title: Dynamic regulation of the Stra13/Sharp/Dec bHLH repressors in mammary epithelium.
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.
authors.affiliation: Programs 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.
authors.forename: Benoit
authors.initials: B
authors.lastname: St-Pierre
authors.forename: Melissa
authors.initials: M
authors.lastname: Cooper
authors.forename: Zhe
authors.initials: Z
authors.lastname: Jiang
authors.forename: Eldad
authors.initials: E
authors.lastname: Zacksenhaus
authors.forename: Sean E
authors.initials: SE
authors.lastname: Egan
mesh_terms: D000818:Animals; D017209:Apoptosis; D051792:Basic Helix-Loop-Helix Proteins; D015152:Blotting, Northern; D015153:Blotting, Western; D004268:DNA-Binding Proteins; D004848:Epithelium / Q000196:embryology*; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D008321:Mammary Glands, Animal / Q000196:embryology*; D051379:Mice; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C107989:BHLHE40 protein, human; C491539:Bhlhe40 protein, mouse; C476510:SPEN protein, human