Transcriptomic analysis allows complex, tissue specific analysis of gene expression during different stages of lactation. Differences in the transcriptome in different cell types, different stages of lactation and at different production levels allow identification of genes, which are up- or downregulated in different physiological situations. Careful selection of biological material for transcriptomic analysis of lactation offers a good possibility to decipher transcriptome of different cell types in lactating mammary gland. In addition to detection of transcribed genomic regions and quantification of allele specific transcripts, transcriptomic analysis also allows identification of post-transcriptional changes and detection of non-protein coding transcripts, which can play important role in regulation of gene expression in the mammary gland.
Expression of estrogen receptor 1 (ESR1) and progesterone receptor (PGR) was quantified in primary goat mammary epithelial cells (pgMECs), derived from mammary tissue of lactating and juvenile animals. The expression of ESR1 and PGR was detected in all of the derived pgMECs, but was variable between the different cell lines and growth conditions. Relative expression of both receptors was the highest in cell lines derived from juvenile goats. Maintaining cells in lactogenic conditions resulted in up-regulation of ESR1 that ranged from 1.36 to 12.35-fold, and in down-regulation of PGR that was more consistent, ranging from -2.53 to -3.62-fold. The variability in relative and differential expression between pgMECs, derived from tissues in similar physiological state, could possibly be caused by unintentional variations in cell culture establishment procedure or subtle differences in physiological state of the donor tissues.
The article summarizes technical details in establishing primary cultures of the mammary gland in goat, presents the advantages of the in vitro model and draws attention to technical difficulties in carrying out experiments and evaluates the biological relevance of the model.