Mammary gland remodeling depends on gp130 signaling through Stat3 and MAPK.
The interleukin-6 (IL6) family of cytokines signals through the common receptor subunit gp130, and subsequently activates Stat3, MAPK, and PI3K. Stat3 controls cell death and tissue remodeling in the mouse mammary gland during involution, which is partially induced by IL6 and LIF. However, it is not clear whether Stat3 activation is mediated solely through the gp130 pathway or also through other receptors. This question was explored in mice carrying two distinct mutations in the gp130 gene; one that resulted in the complete ablation of gp130 and one that led to the loss of Stat3 binding sites (gp130Delta/Delta). Deletion of gp130 specifically from mammary epithelium resulted in a complete loss of Stat3 activity and resistance to tissue remodeling comparable to that seen in the absence of Stat3. A less profound delay of mammary tissue remodeling was observed in gp130Delta/Delta mice. Stat3 tyrosine and serine phosphorylation was still detected in these mice suggesting that Stat3 activation could be the result of gp130 interfacing with other receptors. Experiments in primary mammary epithelial cells and transfected COS-7 cells revealed a p44/42 MAPK and EGFR-dependent Stat3 activation. Moreover, the gp130-dependent EGFR activation was independent of EGF ligands, suggesting a cytoplasmic interaction and cross-talk between these two receptors. These experiments establish that two distinct Stat3 signaling pathways emanating from gp130 are utilized in mammary tissue.
Zhao
Ling
L
Laboratory of Genetics and Physiology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Hart
Stefan
S
Cheng
JrGang
J
Melenhorst
J Joseph
JJ
Bierie
Brian
B
Ernst
Matthias
M
Stewart
Colin
C
Schaper
Fred
F
Heinrich
Peter C
PC
Ullrich
Axel
A
Robinson
Gertraud W
GW
Hennighausen
Lothar
L
D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000502:physiology*; D019556:COS Cells; D016923:Cell Death; D002522:Chlorocebus aethiops; D050822:Cytokine Receptor gp130; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004622:Embryo, Mammalian; D005260:Female; D017353:Gene Deletion; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000502:physiology; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection
D015703:Antigens, CD; D050822:Cytokine Receptor gp130; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D050796:STAT3 Transcription Factor; D015534:Trans-Activators; C494200:Il6st protein, mouse; C494087:Stat3 protein, mouse