The Fas/CD95 surface receptor mediates rapid death of various cell types, including autoreactive T cells with the potential for triggering autoimmunity. Here, we present novel aspects of Fas signalling that define a ‘social’ dimension to receptor-induced apoptosis. Fas stimulation rapidly induces extensive membrane nanotube formation between neighbouring T cells. This is critically dependent on Rho GTPases but not on caspase activation. Bidirectional transfer of membrane and cytosolic elements including active caspases can be observed to occur via these nanotubes. Nanotube formation and intercellular exchanges of death signals are defective in T lymphocytes from patients with autoimmune lymphoproliferative syndrome harbouring mutations in the Fas receptor. We conclude that nanotube-mediated exchanges constitute a novel form of intercellular communication that augments the propagation of death signalling between neighbouring T cells.
Transient increase in cytosolic Cam , including regulation and activation of a number of Ca 2+ dependent enzymes, such as phospholipases, proteases and nucleases. Mitochondria and endoplasmic reticulum (ER) play pivotal roles in the maintenance of intracellular Ca 2+ homeostasis and regulation of cell death. Several lines of evidence have shown that, in the presence of some apoptotic stimuli, the activation of mitochondrial processes may lead to the release of cytochrome c followed by the activation of caspases, nuclear fragmentation and apoptotic cell death. The aim of this review was to show how changes in calcium signaling can be related to the apoptotic cell death induction. Calcium homeostasis was also shown to be an important mechanism involved in neurodegenerative and aging processes.
Apoptosis is a highly complex form of cell death that can be triggered by alterations in Ca(2+) homeostasis. Members of the Bcl-2 family may regulate apoptosis and modulate Ca(2+) distribution within intracellular compartments. Bax, a proapoptotic member of the family, is constitutively expressed and soluble in the cytosol and, under apoptotic induction, translocates to mitochondrial membranes. However, it is not clear if the intracellular Ca(2+) stores and selective Ca(2+) releases can modulate or control Bax translocation. The aim of this study was to investigate the relation of intracellular Ca(2+) stores with Bax translocation in rat cortical astrocytes. Results show that the classical apoptotic inducer, staurosporine, caused high elevations of cytosolic Ca(2+) that precede Bax translocation. On the other hand, agents that mobilize Ca(2+) from endoplasmic reticulum such as noradrenaline or thapsigargin, induced Bax translocation, while mitochondrial Ca(2+) release evoked by carbonyl cyanide-p-(trifluoromethoxyphenyl) hydrazone was not able to cause Bax punctation. In addition, microinjection of inositol 1,4,5- trisphosphate induced Bax translocation. Taken together, our results show that in Bax overexpressing cortical astrocytes, endoplasmic reticulum-Ca(2+) release may induce Bax transactivation and specifically control apoptosis.
Resumo Nove em cada dez brasileiros não sabem dizer o nome de uma instituição que faça pesquisa no país ou de um cientista brasileiro (CGEE, 2019) – o que escancara a necessidade de estratégias para conectar a imprensa e a ciência no Brasil. É nesse campo que se insere a Agência Bori, iniciativa que dissemina estudos científicos brasileiros para jornalistas de todo o país e os explica por meio de texto híbrido, que se coloca entre um press release e um texto noticioso. No presente artigo, apresentamos a construção do modelo híbrido de texto de divulgação científica da Agência Bori com base em cinco perguntas essenciais: Qual principal achado da pesquisa? Como a pesquisa foi feita? Como os resultados mudam a vida das pessoas? Como os resultados mudam o que já se sabia na área do conhecimento? O que acontece agora diante dos resultados/conclusões? Experiências preliminares de monitoramento da repercussão dos estudos disseminados para a imprensa mostram que o modelo tem boa aceitação no meio jornalístico.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.