title: Variable phosphorylation states of pigment-epithelium-derived factor differentially regulate its function.
abstract: The pigment epithelium-derived factor (PEDF) belongs to the family of noninhibitory serpins. Although originally identified in the eye, PEDF is widely expressed in other body regions including the plasma. This factor can act either as a neurotrophic or as an antiangiogenic factor, and we previously showed that the 2 effects of PEDF are regulated through phosphorylation by PKA and CK2. Here, we studied the interplay between the PKA and CK2 phosphorylation of PEDF, and found that a PEDF mutant mimicking the CK2-phosphorylated PEDF cannot be phosphorylated by PKA, while the mutant mimicking the PKA-phosphorylated PEDF is a good CK2 substrate. Using triple mutants that mimic the PKA- and CK2-phosphorylated and nonphosphorylated PEDF, we found that PEDF can induce several distinct cellular activities dependent on its phosphorylation. The mutant mimicking the accumulative PKA plus CK2 phosphorylation exhibited the strongest antiangiogenic and neurotrophic activities, while the mutants mimicking the individual phosphorylation site mutants had either a reduced activity or only one of these activities. Thus, differential phosphorylation induces variable effects of PEDF, and therefore contributes to the complexity of PEDF action. It is likely that the triple phosphomimetic mutant can be used to generate effective antiangiogenic or neurotrophic drugs.
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Galia
authors.initials: G
authors.lastname: Maik-Rachline
authors.forename: Rony
authors.initials: R
authors.lastname: Seger
mesh_terms: D020533:Angiogenesis Inhibitors; D020013:Calcium Signaling / Q000502:physiology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D005136:Eye Proteins / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007700:Kinetics; D009414:Nerve Growth Factors / Q000502:physiology*; D019007:P-Selectin / Q000502:physiology*; D037342:Pertussis Toxin / Q000494:pharmacology; D010766:Phosphorylation; D021381:Protein Transport; D044463:Receptor, PAR-1 / Q000502:physiology; D015843:Serpins / Q000502:physiology*; D013917:Thrombin / Q000494:pharmacology; D014471:Umbilical Veins; D014841:von Willebrand Factor / Q000187:drug effects / Q000378:metabolism*; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D020533:Angiogenesis Inhibitors; D000242:Cyclic AMP; D005136:Eye Proteins; D009414:Nerve Growth Factors; D019007:P-Selectin; D037342:Pertussis Toxin; D044463:Receptor, PAR-1; D015843:Serpins; D013917:Thrombin; D014841:von Willebrand Factor; D000099174:Pigment Epithelium-Derived Factor