The role of CaMKII in BDNF-mediated neuroprotection of retinal ganglion cells (RGC-5).
The purpose of the study is to determine if expression or secretion of brain-derived neurotrophic factor (BDNF) in retinal ganglion cells (RGC-5) is mediated by NFkappaB or Ca2+/calmodulin-dependent protein kinase II (CaMKII). RGC-5 cells were exposed to 1 mM glutamate for various periods of time, in the presence or absence of prospective regulatory molecules. BDNF mRNA and protein expression were assessed with the aid of real-time PCR and immunoblots, respectively, and BDNF secretion was determined by ELISA. The NFkappaB inhibitor (TLCK and PTD-p65), or a specific CaMKII inhibitor (m-AIP), was used to study association of NFkappaB or CaMKII with BDNF expression/secretion in RGC-5 cells. Glutamate stimulated a transient increase in BDNF mRNA and protein in RGC-5 cells, and also stimulated an early release of BDNF into the culture media. Neutralizing the BDNF or blocking the TrkB receptor enhanced the glutamate-induced cytotoxicity. NFkappaB nuclear translocation was revealed in response to glutamate treatment. Application of TLCK or PTD-p65 inhibited the glutamate-induced BDNF expression and secretion. Inhibition of CaMKII by m-AIP did not affect expression but significantly enhanced the release of BDNF from glutamate challenged cells. Our data suggest that glutamate treatment may stimulate expression of BDNF in RGC-5 cells through NFkappaB activation. A novel mechanism for neuroprotection is proposed for the CaMKII inhibitor, AIP, which appears to protect RGC-5 cells from cytotoxicity by enhancing the release of BDNF from glutamate challenged cells.
Fan
Wei
W
Department of Anatomical Sciences and Neurobiology, 500 S. Preston St., Louisville, KY 40292, USA.
Agarwal
Neeraj
N
Cooper
Nigel G F
NG
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000502:physiology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D002470:Cell Survival; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000502:physiology*
D019208:Brain-Derived Neurotrophic Factor; D018696:Neuroprotective Agents; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases