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Expression of the c-erbB-3 protein in normal human adult and fetal tissues
S A Prigent1, N R Lemoine, C M Hughes
1Molecular Oncology Laboratory, ICRF Oncology Group, Hammersmith Hospital, London, UK.
Abstract:
c-erbB-3 is a member of the type I family of growth factor receptors which includes the epidermal growth factor (EGF) receptor and c-erbB-2. Whereas for EGF receptor and c-erbB-2 the expression patterns in normal tissues are well documented, there is currently little information available about the sites of c-erbB-3 expression. In order to examine the normal tissue distribution of c-erbB-3, polyclonal antibodies were raised against eight synthetic peptides corresponding to distinct sites on the intracellular domain of c-erbB-3. Of these, three produced antibodies which reacted with a 160-kDa protein on immunoblots of human embryonal cells (293 cells) transfected with the cDNA encoding c-erbB-3, and two of the three antibodies immunoprecipitated a protein of similar size from the same cells. These antibodies were used for immunochemical staining of a wide variety of normal human adult and fetal tissues employing formalin-fixed, paraffin-embedded material. The c-erbB-3 protein was identified in cells of the gastrointestinal, reproductive, respiratory and urinary tracts as well as the skin, endocrine and nervous system in a distribution distinctly different from that observed for EGF receptor and c-erbB-2. The level of expression of the mRNA for c-erbB-3 was also examined in extracts of a selection of fetal tissues. In general the sites of mRNA and protein expression were concordant.
Insights
The c-erbB-3 protein is expressed in various normal human tissues, including the gastrointestinal, reproductive, and nervous systems. Its distribution differs significantly from related growth factor receptors like EGF receptor and c-erbB-2.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- The c-erbB-3 protein belongs to the type I growth factor receptor family, alongside EGF receptor and c-erbB-2.
- While the expression patterns of EGF receptor and c-erbB-2 in normal tissues are well-documented, information on c-erbB-3 expression is limited.
Purpose of the Study:
- To investigate the normal tissue distribution of the c-erbB-3 protein.
- To compare the expression pattern of c-erbB-3 with that of EGF receptor and c-erbB-2.
Main Methods:
- Development of polyclonal antibodies against synthetic peptides of the c-erbB-3 intracellular domain.
- Immunoblotting and immunoprecipitation using transfected human embryonal cells to validate antibodies.
- Immunohistochemical staining of diverse normal human adult and fetal tissues using formalin-fixed, paraffin-embedded samples.
- Analysis of c-erbB-3 mRNA expression in fetal tissues.
Main Results:
- Three validated antibodies recognized a 160-kDa c-erbB-3 protein.
- The c-erbB-3 protein was detected in the gastrointestinal, reproductive, respiratory, and urinary tracts, skin, endocrine, and nervous systems.
- The expression pattern of c-erbB-3 was distinct from EGF receptor and c-erbB-2.
- mRNA and protein expression sites for c-erbB-3 were generally concordant in fetal tissues.
Conclusions:
- c-erbB-3 exhibits a unique tissue distribution in normal human adult and fetal tissues.
- The findings provide a foundation for understanding c-erbB-3's role in normal physiology and disease.