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La acumulación dependiente de ATP y la liberación mediada por inositol trifosfato o ADP-ribosa cíclica de Ca2+ desde
O V Gerasimenko1, J V Gerasimenko, A V Tepikin
1Physiological Laboratory, University of Liverpool, England.
Cell
|February 10, 1995
Resumen
La absorción y liberación de calcio (Ca2+) en los núcleos hepáticos ocurren en la envoltura nuclear, no en el nucleoplasma. El inositol 1,4,5-trisfosfato (IP3) desencadena la liberación de Ca2+ de estas reservas hacia el nucleoplasma.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
Sus antecedentes:
- Los iones de calcio (Ca2+) juegan un papel crucial en la señalización celular y las funciones nucleares.
- Estudios previos indicaron la absorción de Ca2+ dependiente de ATP y la liberación mediada por inositol 1,4,5-trisfosfato (IP3) en núcleos aislados.
Objetivo del estudio:
- Para dilucidar la ubicación precisa y los mecanismos del transporte de Ca2+ dentro de núcleos hepáticos aislados.
- Para diferenciar entre el manejo de Ca2+ por la envoltura nuclear frente al nucleoplasma.
Principales métodos:
- Utilizó sondas fluorescentes de Ca2+ (Fura 2, calcio-verde 1) con imágenes digitales y microscopía confocal.
- Empleó marcadores del retículo endoplasmático para evaluar la localización de la sonda.
- Investigó los efectos de ATP, IP3 y ADP-ribosa cíclica en la dinámica nuclear de Ca2+.
Principales resultados:
- La sonda Fura 2 sensible al Ca2+ se localizó en la envoltura nuclear, reflejando la distribución de los marcadores del retículo endoplasmático.
- La absorción de Ca2+ dependiente de ATP y la liberación inducida por IP3 se atribuyeron a la envoltura nuclear, no al nucleoplasma.
- Los niveles nucleoplásmicos de Ca2+ reflejaron rápidamente los cambios externos de Ca2+, mientras que la IP3 y la ADP-ribosa cíclica indujeron elevaciones transitorias de Ca2+ intranucleares.
Conclusiones:
- El transporte de Ca2+ en núcleos hepáticos aislados está mediado principalmente por la envoltura nuclear.
- La liberación de las reservas de la envolvente nuclear se dirige hacia el nucleoplasma, difundiéndose posteriormente a través de los poros nucleares.
- Esto aclara la regulación espacial de las vías de señalización nucleares de Ca2+.
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