Limits...
ErbB4 signaling in the mammary gland is required for lobuloalveolar development and Stat5 activation during lactation.

Jones FE, Welte T, Fu XY, Stern DF - J. Cell Biol. (1999)

Bottom Line: However, whey acidic protein mRNA was reduced, and alpha-lactalbumin mRNA was undetectable.This phosphorylation required an intact Stat5 SH2 domain.In summary, our results demonstrate that ErbB4 signaling is necessary for mammary terminal differentiation and Stat5 activation at mid-lactation.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, BML 342, Yale University School of Medicine, New Haven, Connecticut 06520-8023, USA.

ABSTRACT
Signaling by members of the epidermal growth factor receptor family plays an important role in breast development and breast cancer. Earlier work suggested that one of these receptors, ErbB4, is coupled to unique responses in this tissue. To determine the function of ErbB4 signaling in the normal mouse mammary gland, we inactivated ErbB4 signaling by expressing a COOH terminally deleted dominant-negative allele of ErbB4 (ErbB4DeltaIC) as a transgene in the mammary gland. Despite the expression of ErbB4DeltaIC from puberty through later stages of mammary development, an ErbB4DeltaIC-specific phenotype was not observed until mid-lactation. At 12-d postpartum, lobuloalveoli expressing ErbB4DeltaIC protein were condensed and lacked normal lumenal lactation products. In these lobuloalveoli, beta-casein mRNA, detected by in situ hybridization, was normal. However, whey acidic protein mRNA was reduced, and alpha-lactalbumin mRNA was undetectable. Stat5 expression was detected by immunohistochemistry in ErbB4DeltaIC-expressing tissue. However, Stat5 was not phosphorylated at Y694 and was, therefore, probably inactive. When expressed transiently in 293T cells, ErbB4 induced phosphorylation of Stat5. This phosphorylation required an intact Stat5 SH2 domain. In summary, our results demonstrate that ErbB4 signaling is necessary for mammary terminal differentiation and Stat5 activation at mid-lactation.

Show MeSH

Related in: MedlinePlus

Immunohistochem- ical detection of Stat5 phosphorylated at Y694 in ErbB4ΔIC-expressing mammary glands at 12-d postpartum. High magnification representations of expanded lobuloalveoli lacking detectable ErbB4ΔIC expression (A–C) or a different region of the same section containing condensed lobuloalveoli expressing high levels of ErbB4ΔIC protein (D–F). Sections were stained with hematoxylin/eosin (A and D), or stained by immunohistochemistry with antiphospho-Stat5 antibody preadsorbed with peptide immunogen and counterstained with methyl green (B and E), or phospho-Stat5 antibody without counterstain (C and F). Bar in D, 30 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2164978&req=5

Figure 5: Immunohistochem- ical detection of Stat5 phosphorylated at Y694 in ErbB4ΔIC-expressing mammary glands at 12-d postpartum. High magnification representations of expanded lobuloalveoli lacking detectable ErbB4ΔIC expression (A–C) or a different region of the same section containing condensed lobuloalveoli expressing high levels of ErbB4ΔIC protein (D–F). Sections were stained with hematoxylin/eosin (A and D), or stained by immunohistochemistry with antiphospho-Stat5 antibody preadsorbed with peptide immunogen and counterstained with methyl green (B and E), or phospho-Stat5 antibody without counterstain (C and F). Bar in D, 30 μm.

Mentions: Since functional Stat5 is phosphorylated at Y694 (reviewed in Groner and Gouilleux 1995), we used an antibody specific for Stat5 phosphorylated at Y694 to evaluate the phosphorylation state of Stat5 (Fig. 5). Strong nuclear staining and moderate cytoplasmic staining of phosphorylated Stat5 was detected within normal lobuloalveolar epithelium at 12-d postpartum (Fig. 5 C). Immunoreactivity was blocked by preadsorption with the peptide immunogen (Fig. 5 B) and was undetectable in sections incubated with affinity-purified rabbit IgG control primary antibody (data not shown). Immunoreactive Stat5 and Phospho-Stat5 were detected in both normal mammary glands and phenotypically normal areas of transgenic mammary glands at 1-, 3-, 6-, 9-, and 15-d postpartum, but not at day 18 (data not shown). However, at day 12 postpartum, Stat5 was localized to the nucleus, but not phosphorylated in areas expressing ErbB4ΔIC (Fig. 5 F). The lack of Y694 phosphorylation of nuclear Stat5 in ErbB4ΔIC-expressing lobuloalveolar epithelium suggests that it is functionally inactive.


ErbB4 signaling in the mammary gland is required for lobuloalveolar development and Stat5 activation during lactation.

Jones FE, Welte T, Fu XY, Stern DF - J. Cell Biol. (1999)

Immunohistochem- ical detection of Stat5 phosphorylated at Y694 in ErbB4ΔIC-expressing mammary glands at 12-d postpartum. High magnification representations of expanded lobuloalveoli lacking detectable ErbB4ΔIC expression (A–C) or a different region of the same section containing condensed lobuloalveoli expressing high levels of ErbB4ΔIC protein (D–F). Sections were stained with hematoxylin/eosin (A and D), or stained by immunohistochemistry with antiphospho-Stat5 antibody preadsorbed with peptide immunogen and counterstained with methyl green (B and E), or phospho-Stat5 antibody without counterstain (C and F). Bar in D, 30 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2164978&req=5

Figure 5: Immunohistochem- ical detection of Stat5 phosphorylated at Y694 in ErbB4ΔIC-expressing mammary glands at 12-d postpartum. High magnification representations of expanded lobuloalveoli lacking detectable ErbB4ΔIC expression (A–C) or a different region of the same section containing condensed lobuloalveoli expressing high levels of ErbB4ΔIC protein (D–F). Sections were stained with hematoxylin/eosin (A and D), or stained by immunohistochemistry with antiphospho-Stat5 antibody preadsorbed with peptide immunogen and counterstained with methyl green (B and E), or phospho-Stat5 antibody without counterstain (C and F). Bar in D, 30 μm.
Mentions: Since functional Stat5 is phosphorylated at Y694 (reviewed in Groner and Gouilleux 1995), we used an antibody specific for Stat5 phosphorylated at Y694 to evaluate the phosphorylation state of Stat5 (Fig. 5). Strong nuclear staining and moderate cytoplasmic staining of phosphorylated Stat5 was detected within normal lobuloalveolar epithelium at 12-d postpartum (Fig. 5 C). Immunoreactivity was blocked by preadsorption with the peptide immunogen (Fig. 5 B) and was undetectable in sections incubated with affinity-purified rabbit IgG control primary antibody (data not shown). Immunoreactive Stat5 and Phospho-Stat5 were detected in both normal mammary glands and phenotypically normal areas of transgenic mammary glands at 1-, 3-, 6-, 9-, and 15-d postpartum, but not at day 18 (data not shown). However, at day 12 postpartum, Stat5 was localized to the nucleus, but not phosphorylated in areas expressing ErbB4ΔIC (Fig. 5 F). The lack of Y694 phosphorylation of nuclear Stat5 in ErbB4ΔIC-expressing lobuloalveolar epithelium suggests that it is functionally inactive.

Bottom Line: However, whey acidic protein mRNA was reduced, and alpha-lactalbumin mRNA was undetectable.This phosphorylation required an intact Stat5 SH2 domain.In summary, our results demonstrate that ErbB4 signaling is necessary for mammary terminal differentiation and Stat5 activation at mid-lactation.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, BML 342, Yale University School of Medicine, New Haven, Connecticut 06520-8023, USA.

ABSTRACT
Signaling by members of the epidermal growth factor receptor family plays an important role in breast development and breast cancer. Earlier work suggested that one of these receptors, ErbB4, is coupled to unique responses in this tissue. To determine the function of ErbB4 signaling in the normal mouse mammary gland, we inactivated ErbB4 signaling by expressing a COOH terminally deleted dominant-negative allele of ErbB4 (ErbB4DeltaIC) as a transgene in the mammary gland. Despite the expression of ErbB4DeltaIC from puberty through later stages of mammary development, an ErbB4DeltaIC-specific phenotype was not observed until mid-lactation. At 12-d postpartum, lobuloalveoli expressing ErbB4DeltaIC protein were condensed and lacked normal lumenal lactation products. In these lobuloalveoli, beta-casein mRNA, detected by in situ hybridization, was normal. However, whey acidic protein mRNA was reduced, and alpha-lactalbumin mRNA was undetectable. Stat5 expression was detected by immunohistochemistry in ErbB4DeltaIC-expressing tissue. However, Stat5 was not phosphorylated at Y694 and was, therefore, probably inactive. When expressed transiently in 293T cells, ErbB4 induced phosphorylation of Stat5. This phosphorylation required an intact Stat5 SH2 domain. In summary, our results demonstrate that ErbB4 signaling is necessary for mammary terminal differentiation and Stat5 activation at mid-lactation.

Show MeSH
Related in: MedlinePlus