Evolution of the folding landscape of effector caspases

Abstract

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Differential Inhibite Effect of Xanthohumol on HepG2 Cells and Primary Hepatocytes

“… 20 Both activation of caspase-3 and proteolytic cleavage of PARP have been considered to be crucial events in apoptosis. 21 , 22 Procaspase-3 has been found to have elevated concentrations in cells from various cancerous tissues including certain neuroblastomas, lymphomas, leukemias, melanomas, and liver cancers. 23 This allows for a therapeutic index to be achieved for caspase-3-directed agents.…”

Caspase 3 and Cleaved Caspase 3 Expression in Tumorogenesis and Its Correlations with Prognosis in Head and Neck Cancer: A Systematic Review and Meta-Analysis

“…The apoptotic machinery has main upstream components, the so-called regulatory agents, and downstream ones, so-called effector agents. These regulators are part of two main circuits: one responsible for receiving and processing extracellular death-inducing signals (the extrinsic apoptotic program) and the other responsible for detecting and integrating intracellular signals (the intrinsic program) [ 22 , 25 , 27 , 28 , 29 , 30 , 31 , 32 ]. Both end up generating the activation of a cascade of proteases called caspases (cysteine-containing aspartic acid-specific proteases) that are synthesized as proenzymes, activated by proteolytic cleavage, which may cleave other caspases as part of the apoptotic signaling cascade [ 21 , 22 , 25 , 27 , 29 , 30 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ].…”

Conserved folding landscape of monomeric initiator caspases

“…The higher m-values for the N↔I transition in caspase-8 indicates a larger exposure of hydrophobic surface area compared to the same transition for cFLIPL, while the m-values for the second transition (I↔U) is higher for cFLIPL indicating a more compact conformation for the intermediate state in cFLIPL. The protomers of caspase-8 and cFLIPL exhibit a G 0 conf of 6-8 kcal mol -1 , which is comparable to the monomeric intermediate observed in the equilibrium unfolding of executioner caspases-3 and -7 as well as that of the common ancestor of effector caspase dimers (6,14). In those cases, the G 0 conf of the monomeric folding intermediate was determined to be ~5-7 kcal mol -1 at pH 7.5 and 25 0 C. Using the values acquired from the global fits of the equilibrium unfolding data and the cooperativity indices determined for each transition (Supplemental Tables S1 and S2), we calculated the equilibrium distribution of species (N, I and U) for each protein at each pH and throughout the urea concentration range of 0 to 9 M, as described previously (17).…”

“…3C,D). Altogether, the data for folding/unfolding from pH 3.5-9 show that both caspase-8 and cFLIPL are sensitive to pH changes, similar to the effector caspase dimers (6,14), due to destabilizing the native conformation relative to a partially folded intermediate. The higher m-values for the N↔I transition in caspase-8 indicates a larger exposure of hydrophobic surface area compared to the same transition for cFLIPL, while the m-values for the second transition (I↔U) is higher for cFLIPL indicating a more compact conformation for the intermediate state in cFLIPL.…”

“…Excitation at 280 nm follows tyrosinyl and tryptophanyl fluorescence emission, whereas excitation at 295 nm follows the tryptophanyl fluorescence emission. Experiments on folding/unfolding were carried out as previously described (6,14,21).In brief, stock solutions of urea (10 M), citrate buffer (50 mM sodium citrate/citric acid, pH 3.5-5.5, 1 mM DTT), phosphate buffer (pH 6-8, 1 mM DTT), and Tris buffer (50 mM Tris-HCl, pH 8.5-9, 1 mM DTT) were made as indicated (21). Protein samples were incubated in buffer containing urea concentrations ranging from 0 to 9 M for unfolding and at final pHs shown in the figures.…”