The transition from pregnancy to lactation is a critical event in the survival of the newborn since all the nutrient requirements of the infant are provided by milk. While milk contains numerous components, including proteins, that aid in maintaining the health of the infant, lactose and milk fat represent the critical energy providing elements of milk. Much of the research to date on mammary epithelial differentiation has focused upon expression of milk protein genes, providing a somewhat distorted view of alveolar differentiation and secretory activation. While expression of milk protein genes increases during pregnancy and at secretory activation, the genes whose expression is more tightly regulated at this transition are those that regulate lipid biosynthesis. The sterol regulatory element binding protein (SREBP) family of transcription factors is recognized as regulating fatty acid and cholesterol biosynthesis. We propose that SREBP1 is a critical regulator of secretory activation with regard to lipid biosynthesis, in a manner that responds to diet, and that the serine/threonine protein kinase Akt influences this process, resulting in a highly efficient lipid synthetic organ that is able to support the nutritional needs of the newborn.
Key stages in mammary gland development. Secretory activation in the mammary gland: it's not just about milk protein synthesis!
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View SamplesAn important component of time course microarray studies is the identification of genes that demonstrate significant time-dependent variation in their expression levels. Until recently available methods for performing such significance tests required replicates of individual time points. This paper describes a replicate-free method that was developed as part of a study of the estrous cycle in the rat mammary gland in which no replicate data was collected.
Identifying significant temporal variation in time course microarray data without replicates.
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View SamplesThe floxed insulin receptor was specifically targetted for deletion in the mammary gland using a mouse strain bearing Cre recombinase under the BLG promoter.
The insulin receptor plays an important role in secretory differentiation in the mammary gland.
Specimen part
View SamplesThe mammary gland of the lactating mouse synthesizes and secretes milk lipid equivalent to its entire body weight in a single 20 day lactation cycle, making it one of the most active lipid synthetic organs known. To test the hypothesis that multiple metabolic control points and potential regulatory mechanisms are involved in activating lipid and lactose synthesis at the onset of lactation we compared the mammary transcriptome of 130 genes involved in glucose metabolism between late pregnancy and early lactation and in response to dietary fat. We utilized data obtained from microarray analysis of mammary glands from quadruplicate FVB mice at pregnancy day 17, and lactation day 2. Diets containing 8% or 40% lipid were fed from lactation days 5 to 10 and mammary glands and livers of triplicate FVB mice prepared for microarray analysis. We also compared the metabolome obtained from magnetic resonance spectroscopy of flash frozen glands of the mammary gland at day 17 of pregnancy with that at day 2 of lactation. The results provide a global picture of the multiple metabolic strategies utilized to turn a quiescent organ into an incredibly efficient machine for massive but balanced lipid and lactose synthesis and implicate the transcription factor SREBP-1c in regulation of part of the pathway.
Metabolic regulation in the lactating mammary gland: a lipid synthesizing machine.
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Constitutive expression of microRNA-150 in mammary epithelium suppresses secretory activation and impairs de novo lipogenesis.
Sex, Specimen part, Subject
View SamplesPrevioulsly expression profiling of the whole mammary gland across different stages of pregnancy and lactation has been performed on different strains of mice. Since mammary gland has both epithelial and stromal compartments, to specifically identify the genes involved in the transition from pregnancy to lactation a process termed as secretory activation, expression profiling of isolated mammary epithelial cells (MECs) from four CD1 mice each at Pregnancy day 14 (P14) and Lactation day 2 (L2) was performed in the current study.
Constitutive expression of microRNA-150 in mammary epithelium suppresses secretory activation and impairs de novo lipogenesis.
Sex, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Integrating factor analysis and a transgenic mouse model to reveal a peripheral blood predictor of breast tumors.
Specimen part
View SamplesWe analyzed gene expression in human peripheral blood mononuclear cells (PBMCs) from breast cancer patients, patients with benign breast abnormalities, healthy cancer-free individuals as well as patients with other types of cancer (gastrointestinal and brain cancers).
Integrating factor analysis and a transgenic mouse model to reveal a peripheral blood predictor of breast tumors.
Specimen part
View SamplesFemale MMTV/c-MYC transgenic mice expressed the c-MYC proto-oncogene or a more stable point mutation variant (T58A) of the gene under the control of the hormone-responsive MMTV long terminal repeat (LTR) in an FVB/NJ background (Jackson Laboratories, Bar Harbor, ME). The hormones released during pregnancy and lactation have been shown to enhance expression of the oncogene. Thus, the mice were maintained in a continuous breeding program. Mice were monitored twice weekly for tumor development by palpation and tumors were measured twice weekly. Once the tumors reached 3cm3 the animals were sacrificed and tissue was obtained to confirm the tumors by histological analysis. As a control, female mice of the same age and background strain were maintained in the same facility and under the same breeding conditions as their transgenic counterparts.
Integrating factor analysis and a transgenic mouse model to reveal a peripheral blood predictor of breast tumors.
Specimen part
View SamplesE2F1 has been shown to induce both proliferation and apoptosis.
An E2F1-dependent gene expression program that determines the balance between proliferation and cell death.
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