Author(s): Truesdell PF, Zirngibl RA, Francis S, Sangrar W, Greer PA
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Abstract The fps/fes proto-oncogene encodes a cytoplasmic protein-tyrosine kinase implicated in vesicular trafficking and cytokine and growth factor signaling in hematopoietic, neuronal, vascular endothelial and epithelial lineages. Genetic evidence has suggested a tumor suppressor role for Fps/Fes in breast and colon. Here we used fps/fes knockout mice to investigate potential roles for this kinase in development and function of the mammary gland. Fps/Fes expression was induced during pregnancy and lactation, and its kinase activity was dramatically enhanced. Milk protein and fat composition from nursing fps/fes-null mothers was normal; however, pups reared by them gained weight more slowly than pups reared by wild-type mothers. Fps/Fes displayed a predominantly dispersed punctate intracellular distribution which was consistent with vesicles within the luminal epithelial cells of lactating breast, while a small fraction co-localized with beta-catenin and E-cadherin on their basolateral surfaces. Fps/Fes was found to be a component of the E-cadherin adherens junction (AJ) complex; however, the phosphotyrosine status of beta-catenin and core AJ components in fps/fes-null breast tissue was unaltered, and epithelial cell AJs and gland morphology were intact. We conclude that Fps/Fes is not essential for the maintenance of epithelial cell AJs in the lactating breast but may instead play important roles in vesicular trafficking and milk secretion.
This article was published in Exp Cell Res
and referenced in Journal of Clinical & Cellular Immunology