The recombinant subdomain IIIB of human serum albumin displays activity of gonadotrophin surge‐attenuating factor

• Published in: Human reproduction (Oxford) 2004-04, Vol.19 (4), p.849-858
• Main Authors: Tavoulari, Sotiria, Frillingos, Stathis, Karatza, Panayiota, Messinis, Ioannis E., Seferiadis, Konstantin
• Format: Article
• Language: English
• Subjects: albumin/GnRH/GnSAF/LH/Pichia pastoris; Animals; Antibodies - pharmacology; Biological and medical sciences; Cells, Cultured; Embryology: invertebrates and vertebrates. Teratology; Female; Follicle Stimulating Hormone - secretion; Fundamental and applied biological sciences. Psychology; Gonadal Hormones; Humans; Luteinizing Hormone - secretion; Male; Peptide Fragments - genetics; Peptide Fragments - immunology; Peptide Fragments - metabolism; Peptide Fragments - pharmacology; Pichia - metabolism; Pituitary Gland - cytology; Pituitary Gland - secretion; Protein Structure, Tertiary - physiology; Proteins - antagonists & inhibitors; Proteins - pharmacology; Rats; Rats, Wistar; Recombinant Proteins - genetics; Recombinant Proteins - immunology; Recombinant Proteins - metabolism; Recombinant Proteins - pharmacology; Serum Albumin - genetics; Serum Albumin - immunology; Serum Albumin - metabolism; Serum Albumin - pharmacology; Serum Albumin, Human
• ISSN: 0268-1161; 1460-2350; 1460-2350
• DOI: 10.1093/humrep/deh187

BACKGROUND: Gonadotrophin surge‐attenuating factor (GnSAF) is an as yet unidentified ovarian factor that acts on the pituitary to attenuate the pre‐ovulatory LH surge. In a previous study, GnSAF bioactivity was proposed to derive, at least in part, from a C‐terminal domain (95peptide) of human serum albumin (HSA). METHODS AND RESULTS: We employ here the expression–secretion system of Pichia pastoris to produce and assay selected recombinant polypeptides of HSA for GnSAF activity. We show that the C‐terminal 95peptide of HSA (residues 490–585; subdomain IIIB) can be expressed from P.pastoris in secreted form and supernatants from clones expressing this polypeptide reduce the GnRH‐induced LH secretion of primary rat pituitary cultures by 50–82%. When expressed in the same system, HSA domain III (residues 381–585) or full‐length HSA (residues 1–585) are inactive. The bioactive subdomain IIIB is also separable from either domain III or full‐length HSA on Blue Sepharose chromatography. CONCLUSIONS: Taken together, the findings highlight the putative importance of HSA subdomain IIIB as a GnSAF‐bioactive entity and introduce a unique experimental tool to engineer this molecule for structure–function analysis.