Pro-Inflammatory Activation Suppresses TRAIL-induced Apoptosis of Acute Myeloid Leukemia Cells.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) is a promising agent for treatment of AML due to its specific apoptosis-inducing effect on tumor cells but not normal cells. However, emergence of resistance to TRAIL in the AML cells limits its potential as an antileukemic agent. Previously, we revealed increase in the resistance of the human AML THP-1 cells to the TRAIL-induced death during their LPS-dependent proinflammatory activation and in the in vitro model of LPS-independent proinflammatory activation - in a long-term high-density cell culture.

Dynamics of the permeability transition pore size in isolated mitochondria and mitoplasts.

The size of the permeability transition pore (PTP) is accepted to be ≤1.5 kDa. However, different authors reported values from 650 to 4000 Da.

Investigation of the calcium-induced activation of the bacteriophage T5 peptidoglycan hydrolase promoting host cell lysis.

Peptidoglycan hydrolase of bacteriophage T5 (EndoT5) is a Ca2+-dependent l-alanyl-d-glutamate peptidase, although the mode of Ca2+ binding and its physiological significance remain obscure. Site-directed mutagenesis was used to elucidate the role of the polar amino acids of the mobile loop of EndoT5 (111-130) in Ca2+ binding. The mutant proteins were purified to electrophoretic homogeneity, the overall structures were characterized by circular dichroism, and the calcium dissociation constants were determined via NMR spectroscopy.

Regulation of permeability transition pore opening in mitochondria by external NAD(H).

Background: The opening of the permeability transition pore (PTP) in mitochondria plays a critical role in the pathogenesis of numerous diseases. Mitochondrial matrix pyridine nucleotides are potent regulators of the PTP, but the role of extramitochondrial nucleotides is unclear.

Methods: The PTP opening was explored in isolated mitochondria and mitochondria in permeabilized differentiated and undifferentiated cells in the presence of added NAD(P)(H) in combination with Mg, adenine nucleotides (AN), and the inhibitors of AN translocase (ANT), voltage-dependent anion channel (VDAC), and cyclophilin D.

Mechanism of mitochondrial permeability transition pore induction and damage in the pancreas: inhibition prevents acute pancreatitis by protecting production of ATP.

Objective: Acute pancreatitis is caused by toxins that induce acinar cell calcium overload, zymogen activation, cytokine release and cell death, yet is without specific drug therapy. Mitochondrial dysfunction has been implicated but the mechanism not established.

Design: We investigated the mechanism of induction and consequences of the mitochondrial permeability transition pore (MPTP) in the pancreas using cell biological methods including confocal microscopy, patch clamp technology and multiple clinically representative disease models.

Identification and characterization of the metal ion-dependent L-alanoyl-D-glutamate peptidase encoded by bacteriophage T5.

Although bacteriophage T5 is known to have lytic proteins for cell wall hydrolysis and phage progeny escape, their activities are still unknown. This is the first report on the cloning, expression and biochemical characterization of a bacteriophage T5 lytic hydrolase. The endolysin-encoding lys gene of virulent coliphage T5 was cloned in Escherichia coli cells, and an electrophoretically homogeneous product of this gene was obtained with a high yield (78% of total activity).

Inflammatory cells regulate p53 and caspases in acute pancreatitis.

The inflammatory response during pancreatitis regulates necrotic and apoptotic rates of parenchymal cells. Neutrophil depletion by use of anti-polymorphonuclear serum (anti-PMN) increases apoptosis in experimental pancreatitis but the mechanism has not been determined. Our study was designed to investigate signaling mechanisms in pancreatic parenchymal cells regulating death responses with neutrophil depletion.

Prosurvival Bcl-2 proteins stabilize pancreatic mitochondria and protect against necrosis in experimental pancreatitis.

Acinar cells in pancreatitis die through apoptosis and necrosis, the roles of which are different. The severity of experimental pancreatitis correlates directly with the extent of necrosis and inversely, with apoptosis. Apoptosis is mediated by the release of cytochrome c into the cytosol followed by caspase activation, whereas necrosis is associated with the mitochondrial membrane potential (DeltaPsim) loss leading to ATP depletion.

Mitochondrial mechanisms of death responses in pancreatitis.

Pancreatitis is a severe and frequently lethal disorder, a major cause of which is alcohol abuse. Parenchymal cell death is a major complication of pancreatitis. In experimental models of acute pancreatitis, acinar cells have been shown to die through both necrosis and apoptosis, the two principal pathways of cell death.

Cell death in pancreatitis: effects of alcohol.

Pancreatitis is a severe and frequently lethal disorder, a major cause of which is alcohol abuse. Parenchymal cell death is a major complication of pancreatitis. In experimental models of (non-alcoholic) acute pancreatitis, acinar cells have been shown to die through both necrosis and apoptosis, the two principal pathways of cell death.

Interference of calmidazolium with measurement of mitochondrial membrane potential using the tetraphenylphosphonium electrode or the fluorescent probe rhodamine 123.

Calmidazolium (CMZ) is a positively charged, hydrophobic compound used as a calmodulin antagonist. It may cause unspecific effects in mitochondria, e.g.

Phosphorylation of a peptide related to subunit c of the F0F1-ATPase/ATP synthase and relationship to permeability transition pore opening in mitochondria.

A phosphorylated polypeptide (ScIRP) from the inner membrane of rat liver mitochondria with an apparent molecular mass of 3.5 kDa was found to be immunoreactive with specific antibodies against subunit c of F0F1-ATPase/ATP synthase (Azarashvily, T. S.