Calcineurin inhibitors such as cyclosporine A and FK506 have been used for transplant therapy and treatment of autoimmune diseases. However, the inhibition of calcineurin outside the immune system has a number of side effects, including hyperglycemia. In the search for safer drugs, we developed a cell-permeable inhibitor of NFAT (nuclear factor of activated T cells) using the polyarginine peptide delivery system. This peptide provided immunosuppression for fully mismatched islet allografts in mice. In addition, it did not affect insulin secretion, whereas FK506 caused a dose-dependent decrease in insulin secretion. Cell-permeable peptides can thus provide a new strategy for drug development and may eventually be useful clinically.

The pancreatic and duodenal homeobox factor-1 (PDX-1), also known as IDX-1/STF-1/IPF1, a homeodomaincontaining transcription factor, plays a central role in regulating pancreatic development and insulin gene transcription. Furthermore, even in adults, PDX-1 is associated with islet neogenesis and differentiation of insulin-producing cells from progenitor cells. Here, we report for the first time that PDX-1 protein can permeate cells due to an Antennapedia-like protein transduction domain sequence in its structure and that transduced PDX-1 functions similarly to endogenous PDX-1; it binds to the insulin promoter and activates its expression. PDX-1 protein can also permeate into isolated pancreatic islets, which leads to stimulation of insulin gene expression. Moreover, PDX-1 protein transduced into cultures of pancreatic ducts, thought to be islet progenitor cells, induces insulin gene expression. These data suggest that PDX-1 protein transduction could be a safe and valuable strategy for enhancing insulin gene transcription and for facilitating differentiation of ductal progenitor cells into insulinproducing cells without requiring gene transfer technology. Diabetes 52:1732-1737, 2003 S ince the discovery of protein transduction domains (PTDs) that allow proteins to be translocated across the plasma membrane and into nuclei without endocytosis, there has been increasing interest in their potential for the delivery of bioactive peptides and proteins into eukaryotic cells as a valuable strategy for the transduction of therapeutic proteins into patients. The small PTDs from TAT protein of HIV-1 (1) and from VP22 protein of Herpes simplex virus (2) have been fused to proteins with the remarkable result of delivery of proteins into many mammalian tissues (1,2). The presence of a PTD in the third ␣-helix of the homeodomain of Antennapedia, a Drosophila transcription factor, has been shown to be necessary and sufficient for an "unconventional" translocation of this peptide into the cytoplasm and nuclei of living cells (3).We noticed that the transcription factor PDX-1 protein, which itself contains an Antennapedia-like homeodomain in its structure, has the same amino acid sequence, except for one amino acid toward the NH 2 -terminus, as the Antennapedia PTD (Fig. 1A). The presence of a PTD in PDX-1 is intriguing because PDX-1 plays such a crucial role in pancreatic development (4 -6), ␤-cell differentiation (7-9), and maintenance of normal ␤-cell function by its regulation of multiple important ␤-cell genes (10,11), including insulin (12,13). Adenoviral-mediated introduction of PDX-1 induced insulin expression in the liver and improved the glucose tolerance of streptozotocin-induced diabetic mice (8). The ability of the PDX-1 protein to both regulate its own gene expression through an A-box element in its promoter (14) and to induce the expression of other ␤-cell genes is thought to be the basis of this induced insulin expression.Here, we report for the first time that PDX-1 protein can permeate cells due to the Antenn...

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of elevated liver function tests results, after the commonly investigated causes have been excluded, and frequently coexists with type 2 diabetes mellitus (T2DM) because the conditions have common risk factors. As both T2DM and NAFLD are related to adverse outcomes of the other, diagnosis and valuation of fatty liver is an important part of the management of diabetes. Although noninvasive methods, such as biomarkers, panel markers, and imaging, may support a diagnostic evaluation of NAFLD patients, accurate histopathological findings cannot be achieved without a liver biopsy. As it is important to know whether steatohepatitis and liver fibrosis are present for the management of NAFLD, liver biopsy remains the gold standard for NAFLD diagnosis and evaluation. Therefore, new investigations of the pathogenesis of NAFLD are necessary to develop useful biomarkers that could provide a reliable noninvasive alternative to liver biopsy.

Because of a critical shortage in suitable organs, many patients with terminal liver disease die each year before liver transplantation can be performed. Transplantation of isolated hepatocytes has been proposed for the temporary metabolic support of patients awaiting liver transplantation or spontaneous reversion of their liver disease. A major limitation of this form of therapy is the present inability to isolate an adequate number of transplantable hepatocytes. A highly differentiated cell line, NKNT-3, was generated by retroviral transfer in normal primary adult human hepatocytes of an immortalizing gene that can be subsequently and completely excised by Cre/Lox site-specific recombination. When transplanted into the spleen of rats under transient immunosuppression, reversibly immortalized NKNT-3 cells provided life-saving metabolic support during acute liver failure induced by 90% hepatectomy.