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ErbB2 and EGFR are downmodulated during the differentiation of 3T3‐L1 preadipocytes
Author(s) -
Pagano Eleonora,
Calvo Juan Carlos
Publication year - 2003
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.10647
Subject(s) - neuregulin , epidermal growth factor , endocrinology , biology , erbb3 , medicine , stromal cell , cell culture , receptor , tyrosine phosphorylation , erbb , cancer research , cellular differentiation , microbiology and biotechnology , receptor tyrosine kinase , phosphorylation , signal transduction , biochemistry , genetics , gene
The expression of receptors belonging to the epidermal growth factor receptor subfamily has been largely studied these last years in epithelial cells mainly as involved in cell proliferation and malignant progression. Although much work has focused on the role of these growth factor receptors in the differentiation of a variety of tissues, there is little information in regards to normal stromal cells. We investigated erbB2 expression in the murine fibroblast cell line Swiss 3T3L1, which naturally or hormonally induced undergoes adipocyte differentiation. We found that the Swiss 3T3‐L1 fibroblasts express erbB2, in addition to EGFR, and in a quantity comparable to or even greater than the breast cancer cell line T47D. Proliferating cells increased erbB2 and EGFR levels when reaching confluence up to 4‐ and 10‐fold, respectively. This expression showed a significant decrease when growth‐arrested cells were stimulated to differentiate with dexamethasone and isobutyl‐methylxanthine. Differentiated cells presented a decreased expression of both erbB2 and EGFR regardless of whether the cells were hormonally or spontaneously differentiated. EGF stimulation of serum‐starved cells increased erbB2 tyrosine phosphorylation and retarded erbB2 migration in SDS–PAGE, suggesting receptor association and activation. Heregulin‐α1 and ‐β1, two EGF related factors, had no effect on erbB2 or EGFR phosphorylation. Although 3T3‐L1 cells expressed heregulin, its specific receptors, erbB3 and erbB4, were not found. This is the first time in which erbB2 is reported to be expressed in an adipocytic cell line which does not depend on non EGF family growth factors (thyroid hormone, growth hormone, etc.) to accomplish adipose differentiation. Since erbB2 and EGFR expression were downmodulated as differentiation progressed it is conceivable that a mechanism of switching from a mitogenic to a differentiating signaling pathway may be involved, through regulation of the expression of these growth factor receptors. © 2003 Wiley‐Liss, Inc.