title: An S116R Phosphorylation Site Mutation in Human Fibroblast Growth Factor-1 Differentially Affects Mitogenic and Glucose-Lowering Activities.
abstract: Fibroblast growth factor-1 (FGF-1), a potent human mitogen and insulin sensitizer, signals through both tyrosine kinase receptor-mediated autocrine/paracrine pathways as well as a nuclear intracrine pathway. Phosphorylation of FGF-1 at serine 116 (S116) has been proposed to regulate intracrine signaling. Position S116 is located within a ∼17 amino acid C-terminal loop that contains a rich set of functional determinants including heparin∖heparan sulfate affinity, thiol reactivity, nuclear localization, pharmacokinetics, functional half-life, nuclear ligand affinity, stability, and structural dynamics. Mutational targeting of specific functionality in this region without perturbing other functional determinants is a design challenge. S116R is a non-phosphorylatable variant present in bovine FGF-1 and other members of the human FGF family. We show that the S116R mutation in human FGF-1 is accommodated with no perturbation of biophysical or structural properties, and is therefore an attractive mutation with which to elucidate the functional role of phosphorylation. Characterization of S116R shows reduction in NIH 3T3 fibroblast mitogenic stimulation, increase in fibroblast growth factor receptor-1c activation, and prolonged duration of glucose lowering in ob/ob hyperglycemic mice. A novel FGF-1/fibroblast growth factor receptor-1c dimerization interaction combined with non-phosphorylatable intracrine signaling is hypothesized to be responsible for these observed functional effects.
authors: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida 32306.
authors: Xue
authors: X
authors: Xia
authors: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 60047.
authors: Ozan S
authors: OS
authors: Kumru
authors: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida 32306.
authors: Sachiko I
authors: SI
authors: Blaber
authors: Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 60047.
authors: C Russell
authors: CR
authors: Middaugh
authors: Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors: Ling
authors: L
authors: Li
authors: Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110.
authors: David M
authors: DM
authors: Ornitz
authors: Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037.
authors: Jae Myoung
authors: JM
authors: Suh
authors: Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037.
authors: Annette R
authors: AR
authors: Atkins
authors: Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037.
authors: Michael
authors: M
authors: Downes
authors: Gene Expression Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037; Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037.
authors: Ronald M
authors: RM
authors: Evans
authors: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida 32306.
authors: Connie A
authors: CA
authors: Tenorio
authors: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida 32306.
authors: Ewa
authors: E
authors: Bienkiewicz
authors: Department of Biomedical Sciences, Florida State University, Tallahassee, Florida 32306. Electronic address: michael.blaber@med.fsu.edu.
authors: Michael
authors: M
authors: Blaber
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002470:Cell Survival / Q000502:physiology; D018360:Crystallography, X-Ray; D004305:Dose-Response Relationship, Drug; D016220:Fibroblast Growth Factor 1 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008934:Mitogens / Q000378:metabolism*; D009154:Mutation / Q000502:physiology*; D041681:NIH 3T3 Cells; D010766:Phosphorylation / Q000502:physiology; D017433:Protein Structure, Secondary
chemical_list: D008934:Mitogens; D016220:Fibroblast Growth Factor 1; D005947:Glucose
keywords: X-ray crystallography; fibroblast growth factor receptor; heparan sulfate proteoglycan; human fibroblast growth factor-1; protein engineering; protein stability; thermodynamics