Past, Present, and Future of Dynamic Kidney and Liver Preservation and Resuscitation.

The increased demand for organs has led to the increased usage of "higher risk" kidney and liver grafts. These grafts from donation after circulatory death or expanded criteria donors are more susceptible to preservation injury and have a higher risk of unfavorable outcomes. Dynamic, instead of static, preservation could allow for organ optimization, offering a platform for viability assessment, active organ repair and resuscitation. Ex situ machine perfusion and in situ regional perfusion in the donor are emerging as potential tools to preserve and resuscitate vulnerable grafts. Preclinical findings have ignited clinical organ preservation research that investigates dynamic preservation, its various modes (continuous, preimplantation) and temperatures (hypo-, sub, or normothermic). This review outlines the current status of dynamic preservation of kidney and liver grafts and describes ongoing research and emerging clinical trials.

GSK3ß phosphorylation of the KLF6 tumor suppressor promotes its transactivation of p21.

KLF6, a ubiquitously expressed Krüppel-like transcription factor, is frequently inactivated in human cancer and has significant roles in cellular proliferation, apoptosis, differentiation and development. A key mechanism of KLF6-mediated growth suppression is through p53-independent transactivation of p21. Several cancer-derived KLF6 mutants lead to the loss of p21-mediated growth suppression through an unknown mechanism. Because several colorectal cancer and hepatocellular carcinoma-derived KLF6 mutations affect a glycogen synthase kinase 3ß (GSK3ß) phosphorylation consensus site, we investigated the role of GSK3ß in the regulation of KLF6 function. Based on transient transfection, GSK3ß augments the transactivation of a p21 promoter luciferase by KLF6. Reciprocal co-immunoprecipitation of hemagglutinin (HA)-GSK3ß and Flag-KLF6 validated the interaction between these two proteins. KLF6 phosphorylation is augmented in the presence of GSK3ß based on in vitro and in vivo (32)P incorporation assays. Site-directed mutagenesis of the candidate phosphorylation sites to alanines ('KLF6-4A' phosphomutant) eliminated a higher molecular weight phosphorylated isoform of KLF6 based on western blot. GSK3ß augmented the transactivation by wild-type KLF6, but not KLF6-4A, towards the p21 promoter, and increased p21 protein. Functionally, GSK3ß enhanced KLF6-mediated growth suppression, which was abrogated by the KLF6-4A phosphomutant. These data establish that GSK3ß directly phosphorylates KLF6, which augments its induction of p21 and resultant growth suppression. This interaction may account for the growth-promoting effects of cancer-derived KLF6 mutants that lack tumor suppressor activity.