We have identified two cell types, each using almost exclusively one of two different CD95 (APO‐1/Fas) signaling pathways. In type I cells, caspase‐8 was activated within seconds and caspase‐3 within 30 min of receptor engagement, whereas in type II cells cleavage of both caspases was delayed for ∼60 min. However, both type I and type II cells showed similar kinetics of CD95‐mediated apoptosis and loss of mitochondrial transmembrane potential (ΔΨ m ). Upon CD95 triggering, all mitochondrial apoptogenic activities were blocked by Bcl‐2 or Bcl‐x L overexpression in both cell types. However, in type II but not type I cells, overexpression of Bcl‐2 or Bcl‐x L blocked caspase‐8 and caspase‐3 activation as well as apoptosis. In type I cells, induction of apoptosis was accompanied by activation of large amounts of caspase‐8 by the death‐inducing signaling complex (DISC), whereas in type II cells DISC formation was strongly reduced and activation of caspase‐8 and caspase‐3 occurred following the loss of ΔΨ m . Overexpression of caspase‐3 in the caspase‐3‐negative cell line MCF7‐Fas, normally resistant to CD95‐mediated apoptosis by overexpression of Bcl‐x L , converted these cells into true type I cells in which apoptosis was no longer inhibited by Bcl‐x L . In summary, in the presence of caspase‐3 the amount of active caspase‐8 generated at the DISC determines whether a mitochondria‐independent apoptosis pathway is used (type I cells) or not (type II cells).

/pdf/two-cd95-apo-1-fas-signaling-pathways-4ujtlhag1g.pdf

Two CD95 (APO-1/Fas) signaling pathways

It has become increasingly difficult to find an area of cell biology in which lipids do not have important, if not key, roles as signalling and regulatory molecules. The rapidly expanding field of bioactive lipids is exemplified by many sphingolipids, such as ceramide, sphingosine, sphingosine-1-phosphate (S1P), ceramide-1-phosphate and lyso-sphingomyelin, which have roles in the regulation of cell growth, death, senescence, adhesion, migration, inflammation, angiogenesis and intracellular trafficking. Deciphering the mechanisms of these varied cell functions necessitates an understanding of the complex pathways of sphingolipid metabolism and the mechanisms that regulate lipid generation and lipid action.

Principles of bioactive lipid signalling: lessons from sphingolipids

Novel p19 protein engages IL-12p40 to form a cytokine, IL-23, with biological activities similar as well as distinct from IL-12.

Apoptosis is a physiological cell suicide program that is critical for the development and maintenance of healthy tissues. Dysregulation of cell death pathways occur in cancer, autoimmune and immunodeficiency diseases, reperfusion injury after ischemic episodes, and in neurodegenerative disorders. Thus, proteins involved in apoptosis regulation are of intense biological interest and many are attractive therapeutic targets. This review discusses the Inhibitor of Apoptosis (IAP) family of proteins. First discovered in baculoviruses, IAPs were shown to be involved in suppressing the host cell death response to viral infection. Interestingly, ectopic expression of some baculoviral IAPs blocks apoptosis in mammalian cells, suggesting conservation of the cell death program among diverse species and commonalities in the mechanism used by the IAPs to inhibit apoptosis. Although the mechanism used by the IAPs to suppress cell death remains debated, several studies have provided insights into the biochemical functions of these intriguing proteins. Moreover, a variety of reports have suggested an important role for the IAPs in some human diseases.

/pdf/iap-family-proteins-suppressors-of-apoptosis-49tztuyxcj.pdf

IAP family proteins—suppressors of apoptosis

The evolutionarily conserved actions of the sphingolipid metabolite, sphingosine-1-phosphate (S1P), in yeast, plants and mammals have shown that it has important functions. In higher eukaryotes, S1P is the ligand for a family of five G-protein-coupled receptors. These S1P receptors are differentially expressed, coupled to various G proteins, and regulate angiogenesis, vascular maturation, cardiac development and immunity, and are important for directed cell movement.

Sphingosine-1-phosphate: an enigmatic signalling lipid

Zinc is a potent inhibitor of the apoptotic protease, caspase-3. A novel target for zinc in the inhibition of apoptosis.

The role of ceramide in cell signaling.

Serine Palmitoyltransferase Regulates de NovoCeramide Generation during Etoposide-induced Apoptosis

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.510300513

David K. Perry

Papers

Zinc is a potent inhibitor of the apoptotic protease, caspase-3. A novel target for zinc in the inhibition of apoptosis.

The role of ceramide in cell signaling.

Serine Palmitoyltransferase Regulates de NovoCeramide Generation during Etoposide-induced Apoptosis

Ischemic preconditioning protects the mouse liver by inhibition of apoptosis through a caspase-dependent pathway.

(1S,2R)-D-erythro-2-(N-Myristoylamino)-1-phenyl-1-propanol as an Inhibitor of Ceramidase