Hormonal regulation of pituitary FSH sialylation in male rats

• Published in: Molecular and cellular endocrinology Vol. 309; no. 1; pp. 39 - 47
• Main Authors: Ambao, V., Rulli, S.B., Carino, M.H., Cónsole, G., Ulloa-Aguirre, A., Calandra, R.S., Campo, S.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 15-10-2009
• Subjects: Aging - metabolism; Animals; Castration; Chromatography; Concanavalin A - metabolism; Follicle Stimulating Hormone - blood; Follicle Stimulating Hormone - metabolism; FSH isoforms; Gene Expression Regulation, Enzymologic; Gonadotrophs - cytology; Gonadotrophs - metabolism; Hormonal regulation; Immunohistochemistry; Isoelectric Focusing; Male; N-Acetylneuraminic Acid - metabolism; Pituitary Gland - metabolism; Protein Isoforms - genetics; Protein Isoforms - metabolism; Rats; Rats, Sprague-Dawley; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sexual Development; Sialyltransferases; Sialyltransferases - genetics; Sialyltransferases - metabolism; Testosterone - blood; Sialyltransferases; FSH isoforms; Hormonal regulation
• ISSN: 0303-7207; 1872-8057
• DOI: 10.1016/j.mce.2009.05.002

Sialic acid content in FSH is modulated by GnRH and sexual steroids. Galβ1,3GlcNAcα2,3-sialyltransferase (ST3Gal III) and Galβ1,4GlcNAcα2,6-sialyltransferase (ST6Gal I) incorporate sialic acid residues into FSH oligosaccharides. The aim of the present study was to assess pituitary FSH molecular microheterogeneity and ST3Gal III/ST6Gal I expression during sexual development and after castration in male rats. Preparative isoelectric focusing and lectin chromatography were used to isolate FSH glycosylation variants according to charge and complexity of their oligosaccharides; RT-PCR and immunohistochemistry were employed to analyse sialyltransferase expression. Sexual development was associated with a progressive shift towards more acidic/sialylated FSH glycoforms concomitantly with an increment in ST6Gal I gene and protein expression. After castration, a transient decrease followed by a marked increase in ST6Gal I expression were observed. Less acidic/sialylated FSH glycoforms bearing incomplete oligosaccharides increased after castration, despite high ST6Gal I expression. ST3Gal III expression remained unchanged in all the experimental conditions examined. These results show that the synthesis of FSH isoforms possessing α2,6-linked sialic acid is hormonally regulated in male rats.