Regulation of gap junctions by protein phosphorylation

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.

Accion de la esporotoxina de Clostridium perfringens (welchii) en el intestino aislado de conejo. / Action of the sporotoxin of Clostridium perfringens (welchii) in the isolated intestine of ralbits

Se estudio por primera vez la enterotoxina de Clostridium perfringens (CPE) en el modelo intestino aislado de conejo.Se observaron cambios marcados sobre todo en fuerza con aumento inicial (6 min.) y luego disminucion paulatina (80 min.) para luego dar lugar a paralisis total (180 min.). La frecuencia por lo tanto tambien fue afectada en los estudios finales.A los 128 min se observaron periodos intermitentes de paralisis. El modelo sugirio la posibilidad de replicar in vitro pero en un modelo biologico, un "colico". Las lesiones histopatologicas observadas fueron principalmente de tipo descamacion, necrosis y degeneracion de la mucosa y vellosidades pero sin alteracion de la arquitectura. Se sugiere que los cambios observados son mas de tipo topico por lesiones a la mucosa, que de tipo farmaco sistemico