Video Experimental Relacionado
Updated: Jun 16, 2026
13:21
In Vivo Biosensor Tracks Non-apoptotic Caspase Activity in Drosophila
Published on: November 27, 2016
Bases estructurales y bioquímicas de la activación apoptótica por Smac/DIABLO
Nature
|September 6, 2000
Resumen
La proteína Smac/DIABLO activa la apoptosis al unirse a las proteínas inhibidoras (IAP) y liberar las caspasas. Su estructura revela una interfaz homodimérica esencial para la función, conservada en todas las especies.
Área de la Ciencia:
- Biología celular Biología celular.
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La apoptosis, o muerte celular programada, es vital para el desarrollo metazoario y la homeostasis, regulada por caspases.
- Los inhibidores de las proteínas de la apoptosis (IAP) suprimen las caspasas, controlando la muerte celular.
- Smac/DIABLO, una proteína mitocondrial, contrarresta las IAP para promover la apoptosis.
Objetivo del estudio:
- Para aclarar el mecanismo por el cual Smac/DIABLO activa la apoptosis.
- Para determinar la base estructural para la función de Smac/DIABLO.
- Investigar el papel de la homodimerización y el extremo N de Smac/DIABLO en su actividad.
Principales métodos:
- Cristalografía de rayos X para determinar la estructura Smac/DIABLO a una resolución de 2.2 A.
- Mutagénesis dirigida al sitio para evaluar la función de la interfaz dimérica.
- Ensayos in vitro utilizando un péptido derivado del N-termino de Smac/DIABLO para estudiar la activación de la procaspasa-3.
Principales resultados:
- Smac/DIABLO homodimeriza a través de una extensa interfaz hidrofóbica, crucial para su función.
- Las mutaciones que interrumpen la interfaz dimérica perjudican significativamente la actividad pro-apoptótica de Smac/DIABLO.
- Un péptido del extremo N de Smac/DIABLO activa efectivamente la procaspasa-3 in vitro, de manera similar a las proteínas de la Drosophila.
Conclusiones:
- La interacción física de Smac/DIABLO con los IAP es clave para activar tanto la procapasa-3 como la caspasa-3 madura.
- La homodimerización a través de una interfaz hidrofóbica específica es esencial para la función de Smac/DIABLO.
- El extremo N de Smac/DIABLO juega un papel crítico en la activación de la apoptosis, lo que demuestra la conservación evolutiva.
Videos de Conceptos Relacionados
01:30Apoptosis
Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
01:24Caspases
Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
01:17The Extrinsic Apoptotic Pathway
The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
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...
01:17Phagocytosis of Apoptotic Cells
Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or immature dendritic cells. Non-professional phagocytes such as epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
Normal cells contain receptors that prevent them from being recognized by phagocytes.
01:22Cellular Injury V: Apoptosis and Autophagy
Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...