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Updated: Aug 24, 2026

Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland
Published on: December 1, 2015
Dynamic regulation of the Stra13/Sharp/Dec bHLH repressors in mammary epithelium
Benoit St-Pierre1, Melissa Cooper, Zhe Jiang
1Programs in Cancer Research and Developmental Biology, The Hospital for Sick Children, and Department of Molecular and Medical Genetics, The University of Toronto, Toronto, Ontario, Canada.
Abstract:
Mammary gland development is a dynamic process involving cyclical proliferation, cellular differentiation, and cell death. In this study, we have determined that expression of the Stra13/Sharp/Dec basic helix-loop-helix (bHLH) family is dynamically regulated in mammary epithelium. In cultured HC11 cells, epidermal growth factor (EGF) treatment rapidly induces Stra13 protein accumulation, which is blocked by the synthetic glucocorticoid, dexamethasone. Neither the induction of Stra13 by EGF nor its repression by dexamethasone correlates with changes in Stra13 mRNA levels. During mouse mammary gland development in vivo, Stra13 is highly expressed in epithelial ducts during puberty, and strongly induced in both ducts and alveoli during early involution, while the related Sharp-1 gene is highly expressed only during late stages of involution. Together, these data indicate that Stra13/Dec/Sharp-family bHLH repressors are dynamically regulated during mammary gland development and may function to regulate apoptosis in this tissue.
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