RESUMO
Elevated levels of systemic and pulmonary leptin are associated with diseases related to lung injury and lung cancer. However, the role of leptin in lung biology and pathology, including the mechanism of leptin gene expression in the pathogenesis of lung diseases, including lung cancer, remains elusive. Here, using conditional deletion of tumor suppressor gene Pten in the lung epithelium in vivo in transgenic mice and human PTEN-null lung epithelial cells, we identify the leptin-driven feed-forward signaling loop in the lung epithelial cells. Leptin-mediated leptin/leptin-receptor gene expression likely amplifies leptin signaling that may contribute to the pathogenesis and severity of lung diseases, resulting in poor clinical outcomes. Loss of Pten in the lung epithelial cells in vivo activated adipokine signaling and induced leptin synthesis as ascertained by genome-wide mRNA profiling and pathway analysis. Leptin gene transcription was mediated by binding of transcription factors NRF-1 and CCAAT/enhancer-binding protein δ (C/EBP) to the proximal promoter regions and STAT3 to the distal promoter regions as revealed by leptin promoter-mutation, chromatin immunoprecipitation, and gain- and loss-of-function studies in lung epithelial cells. Leptin treatment induced expression of the leptin/leptin receptor in the lung epithelial cells via activation of MEK/ERK, PI3K/AKT/mammalian target of rapamycin (mTOR), and JAK2/STAT3 signaling pathways. Expression of constitutively active MEK-1, AKT, and STAT3 proteins increased expression, and treatment with MEK, PI3K, AKT, and mTOR inhibitors decreased LEP expression, indicating that leptin via MAPK/ERK1/2, PI3K/AKT/mTOR, and JAK2/STAT3 pathways, in turn, further induces its own gene expression. Thus, targeted inhibition of the leptin-mediated feed-forward loop provides a novel rationale for pharmacotherapy of disease associated with lung injury and remodeling, including lung cancer.
Assuntos
Leptina/genética , Pulmão/metabolismo , PTEN Fosfo-Hidrolase/genética , Receptores para Leptina/genética , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Proteína delta de Ligação ao Facilitador CCAAT/genética , Proteína delta de Ligação ao Facilitador CCAAT/metabolismo , Linhagem Celular Tumoral , Expressão Gênica/efeitos dos fármacos , Perfilação da Expressão Gênica , Humanos , Imuno-Histoquímica , Leptina/metabolismo , Leptina/farmacologia , Pulmão/patologia , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Quinases de Proteína Quinase Ativadas por Mitógeno/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Fator 1 Relacionado a NF-E2/genética , Fator 1 Relacionado a NF-E2/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Regiões Promotoras Genéticas/genética , Ligação Proteica , Interferência de RNA , Receptores para Leptina/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genéticaRESUMO
The replication of bone physiology under laboratory conditions is a prime target behind the development of in vitro bone models. The model should be robust enough to elicit an unbiased response when stimulated experimentally, giving reproducible outcomes. In vitro bone tissue generation majorly requires the availability of cellular components, the presence of factors promoting cellular proliferation and differentiation, efficient nutrient supply, and a supporting matrix for the cells to anchor - gaining predefined topology. Calcium phosphates (CaP) are difficult to ignore while considering the above requirements of a bone model. Therefore, the current review focuses on the role of CaP in developing an in vitro bone model addressing the prerequisites of bone tissue generation. Special emphasis is given to the physico-chemical properties of CaP that promote osteogenesis, angiogenesis and provide sufficient mechanical strength for load-bearing applications. Finally, the future course of action is discussed to ensure efficient utilization of CaP in the in vitro bone model development field.
RESUMO
Mitochondrial dysfunction has been proposed to play a role in the neuropathology of multiple sclerosis (MS). Previously, we reported significant alterations in the transcription of nuclear-encoded electron transport chain genes in MS and confirmed translational alterations for components of Complexes I and III that resulted in reductions in their activity. To more thoroughly and efficiently elucidate potential alterations in the expression of mitochondrial and related proteins, we have characterized the mitochondrial proteome in postmortem MS and control cortex using Surface-Enhanced Laser Desorption Ionization Time of Flight Mass Spectrometry (SELDI-TOF-MS). Using principal component analysis (PCA) and hierarchical clustering techniques we were able to analyze the differential patterns of SELDI-TOF spectra to reveal clusters of peaks which distinguished MS from control samples. Four proteins in particular were responsible for distinguishing disease from control. Peptide fingerprint mapping unambiguously identified these differentially expressed proteins. Three proteins identified are involved in respiration including cytochrome c oxidase subunit 5b (COX5b), the brain specific isozyme of creatine kinase, and hemoglobin ß-chain. The fourth protein identified was myelin basic protein (MBP). We then investigated whether these alterations were consistent in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. We found that MBP was similarly altered in EAE but the respiratory proteins were not. These data indicate that while the EAE mouse model may mimic aspects of MS neuropathology which result from inflammatory demyelinating events, there is another distinct mechanism involved in mitochondrial dysfunction in gray matter in MS which is not modeled in EAE.
Assuntos
Biomarcadores/análise , Encéfalo/metabolismo , Córtex Cerebral/metabolismo , Encefalomielite Autoimune Experimental/metabolismo , Esclerose Múltipla/metabolismo , Proteoma/análise , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Autopsia , Western Blotting , Encéfalo/patologia , Estudos de Casos e Controles , Córtex Cerebral/patologia , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/etiologia , Encefalomielite Autoimune Experimental/patologia , Feminino , Imunofluorescência , Glicoproteínas/administração & dosagem , Humanos , Imunoprecipitação , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Esclerose Múltipla/patologia , Proteína Básica da Mielina/metabolismo , Glicoproteína Mielina-Oligodendrócito , Fragmentos de Peptídeos/administração & dosagem , Mapeamento de Peptídeos , Análise de Componente Principal , Proteômica , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
Utility of plant-based materials in tissue engineering has exponentially increased over the years. Recent efforts in this area have been focused on substituting synthetic cross-linkers with natural ones derived from biological sources. These cross-linkers are essentially derived from the vegetative components of plants therefore suitably categorised as 'green' and renewable materials. Utilization of plant based cross-linkers in scaffolds and hydrogels offers several advantages compared to the synthetic ones. Natural compounds, like ferulic acid and genipin, when incorporated into scaffolds can promote cellular proliferation and growth, by regulation of growth factors. They participate in crucial activities, thus providing impetus for cell growth, function, differentiation and angiogenesis. Several natural compounds inherently possess anti-microbial, antioxidant and anti-inflammatory effects, which enhance the inherent characteristics of the scaffolds. Versatility of natural cross-linkers can be exploited for diverse applications. Integrating such potent molecules can enable the scaffold to display relevant characteristics for each function. This review article focuses on the recent developments with plant based cross-linkers that are employed for scaffold synthesis and their applications, which may be explored to synthesize scaffolds suitable for diverse biomedical applications.
Assuntos
Hidrogéis , Engenharia Tecidual/métodos , Alicerces Teciduais , Materiais Biocompatíveis , Diferenciação Celular , Proliferação de Células , Humanos , Iridoides , Teste de MateriaisRESUMO
BACKGROUND: Recent integrated approaches involving nanotechnology and gene therapy have accelerated development of efficient drug delivery to the central nervous system (CNS). Neurodegenerative disorders are closely associated with genetic inheritance and mutation. MATERIALS: Nanotechnology has allowed effective engineering of various such polymeric structures. Moreover, availability of a wide array of polymeric materials has enabled fabrication of biocompatible and biodegradable delivery vehicles. Our manuscript focuses on the ideal features and properties of polymeric nanoparticles that have enabled successful gene therapy for neurodegenerative disorders, as well as the challenges that are posing difficulties in their practical application. We have highlighted these aspects through examples of polymeric nanoparticles that have exhibited therapeutic promise in the treatment of neurological disorders and mutations. METHODS: Complete cure of these diseases is a challenging task and gene therapy appears as a realistic approach for their treatment. Gene therapy allows effective replacement or suppression of faulty genes, thereby increasing chances for neuron survival and repair. However, successful delivery of naked genetic material to CNS faces severe obstacles due to possible degradation and restricted transportation of these biological entities across the blood brain barrier (BBB). Structurally, the BBB is composed of several tight junctions, making the membrane highly selective towards the entry of molecules. CONCLUSION: In order to target BBB for treating neurodegenerative diseases, it is essential to develop a tailor-made system that may not only cross this barrier, but also effectively modulate the expression of disease-causing genes. Stabilization of therapeutic genes and their effective, targeted delivery may be possible using polymeric nanoparticles as carriers.
Assuntos
Terapia Genética/métodos , Nanopartículas/administração & dosagem , Doenças Neurodegenerativas/terapia , Polímeros/administração & dosagem , Animais , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Técnicas de Transferência de Genes , Humanos , Nanopartículas/química , Nanotecnologia/métodos , Doenças Neurodegenerativas/genética , Polímeros/químicaRESUMO
Multiple sclerosis (MS) is an inflammatory neurodegenerative disease. Recently, decreased expression of nuclear encoded electron transport chain genes was found in neurons in MS cortex. To understand the transcriptional mechanisms responsible for the coordinate down regulation of these genes, we performed electrophoretic mobility shifts with nuclear extracts isolated from gray matter from nonlesion areas of postmortem MS and control cortex. Nine tissue blocks from eight different MS brains and six matched control blocks from five control brains were analyzed. We identified a decrease in a transcription factor complex containing nuclear respiratory factor 2 (NRF-2) in nuclear extracts isolated from MS cortex. This decrease is correlated with decreased expression of electron transport chain subunit genes and increased oxidative damage measured by increased anti-nitrotyrosine immunoreactivity. We conclude that in MS cortex a chronic increase in oxidative stress leads to aberrant regulation of transcription of genes involved in energy metabolism.