Nuclear Localization of STAT5A Modified with O-Linked N-Acetylglucosamine and Early Involution in the Mammary Gland of Hirosaki Hairless Rat

The study examined the early involution of the mammary gland in Hirosaki Hairless Rats (HHR) during lactation, focusing on the role of the transcription factor STAT5A. In HHRs, STAT5A was modified with O-Linked N-Acetylglucosamine (O-GlcNAc) rather than being tyrosine-phosphorylated, which was linked to its transient activation and early involution of the mammary gland. This modification enhanced STAT5A's binding to its responsive element, suggesting a unique activation mechanism in HHRs. The study involved at least four female rats of each genotype and indicated that changes in O-GlcNAc transferase or O-GlcNAcase activities might contribute to the observed phenotypes, highlighting a potential mechanism by which O-GlcNAcylation of STAT5A could affect mammary gland development and function.