[30] The level of infection was monitored by confocal imaging of liver sections to detect mRFP-positive cells. InsP3-Buffer-NLS was efficiently delivered and expressed in nearly 100% of hepatocyte nuclei (Fig 5A, insert). A comparable Veliparib cell line efficiency of infection was observed in InsP3-Buffer-NES animals (not shown). BrdU uptake was impaired in animals expressing InsP3-Buffer-NLS, compared to control hepatectomized (PH) animals (Fig. 5B). Of note, expression of InsP3-Buffer-NES did not significantly alter BrdU

uptake, when compared to control PH animals, although this value was significantly higher than in InsP3-Buffer-NLS animals (Fig. 5B). Additionally, liver/body weight ratio after PH was reduced in InsP3-Buffer-NLS animals, when compared to sham or PH animals (Fig. 5C). InsP3-Buffer-NES animals had a smaller liver/body weight ratio, when compared to sham animals, although this value was not significantly different from control PH animals. Indeed, IR levels in the nucleus check details were increased 24 hours after PH in PH animals, compared to sham animals, as evidenced by IHC (Fig. 5D) and immunoblotting (Supporting Fig.

2). The 24-hour time point was chosen because it is the time at which the rate of DNA synthesis reaches its peak in hepatocytes after PH.[2] Positive proliferating cell nuclear antigen labeling in PH animals confirms Alanine-glyoxylate transaminase that hepatocytes are undergoing cell proliferation under these conditions (Supporting Fig. 2). These results show that liver regeneration after PH depends on nuclear InsP3, and increased nuclear IR may contribute, at least

in part, to this process, in accord with our observations in vitro. To investigate whether either cytosolic or nuclear InsP3 participate in insulin’s metabolic actions, we analyzed blood glucose levels and liver glycogen content under control, nuclear (InsP3-Buffer-NLS), and cytosolic (InsP3-Buffer-NES) InsP3 buffering. Using one-way ANOVA with Bonferroni’s post-tests, cytosolic, but not nuclear InsP3 buffering significantly reduced blood glucose levels (Fig. 5E) and increased liver glycogen content, compared to control animals (Fig. 5F). These results are consistent with the idea that nuclear InsP3 mediates insulin’s effects on liver regeneration, but is unrelated to insulin’s metabolic actions. The effects of Ca2+ on hepatocyte proliferation are closely related to the subcellular compartments where it is released. For instance, buffering mitochondrial Ca2+ inhibits apoptosis and accelerates liver regeneration on that basis.[30] On the other hand, buffering cytosolic Ca2+ retards liver regeneration and progression through the cell cycle after PH,[31] although there are a number of mechanisms by which cytosolic Ca2+ can increase,[10] and different sources of cytosolic Ca2+ may have different effects.