Las mutaciones que aumentan la autoinhibición inactivan los supresores tumorales Smad2 y Smad4
1Cell Biology Program and Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York 10021, USA.
Nature
|July 3, 1997
Resumen
Las proteínas supresoras de tumores Smad2 y Smad4 normalmente inhiben el crecimiento. Las mutaciones en sus dominios N aumentan la autoinhibición, bloqueando la señalización del TGF-beta y la supresión tumoral.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología del cáncer Biología del cáncer.
- Transducción de señales Transducción de señales.
Sus antecedentes:
- Smad2 y Smad4 son supresores de tumores que forman un complejo sobre la estimulación de TGF-beta para inhibir el crecimiento celular.
- Su función efector reside en el dominio C-terminal (C), pero es inhibida por el dominio N-terminal (N).
- Las mutaciones derivadas de tumores pueden afectar a estas proteínas Smad.
Objetivo del estudio:
- Investigar el mecanismo por el cual el dominio N de las proteínas Smad inhibe su función.
- Para determinar el papel de las mutaciones específicas del dominio N encontradas en los tumores.
Principales métodos:
- Estudió la interacción entre los dominios N y C de Smad2 y Smad4.
- Se analizó el efecto de las mutaciones derivadas de tumores en las interacciones de la proteína Smad y la señalización TGF-beta.
- Investigó el papel de un residuo de arginina conservada en el dominio N.
Principales resultados:
- El dominio N inhibe la función Smad al interactuar con el dominio C, evitando la formación del complejo Smad2-Smad4.
- Las mutaciones derivadas de tumores en el residuo de arginina del dominio N aumentan su afinidad con el dominio C.
- Estas mutaciones mejoran la autoinhibición, bloqueando la formación del complejo Smad inducido por TGF-beta y la señalización aguas abajo.
Conclusiones:
- Las mutaciones del dominio N en las proteínas Smad conducen a una ganancia de la función autoinhibidora, un nuevo mecanismo para la inactivación del supresor tumoral.
- Esta ganancia de autoinhibición evita la formación de complejos Smad y la señalización de TGF-beta, lo que contribuye a la tumorigénesis.
Más Videos Relacionados
Videos de Conceptos Relacionados
02:34Inhibition of Cdk Activity
The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
02:23Abnormal Proliferation
Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
01:12Loss of Tumor Suppressor Gene Functions
Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
03:03mTOR Signaling and Cancer Progression
The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
The mTOR pathway or the...
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
01:31The Intrinsic Apoptotic Pathway
Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...