Expression levels of STAT5A and STAT5B in mammary parenchymal tissue from Upton-Meishan and Large White gilts

Abstract

. 2002. Expression levels of STAT5A and STAT5B in mammary parenchymal tissue from Upton-Meishan and Large White gilts. Can. J. Anim. Sci. 82: 507-518. The implication of STAT5A and STAT5B in mammary gland development and maintenance of lactation is well documented in rodents and humans. However, little is known regarding their roles in mammary gland development during gestation in pigs. We identified and analyzed the complete coding sequences of swine STAT5A and STAT5B and evaluated their mRNA levels in mammary glands of gestating gilts (day 110) in two different breeds, Upton-Meishan and Large White. Sequence analysis revealed a new APASA insertion in the STAT5A amino acid sequence that is in close proximity to residue Tyr 699 and whose phosporylation leads to the activation of target genes' transcription. STAT5A mRNA levels were higher in Upton-Meishan than in Large White. In both breeds, STAT5B mRNA levels were higher than those of STAT5A, which is contrary to what was found in other mammals. A correlation between circulating IGF-I levels and STAT5B mRNA levels in the mammary gland was noticed in the Upton-Meishan breed only. STAT5B mRNA levels in mammary tissue of Large White gilts were highly correlated with extra-parenchymal tissue weight, parenchymal tissue weight, total parenchymal DNA, RNA and RNA/DNA ratio. In Upton-Meishan gilts, correlations were observed only between extra-parenchymal weight and STAT5A and STAT5B mRNA levels. These results indicate that there are significant differences in mRNA levels of STAT5A and STAT5B in the mammary glands of pregnant gilts when compared to other mammals, and between swine breeds.

Gene expression of leptin, leptin receptor, prolactin receptor and whey acidic protein in mammary glands of late-pregnant gilts from two breeds

“…The negative association between STAT5A and PRL-R mRNA levels in the LW breed may be explained by the fact that STAT5B, and not STAT5A, mRNA levels are associated with mammary gland development in this breed (Palin et al 2002). Positive associations between leptin receptor mRNA levels and WAP, STAT5A and STAT5B are seen in the UM breed only.…”

“…STAT5A and STAT5B mRNA levels were reported in Palin et al (2002). In the overall, as well as in the LW and UM gilt populations, significant correlations were observed between PRL-R mRNA levels and WAP, leptin (significant only in overall and LW), leptin receptor, STAT5A and STAT5B mRNA levels.…”

“…Moreover, it was reported that IGF-I can stimulate PRL-R mRNA expression in human endometrial cells (Tseng and Zhu 1998). Interestingly, we previously observed a correlation between circulating IGF-I concentrations and STAT5B mRNA levels in the parenchymal tissue of UM gilts (Palin et al 2002). The possibility arises that circulating IGF-I could stimulate PRL-R mRNA in pig mammary gland, which could then lead to activation of STAT5 DNA binding activity.…”

“…The side of the udder with the largest number of functional glands was stored at -20°C until dissection and analyses for tissue composition as described by Farmer et al (2000). Parenchymal tissue samples of pregnant and non-pregnant gilts were also collected for RNA extraction as previously described (Palin et al 2002). In this case, tissues were immediately frozen in liquid nitrogen and stored at -80°C until analyzed by semiquantitative reverse transcription polymerase chain reaction (RT-PCR).…”

Hormonal, behavioural and performance characteristics of Meishan sows during pregnancy and lactation

“…Furthermore, these differences may also be associated to prolactin-regulated genes, namely STAT5A and STAT5B, that are important in the development of the mammary glands. Indeed, Palin et al (2002) found that the expression level of STAT5A in mammary glands on day 110 of gestation was greater in Meishan than in Large White gilts, while mRNA expression levels for STAT5B were similar in both breeds.…”