RESUMO
Among the soluble factors that regulate skeletal muscle function, Transforming Growth Factor type Beta 1 (TGF-ß1) is one of the most studied. This factor inhibits myogenesis and regeneration by regulating the activity and function of satellite cells (SCs). Indeed, TGF-ß has a central role in muscle pathologies in which there is development of fibrosis and/or atrophy of skeletal muscle. Thus, in this review we present the critical and recent antecedents regarding the mechanisms and cellular targets involved in the effects of TGF-ß1 in the muscle, in pathological processes such as the inhibition of regeneration, fibrosis and atrophy. In addition, an update on the development of new strategies with therapeutic potential to inhibit the deleterious actions of TGF-ß in skeletal muscle is discussed.
Assuntos
Músculo Esquelético/fisiologia , Fator de Crescimento Transformador beta1/metabolismo , Animais , Fibrose/tratamento farmacológico , Fibrose/metabolismo , Humanos , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Atrofia Muscular/tratamento farmacológico , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Mioblastos/citologia , Mioblastos/efeitos dos fármacos , Regeneração , Transdução de Sinais , Fator de Crescimento Transformador beta1/antagonistas & inibidores , Fator de Crescimento Transformador beta1/genéticaRESUMO
Causes of lower induction of Hsp70 in neurons during heat shock are still a matter of debate. To further inquire into the mechanisms regulating Hsp70 expression in neurons, we studied the activity of Heat Shock Factor 1 (HSF1) and histone posttranslational modifications (PTMs) at the hsp70 promoter in rat cortical neurons. Heat shock induced a transient and efficient translocation of HSF1 to neuronal nuclei. However, no binding of HSF1 at the hsp70 promoter was detected while it bound to the hsp25 promoter in cortical neurons during heat shock. Histone PTMs analysis showed that the hsp70 promoter harbors lower levels of histone H3 and H4 acetylation in cortical neurons compared to PC12 cells under basal conditions. Transcriptomic profiling data analysis showed a predominant usage of cryptic transcriptional start sites at hsp70 gene in the rat cerebral cortex, compared with the whole brain. These data support a weaker activation of hsp70 canonical promoter. Heat shock increased H3Ac at the hsp70 promoter in PC12 cells, which correlated with increased Hsp70 expression while no modifications occurred at the hsp70 promoter in cortical neurons. Increased histone H3 acetylation by Trichostatin A led to hsp70 mRNA and protein induction in cortical neurons. In conclusion, we found that two independent mechanisms maintain a lower induction of Hsp70 in cortical neurons. First, HSF1 fails to bind specifically to the hsp70 promoter in cortical neurons during heat shock and, second, the hsp70 promoter is less accessible in neurons compared to non-neuronal cells due to histone deacetylases repression.
Assuntos
Córtex Cerebral/citologia , Proteínas de Ligação a DNA/metabolismo , Resposta ao Choque Térmico/genética , Neurônios/metabolismo , Regiões Promotoras Genéticas , Processamento de Proteína Pós-Traducional , Fatores de Transcrição/metabolismo , Acetilação , Animais , Perfilação da Expressão Gênica , Proteínas de Choque Térmico HSP70/genética , Fatores de Transcrição de Choque Térmico , Histonas/metabolismo , Células PC12 , Ligação Proteica/genética , Ratos , Ratos Sprague-Dawley , Sítio de Iniciação de Transcrição , Transcriptoma/genéticaRESUMO
Fibrotic disorders are characterized by an increase in extracellular matrix protein expression and deposition, Duchene Muscular Dystrophy being one of them. Among the factors that induce fibrosis are Transforming Growth Factor type ß (TGF-ß) and the matricellular protein Connective Tissue Growth Factor (CTGF/CCN2), the latter being a target of the TGF-ß/SMAD signaling pathway and is the responsible for the profibrotic effects of TGF-ß. Both CTGF and TGF are increased in tissues affected by fibrosis but little is known about the regulation of the expression of CTGF mediated by TGF-ß in muscle cells. By using luciferase reporter assays, site directed mutagenesis and specific inhibitors in C2C12 cells; we described a novel SMAD Binding Element (SBE) located in the 5' UTR region of the CTGF gene important for the TGF-ß-mediated expression of CTGF in myoblasts. In addition, our results suggest that additional transcription factor binding sites (TFBS) present in the 5' UTR of the CTGF gene are important for this expression and that SP1/SP3 factors are involved in TGF-ß-mediated CTGF expression.
Assuntos
Fator de Crescimento do Tecido Conjuntivo/genética , Fator de Crescimento do Tecido Conjuntivo/metabolismo , Mioblastos/efeitos dos fármacos , Fator de Transcrição Sp1/metabolismo , Fator de Crescimento Transformador beta/farmacologia , Regiões 5' não Traduzidas , Animais , Sítios de Ligação , Linhagem Celular , Fator de Crescimento do Tecido Conjuntivo/química , Regulação da Expressão Gênica , Camundongos , Mutagênese Sítio-Dirigida , Mioblastos/metabolismo , Mioblastos/fisiologia , Transdução de Sinais/efeitos dos fármacos , Proteína Smad3/metabolismo , Fator de Transcrição Sp3/metabolismoRESUMO
Skeletal muscle, the main protein reservoir in the body, is a tissue that exhibits high plasticity when exposed to changes. Muscle proteins can be mobilized into free amino acids when skeletal muscle wasting occurs, a process called skeletal muscle atrophy. This wasting is an important systemic or local manifestation under disuse conditions (e.g., bed rest or immobilization), in starvation, in older adults, and in several diseases. The molecular mechanisms involved in muscle wasting imply the activation of specific signaling pathways which ultimately manage muscle responses to modulate biological events such as increases in protein catabolism, oxidative stress, and cell death by apoptosis. Many factors have been involved in the generation and maintenance of atrophy in skeletal muscle, among them angiotensin II (Ang-II), the main peptide of renin-angiotensin system (RAS). Together with Ang-II, the angiotensin-converting enzyme (ACE) and the Ang-II receptor type 1 (AT-1 receptor) are expressed in skeletal muscle, forming an important local axis that can regulate its function. In many of the conditions that lead to muscle wasting, there is an impairment of RAS in a global or local fashion. At this point, there are several pieces of evidence that suggest the participation of Ang-II, ACE, and AT-1 receptor in the generation of skeletal muscle atrophy. Interestingly, the Ang-II participation in muscle atrophy is strongly ligated to the regulation of hypertrophic activity of factors such as insulin-like growth factor 1 (IGF-1). In this article, we reviewed the current state of Ang-II and RAS function on skeletal muscle wasting and its possible use as a therapeutic target to improve skeletal muscle function under atrophic conditions.
Assuntos
Angiotensina II/metabolismo , Músculo Esquelético/metabolismo , Atrofia Muscular/metabolismo , Animais , Humanos , Músculo Esquelético/efeitos dos fármacos , Atrofia Muscular/patologia , Atrofia Muscular/prevenção & controle , Receptores de Angiotensina/metabolismo , Sistema Renina-Angiotensina/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
Transforming growth factor ß (TGF-ß) is a very strong pro-fibrotic factor which mediates its action, at least in part, through the expression of connective tissue growth factor (CTGF/CCN2). Along with these cytokines, the involvement of phospholipids in wound healing and the development of fibrosis has been revealed. Among them, lysophosphatidic acid (LPA) is a novel, potent regulator of wound healing and fibrosis that has diverse effects on many types of cells. We decided to evaluate the effect of LPA together with TGF-ß on CTGF expression. We found that myoblasts treated with LPA and TGF-ß1 produced an additive effect on CTGF expression. In the absence of TGF-ß, the induction of CTGF expression by LPA was abolished by a dominant negative form of the TGF-ß receptor type II (TGF-ßRII) and by the use of SB 431542, a specific inhibitor of the serine/threonine kinase activity of TGF-ßRI, suggesting that CTGF induction is dependent on LPA and requires active TGF-ßRs. Moreover, we show that LPA requires Smad-2/3 proteins for the induction of CTGF expression, but not their phosphorylation or their nuclear translocation. The requirement of TGF-ßRI for LPA mediated-effects is differential, since treatment of myoblasts with LPA in the presence of SB 431542 abolished the induction of stress fibers but not the induction of proliferation. Finally, we demonstrated that CTGF induction in response to LPA requires the activation of JNK, but not ERK, signaling pathways. The JNK requirement is independent of TGF-ßRI-mediated activity. These novel results for the mechanism of action of LPA and TGF-ß are important for understanding the role of pro-fibrotic growth factors and phospholipids involved in wound healing and related diseases.
Assuntos
Fator de Crescimento do Tecido Conjuntivo/biossíntese , Proteínas Quinases JNK Ativadas por Mitógeno/fisiologia , Lisofosfolipídeos/fisiologia , Receptores de Fatores de Crescimento Transformadores beta/metabolismo , Animais , Linhagem Celular , Lisofosfolipídeos/farmacologia , Camundongos , Receptores de Fatores de Crescimento Transformadores beta/genética , Transdução de Sinais , Proteína Smad2/fisiologia , Proteína Smad3/fisiologia , Ativação TranscricionalRESUMO
The mechanisms of peroxisomal biogenesis remain incompletely understood, specially regarding the role of the endoplasmic reticulum (ER) in human cells, where genetic disorders of peroxisome biogenesis lead to Zellweger syndrome (ZS). The Pex3p peroxisomal membrane protein (PMP) required for early steps of peroxisome biogenesis has been detected in the ER in yeast but not in mammalian cells. Here, we show that Pex3p-GFP expressed in a new ZS cell line (MR), which lacks peroxisomes due to a mutation in the PEX3 gene, localizes first in the ER and subsequently in newly formed peroxisomes. Pex3p bearing an artificial N-glycosylation site shows an electrophoretic shift indicative of ER targeting while en route to preformed peroxisomes in normal fibroblast. A signal peptide that forces its entry into the ER does not eliminate its capability to drive peroxisome biogenesis in ZS cells. Thus, Pex3p is able to drive peroxisome biogenesis from the ER and its ER pathway is not privative of ZS cells. Cross-expression experiments of Pex3p in GM623 cells lacking Pex16p or Pex16p in MR cells lacking Pex3p, showed evidence that Pex3p requires Pex16p for ER location but is dispensable for the ER location of Pex16p. These results indicate that Pex3p follows the ER-to-peroxisomal route in mammalian cells and provides new clues to understand its function.
Assuntos
Retículo Endoplasmático/metabolismo , Lipoproteínas/fisiologia , Proteínas de Membrana/fisiologia , Peroxissomos/metabolismo , Aciltransferases , Estudos de Casos e Controles , Catalase , Retículo Endoplasmático/enzimologia , Fibroblastos/citologia , Humanos , Lipoproteínas/genética , Lipoproteínas/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutação , Peroxinas , Transporte Proteico , Síndrome de ZellwegerRESUMO
Peroxisomes are thought to be formed by division of pre-existing peroxisomes after the import of newly synthesized proteins. However, it has been recently suggested that the endoplasmic reticulum (ER) provides an alternative de novo mechanism for peroxisome biogenesis in some cells. To test a possible role of the ER-Golgi transit in peroxisome biogenesis in mammalian cells, we evaluated the biogenesis of three peroxisomal membrane proteins (PMPs): ALDRP (adrenoleukodystrophy related protein), PMP70 and Pex3p in CHO cells. We constructed chimeric genes encoding these PMPs and green fluorescent protein (GFP), and transiently transfected them to wild type and mutant CHO cells, in which normal peroxisomes were replaced by peroxisomal membrane ghosts. The expressed proteins were targeted to peroxisomes and peroxisomal ghosts correctly in the presence or absence of Brefeldin A (BFA), a drug known to block the ER-Golgi transit. Furthermore, low temperature did not disturb the targeting of Pex3p-GFP to peroxisomes. We also constructed two chimeric proteins of PMPs containing an ER retention signal "DEKKMP": GFP-ALDRP-DEKKMP and myc- Pex3p-DEKKMP. These proteins were mostly targeted to peroxisomes. No colocalization with an ER maker was found. These results suggest that the classical ER-Golgi pathway does not play a major role in the biogenesis of mammalian PMPs.
Assuntos
Retículo Endoplasmático/fisiologia , Complexo de Golgi/fisiologia , Proteínas de Membrana/metabolismo , Mutação , Peroxissomos/metabolismo , Animais , Células CHO , Cricetinae , Cricetulus , Retículo Endoplasmático/metabolismo , Proteínas de Membrana/genéticaRESUMO
Peroxisomes are thought to be formed by division of pre-existing peroxisomes after the import of newly synthesized proteins. However, it has been recently suggested that the endoplasmic reticulum (ER) provides an alternative de novo mechanism for peroxisome biogenesis in some cells. To test a possible role of the ER-Golgi transit in peroxisome biogenesis in mammalian cells, we evaluated the biogenesis of three peroxisomal membrane proteins (PMPs): ALDRP (adrenoleukodystrophy related protein), PMP70 and Pex3p in CHO cells. We constructed chimeric genes encoding these PMPs and green fluorescent protein (GFP), and transiently transfected them to wild type and mutant CHO cells, in which normal peroxisomes were replaced by peroxisomal membrane ghosts. The expressed proteins were targeted to peroxisomes and peroxisomal ghosts correctly in the presence or absence of Brefeldin A (BFA), a drug known to block the ER-Golgi transit. Furthermore, low temperature did not disturb the targeting of Pex3p-GFP to peroxisomes. We also constructed two chimeric proteins of PMPs containing an ER retention signal "DEKKMP": GFP-ALDRP-DEKKMP and myc- Pex3p-DEKKMP. These proteins were mostly targeted to peroxisomes. No colocalization with an ER maker was found. These results suggest that the classical ER-Golgi pathway does not play a major role in the biogenesis of mammalian PMPs.
Assuntos
Animais , Cricetinae , Retículo Endoplasmático/fisiologia , Complexo de Golgi/fisiologia , Mutação , Proteínas de Membrana/metabolismo , Peroxissomos/metabolismo , Células CHO , Cricetulus , Retículo Endoplasmático/metabolismo , Proteínas de Membrana/genéticaRESUMO
Objetivo: Identificar los factores de riesgo asociados a muerte perinatal en el Hospital Los Andes de la ciduad de El Alto, Bolivia. Diseño. Caoss y controles incidentes. Lugar: Hospital Los Andes , centro materno infantil institucional de sugundo nivel. Participantes. Se enrolaron al estudio 70 madres de mortinatos in útero y/o fallecidos en los primeros 7 días de vida (casos) y 140 madres de recién nacidos vivos como controles (Controles). Investigación. Ninguna. Mediciónes principales Usando un instrumento previamente probado, 6 enfermeras antes capacitadas en su manejo, entrevistaron alas madres motivo del estudio. El instrumento evaluó el estado socioeconómico, la historia obstétrica. La calidad de atención del parto y la atención del recién nacido fueron solicitados a los médicos tratantes. Resultados. el 25 porciento sucedieron fuera del servicio y el 47.1 porciento en servicio(au)
Assuntos
Humanos , Feminino , Pediatria , Mortalidade Infantil , Fatores de Risco , Causas de Morte , Mortalidade PerinatalRESUMO
La infertilidad es un problema que afecta a millones de parejas en el mundo. En Costa Rica no conocemos con exactitud la magnitud del problema. De acuerdo con estudios realizados en otros países el 15 por ciento de las parejas tiene problemas de infertilidad y en la mitad de éstas existe un factor masculino. El espermograma es un estudio pivote en la valoración inicial en la praeja infértil. Es un examen sencillo, rápido, de bajo costo y no invasivo. Es de suma utilidad ya que permite estudiar el factor masculino y valorar la respuesta a la terapia, ya sea ésta médica o quirúrgica.
Assuntos
Humanos , Masculino , Adulto , Contagem de Espermatozoides , Infertilidade Masculina , Costa RicaRESUMO
Con el fin de hacer una valoración ordenada y sistemática de la patología urológica de nuestros niños y de uniformar criterios en el personal médico de nuestra institución, el Servicio de Urología del Hospital Nacional de Niños presenta su protocolo de estudio de la hematuria
Assuntos
Humanos , Criança , Hematúria/diagnóstico , Hematúria/etiologia , Costa RicaRESUMO
La incontingencia urinaria es uno de los problemas urológicos de más díficil manejo. No sólo el paciente se siente incapacitado para realizar una serie de actividades, sino que el urólogo no siempre cuenta con armas tan efectivas como quisiera. El esfinter urinario artificial es tal vez la única excepción a lo anterior, y hoy día, se considera el tratamiento de elección la incontinencia urinaria debida a falla del mecanismo esfinteriano. Este dispositivo proporciona continencia aceptable a más del 85 por ciento de los pacientes a quienes se les implanta. El presente trabajo describe la experiencia con los primeros ocho casos de esfínter urinario artificial implatados en Costa Rica
Assuntos
Humanos , Masculino , Adulto , Pessoa de Meia-Idade , Esfíncter Urinário Artificial , Costa RicaRESUMO
Con el descubrimiento del antígeno prostático específico (APE) el diagnóstico del cáncer de próstata, en los últimos 15 años, tomó una nueva dimensión. Los esfuerzos actualmente se centran en detectar esta enfermedad en estadíos tempranos para así ofrecer al paciente las mayores oportunidades de sobrevida y una mejor calidad de vida. En este estudio se revisan los resultados de un período de 5 años, con el uso del tacto rectal como único método de detección de cáncer de próstata. Se analizan aspectos como el diagnóstco de ingreso, edad y estadío al momento del diagnóstico así como hallazgos al tacto rectal. Posteriormente se revisa los resultados luego de un año de inclusión del APE al armamento diagnóstico y se comparan con el período anterior
Assuntos
Humanos , Masculino , Neoplasias da Próstata/diagnóstico , Antígeno Prostático Específico , Costa RicaRESUMO
Conforme aumenta la expectativa de vida en nuestro país, aumenta la prevalencia de algunas enfermedades propias de la edad. En Costa Rica, el cáncer de próstata es la segunda causa de muerte por cáncer en hombres. La mayoría de estos tumores, al igual que en el resto del mundo, se diagnostican en estadío avanzado, cuando ya no es posible ofrecer cura. La presente revisión tiene por objeto dar una visión clara acerca de la epidemiología, la historia natural y los métodos con que contamos hoy en día para el diagnóstico del cáncer de próstata y de como utilizar esta información para procurar un diagnóstico temprano.