title: Two polypeptide factors that promote differentiation of insect midgut stem cells in vitro.
abstract: Isolated stem cells from the midguts of Manduca sexta and Heliothis virescens can be induced to differentiate in vitro by either of two polypeptide factors. One of the peptides was isolated from culture medium conditioned by differentiating mixed midgut cells; we used high performance liquid chromatographic separation and Edman degradation of the most prominent active peak. It is a polypeptide with 30 amino acid residues (3,244 Da), with the sequence HVGKTPIVGQPSIPGGPVRLCPGRIRYFKI, and is identical to the C-terminal peptide of bovine fetuin. A portion of this molecule (HVGKTPIVGQPSIPGGPVRLCPGRIR) was synthesized and was found to be very active in inducing differentiation of H. virescens midgut stem cells. It was designated Midgut Differentiation Factor 1 (MDF1). Proteolysis of bovine fetuin with chymotrypsin allowed isolation of a pentamer, Midgut Differentiation Factor 2 (MDF2) with the sequence HRAHY corresponding to a portion of the fetuin molecule near MDF1. Synthetic MDF2 was also biologically active in midgut stem cell bioassays. Dose response curves indicate activity in physiological ranges from 10(-14) to 10(-9) M for MDF1 and 10(-15) to 10(-5) M for MDF2.
authors: Insect Biocontrol Laboratory, U.S. Department of Agriculture, Beltsville, Maryland 20705, USA. mloeb@asrr.arsusda.gov
authors: M J
authors: MJ
authors: Loeb
authors: H
authors: H
authors: Jaffe
authors: D B
authors: DB
authors: Gelman
authors: R S
authors: RS
authors: Hakim
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects; D017077:Culture Media, Conditioned; D004064:Digestive System / Q000166:cytology / Q000187:drug effects; D066298:In Vitro Techniques; D019476:Insect Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D007313:Insecta / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects; D007915:Lepidoptera; D018402:Manduca; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects; D000509:alpha-Fetoproteins / Q000737:chemistry
chemical_list: D017077:Culture Media, Conditioned; D019476:Insect Proteins; D010455:Peptides; D000509:alpha-Fetoproteins