title: Gene expression in the human mammary epithelium during lactation: the milk fat globule transcriptome.
abstract: The molecular physiology underlying human milk production is largely unknown because of limitations in obtaining tissue samples. Determining gene expression in normal lactating women would be a potential step toward understanding why some women struggle with or fail at breastfeeding their infants. Recently, we demonstrated the utility of RNA obtained from breast milk fat globule (MFG) to detect mammary epithelial cell (MEC)-specific gene expression. We used MFG RNA to determine the gene expression profile of human MEC during lactation. Microarray studies were performed using Human Ref-8 BeadChip arrays (Illumina). MFG RNA was collected every 3 h for 24 h from five healthy, exclusively breastfeeding women. We determined that 14,070 transcripts were expressed and represented the MFG transcriptome. According to GeneSpring GX 9, 156 ontology terms were enriched (corrected P < 0.05), which include cellular (n = 3,379 genes) and metabolic (n = 2,656) processes as the most significantly enriched biological process terms. The top networks and pathways were associated primarily with cellular activities most likely involved with milk synthesis. Multiple sampling over 24 h enabled us to demonstrate core circadian clock gene expression and the periodicity of 1,029 genes (7%) enriched for molecular functions involved in cell development, growth, proliferation, and cell morphology. In addition, we found that the MFG transcriptome was comparable to the metabolic gene expression profile described for the lactating mouse mammary gland. This paper is the first to describe the MFG transcriptome in sequential human samples over a 24 h period, providing valuable insights into gene expression in the human MEC.
authors.affiliation: Department of Pediatrics-Nutrition, Baylor College of Medicine, Children's Nutrition Research Center, Houston, Texas 77030, USA.
authors.forename: Patricia D
authors.initials: PD
authors.lastname: Maningat
authors.forename: Partha
authors.initials: P
authors.lastname: Sen
authors.forename: Monique
authors.initials: M
authors.lastname: Rijnkels
authors.forename: Agneta L
authors.initials: AL
authors.lastname: Sunehag
authors.forename: Darryl L
authors.initials: DL
authors.lastname: Hadsell
authors.forename: Molly
authors.initials: M
authors.lastname: Bray
authors.forename: Morey W
authors.initials: MW
authors.lastname: Haymond
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001942:Breast Feeding; D016000:Cluster Analysis; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D006017:Glycolipids / Q000235:genetics*; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D007774:Lactation / Q000235:genetics*; D066292:Lipid Droplets; D042361:Mammary Glands, Human / Q000378:metabolism*; D051379:Mice; D011388:Prolactin / Q000097:blood; D012984:Software; D013997:Time Factors
chemical_list: D006017:Glycolipids; D006023:Glycoproteins; C110367:milk fat globule; D011388:Prolactin