title: S100B-mediated inhibition of the phosphorylation of GFAP is prevented by TRTK-12.
abstract: S100B belongs to a family of calcium-binding proteins involved in cell cycle and cytoskeleton regulation. We observed an inhibitory effect of S100B on glial fibrillary acidic protein (GFAP) phosphorylation, when stimulated by cAMP or Ca2+/calmodulin, in a cytoskeletal fraction from primary astrocyte cultures. We found that S100B has no direct effect on CaM KII activity, the major kinase in this cytoskeletal fraction able to phosphorylate GFAP. The inhibition of GFAP phosphorylation is most likely due to the binding of S100B to the phosphorylation sites on this protein and blocking the access of these sites to the protein kinases. This inhibition was dependent on Ca2+. However, Zn2+ could substitute for Ca2+. The inhibitory effect of S100B was prevented by TRTK-12, a peptide that blocks S100B interaction with several target proteins including glial fibrillary acidic protein. These data suggest a role for S100B in the assembly of intermediate filaments in astrocytes.
authors.affiliation: Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. julianadk@iname.com
authors.forename: Juliana Karl
authors.initials: JK
authors.lastname: Frizzo
authors.forename: Francine
authors.initials: F
authors.lastname: Tramontina
authors.forename: Erica
authors.initials: E
authors.lastname: Bortoli
authors.forename: Carmen
authors.initials: C
authors.lastname: Gottfried
authors.forename: Rodrigo B
authors.initials: RB
authors.lastname: Leal
authors.forename: Imre
authors.initials: I
authors.lastname: Lengyel
authors.forename: Rosario
authors.initials: R
authors.lastname: Donato
authors.forename: Peter R
authors.initials: PR
authors.lastname: Dunkley
authors.forename: Carlos-Alberto
authors.initials: CA
authors.lastname: Gonçalves
mesh_terms: D000818:Animals; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D051347:CapZ Actin Capping Protein; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000037:antagonists & inhibitors / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology*; D010446:Peptide Fragments; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*
chemical_list: D051347:CapZ Actin Capping Protein; D005904:Glial Fibrillary Acidic Protein; D009414:Nerve Growth Factors; D009842:Oligopeptides; D010446:Peptide Fragments; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579158:S100b protein, rat; C475482:TRTK-12 peptide; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases