Hormonal regulation of pituitary FSH sialylation in male rats.
Sialic acid content in FSH is modulated by GnRH and sexual steroids. Galbeta1,3GlcNAcalpha2,3-sialyltransferase (ST3Gal III) and Galbeta1,4GlcNAcalpha2,6-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 alpha2,6-linked sialic acid is hormonally regulated in male rats.
Ambao
V
V
Centro de Investigaciones Endocrinológicas (CEDIE), Hospital General de Niños R. Gutiérrez, CONICET, Gallo 1330, C1425EFD, Ciudad de Buenos Aires, Argentina.
Rulli
S B
SB
Carino
M H
MH
Cónsole
G
G
Ulloa-Aguirre
A
A
Calandra
R S
RS
Campo
S
S
D000375:Aging / Q000378:metabolism; D000818:Animals; D002369:Castration; D002845:Chromatography; D003208:Concanavalin A / Q000378:metabolism; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D052681:Gonadotrophs / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D007525:Isoelectric Focusing; D008297:Male; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D046468:Sexual Development; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism; D013739:Testosterone / Q000097:blood; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
D020033:Protein Isoforms; D012333:RNA, Messenger; D003208:Concanavalin A; D013739:Testosterone; D005640:Follicle Stimulating Hormone; D012799:Sialyltransferases; D019158:N-Acetylneuraminic Acid; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase