RESUMO
Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs) which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo- and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system.
Assuntos
Comunicação Celular/fisiologia , Junções Comunicantes/fisiologia , Timo/fisiologia , Animais , Conexinas/fisiologia , Células Epiteliais , Matriz Extracelular , Humanos , Imunidade Celular , Camundongos , RNA Mensageiro , Timo/citologiaRESUMO
Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs) which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo- and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system
Assuntos
Humanos , Conexinas/fisiologia , Junções Comunicantes/fisiologia , Sistema Imunitário/citologia , Sistema Imunitário/fisiologia , Células da Medula Óssea/citologia , Comunicação Celular/fisiologia , Imunidade Celular/fisiologia , Células Estromais/fisiologiaRESUMO
Gap junctions are constituted by intercellular channels and provide a pathway for transfer of ions and small molecules between adjacent cells of most tissues. The degree of intercellular coupling mediated by gap junctions depends on the number of gap junction channels and their activity may be a function of the state of phosphorylation of connexins, the structural subunit of gap junction channels. Protein phosphorylation has been proposed to control intercellular gap junctional communication at several steps from gene expression to protein degradation, including translational and post-translational modification of connexins (i.e., phosphorylation of the assembled channel acting as a gating mechanism) and assembly into and removal from the plasma membrane. Several connexins contain sites for phosphorylation for more than one protein kinase. These consensus sites vary between connexins and have been preferentially identified in the C-terminus. Changes in intercellular communication mediated by protein phosphorylation are believed to control various physiological tissue and cell functions as well as to be altered under pathological conditions.
Assuntos
Conexinas/metabolismo , Junções Comunicantes/metabolismo , Conexinas/fisiologia , FosforilaçãoRESUMO
Gap junctions are constituted by intercellular channels and provide a pathway for transfer of ions and small molecules between adjacent cells of most tissues. The degree of intercellular coupling mediated by gap junctions depends on the number of gap junction channels and their activity may be a function of the state of phosphorylation of connexins, the structural subunit of gap junction channels. Protein phosphorylation has been proposed to control intercellular gap junctional communication at several steps from gene expression to protein degradation, including translational and post-translational modification of connexins (i.e., phosphorylation of the assembled channel acting as a gating mechanism) and assembly into and removal from the plasma membrane. Several connexins contain sites for phosphorylation for more than one protein kinase. These consensus sites vary between connexins and have been preferentially identified in the C-terminus. Changes in intercellular communication mediated by protein phosphorylation are believed to control various phsysiological tissue and cell functions as well as to be altered under pathological conditions. (AU)Gap junctions are constituted by intercellular channels and provide a pathway for transfer of ions and small molecules between adjacent cells of most tissues. The degree of intercellular coupling mediated by gap junctions depends on the number of gap junction channels and their activity may be a function of the state of phosphorylation of connexins, the structural subunit of gap junction channels. Protein phosphorylation has been proposed to control intercellular gap junctional communication at several steps from gene expression to protein degradation, including translational and post-translational modification of connexins (i.e., phosphorylation of the assembled channel acting as a gating mechanism) and assembly into and removal from the plasma membrane. Several connexins contain sites for phosphorylation for more than one protein kinase. These consensus sites vary between connexins and have been preferentially identified in the C-terminus. Changes in intercellular communication mediated by protein phosphorylation are believed to control various phsysiological tissue and cell functions as well as to be altered under pathological conditions.
Assuntos
Conexinas/metabolismo , Junções Comunicantes/metabolismo , Comunicação Celular , Conexinas/fisiologia , FosforilaçãoRESUMO
This prospective study was performed for the evaluation of the lipids in serum; the metabolic and other effects related with septicaemia, stability and compatibility of the parenteral nutrition combining in one continent amino acids, carbohydrates and fats; this system is called nutritional total mixture, "all in one" or three in one. Twenty prematures neonates were included in the study. The variables analyzed were: weight, gestational age; the laboratory exams taken before the installation of the system and seven days after were: total lipids, triglycerides, phospholipids, cholesterol, sodium, potassium, chloride, glucose, urea nitrogen, creatinine, hepatic enzymes and proteins, cellular blood count and coagulations tests. We obtained the next results: the mean gestational age and weight were 34 +/- 5 weeks and 1327 +/- 172 g, have been observed rise of lipids (P < 0.001), declination of potassium levels (P < 0.001), increment of calcium levels (P < 0.001), increment of albumin (P < 0.001) and platelets (P < 0.01). It is concluded that nutritional total mixture is a sure method in management of premature newborn with good stability, compatibility, with a increment of fats in serum physiological levels, with metabolic tolerance without repercussion renal, hepatic, hematological and without infections.