Phosphorylation of the growth factors bFGF, NGF and BDNF: a prerequisite for their biological activity.
The aim of this work was to test whether growth factors such as basic fibroblast growth factor (bFGF), nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) undergo autophosphorylation and whether this affects their biological activity. Incubation of those growth factors with [gamma-(32)P]ATP resulted in phosphorylation in vitro. The phosphate bond was resistant to alkaline pH, yet acid-labile. Addition of alkaline phosphatase resulted in time and protein dependent dephosphorylation. Concomitantly, alkaline phosphatase abolished the neuroprotective effect of those growth factors upon oxygen and glucose deprivation and upon staurosporine-induced cell death. For those studies, we were using primary cultures of cortical and hippocampal neurons from embryonic and neonatal rats. Incubation of bFGF with non-hydrolyzable ATP-gammaS resulted in phosphorylation and in neuroprotection resistant to alkaline phosphatase. We conclude that bFGF, NGF and BDNF undergo autophosphorylation on site(s) other than serine, threonine, tyrosine and/or ATP-binding, and that this binding of phosphate is essential for neuroprotection in vivo.
Klumpp
Susanne
S
Institut für Pharmazeutische & Medizinische Chemie, Westfälische Wilhelms-Universität, Hittorfstr. 58-62, D-48149 Münster, Germany. klumpp@uni-muenster.de
Kriha
Dorothee
D
Bechmann
Gunther
G
Maassen
Alexander
A
Maier
Sandra
S
Pallast
Stefanie
S
Hoell
Patrick
P
Krieglstein
Josef
J
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D020932:Nerve Growth Factor / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley
D019208:Brain-Derived Neurotrophic Factor; D016222:Fibroblast Growth Factor 2; D000255:Adenosine Triphosphate; D020932:Nerve Growth Factor