[Abstract unavailable

Although NFkappaB binding activity is induced during liver regeneration after partial hepatectomy, the physiological consequence of this induction is unknown. We have assessed the role of NFkappaB during liver regeneration by delivering to the liver a superrepressor of NFkappaB activity using an adenoviral vector expressing a mutated form of IkappaBalpha. This adenovirus (Ad5IkappaB) was almost exclusively expressed in the liver and inhibited NFkappaB DNA binding activity and transcriptional activity in cultured cells as well as in the liver in vivo. After partial hepatectomy, infection with Ad5IkappaB, but not a control adenovirus (Ad5LacZ), resulted in the induction of massive apoptosis and hepatocytes as demonstrated by histological staining and TUNEL analysis. In addition, infection with Ad5IkappaB but not Ad5LacZ decreased the mitotic index after partial hepatectomy. These two phenomena, increased apoptosis and failure to progress through the cell cycle, were associated with liver dysfunction in animals infected with the Ad5IkappaB but not Ad5LacZ, as demonstrated by elevated serum bilirubin and ammonia levels. Thus, the induction of NFkappaB during liver regeneration after partial hepatectomy appears to be a required event to prevent apoptosis and to allow for normal cell cycle progression.

No abstract

Autophagy selectively removes abnormal or damaged organelles such as dysfunctional mitochondria. The mitochondrial permeability transition (MPT) is a marker of impaired mitochondrial function that is evident in hepatic ischemia/reperfusion (I/R) injury. However, the relationship between mitochondrial dysfunction and autophagy in I/R injury is unknown. Cultured rat hepatocytes and mouse livers were exposed to anoxia/reoxygenation (A/R) and I/R, respectively. Expression of autophagyrelated protein 7 (Atg7), Beclin-1, and Atg12, autophagy regulatory proteins, was analyzed by western blots. Some hepatocytes were incubated with calpain 2 inhibitors or infected with adenoviruses encoding green fluorescent protein (control), Atg7, and Beclin-1 to augment autophagy. To induce nutrient depletion, a condition stimulating autophagy, hepatocytes were incubated in an amino acid-free and serum-free medium for 3 hours prior to onset of anoxia. For confocal imaging, hepatocytes were coloaded with calcein and tetramethylrhodamine methyl ester to visualize onset of the MPT and mitochondrial depolarization, respectively. To further examine autophagy, hepatocytes were infected with an adenovirus expressing green fluorescent protein-microtubule-associated protein light chain 3 (GFP-LC3) and subjected to A/R. Calpain activity was fluorometrically determined with succinyl-Leu-Leu-Val-Tyr-7-amino-4-methylcoumarin. A/R markedly decreased Atg7 and Beclin-1 concomitantly with a progressive increase in calpain activity. I/R of livers also decreased both proteins. However, inhibition of calpain isoform 2, adenoviral overexpression, and nutrient depletion all substantially suppressed A/R-induced loss of autophagy proteins, prevented onset of the MPT, and decreased cell death after reoxygenation. Confocal imaging of GFP-LC3 confirmed A/R-induced depletion of autophagosomes, which was reversed by nutrient depletion and adenoviral overexpression. Conclusion: Calpain 2-mediated degradation of Atg7 and Beclin-1 impairs mitochondrial autophagy, and this subsequently leads to MPT-dependent hepatocyte death after A/R. (HEPATOLOGY 2008;47:1725-1736 H epatocyte ischemia during liver transplantation, resection, and shock causes anoxia, depletion of glycolytic substrates, loss of adenosine triphosphate (ATP), and acidosis. 1 When blood flow returns to hepatocytes, the normal oxygen concentration and acidbase balance are restored; however, paradoxically, hepatocyte injury is prominent upon reperfusion. 1 The mechanisms underlying ischemia/reperfusion (I/R) injury are multifactorial, including increased Ca 2ϩ , formation of reactive oxygen species (ROS), activation of injurious catabolic enzymes, and mitochondrial dysfunction. 2 Reperfusion causes onset of the mitochondrial permeability transition (MPT), leading to uncoupling of oxidative phosphorylation and necrotic cell death. 1,[3][4][5] Onset of the MPT also induces large-amplitude swelling of mitochondria and apoptosis by releasing proapoptotic factors that are normally sequestered in the mitochondri...

This study provides level 1 data, suggesting that elimination of intraperitoneal drainage in all cases of PD increases the frequency and severity of complications.