Transcription factor expression in the developing human fetal endocrine pancreas.
OBJECTIVE
Morphological changes that occur during pancreatic endocrine cell differentiation have been shown in rodent systems to be dependent on sequential alterations in transcription factor expression. However, similar data for humans have been limited. The aim of the present study was to provide a connection between pancreatic morphology, transcription factor gene expression and protein localisation during human fetal development.


METHODS
Human fetal pancreases were examined at early (8-12 weeks of fetal age), middle (14-16 weeks) and late (19-21 weeks) stages, using immunohistological, microarray and qRT-PCR analyses.


RESULTS
We observed a significant decrease in pancreatic duodenal homeobox 1 (PDX-1)(+)/cytokeratin 19(+) cells (p < 0.001), with a simultaneous increase in PDX-1(+)/insulin(+) cells from 8 to 21 weeks (p < 0.05). Increased PDX-1/insulin co-localisation within islet clusters was noted, while no co-expression of PDX-1 with glucagon was found, suggesting that loss of PDX-1 is essential for alpha cell formation. Given that neurogenin 3 (NGN3) expression is critical for establishing the endocrine cell programme in the rodent pancreas, we examined its expression pattern and co-localisation in PDX-1(+), insulin(+) and glucagon(+) cells. Co-localisation of NGN3 with PDX-1, insulin and glucagon was noted during early development, with significant decreases in middle and late stages (p < 0.001). Our microarray and co-localisation analyses of transcription factors linked to NGN3 demonstrated that ISL1 transcription factor (ISL1), neurogenic differentiation 1 (NEUROD1), NK2 related transcription factor related, locus 2 (NKX2-2) and paired box gene 6 (PAX6) were upregulated during development and present in all four endocrine cell types, while NK6 related transcription factor related, locus 1 (NKX6-1) was expressed exclusively in beta cells.


CONCLUSIONS
This study is an important step towards identifying key molecular factors involved in development of the human fetal endocrine pancreas.
Lyttle
B M
BM
Children's Health Research Institute, University of Western Ontario, London, ON, Canada.
Li
J
J
Krishnamurthy
M
M
Fellows
F
F
Wheeler
M B
MB
Goodyer
C G
CG
Wang
R
R
D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D015415:Biomarkers; D015536:Down-Regulation / Q000235:genetics; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000235:genetics; D051542:Hepatocyte Nuclear Factor 3-beta / Q000235:genetics; D051559:Hepatocyte Nuclear Factor 6 / Q000235:genetics; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D009419:Nerve Tissue Proteins / Q000235:genetics; D009687:Nuclear Proteins; D051761:Paired Box Transcription Factors / Q000235:genetics; D010179:Pancreas / Q000196:embryology* / Q000502:physiology*; D000071250:Snail Family Transcription Factors; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D015854:Up-Regulation / Q000235:genetics; D029961:Zebrafish Proteins
D051792:Basic Helix-Loop-Helix Proteins; D015415:Biomarkers; D051538:Hepatocyte Nuclear Factor 1-alpha; D051542:Hepatocyte Nuclear Factor 3-beta; D051559:Hepatocyte Nuclear Factor 6; D000090322:Homeobox Protein Nkx-2.2; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D051761:Paired Box Transcription Factors; D000071250:Snail Family Transcription Factors; D015534:Trans-Activators; D014157:Transcription Factors; D029961:Zebrafish Proteins; C496502:FOXA2 protein, human; C496487:HNF1A protein, human; C490003:MNX1 protein, human; C498695:NEUROG3 protein, human; C000715631:NKX2-2 protein, human; C496605:ONECUT1 protein, human; C491709:PAX4 protein, human; C000715630:nkx2.2b protein, zebrafish; C084010:pancreatic and duodenal homeobox 1 protein