Serum after partial hepatectomy stimulates iNOS gene transcription via downstream NF-kappa B site

The molecular physiology of liver regeneration following partial hepatectomy

The ability of the liver to regenerate after resection has been known for many years. Two reports from Germany in the late 1800s probably mark the introduction of the phenomenon into the scientific literature, but in the early 1900s the first reviews of this subject had appeared in the English literature. Predating these early scientific reports the legends from the Greek mythology described the fate of Prometheus. As punishment for defying Zeus and revealing the secret of fire to man, Prometheus was chained to a rock and each day had part of his liver ripped out by an eagle which, returning the following day, repeated the torture because his liver regenerated itself overnight. Although the speed of regeneration in the Greek legend is somewhat greater than that observed either clinically or in the laboratory, the myth does serve to emphasise the remarkable ability of the liver to repeatedly regenerate following repeated resections. This review aims to summarise the more recent literature concerning the early molecular events accompanying liver regeneration and to integrate this with the existing knowledge of this subject.

Leishmania donovani suppresses activated protein 1 and NF-kappaB activation in host macrophages via ceramide generation: involvement of extracellular signal-regulated kinase

In vitro infection of murine peritoneal macrophages with the protozoan Leishmania donovani has been found to alter the signaling parameters of the host. The present study indicates that the enhancement of intracellular ceramide level in macrophages after infection is a major event relating to macrophage dysfunction. We have previously demonstrated that increased ceramide synthesis in host macrophages was involved in the dephosphorylation of extracellular signal-regulated kinase (ERK). In the present study, we further show that downregulation of ERK by ceramide was found to be associated with the inhibition of activated protein 1 (AP-1) and NF-kappaB transactivation. Pharmacological inhibition of ceramide synthesis by Fumonisin B1 restored the induction of AP-1 and NF-kappaB DNA-binding activities in infected BALB/c macrophages. On the contrary, in the case of macrophages from the leishmaniasis-resistant C.D2 mice, L. donovani failed to induce sustained ceramide synthesis. Enhanced mitogen-activated protein kinase phosphorylation, AP-1 and NF-kappaB DNA-binding activity, and the generation of nitric oxide (NO) were observed in L. donovani-infected C.D2 macrophages. ERK activation was necessary for the activation of transcription factors AP-1 and NF-kappaB, NO generation, and restriction of the parasite burden in the resistant murine host macrophages. Hence, the induction of ceramide synthesis in host macrophages appears to be instrumental and one of the turning points leading to silencing of the macrophage antileishmanial responses.