title: Pancreatic transcription factors containing protein transduction domains drive mouse embryonic stem cells towards endocrine pancreas.
abstract: Protein transduction domains (PTDs), such as the HIV1-TAT peptide, have been previously used to promote the uptake of proteins into a range of cell types, including stem cells. Here we generated pancreatic transcription factors containing PTD sequences and administered these to endoderm enriched mouse embryonic stem (ES) cells under conditions that were designed to mimic the pattern of expression of these factors in the developing pancreas. The ES cells were first cultured as embryoid bodies and treated with Activin A and Bone morphogenetic protein 4 (BMP4) to promote formation of definitive endoderm. Cells were subsequently plated as a monolayer and treated with different combinations of the modified recombinant transcription factors Pdx1 and MafA. The results demonstrate that each transcription factor was efficiently taken up by the cells, where they were localized in the nuclei. RT-qPCR was used to measure the expression levels of pancreatic markers. After the addition of Pdx1 alone for a period of five days, followed by the combination of Pdx1 and TAT-MafA in a second phase, up-regulation of insulin 1, insulin 2, Pdx1, Glut2, Pax4 and Nkx6.1 was observed. As assessed by immunocytochemistry, double positive insulin and Pdx1 cells were detected in the differentiated cultures. Although the pattern of pancreatic markers expression in these cultures was comparable to that of a mouse transformed β-cell line (MIN-6) and human islets, the expression levels of insulin observed in the differentiated ES cell cultures were several orders of magnitude lower. This suggests that, although PTD-TFs may prove useful in studying the role of exogenous TFs in the differentiation of ES cells towards islets and other pancreatic lineages, the amount of insulin generated is well below that required for therapeutically useful cells.
authors.affiliation: School of Medical Sciences, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen, United Kingdom.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Lima
authors.forename: Hilary M
authors.initials: HM
authors.lastname: Docherty
authors.forename: Yuanxiao
authors.initials: Y
authors.lastname: Chen
authors.forename: Ludovic
authors.initials: L
authors.lastname: Vallier
authors.forename: Kevin
authors.initials: K
authors.lastname: Docherty
mesh_terms: D028341:Activins / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004707:Endoderm / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D051273:Glucose Transporter Type 2 / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D051473:Maf Transcription Factors, Large / Q000235:genetics / Q000378:metabolism; D051379:Mice; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D055415:Bone Morphogenetic Protein 4; D051273:Glucose Transporter Type 2; D018398:Homeodomain Proteins; D007328:Insulin; D051473:Maf Transcription Factors, Large; C485160:Mafa protein, mouse; C491328:Nkx6-1 protein, mouse; D051761:Paired Box Transcription Factors; C110218:Pax4 protein, mouse; C495682:Slc2a2 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; C422405:activin A; C084010:pancreatic and duodenal homeobox 1 protein; D028341:Activins