Bovine Mammary Gene Expression Profiling during the Onset of Lactation

• Published in: PloS one Vol. 8; no. 8; p. e70393
• Main Authors: Gao, Yuanyuan, Lin, Xueyan, Shi, Kerong, Yan, Zhengui, Wang, Zhonghua
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 21.08.2013; Public Library of Science (PLoS)
• Subjects: Algorithms; Animal lactation; Animal sciences; Animals; Biology; Bovidae; Breasts; Cattle; Cell cycle; Cluster Analysis; Computer Science; Dairying; Deoxyribonucleic acid; DNA; Down-Regulation; Epithelial Cells - cytology; Fatty acids; Female; Gene expression; Gene Expression Profiling; Gene Expression Regulation; Gene Library; Genes; Genomes; Genomic libraries; Genomics; Immune response; Immune system; Laboratories; Lactation; Lactation - genetics; Lactation - physiology; Lactic acid; Lipid Metabolism; Lipids; Mammary gland; Mammary Glands, Animal - metabolism; Metabolism; Milk; Oils & fats; Oligonucleotide Array Sequence Analysis; Parturition; Physiology; Protein synthesis; Proteins; RNA - analysis; Sequence Analysis, DNA; Sterols; Time Factors; Transcription factors; Veterinary medicine; Zoology; China
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0070393

Lactogenesis includes two stages. Stage I begins a few weeks before parturition. Stage II is initiated around the time of parturition and extends for several days afterwards. To better understand the molecular events underlying these changes, genome-wide gene expression profiling was conducted using digital gene expression (DGE) on bovine mammary tissue at three time points (on approximately day 35 before parturition (-35 d), day 7 before parturition (-7 d) and day 3 after parturition (+3 d)). Approximately 6.2 million (M), 5.8 million (M) and 6.1 million (M) 21-nt cDNA tags were sequenced in the three cDNA libraries (-35 d, -7 d and +3 d), respectively. After aligning to the reference sequences, the three cDNA libraries included 8,662, 8,363 and 8,359 genes, respectively. With a fold change cutoff criteria of ≥ 2 or ≤-2 and a false discovery rate (FDR) of ≤ 0.001, a total of 812 genes were significantly differentially expressed at -7 d compared with -35 d (stage I). Gene ontology analysis showed that those significantly differentially expressed genes were mainly associated with cell cycle, lipid metabolism, immune response and biological adhesion. A total of 1,189 genes were significantly differentially expressed at +3 d compared with -7 d (stage II), and these genes were mainly associated with the immune response and cell cycle. Moreover, there were 1,672 genes significantly differentially expressed at +3 d compared with -35 d. Gene ontology analysis showed that the main differentially expressed genes were those associated with metabolic processes. The results suggest that the mammary gland begins to lactate not only by a gain of function but also by a broad suppression of function to effectively push most of the cell's resources towards lactation.