Comparison of mesoderm-inducing activity with monomeric and dimeric inhibin alpha and beta-A subunits on Xenopus ectoderm.
Activin possesses mesoderm-inducing activity, erythroid-differentiating activity, and follicle-stimulating hormone-releasing activity. The chemical structures of the activin molecule are formed by a combination of two beta-subunit peptides of inhibin. Inhibin is a dimer consisting of an alpha and beta subunit. To examine the mesoderm-inducing activity of these substances, we tested several configurations including: (1) two types of alpha-subunit peptide; (2) two types of inhibin A and B dimer; (3) beta A-subunit peptide monomer; (4) three types of activins A, AB and B, and (5) follistatin (activin-binding protein) by the animal cap assay using Xenopus laevis ectoderm, and by the erythroid-differentiating factor (EDF) test. Activins, which are composed of dimeric inhibin beta A- or beta B-subunit peptides, had the highest mesoderm-inducing and EDF activities. The monomeric beta A-subunit peptide exhibited mesoderm-inducing and EDF activities that were much lower than activin A. The inhibitory effect of follistatin on mesodermal induction by the beta A-subunit peptide was also lower than that of activin. Both inhibins A and B had very weak mesoderm-inducing activity and no EDF activity. The two types of inhibin alpha-subunit monomer had little mesoderm-inducing activity and no EDF activity. The mesoderm induction caused by activin A was not suppressed by the addition of the alpha-subunit monomer and inhibin. The mesoderm-inducing activity in relation to the chemical structures of the monomeric and/or dimeric inhibin alpha and beta A subunits is discussed.
Nakano
H
H
Department of Biology, Yokohama City University, Japan.
Uchiyama
H
H
Fukui
A
A
Sugino
H
H
Asashima
M
M
D028341:Activins; D000818:Animals; D002454:Cell Differentiation; D004475:Ectoderm / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology; D038681:Follistatin; D006023:Glycoproteins / Q000494:pharmacology; D006801:Humans; D007265:Inhibins / Q000494:pharmacology; D046911:Macromolecular Substances; D008648:Mesoderm / Q000502:physiology*; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D029584:Prostatic Secretory Proteins; D014982:Xenopus laevis
D038681:Follistatin; D006023:Glycoproteins; D046911:Macromolecular Substances; D010455:Peptides; D029584:Prostatic Secretory Proteins; C043076:beta-microseminoprotein; C094377:inhibin-alpha subunit; D028341:Activins; D007265:Inhibins