Background/Aims: The lack of available beta cells greatly limits the use of beta cell transplantation as a therapy for diabetes. Thus, generation of beta cells from other sources is substantially required. Pax4 has been shown to induce reprograming of alpha cells into beta cells during embryogenesis. Nevertheless, whether expression of Pax4 in adult alpha cells could trigger this alpha-to-beta cell reprogramming is unknown. Methods: Here we generated an adeno-associated virus carrying Pax4 and GFP under a CMV promoter (AAV-Pax4). We used AAV-Pax4 to transduce a mouse alpha cell line in vitro, and to transduce primary alpha cells in diabetic mice. Reprogramming was examined by double immunostaining and by changes in beta cell number. The effects on blood glucose were evaluated by fasting blood glucose and glucose response. Results: In vitro, Pax4 overexpression neither induced insulin expression, nor suppressed glucagon expression in alpha cells. In vivo, Pax4 overexpression failed to increase beta cell number, and did not alter hyperglycemia and glucose response in diabetic mice. Conclusion: Pax4 expression is not sufficient to transduce pancreatic alpha cells into beta cells. Overexpression of Pax4 in alpha cells may not increase functional beta cell number in diabetic patients.
Conversion of proglucagon in pancreatic alpha cells: the major endproducts are glucagon and a single peptide, the major proglucagon fragment, that contains two glucagon-like sequences.
