Related Experiment Videos
Transforming growth factor-alpha (TGF-alpha) and insulin gene expression in human fetal pancreas
1Department of Pathology, University of Helsinki, Finland.
Abstract:
Transforming growth factor-alpha (TGF-alpha) mRNA is expressed in several pancreatic cancer cell lines, but its expression during normal fetal pancreas development has not been studied. We investigated the expression of TGF-alpha, its receptor (EGF-R) and insulin mRNA and their corresponding peptides in human fetal pancreata (15-20 gestation weeks). Polymerase chain reaction (PCR) and RNAase protection analysis revealed that TGF-alpha and insulin mRNAs were detectable in pancreas during the developmental span studied. In northern blot analysis a single band of 4.8 kilobases (kb) corresponding to the TGF-alpha transcript and a 0.6 kb for the insulin mRNA were detected in the pancreas. Using in situ hybridization, TGF-alpha mRNA expression was seen in a low copy number in both the exo- and endocrine pancreas. By immunohistochemistry TGF-alpha-immunoreactive cells were detected in the ducts, acini and islets showing that the mRNA was translated into protein. By contrast, insulin transcripts were detected in a high copy number, restricted to the islets of Langerhans. However, monoclonal insulin antibody detected less insulin containing cells than could be expected from the mRNA pattern suggesting that fetal beta-cells rapidly secrete insulin instead of storing it in the secretory granules. Alternatively, the translation of insulin mRNA could be inefficient. By double labeling the pancreas sections with polyclonal TGF-alpha antiserum and monoclonal insulin antibody the TGF-alpha- and insulin-like immunoreactivity was localized to beta-cells. Furthermore, mRNA for the TGF-alpha receptor, EGF-R, together with EGF-R-immunoreactive cells were also present in pancreas.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Transforming growth factor-alpha (TGF-alpha) and insulin are expressed in the developing human pancreas. These molecules, along with their receptor (EGF-R), are found in pancreatic cells during fetal development.
Area of Science:
- Developmental Biology
- Endocrinology
- Molecular Biology
Background:
- Transforming growth factor-alpha (TGF-alpha) mRNA is known in pancreatic cancer cell lines.
- Its expression during normal human fetal pancreas development remains unstudied.
Purpose of the Study:
- To investigate the expression of TGF-alpha, its receptor (EGF-R), and insulin mRNA and peptides in human fetal pancreata.
- To determine the localization and co-expression of these molecules during pancreatic development.
Main Methods:
- Polymerase chain reaction (PCR) and RNAase protection analysis for mRNA detection.
- Northern blot analysis for transcript size.
- In situ hybridization for mRNA localization.
- Immunohistochemistry for peptide localization.
- Double labeling for co-localization studies.
Main Results:
- TGF-alpha and insulin mRNAs were detected in human fetal pancreata (15-20 weeks gestation).
- TGF-alpha mRNA and protein were found in exocrine and endocrine pancreas; insulin mRNA was restricted to islets.
- Insulin-containing cells were fewer than expected from mRNA levels, suggesting rapid secretion or inefficient translation.
- TGF-alpha and insulin immunoreactivity co-localized to beta-cells; EGF-R mRNA and protein were also present.
Conclusions:
- TGF-alpha and insulin are expressed during human fetal pancreatic development.
- Both molecules are present in beta-cells, indicating a potential role in islet cell development or function.
- The EGF-R is also expressed, suggesting a functional signaling pathway.