1. Volume 123, Issue 6, Pages 2017-2027 (December 2002)
Diverse expression of ErbB receptor proteins during rat liver development and regeneration 
Robert S. Carver, *, Mary C. Stevenson, ‡, Lawrence A. Scheving, ‡, William E. Russell, *,‡,§ 
Gastroenterology 
Volume 123, Issue 6, Pages (December 2002)
DOI: /gast
Copyright © 2002 American Gastroenterological Association Terms and Conditions

2. Fig. 1
Relative expression of ErbB receptors during hepatic development. Livers were harvested from male rats at the indicated age, homogenized in lysis buffer, and immunoprecipitated with antibodies directed against EGF-R, ErbB2, or ErbB3. Immune complexes were electrophoresed, transferred to membranes, and blotted with the immunoprecipitating antibodies. Target proteins were detected using enhanced chemiluminescence and x-ray film. Each lane depicts an immunoprecipitation from a single rat liver except for E16, which is formed pooled embryos.
Gastroenterology  , DOI: ( /gast )
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3. Fig. 2
Immunodetection of ErbB2 in neonatal liver. (A and B) Liver sections from male neonatal rats (day 1) were stained with rabbit anti-ErbB2 antibodies followed by biotinylated anti-rabbit antibodies and avidin-conjugated horseradish peroxidase. Staining was localized to parenchymal and biliary cells. Hematopoietic cells were negative. (C and D) Sections stained with antibodies preincubated with immunizing peptide, confirming specificity for ErbB2 protein.
Gastroenterology  , DOI: ( /gast )
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4. Fig. 3
Fetal and adult ErbB receptor tyrosine phosphorylation in response to EGF or heregulin. (A) Primary cultures of hepatocytes were prepared from fetal (left panel) or adult (right panel) liver. The cells were treated with harvested serum-free media at the indicated times and then evaluated for ErbB protein expression. AL and AH represent adult liver and adult heart whole organ controls. (B) Fetal or adult hepatocytes were exposed to EGF or heregulin-type ligands (100 nmol/L) for 5 minutes. ErbB receptors were solubilized, immunoprecipitated with monospecific anti-ErbB protein antibodies, and then immunoblotted with the RC20H anti-phosphotyrosine antibody. Lanes are untreated (−), EGF-treated (E), and heregulin β-treated (H). The unmarked lane to the left of these treatment groups was unstimulated adult liver tissue. The positions of ErbB 1, 2, and 3 are designated by the numbers 1, 2, and 3 to the right of the lanes and were confirmed by immunoblot of positive controls (adult liver for ErbB1 and ErbB3; adult heart for ErbB2, not shown). Besides the ErbB proteins detected, the other major phosphotyrosine protein detected in these immunoprecipitates was the 51-kilodalton protein shc, which is shown in the bottom panel. The identity of this protein was confirmed by immunoblot (not shown).
Gastroenterology  , DOI: ( /gast )
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5. Fig. 4
ErbB expression in liver after PH and at different circadian periods. (A) At the indicated time after surgery, livers were harvested from hepatectomized rats, homogenized in lysis buffer, and immunoprecipitated with ErbB2 antibodies. The hepatoma line H4IIe strongly expressed ErbB2 and was used as a positive control (+). Immunoprecipitates were electrophoresed, transferred to membranes, and blotted with the same antibody used for immunoprecipitation. Each lane represents an immunoprecipitation from a single animal. (B) The samples from A were immunoprecipitated with an antibody against ErbB3 and then blotted with the same antibody used for immunoprecipitation. Densitometric analysis was used for statistical analysis and to generate a graph from PH (■) and SH (□) rats. The increase at 12 hours was statistically significant (P < 0.01). Data are means of densitometric units normalized to a value of 1.0 for unoperated rats ± SD. (C) The experiment described in A was repeated; however, for this experiment, all animals were killed at the same time but subjected to SH or PH at different times. No statistically significant differences were observed in this experiment except for a 30%–40% decrease in ErbB3 expression in both SH and PH groups at 3 hours after surgery (data not shown). (D) Adult rats were killed at 3-hour intervals (n = 3) spanning a single light-dark cycle. Trough and peak expression of hepatic EGF-R and ErbB3 are shown at 8 AM and 8 PM. (E) Densitometric analysis of immunoblots for EGF-R and ErbB3 is shown for all time points examined. No ErbB2 or ErbB4 was detected (data not shown). Peak and trough expression differed for both ErbB3 and EGF-R (P < 0.01).
Gastroenterology  , DOI: ( /gast )
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6. Fig. 5
Expression of ErbB proteins in RLE and H4IIe cells. Lysates of RLE (A and B) or H4IIe (B) cells were prepared and immunoblotted with specific ErbB antibodies. A is an immunoblot of whole lysate, whereas B is an immunoblot of an immunoprecipitate. The lane nearest to the molecular standards in A represents expression in positive controls (EGF-R, liver lysate; ErbB2, heart; ErbB3, liver; ErbB4, brain).
Gastroenterology  , DOI: ( /gast )
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7. Fig. 6
A model showing changes in the composition of the hepatic binding site for EGF-like ligands during development. Expression of ErbB2 in fetal/neonatal liver cells allows the formation of 3 possible heterodimers (EGF-R/ErbB2, ErbB3/ErbB2, and EGF-R/ErbB3), whereas only one possible heterodimer (EGF-R/ErbB3) occurs in adult liver cells. ErbB2 has no known ligand. ErbB3 is kinase defective but couples EGF-R or ErbB2 to phosphatidylinositol 3-kinase. Alterations in the signal pattern, strength, and duration will result in distinct downstream effects in young versus adult rat liver. Similar alterations are predicted in adult rats with a change in the relative amount of EGF-R or ErbB3. Dashed arrows indicate heterodimer formation, and solid arrows show transphosphorylation events. An inactive tyrosine kinase prevents ErbB3 from phosphorylating EGF-R or ErbB2 in heterodimeric pairings.
Gastroenterology  , DOI: ( /gast )
Copyright © 2002 American Gastroenterological Association Terms and Conditions