Descarboxilase/genética , Inibidores da Ornitina Descarboxilase , Poliaminas/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Baço/patologia , Taxa de Sobrevida , Proteína Supressora de Tumor p14ARF/genética , Proteína Supressora de Tumor p14ARF/metabolismo , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismoRESUMO
Normal cardiac function is maintained through dynamic interactions of cardiac cells with each other and with the extracellular matrix. These interactions are important for remodeling during cardiac growth and pathophysiological conditions. However, the precise mechanisms of these interactions remain unclear. In this study we examined the importance of desmoplakin (DSP) in cardiac cell-cell interactions. Cell-cell communication in the heart requires the formation and preservation of cell contacts by cell adhesion junctions called desmosome-like structures. A major protein component of this complex is DSP, which plays a role in linking the cytoskeletal network to the plasma membrane. Our laboratory previously generated a polyclonal antibody (1611) against the detergent soluble fraction of cardiac fibroblast plasma membrane. In attempting to define which proteins 1611 recognizes, we performed two-dimensional electrophoresis and identified DSP as one of the major proteins recognized by 1611. Immunoprecipitation studies demonstrated that 1611 was able to directly pulldown DSP. We also demonstrate that 1611 and anti-DSP antibodies co-localize in whole heart sections. Finally, using a three-dimensional in vitro cell-cell interaction assay, we demonstrate that 1611 can inhibit cell-cell interactions. These data indicate that DSP is an important protein for cell-cell interactions and affects a variety of cellular functions, including cytokine secretion.
Assuntos
Comunicação Celular , Desmoplaquinas/metabolismo , Fibroblastos/fisiologia , Coração/fisiologia , Células Musculares/fisiologia , Animais , Células Cultivadas , RatosRESUMO
The heart is composed of both cellular and acellular components that act in a dynamic fashion from birth to death. The cellular components consist of myocytes, fibroblasts, and vascular cells, including endothelium and smooth muscle. Changes in these components are intimately associated with function by altering the mechanical, chemical, and electrical properties of the heart. In future investigations, it will be important to examine these interactions as dynamic changes in response to physiological signals.
Assuntos
Matriz Extracelular/fisiologia , Miocárdio/citologia , Miocárdio/metabolismo , Transdução de Sinais/fisiologia , Animais , Fibroblastos/citologia , Fibroblastos/fisiologia , Modelos Cardiovasculares , Células Musculares/citologia , Células Musculares/fisiologia , Células-Tronco/citologia , Células-Tronco/fisiologiaRESUMO
BACKGROUND: Type 1 cyclic 3',5'-guanosine monophosphate-dependent protein kinase (PKG) has recently been reported to inhibit tumor growth and angiogenesis. These effects suggest that PKG activation may have therapeutic value for colon cancer treatment, but the signaling downstream of this enzyme is poorly understood. The present study examined the mechanism underlying the inhibition of angiogenesis by PKG. METHODS: The effect of ectopically expressed PKG on colon cancer cell adaptation to a 1% O(2) (hypoxic) environment was examined in vitro by measuring hypoxic markers, cell death/viability, and hypoxia inducible factor (HIF) activity. RESULTS: Ectopic PKG inhibited angiogenesis in SW620 xenografts and significantly attenuated hypoxia-induced increases in vascular endothelial growth factor at both the mRNA and protein levels. PKG activation also blocked hypoxia-induced hexokinase 2 expression, which corresponded with reduced cellular adenosine triphosphate levels. Moreover, PKG expression significantly reduced cell viability and promoted necrotic cell death after 2 days in a hypoxic environment. To gain some mechanistic insight, the effect of PKG on HIF activation was determined using luciferase reporter assays. PKG activation inhibited HIF transcriptional activity in several colon cancer cell lines, including SW620, HCT116, and HT29. The mechanism by which PKG can inhibit HIF activity is not known, but it does not affect HIF-1α protein accumulation or nuclear translocation. CONCLUSIONS: These findings demonstrate for the first time that PKG can block the adaptation of colon cancer cells to hypoxia and highlights this enzyme for further evaluation as a potential target for colon cancer treatment.
Assuntos
Adaptação Fisiológica , Neoplasias do Colo/patologia , Proteínas Quinases Dependentes de GMP Cíclico/fisiologia , Neovascularização Patológica/prevenção & controle , Animais , Hipóxia Celular , Linhagem Celular Tumoral , Neoplasias do Colo/irrigação sanguínea , Neoplasias do Colo/metabolismo , Humanos , Fator 1 Induzível por Hipóxia/fisiologia , Camundongos , NecroseRESUMO
The permanent cellular constituents of the heart include cardiac fibroblasts, myocytes, endothelial cells, and vascular smooth muscle cells. Previous studies have demonstrated that there are undulating changes in cardiac cell populations during embryonic development, through neonatal development and into the adult. Transient cell populations include lymphocytes, mast cells, and macrophages, which can interact with these permanent cell types to affect cardiac function. It has also been observed that there are marked differences in the makeup of the cardiac cell populations depending on the species, which may be important when examining myocardial remodeling. Current dogma states that the fibroblast makes up the largest cell population of the heart; however, this appears to vary for different species, especially mice. Cardiac fibroblasts play a critical role in maintaining normal cardiac function, as well as in cardiac remodeling during pathological conditions such as myocardial infarct and hypertension. These cells have numerous functions, including synthesis and deposition of extracellular matrix, cell-cell communication with myocytes, cell-cell signaling with other fibroblasts, as well as with endothelial cells. These contacts affect the electrophysiological properties, secretion of growth factors and cytokines, as well as potentiating blood vessel formation. Although a plethora of information is known about several of these processes, relatively little is understood about fibroblasts and their role in angiogenesis during development or cardiac remodeling. In this review, we provide insight into the various properties of cardiac fibroblasts that helps illustrate their importance in maintaining proper cardiac function, as well as their critical role in the remodeling heart.
Assuntos
Fibroblastos/metabolismo , Cardiopatias/metabolismo , Miocárdio/metabolismo , Transdução de Sinais , Animais , Comunicação Celular , Matriz Extracelular/metabolismo , Fibroblastos/patologia , Cardiopatias/patologia , Cardiopatias/fisiopatologia , Humanos , Potenciais da Membrana , Miocárdio/patologia , Neovascularização Fisiológica , Remodelação VentricularRESUMO
Cardiac development is reliant upon the spatial and temporal regulation of both genetic and chemical signals. Central to the communication of these signals are direct interactions between cells and their surrounding environment. The extracellular matrix (ECM) plays an integral role in cell communication and tissue growth throughout development by providing both structural support and chemical signaling factors. The present review discusses elements of cell-cell and cell-ECM interactions involved in cardiogenesis, and how disruption of these interactions can result in numerous heart defects. Examining the relationships between cells and their immediate environment has implications for novel and existing therapeutic strategies to combating congenital disorders.
Assuntos
Comunicação Celular/fisiologia , Desenvolvimento Embrionário/fisiologia , Matriz Extracelular/fisiologia , Desenvolvimento Fetal/fisiologia , Coração/embriologia , Transdução de Sinais/fisiologia , Animais , Apoptose/fisiologia , Adesão Celular/fisiologia , Movimento Celular/fisiologia , Cardiopatias Congênitas/embriologia , Cardiopatias Congênitas/genética , Cardiopatias Congênitas/fisiopatologia , HumanosRESUMO
The extracellular matrix is not only a scaffold that provides support for cells, but it is also involved in cell-cell interactions, proliferation and migration. The intricate relationships among the cellular and acellular components of the heart drive proper heart development, homeostasis and recovery following pathological injury. Cardiac myocytes, fibroblasts and endothelial cells differentially express and respond to particular extracellular matrix factors that contribute to cell communication and overall cardiac function. In addition, turnover and synthesis of ECM components play an important role in cardiac function. Therefore, a better understanding of these factors and their regulation would lend insight into cardiac development and pathology, and would open doors to novel targeted pharmacologic therapies. This review highlights the importance of contributions of particular cardiac cell populations and extracellular matrix factors that are critical to the development and regulation of heart function.
Assuntos
Matriz Extracelular/metabolismo , Animais , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Feminino , Coração/fisiologia , Humanos , Masculino , Modelos Biológicos , Miocárdio/metabolismo , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Transdução de Sinais/fisiologiaRESUMO
Tumors are supported by the development of a unique vascular bed. We used fractal dimension (Db) and image analysis to quantify differences in the complexity of the vasculature in normal intestinal submucosa and intestinal polyps. Apc(Min/+) mice and wild-type mice were perfused with a curable latex compound, intestines sectioned, and images collected via confocal microscopy. The images were analyzed and area (A), perimeter (P), and integrated optical density (IOD) of the normal and tumor vascular beds were measured. The Db, a quantitative descriptor of morphological complexity, was significantly greater for the polyp vasculature from Apc(Min/+) mice than controls. This indicates that the polyp microvasculature is more chaotic than that of the controls, while the IOD and average vascular density values displayed no differences. This suggests the mass of blood volume is equivalent in normal and polyp microvasculature. The lower vascular area-perimeter ratios expressed by the polyp microvasculature suggest it is composed of smaller, more tortuous vessels. These data demonstrate that fractal analysis is applicable for providing a quantitative description of vascular complexity associated with angiogenesis occurring in normal or diseased tissue. Application of Db, IOD, and average density provides a clearer quantification of the complex morphology associated with tissue microvasculature.
Assuntos
Processamento de Imagem Assistida por Computador/métodos , Mucosa Intestinal/anatomia & histologia , Pólipos Intestinais/patologia , Microscopia Confocal/métodos , Microvasos/anatomia & histologia , Patologia/métodos , Animais , Camundongos , Camundongos Endogâmicos C57BL , Neovascularização Patológica , Neovascularização FisiológicaRESUMO
The formation and the patterning of the coronary vasculature are critical to the development and pathology of the heart. Alterations in cytokine signaling and biomechanical load can alter the vascular distribution of the vessels within the heart. Changes in the physical patterning of the vasculature can have significant impacts on the relationships of the pressure-flow network and distribution of critical growth and survival factors to the tissue. Interleukin-6 (IL-6) is a pleiotropic cytokine that regulates several biological processes, including vasculogenesis. Using both immunohistological and cardioangiographic analyses, we tested the hypothesis that IL-6-loss will result in decreased vessel density, along with changes in vascular distribution. Moreover, given the impact of vascular patterning on pressure-flow and distribution mechanics, we utilized non-Euclidean geometrical fractal analysis to quantify the changes in patterning resulting from IL-6-loss. Our analyses revealed that IL-6-loss results in a decreased capillary density and increase in intercapillary distances, but does not alter vessel size or diameter. We also observed that the IL-6-/- coronary vasculature had a marked increase in fractal dimension (D value), indicating that IL-6-loss alters vascular patterning. Characterization of IL-6-loss on coronary vasculature may lend insight into the role of IL-6 in the formation and patterning of the vascular bed.
Assuntos
Vasos Coronários/crescimento & desenvolvimento , Interleucina-6/fisiologia , Neovascularização Fisiológica , Angiografia , Animais , Imuno-Histoquímica , Interleucina-6/deficiência , Camundongos , Camundongos Endogâmicos C57BL , Camundongos KnockoutRESUMO
The c-myc oncogene plays an important role in tumorigenesis and is frequently deregulated in many human cancers, including gastrointestinal cancers. In humans, mutations of the adenomatous polyposis coli (Apc) tumor suppressor gene occur in most colorectal cancers. Mutation of Apc leads to stabilization of beta-catenin and increases in beta-catenin target gene expression (c-myc and cyclin D1), whose precise functional significance has not been examined using genetic approaches. Apc(Min/+) mice are a model of familial adenomatous polyposis and are heterozygous for an Apc truncation mutation. We have developed a model for examining the role of c-Myc in Apc-mediated tumorigenesis. We crossed c-myc(+/-) mice to Apc(Min/+) to generate Apc(Min/+) c-myc(+/-) animals. The compound Apc(Min/+) c-myc(+/-) mice were used to evaluate the effect of c-myc haploinsufficiency on the Apc(Min/+) phenotype. We observed a significant reduction in tumor numbers in the small intestine of Apc(Min/+) c-myc(+/-) mice compared with control Apc(Min/+) c-myc(+/+) mice. In addition, we observed one to three polyps per colon in Apc(Min/+) c-myc(+/+) mice, whereas only two lesions were observed in the colons of Apc(Min/+) mice that were haploinsufficient for c-myc. Moreover, reduction in c-myc levels resulted in a significant increase in the survival of these animals. Finally, we observed marked decreases in vascular endothelial growth factor, EphA2, and ephrin-B2 expression as well as marked decreases in angiogenesis in intestinal polyps in Apc(Min/+) c-myc(+/-) mice. This study shows that c-Myc is critical for Apc-dependent intestinal tumorigenesis in mice and provides a potential therapeutic target in the treatment of colorectal cancer.
Assuntos
Polipose Adenomatosa do Colo/genética , Genes APC/fisiologia , Neovascularização Patológica/genética , Proteínas Proto-Oncogênicas c-myc/genética , Polipose Adenomatosa do Colo/mortalidade , Polipose Adenomatosa do Colo/patologia , Animais , Apoptose/fisiologia , Divisão Celular/fisiologia , Modelos Animais de Doenças , Feminino , Regulação Neoplásica da Expressão Gênica/fisiologia , Hematócrito , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Neovascularização Patológica/mortalidade , Neovascularização Patológica/patologia , Índice de Gravidade de Doença , Baço/patologia , Taxa de SobrevidaRESUMO
The neonatal heart undergoes normal hypertrophy or compensation to complete development and adapt to increased systolic pressures. Hypertrophy and increased neonatal wall stiffness are associated with a doubling of the number of fibroblasts and de novo formation of collagen. Normal postnatal remodeling is completed within 3-4 weeks after birth but can be rekindled in adult life in response to environmental signals that lead to pathological hypertrophy, fibrosis, and heart failure. The signals that trigger fibroblast and collagen formation (fibrosis) as well as the origin and differentiation of the cardiac fibroblast lineage are not well understood. Using mice studies and a single-cell engraftment model, we have shown that cardiac fibroblasts are derived from two extracardiac sources: the embryonic proepicardial organ and the recruitment of circulating bone marrow cells of hematopoietic stem cell origin. Periostin, a matricellular protein, is normally expressed in differentiating fibroblasts but its expression is elevated several fold in pathological remodeling and heart failure. Our hypothesis that periostin is profibrogenic (i.e., it promotes differentiation of progenitor mesenchymal cells into fibroblasts and their secretion and compaction of collagen) was tested using isolated and cultured embryonic, neonatal, and adult wild-type and periostin-null, nonmyocyte populations. Our findings indicate that abrogation of periostin by targeted gene deletion inhibits differentiation of nonmyocyte progenitor cells or permits misdirection into a cardiomyocyte lineage. However, if cultured with periostin or forced to express periostin, they became fibroblasts. Periostin plays a significant role in promoting fibrogenesis residual stress, and tensile testings indicated that periostin played an essential regulatory role in maintaining the biomechanical properties of the adult myocardium. These findings indicate that periostin is a profibrogenic matricellular protein that promotes collagen fibrogenesis, inhibits differentiation of progenitor cells into cardiomyocytes, and is essential for maintaining the biomechanical properties of the adult myocardium.
Assuntos
Sistema Cardiovascular/fisiopatologia , Moléculas de Adesão Celular/fisiologia , Adulto , Animais , Animais Recém-Nascidos , Sistema Cardiovascular/crescimento & desenvolvimento , Diferenciação Celular , Fibroblastos/fisiologia , Coração/crescimento & desenvolvimento , Coração/fisiologia , Humanos , Recém-Nascido , Camundongos , Miocárdio/citologia , Células-Tronco/fisiologiaRESUMO
Myc oncoproteins are overexpressed in most cancers and are sufficient to accelerate cell proliferation and provoke transformation. However, in normal cells Myc also triggers apoptosis. All of the effects of Myc require its function as a transcription factor that dimerizes with Max. This complex induces genes containing CACGTG E-boxes, such as Ornithine decarboxylase (Odc), which harbors two of these elements. Here we report that in quiescent cells the Odc E-boxes are occupied by Max and Mnt, a putative Myc antagonist, and that this complex is displaced by Myc-Max complexes in proliferating cells. Knockdown of Mnt expression by stable retroviral RNA interference triggers many targets typical of the "Myc" response and provokes accelerated proliferation and apoptosis. Strikingly, these effects of Mnt knockdown are even manifest in cells lacking c-myc. Moreover, Mnt knockdown is sufficient to transform primary fibroblasts in conjunction with Ras. Therefore, Mnt behaves as a tumor suppressor. These findings support a model where Mnt represses Myc target genes and Myc functions as an oncogene by relieving Mnt-mediated repression.
Assuntos
Apoptose , Transformação Celular Neoplásica , Proteínas Nucleares/deficiência , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Repressoras , Transcrição Gênica/genética , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos , Divisão Celular , Células Cultivadas , Fibroblastos , Regulação Neoplásica da Expressão Gênica , Genes Supressores , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Ornitina Descarboxilase/genética , Fenótipo , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
Cardiac function is determined by the coordinated and dynamic interaction of several cell types together with components of the extracellular matrix (ECM). This interaction is regulated by mechanical, chemical, and electrical signals between the cellular and noncellular components of the heart. Recent studies using fluorescence-activated cell sorting indicate that the number of myocytes remains relatively constant during development and disease, whereas the number of fibroblasts and other cell types can change dramatically. Cardiac fibroblasts appear to have different origins at different stages of development and fluctuate in response to a variety of physiological signals. Fibroblasts form a network of cells that are connected to each other via specific cadherins and connexins, to the ECM via integrins, and to myocytes by a variety of receptors, including connexins. Examples of the integration of signals include the role of angiotensin II (Ang II), which stimulates mechanical contraction of fibroblasts, as well as cytokine signaling. Cytokine signaling alters connexin and K(+) channel activation, which in turn is regulated by Ang II, essentially forming a feedback loop. Quantitative changes in mechanical, chemical, and electrical signals that can alter the overall cardiac form and function will be discussed here.
Assuntos
Matriz Extracelular/metabolismo , Miocárdio/citologia , Animais , Fibroblastos/metabolismo , HumanosRESUMO
Cancer is one of the leading causes of death in the United States along with heart disease. The hallmark of cancer treatment has been conventional chemotherapy. Chemotherapeutic drugs are designed to target not only rapidly dividing cells, such as cancer cells, but also certain normal cells, such as intestinal epithelium. Over the past several years, a new generation of cancer treatment has come to the forefront, i.e, targeted cancer therapies. Like conventional chemotherapy, targeted cancer therapies use pharmacological agents that inhibit growth, increase cell death and restrict the spread of cancer. As the name suggests, targeted therapies interfere with specific proteins involved in tumorigenesis. Rather than using broad base cancer treatments, focusing on specific molecular changes which are unique to a particular cancer, targeted cancer therapies may be more therapeutically beneficial for many cancer types, including lung, colorectal, breast, lymphoma and leukemia. Moreover, recent advances have made it possible to analyze and tailor treatments to an individual patient's tumor. There are three main types of targeted cancer therapies; 1) monoclonal antibodies, 2) small molecule inhibitors and 3) immunotoxins. This review will discuss these three classes of targeted therapies in detail, as well as the biology behind targeted cancer therapies.
Assuntos
Antineoplásicos/uso terapêutico , Terapia de Alvo Molecular , Neoplasias/tratamento farmacológico , Animais , Antineoplásicos/farmacologia , Humanos , Neoplasias/metabolismoRESUMO
Cardiac function is mediated by interactions between the cellular constituents of the heart, as well as the extracellular matrix. The major cell types of the heart include cardiac fibroblasts, myocytes, endothelial cells, and vascular smooth muscle cells. In addition, there are also resident stem cells and transient cell types, such as immune cells. Interactions in the heart include chemical, mechanical, and electrical signals, which vary depending on the developmental stage, disease state, and specific cell type. Understanding how these different signals interact at the molecular, cellular, and organ levels is important for better understanding cardiac function under a variety of physiological and pathological conditions. Cardiac fibroblasts play key roles in maintaining normal cardiac form and function, as well as in the cardiac remodeling process during pathological conditions, such as myocardial infarction and hypertension. Regardless of normal or pathological status of the heart, fibroblasts have multiple functions, such as synthesis and deposition of extracellular matrix and cell-cell communication with other cardiac cells, including myocytes and endothelial cells. Interactions with other cell types can affect multiple cell signaling pathways (e.g., ERK, JNK, and p38), the expression and secretion of numerous growth factors and cytokines, microRNA exchange, gene and protein expression, and angiogenesis. In this review, we provide insight into the cardiac fibroblast under normal and pathological conditions to illustrate their importance in maintaining proper cardiac function.
Assuntos
Fibroblastos/metabolismo , Fibroblastos/patologia , Cardiopatias/metabolismo , Cardiopatias/patologia , Miocárdio/metabolismo , Miocárdio/patologia , Animais , Humanos , Modelos CardiovascularesRESUMO
The organization of cells is key to the proper formation and function of tissues and it appears to be dependent upon various intracellular and extracellular signals. These signals come from cell-cell interactions, as well as interactions with the surrounding extracellular milieu. In order to investigate these properties and interactions among cells, our lab utilizes and has developed several techniques that provide a 3-dimensional, in vivo-like environment for in vitro cell culture. In this chapter, we describe several techniques for isolating primary cardiac cells, including myocytes, endothelial cells, and fibroblasts. In addition, we discuss and outline an adhesion assay and an aggregation assay that can be used for numerous cell types, as well as a collagen gel assay for examination of cell-cell and cell-matrix interactions.