Gene expression analysis of mammary tissue during fetal bud formation and growth in two pig breeds – indications of prenatal initiation of postnatal phenotypic differences

Abstract

BackgroundThe mammary gland is key to all mammal species; in particular in multiparous species like pigs the number and the shape of functional mammary gland complexes are major determinants of fitness. Accordingly, we aimed to catalog the genes relevant to mammogenesis in pigs. Moreover, we aimed to address the hypothesis that the extent and timing of proliferation, differentiation, and maturation proccesses during prenatal development contribute to postnatal numerical, morphological and functional properties of the mammary gland. Thus we focused on differentially expressed genes and networks relevant to mammary complex development in two breeds that are subject to different selection pressure on number, shape and function of teats and show largely different prevalence of non-functional inverted teats. The expression patterns of fetal mammary complexes obtained at 63 and 91 days post conception (dpc) from German Landrace (GL) and Pietrain (PI) were analyzed by Affymetrix GeneChip Porcine Genome Arrays.ResultsThe expression of 11,731 probe sets was analysed between the two stages within and among breeds. The analysis showed the largest distinction of samples of the breed GL at 63 dpc from all other samples. According to Ingenuity Pathways Analysis transcripts with abundance at the four comparisons made (GL63-GL91, PI63-PI93, GL63-PI63 and GL91-PI91) were predominantly assigned to biofunctions relevant to `cell maintenance, proliferation, differentiation and replacement´, `organismal, organ and tissue development´ and `genetic information and nucleic acid processing´. Moreover, these transcripts almost exclusively belong to canonical pathways related to signaling rather than metabolic pathways. The accumulation of transcripts that are up-regulated in GL compared to PI indicate a higher proliferating activity in GL, whereas processes related to differentiation, maturation and maintenance of cells are more prominent in PI. Differential expression was validated by quantitative RT-PCR of five genes (GAB1, MAPK9, PIK3C2B, PIK3C3 and PRKCH) that are involved in several relevant signaling pathways.ConclusionsThe results indicate that mammary complex development in PI precedes GL. The differential expression between the two breeds at fetal stages likely reflects the prenatal initiation of postnatal phenotypes concerning the number and shape as well as functionality of teats.

MicroRNA Expression Profiling of Lactating Mammary Gland in Divergent Phenotype Swine Breeds

“…In multiparous pigs, the number and the shape of functional mammary gland complexes are major determinants of the mothering ability of sows. Sow milk yield and quality is crucial for the survival and growth of piglets [ 16 ]. The mammary gland prepares for lactation by undergoing extensive growth and differentiation during pregnancy.…”

Angiogenic Potential of Human Neonatal Foreskin Stromal Cells in the Chick Embryo Chorioallantoic Membrane Model

“…hNSSCs were isolated and cultured in accordance with our previously published protocols [ 6 , 8 ]. In brief, cells were isolated by explant organ culture to establish outgrowth cell culture ( Figure 1(a) ).…”

“…In our previous study, hNSSCs were shown to express thirty-three CD markers including known stromal cell-associated as well as several novel markers [ 6 ]. Moreover, these cells could be induced to differentiate into cells expressing endothelial markers and to form densely packed large diameter tubules during in vitro angiogenesis assay [ 5 , 8 ]. However, the angiogenic capacity of hNSSCs ex vivo remains unclear.…”

“…Nonetheless, there is substantial heterogeneity in the system of recruitment, collection, and storage of autologous clinical grade source [ 9 ]. Our preliminary studies using neonatal foreskin showed promising results indicating that hNSSCs could be an alternative potential source for cell based angiogenesis [ 6 , 8 ]. Thus, improved understanding of the cellular mechanisms of hNSSCs vasculogenesis and angiogenesis could offer new therapeutic approaches for hNSSCs.…”

Genotyping by sequencing reveals a new locus for pig teat number

“…Moreover, RAPGEF1 was also found to be a differentially expressed gene relevant to mammogenesis in pigs during fetal bud formation (Chomwisarutkun et al . ). Thus, we inferred that the SSC5:60296617 SNP may affect teat number by regulating the interaction of EPS8 and RAPGEF1 and, finally, affecting the mammogenesis of pigs.…”