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Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation
Published on: March 5, 2018
Participación de una proteasa ICE-like en la apoptosis mediada por Fas
Nature
|May 4, 1995
Resumen
Este estudio revela que una proteasa similar a la enzima de conversión beta de la interleucina-1 (ICE) juega un papel crucial en la citotoxicidad de la apoptosis mediada por Fas y el factor de necrosis tumoral (TNF). La inhibición de esta proteasa bloquea la muerte celular, destacando su importancia en estos procesos celulares.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología molecular La biología molecular.
- Inmunología Inmunología.
Sus antecedentes:
- Fas es una proteína de membrana de tipo I que inicia la apoptosis al unirse al ligando Fas o al anticuerpo agonista anti-Fas.
- Los estudios en Caenorhabditis elegans sugieren que las proteasas como la enzima de conversión beta de la interleucina-1 (ICE) y ced-3 están involucradas en la señalización apoptótica.
- El modificador de la respuesta citoquina A (crmA) codificado por el virus de la viruela de vaca inhibe la actividad de ICE.
Objetivo del estudio:
- Investigar el papel de las proteasas similares al ICE en la apoptosis mediada por Fas y la citotoxicidad inducida por el TNF.
- Determinar si la inhibición de las proteasas ICE-like puede prevenir la muerte celular inducida por el anticuerpo anti-Fas o el TNF.
Principales métodos:
- Expresión de crmA, un inhibidor de la ECI, en las células.
- Tratamiento con un anticuerpo anti-Fas o con el factor de necrosis tumoral (TNF).
- La administración de un tetrapeptido inhibidor específico del ICE (acetil-Tyr-Val-Ala-Asp-clorometilcetona).
Principales resultados:
- Expresión de citotoxicidad inhibida por crmA inducida tanto por el anticuerpo anti-Fas como por el TNF.
- El tetrapeptido inhibidor específico del ICE también impidió la apoptosis inducida por el anticuerpo anti-Fas.
- Estos hallazgos indican un papel crítico para las proteasas similares al ICE en estas vías de muerte celular.
Conclusiones:
- Una proteasa similar al ICE está involucrada en la apoptosis mediada por Fas.
- Las proteasas ICE-like están implicadas en la citotoxicidad inducida por el TNF.
- Dirigirse a las proteasas similares al ICE puede ofrecer estrategias terapéuticas para controlar la apoptosis y la citotoxicidad.
Videos de Conceptos Relacionados
Apoptosis
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.
Caspases
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.
The 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...
The 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...
Phagocytosis 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.
MAPK Signaling Cascades
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...

