beta-Galactoside alpha-2,3-sialyltransferase messenger RNA increases in thyrotrophs of hypothyroid mice

Our goal was to learn about the cellular mechanism(s) responsible for the increased sialylation of thyroid-stimulating hormone (TSH) during hypothyroidism. We used in situ hybridization to examine the beta-galactoside alpha-2,3-sialyltransferase mRNA content in thyrotrophs and corticotrophs of euthyroid and hypothyroid [propylthiouracil (PTU)-treated] mice. The alpha-2,3-sialyltransferase mRNA level was 66, 70, 296, and 223% higher in hypothyroid thyrotrophs than in euthyroid thyrotrophs after mice received PTU for 1, 2, 3, and 6 weeks, respectively. Increased transcription of this gene, or mRNA stabilization, may partially explain the increased sialylation of TSH during hypothyroidism.