The Salk Institute for Biological Studies

Shao-Yao Ying

Nicholas C Ling

Roger C Guillemin

Frederick S Esch

Naoto Ueno

Shunichi Shimasaki

Jean E Rivier

Wylie W Vale, Jr

Joachim Spiess

Joan Vaughan

Fred S Esch

Anne Corrigan

Richard A McClintock

Two follistatin proteins with inhibin-like activity were isolated from porcine follicular fluid using heparin-Sepharose affinity chromatography, followed by gel filtration on Sephacryl S-200 and then six steps of high-performance liquid chromatography. The larger protein has 315 residues and is believed to be glycosylated. The smaller protein is a 288-residue, C-terminally shortened version thereof. These proteins specifically inhibit basal secretion of FSH, but not of LH, in a rat anterior pituitary monolayer culture system. The half-maximal effective dose for both is 2.5-6.0 ng/ml. Human and rat follistatins exhibit very high homology with the porcine protein, with the human differing from porcine in only 4 residues out of 315 and with the rat differing from porcine in only 8 residues out of 315. Using the porcine amino acid sequence information, cDNA clones encoding these proteins were identified from a porcine ovarian cDNA library. Then, using the porcine cDNA as a probe, the cloning and sequencing of the corresponding human and rat proteins were accomplished.

DNA encoding follistatin

Two follistatin proteins with inhibin-like activity were isolated from porcine follicular fluid using heparin-Sepharose affinity chromatography, followed by gel filtration on Sephacryl S-200 and then six steps of high-performance liquid chromatography. Each isolated molecule is a monomer having a molecular weight of at least about 32,000 daltons. Microsequencing revealed the NH.sub.2 -terminal portions both to be Gly-Asn-Cys-Trp-Leu-Arg-Gln-Ala-Lys-Asn-Gly-Arg-Cys-Gln-Val-Leu. The larger protein has 315 residues and is believed to be glycosylated. The smaller protein is a 288-residue, C-terminally shortened version thereof. These proteins specifically inhibit basal secretion of FSH, but not of LH, in a rat anterior pituitary monolayer culture system. The Half-maximal effective dose for both is 2.5-6.0 ng/ml. Human and rat follistatins exhibit very high homology with the porcine protein, with the human differing from porcine in only 4 residues out of 315 and with the rat differing from porcine in only 8 residues out of 315.

Mammalian follistatin

A 28,000-dalton protein with FSH-releasing activity is isolated from porcine follicular fluid in a multi-step procedure including gel filtration, ion exchange chromatography and several reverse-phase high-performance liquid chromatography steps. The 28 kD protein promotes secretion of FSH, but not of LH, in a rat anterior pituitary monolayer culture system, exhibiting an EC.sub.50 of 0.5 ng/ml. These peptides are dimers of inhibin .beta.-chains of mammals, and homodimers or heterodimers of the .beta..sub.A and .beta..sub.B chains are biologically active to regulate fertility of various mammalian species, including humans.

FSH-releasing peptides

Two 32,000-dalton proteins with inhibin activity were isolated from porcine follicular fluid using heparin-Sepharose affinity chromatography, followed by gel filtration on Sephacryl S-200 and then four steps of reverse-phase high-performance liquid chromatography. Each isolated molecular is composed of two chains having molecular weights of about 18,000 and about 14,000 daltons, respectively, which are bound together by disulfide bonding. Microsequencing revealed the NH.sub.2 -terminal portion of the 18K chain of both to be Ser-Thr-Ala-Pro-Leu-Pro-Trp-Pro-Trp-Ser-Pro-Ala-Ala-Leu-Arg-Leu-Leu-Gln-Ar g-Pro-Pro-Glu-Glu-Pro-Ala-Val, of one of the 14K chains to be Gly-Leu-Glu-Cys-Asp-Gly-Arg-Thr-Asn-Leu-Cys-Cys-Arg-Gln-Gln-Phe-Phe-Ile-As p-Phe-Arg-Leu-Ile-Gly-Trp, and of the other 14K chain to be Gly-Leu-Glu-Cys-Asp-Gly-Lys-Val-Asn-Ile-Cys-Cys-Lys-Lys-Gln-Phe-Phe-Val-Se r-Phe-Lys-Asp-Ile-Gly-Trp-Asn-Asp-Trp-Ile-Ile-Ala-Pro. Both proteins have now been completely characterized, each having a first chain 134 residues long linked by disulfide bonding to a second chain 116 or 115 residues long. The first chain is believed to be glycosylated, which accounts for the disparity between the number of residues and the apparent molecular weight of 18K. These 32K proteins specifically inhibit basal secretion of FSH, but not of LH, in a rat anterior pituitary monolayer culture system. The half-maximal effective does of one is 450 pg/ml and of the other is 900 pg/ml.

Inhibin and method of purifying same

A substantially purified substance has been isolated from bovine gonadal secretions which mediates pituitary hormone secretion, using an extraction and purification sequence that includes gel filtration, partition chromatography and HPLC in that order. The substance, designated gonadostatin, is a moderate-size peptide which below a threshold level selectively inhibits LRF-stimulated pituitary secretion of LH and FSH. Above a threshold level, gonadostatin generally stimulates pituitary hormone secretion.

Growing community of inventors

San Diego, CA, United States of America

Shao-Yao Ying