title: Activation of the neuroprotective ERK signaling pathway by fructose-1,6-bisphosphate during hypoxia involves intracellular Ca2+ and phospholipase C.
abstract: The mechanism of the neuroprotective action of the glycolytic pathway intermediate fructose-1,6-bisphosphate (FBP) may involve activation of a phospholipase-C (PLC) dependent MAP kinase signaling pathway. In this study, we determined whether FBP's capacity to decrease delayed cell death in hippocampal slice cultures is dependent on PLC signaling or activation of the intracellular Ca(2+)-MEK/ERK neuroprotective signaling cascade. FBP (3.5 mM) reduced delayed death from oxygen/glucose deprivation in CA1, CA3 and dentate neurons in slice cultures. The phospholipase-C inhibitor U73122 and the MEK1/2 inhibitor U0126 prevented this protection. In hippocampal and cortical neurons, FBP increased phospho-ERK1/2 (p42/44) immunostaining during hypoxic, but not normoxic conditions. Increased phospho-ERK immunostaining was dependent on PLC and also on MEK 1/2, an upstream regulator of ERK. Further, we found that FBP enhancement of phospho-ERK immunostaining depended on [Ca(2+)](i): PLC inhibition and the IP(3) receptor blocker xestospongin C prevented FBP from increasing [Ca(2+)](i) and increasing phospho-ERK levels. However, while FBP-induced increases in [Ca(2+)](i) were blocked by xestospongin and a PLC inhibitor, [Ca(2+)](i) increases induced by the neuroprotective growth factor BDNF were not prevented. We conclude that during hypoxia FBP initiates a series of neuroprotective signals which include PLC activation, small increases in [Ca(2+)](i), and increased activity of the MEK/ERK signaling pathway.
authors.affiliation: Department of Anesthesia and Perioperative Care, University of California at San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143-0542, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Fahlman
authors.forename: P E
authors.initials: PE
authors.lastname: Bickler
authors.forename: Breandan
authors.initials: B
authors.lastname: Sullivan
authors.forename: G A
authors.initials: GA
authors.lastname: Gregory
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D005635:Fructosediphosphates / Q000378:metabolism* / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020925:Hypoxia-Ischemia, Brain / Q000188:drug therapy / Q000201:enzymology* / Q000503:physiopathology; D007150:Immunohistochemistry; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D018696:Neuroprotective Agents / Q000378:metabolism* / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D005635:Fructosediphosphates; D018696:Neuroprotective Agents; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D010738:Type C Phospholipases; C029063:fructose-1,6-diphosphate; D002118:Calcium