In vitro reprogramming of pancreatic alpha cells towards a beta cell phenotype following ectopic HNF4α expression

2015 ◽  
Vol 399 ◽  
pp. 50-59 ◽  
Author(s):  
Caroline B. Sangan ◽  
Ramiro Jover ◽  
Harry Heimberg ◽  
David Tosh
Keyword(s):  
Beta Cell ◽  
Cell Phenotype ◽  
Alpha Cells ◽  
Pancreatic Alpha Cells

scholarly journals Pax4 Expression does not Transduce Pancreatic Alpha Cells to Beta Cells

2015 ◽  
Vol 36 (5) ◽  
pp. 1735-1742 ◽  
Author(s):  
Ling Chen ◽  
Jing Zhang ◽  
Zhuo Zhang ◽  
Yaping Chu ◽  
Bing Song ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Beta Cell ◽  
Beta Cells ◽  
Cell Number ◽  
Diabetic Patients ◽  
Alpha Cells ◽  
Diabetic Mice ◽  
Glucose Response ◽  
Pancreatic Alpha Cells

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.

scholarly journals Reprogramming of pancreatic exocrine cells towards a beta (β) cell character using Pdx1, Ngn3 and MafA

2012 ◽  
Vol 442 (3) ◽  
pp. 539-550 ◽  
Author(s):  
Ersin Akinci ◽  
Anannya Banga ◽  
Lucas V. Greder ◽  
James R. Dutton ◽  
Jonathan M. W. Slack
Keyword(s):  
Beta Cell ◽  
Cell Function ◽  
Cell Model ◽  
Severe Combined Immunodeficiency ◽  
Rapid Change ◽  
Cell Phenotype ◽  
Gene Promoters ◽  
Exocrine Cells ◽  
Pancreatic Exocrine

Pdx1 (pancreatic and duodenal homeobox 1), Ngn3 (neurogenin 3) and MafA (v-maf musculoaponeurotic fibrosarcoma oncogene family, protein A) have been reported to bring about the transdifferentiation of pancreatic exocrine cells to beta (β) cells in vivo. We have investigated the mechanism of this process using a standard in vitro model of pancreatic exocrine cells, the rat AR42j-B13 cell line. We constructed a new adenoviral vector encoding all three genes, called Ad-PNM (adenoviral Pdx1, Ngn3, MafA construct). When introduced into AR42j-B13 cells, Ad-PNM caused a rapid change to a flattened morphology and a cessation of cell division. The expression of exocrine markers is suppressed. Both insulin genes are up-regulated as well as a number of transcription factors normally characteristic of beta cells. At the chromatin level, histone tail modifications of the Pdx1, Ins1 (insulin 1) and Ins2 (insulin 2) gene promoters are shifted in a direction associated with gene activity, and the level of DNA CpG methylation is reduced at the Ins1 promoter. The transformed cells secrete insulin and are capable of relieving diabetes in streptozotocin-treated NOD-SCID (non-obese diabetic severe combined immunodeficiency) mice. However the transformation is not complete. The cells lack expression of several genes important for beta cell function and they do not show glucose-sensitive insulin secretion. We conclude that, for this exocrine cell model, although the transformation is dramatic, the reprogramming is not complete and lacks critical aspects of the beta cell phenotype.

scholarly journals Up-regulation of clusterin (sulfated glycoprotein-2) in pancreatic islet cells upon streptozotocin injection to rats

1999 ◽  
Vol 162 (1) ◽  
pp. 57-65 ◽  
Author(s):  
IS Park ◽  
YZ Che ◽  
M Bendayan ◽  
SW Kang ◽  
BH Min
Keyword(s):  
Cell Death ◽  
Embryonic Development ◽  
Beta Cell ◽  
Beta Cells ◽  
Endocrine Cells ◽  
Morphological Alteration ◽  
Alpha Cells ◽  
Pancreatic Alpha Cells ◽  
Tissue Reorganization ◽  
Clusterin Expression

Clusterin is a heterodimeric glycoprotein which has been shown to play important roles in programmed cell death and/or in tissue reorganization not only during embryonic development but also in damaged tissues. Recently, we reported the transient induction of clusterin in pancreatic endocrine cells during early developmental stages of islet formation. In the present study, we have investigated the expression of clusterin in pancreatic tissue of streptozotocin-treated rats which were undergoing extensive islet tissue reorganization due to degeneration of insulin beta cells. Clusterin was found in endocrine cells identified as glucagon-secreting alpha cells at the periphery of the islet. Using immunoelectron microscopy, clusterin-positive cells showed the typical ultrastructural features of pancreatic alpha cells. In addition, colocalization of clusterin and glucagon in the same secretory granules was shown by double immunogold labeling. These results imply that clusterin is a secretory molecule having endocrine and/or paracrine actions in parallel with glucagon. Further, we noted that clusterin expression was increased in pancreatic alpha cells during the process of beta cell death upon streptozotocin injection. The increase was significant as early as 1-3 h after streptozotocin treatment prior to any morphological alteration of islet beta cell and any manifestation of hyperglycemia. The expression of clusterin was steady-stately up-regulated during the process of islet reorganization caused by streptozotocin-induced cytotoxic injury. Therefore, we suggest that clusterin might be considered as a molecule induced by both embryonic development and drug-induced reorganization of the endocrine pancreas. Since clusterin expression is up-regulated in alpha cells, but not in beta cells undergoing degeneration, it may play a protective role against the cytotoxic insult.

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