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Dependencia del pH de la clasificación polarizada de las proteínas secretadas

M J Caplan¹, J L Stow, A P Newman

¹Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.

|October 15, 1987

Resumen

Las células epiteliales clasifican con precisión las proteínas en dominios específicos de la membrana. Las células del túbulo renal canino (MDCK) clasifican activamente los componentes de la membrana basal, como la laminina y el proteoglicano de sulfato de heparan (HSPG), para su liberación basolateral, lo que requiere un ambiente intracelular ácido.

Área de la Ciencia:

Biología celular Biología celular.
La bioquímica es la bioquímica.
Biología Molecular Biología Molecular

Sus antecedentes:

Las células epiteliales poseen distintos dominios de la membrana plasmática apical y basolateral.
Esta especialización en el dominio permite la entrega específica de proteínas de membrana y la secreción polarizada de productos.
Las células del túbulo renal canino (MDCK) son un sistema modelo para estudiar la polaridad epitelial y la clasificación de proteínas.

Objetivo del estudio:

Investigar los mecanismos subyacentes a la secreción polarizada de los componentes de la membrana basal por las células MDCK.
Para determinar si la liberación de proteoglicano de laminina y sulfato de heparan (HSPG) está activamente ordenada o sigue una ruta predeterminada.
Para identificar los compartimentos intracelulares involucrados en la clasificación polarizada de las proteínas secretoras.

Principales métodos:

Se utilizaron células MDCK para estudiar la secreción de componentes de la membrana basal.
Manipulación del pH intracelular mediante el uso de cloruro de amonio (NH4Cl) para alterar los compartimentos ácidos.
Cuantificó la liberación de laminina y HSPG en los compartimentos apical y basolateral.

Principales resultados:

Los componentes de la membrana de base, la laminina y el proteoglicano de sulfato de heparano (HSPG), se secretan predominantemente desde la superficie basolateral de las células MDCK.
Esta secreción polarizada es un proceso de clasificación activo.
La alteración de los compartimentos intracelulares ácidos con NH4Cl condujo a la secreción no polarizada de laminina y HSPG en los medios apical y basolateral.

Conclusiones:

La secreción polarizada de los componentes de la membrana basal por las células MDCK está mediada por un mecanismo de clasificación activo.
Un compartimento intracelular ácido es esencial para este proceso de clasificación.
En ausencia de compartimentos ácidos funcionales, las proteínas se secretan a través de una vía predeterminada, lo que resulta en una liberación no polarizada.

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