Activation of signal transducer and activator of transcription 5 (STAT5) is linked to b1-integrin protein abundance in unilaterally milked XXXX mammary glands.

@entity11733 @entity1267 @entity34121 @entity5947 @entity53668 @entity291 @entity35422
UNASSIGNED: @entity5947 (PRL) is important in the regulation of milk synthesis in mammary epithelial cells (MEC). In @entity291 , circulating levels of PRL are not limiting, suggesting the possible involvement of other factors that may control the response to PRL at the cellular level. The effects of @entity1267 ( @entity1267 ) on milk synthesis are controlled locally within mammary glands and involve PRL signaling. To further investigate this relationship between @entity1267 and PRL signaling, udder halves of 17 dairy @entity291 were milked either 4 times a day (4*) or once a day (1*) for 14 d in early lactation. Mammary biopsies were obtained 3 to 5h following milking from both udder halves of 10 @entity291 , and changes in PRL and associated pathways were measured. The abundance of @entity11733 mRNA was higher after 4* milking, whereas that of the @entity53668 ( @entity53668 ) and @entity34121 were lower relative to that after 1* milking. In 4* mammary tissues, the protein levels of STAT5, activated STAT5, and b1-integrin were higher, whereas the those of the long isoform of @entity53668 and activated @entity34121 were lower than 1* tissues. The activation of STAT5 correlated strongly with major @entity35422 mRNA abundance (r=0.86 to 0.94) and b1-integrin protein levels (r=0.91). These results confirm that major @entity35422 gene expression is associated with STAT5 activation and suggests that the STAT5 and b1-integrin signaling pathways are linked. Modulation of b1-integrin abundance in response to changes in @entity1267 may be a mechanism that controls the MEC ability to respond to PRL and therefore its secretory activity.
