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El nivel de fosforilación de la caja PIP-p21 modula la interacción con el PCNA en las células vivas

Christian Melle¹, Birgit Hoffmann¹, Annett Wiesenburg¹

¹Biomolecular Photonics Group, Jena University Hospital, Friedrich Schiller University Jena, Jena, 07740, Germany.

Biochemical and biophysical research communications

|February 22, 2026

Resumen

La fosforilación del regulador del ciclo celular p21 (CDKN1A) afecta su interacción con el antígeno nuclear celular proliferante (PCNA). Fosforilación simultánea de T145 y S146 en p21

Área de la Ciencia:

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

Sus antecedentes:

Las proteínas funcionan a través de interacciones dentro de complejos.
El antígeno nuclear celular proliferante (PCNA) y p21 (CDKN1A) son reguladores clave de la progresión del ciclo celular.
Comprender su interacción es crucial para el control del ciclo celular.

Objetivo del estudio:

Investigar el impacto de las modificaciones post-transcripcionales de p21 en su interacción con PCNA en células vivas.
Para determinar cómo la fosforilación en sitios específicos dentro de la caja de proteínas de interacción con PCNA (PIP-box) de p21 influye en la afinidad de unión.
Para aclarar el papel de la fosforilación de p21 en la regulación de la formación del complejo PCNA-p21.

Principales métodos:

Utilizó mediciones de transferencia de energía de resonancia Förster (FRET) basadas en microscopía de imágenes de fluorescencia de por vida (FLIM).
Mutagénesis dirigida en el sitio empleada para crear variantes de p21 que imitan la fosforilación y que previenen la fosforilación.
Interacciones investigadas utilizando una variante p21 con una caja PIP eliminada (p21ΔPIP).

Principales resultados:

La fosforilación simultánea de treonina 145 y serina 146 en la caja PIP de p21 redujo significativamente la eficiencia de FRET, lo que indica una interacción PCNA debilitada.
La mutagenesis que impide la fosforilación de T145 y S146 a la alanina aumentó la eficiencia de FRET, lo que significa una interacción PCNA-p21 más fuerte.
La eliminación de la caja PIP en p21ΔPIP restringió su interacción con PCNA.

Conclusiones:

El estado de fosforilación de la caja PIP de p21 es un regulador crítico de su interacción con PCNA.
Los patrones específicos de fosforilación modulan la afinidad de unión entre las variantes p21 y PCNA bajo condiciones fisiológicas.
Esta regulación proporciona un mecanismo para controlar la progresión del ciclo celular a través de la dinámica compleja PCNA-p21.

Palabras clave:

El FLIM-FRETET es el frete de vuelo.El PCNA es el PCNA.PIP-caja de la caja.El PTM es PTM.La interacción proteína-proteína es la interacción proteína-proteína.p21 p21 p21 p21 p21 p21 p21 p21 p21 p21 p21 p21 p21 p21 p2 p2 p2 p2 p2 p2 p2 p3 p2 p2 p2 p2 p2 p3

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