Functional development of the adult ovine mammary gland—insights from gene expression profiling

Abstract

BackgroundThe mammary gland is a dynamic organ that undergoes dramatic physiological adaptations during the transition from late pregnancy to lactation. Investigation of the molecular basis of mammary development and function will provide fundamental insights into tissue remodelling as well as a better understanding of milk production and mammary disease. This is important to livestock production systems and human health.Here we use RNA-seq to identify differences in gene expression in the ovine mammary gland between late pregnancy and lactation.ResultsBetween late pregnancy (135 days of gestation ± 2.4 SD) and lactation (15 days post partum ± 1.27 SD) 13 % of genes in the sheep genome were differentially expressed in the ovine mammary gland. In late pregnancy, cell proliferation, beta-oxidation of fatty acids and translation were identified as key biological processes. During lactation, high levels of milk fat synthesis were mirrored by enrichment of genes associated with fatty acid biosynthesis, transport and lipogenesis. Protein processing in the endoplasmic reticulum was enriched during lactation, likely in support of active milk protein synthesis. Hormone and growth factor signalling and activation of signal transduction pathways, including the JAK-STAT and PPAR pathways, were also differently regulated, indicating key roles for these pathways in functional development of the ovine mammary gland. Changes in the expression of epigenetic regulators, particularly chromatin remodellers, indicate a possible role in coordinating the large-scale transcriptional changes that appear to be required to switch mammary processes from growth and development during late pregnancy to synthesis and secretion of milk during lactation.ConclusionsCoordinated transcriptional regulation of large numbers of genes is required to switch between mammary tissue establishment during late pregnancy, and activation and maintenance of milk production during lactation. Our findings indicate the remarkable plasticity of the mammary gland, and the coordinated regulation of multiple genes and pathways to begin milk production. Genes and pathways identified by the present study may be important for managing milk production and mammary development, and may inform studies of diseases affecting the mammary gland.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1947-9) contains supplementary material, which is available to authorized users.

Integrated analysis of long noncoding RNA and mRNA expression profiles reveals the potential role of long noncoding RNA in different bovine lactation stages

“…In addition, the overrepresented pathways differed between the 2 lactation stages. For example, steroid hormone biosynthesis, glycerolipid metabolism, and biosynthesis of AA were overrepresented in peak lactation, and this was in agreement with a previous study in the ovine mammary gland (Paten et al, 2015). There were more overrepresented metabolic pathways at the peak lactation stage than at the late lactation stage, reflecting the heavier request of energy and metabolites at peak lactation than at late lactation.…”

RNA-Sequencing for profiling goat milk transcriptome in colostrum and mature milk

“…However, in cattle and sheep mammary gland, the role of JaK2-STAT5 signaling pathway seemed to support a minor role for milk protein synthesis [29, 66]. In the present work we did not find STAT5 between the highly expressed genes either in D1 or D2 samples but we found the transcription factor E74-like factor 5 ( ELF5 ) expressed.…”

“…In the present work we did not find STAT5 between the highly expressed genes either in D1 or D2 samples but we found the transcription factor E74-like factor 5 ( ELF5 ) expressed. This factor has been postulated to work as regulator of milk protein expression, encompassing STAT5 as a key player and its expression has been found increased during cow and sheep lactation [29, 66]. Therefore our findings allow to hypothesize a similar physiological role of this gene during lactation in goats.…”

“…The recent development of Next-Generation Sequencing technologies allows a much broader and detailed knowledge on the biology of the mammary gland [25]. RNA-seq transcriptomic analysis has been widely used for model and non-model organisms and in particular for organisms for which limited genomic resources are available [26–29]. …”

Zinc Finger Homeodomain Factor Zfhx3 Is Essential for Mammary Lactogenic Differentiation by Maintaining Prolactin Signaling Activity

“…It has been established that lactation involves the expression of numerous genes and the secretion of their gene products in the milk (43,44). Our previous study demonstrated that dele- ϩ/ϩ and MMTV-Cre/Zfhx3 f/f mice at day 2 of lactation.…”