Selective Hyperactivation of JNK2 in an Animal Model of Chronic Epilepsy
Abstract number :
1.008
Submission category :
1. Basic Mechanisms / 1A. Epileptogenesis of acquired epilepsies
Year :
2019
Submission ID :
2421004
Source :
www.aesnet.org
Presentation date :
12/7/2019 6:00:00 PM
Published date :
Nov 25, 2019, 12:14 PM
Authors :
Francis Concepcion, University of Washington; Marium Khan, University of Washington; Nicholas P. Poolos, University of Washington
Rationale: c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase (MAPK) family. Hyperactivation of JNKs by phosphorylation (pJNK) is associated with debilitating neurodegenerative diseases, including Alzheimer’s and Parkinson’s. In a rat model of epilepsy produced by chemoconvulsant-induced status epilepticus, we previously reported elevated pJNK levels during chronic epilepsy, and showed that pharmacological JNK inhibition reduced seizure frequency (Tai TY et al., Neuroscience, 2017). In this current study, we sought to identify which of the JNK isoforms (JNK1, JNK2, or JNK3) contributes to the overall increased pJNK levels seen in chronic epilepsy in our animal model. Methods: After pJNK enrichment by immunoprecipitating CA1 hippocampal homogenates with an anti-pJNK antibody (Ab), the ratios of individual JNK isoforms between chronically epileptic rats and their naïve, age-matched controls were determined by Western blotting for the two JNK electrophoretic bands at 54 kDa and 46 kDa. Subsequent Western blotting with an anti-pJNK Ab was used to normalize protein loading between experimental and control samples. Results: These experiments revealed a significant increase in pJNK2 levels in chronic epilepsy when compared to naïve controls (54 kDa: 142 ± 12.4%, n=8, p=0.012; 45 kDa: 114 ± 5.9%, n=8, p=0.048). No changes in phosphorylation/activation levels were observed for either JNK1 (54 kDa band: 99 ± 7.5%, n=8, p=0.883; 45 kDa band: 104 ± 4.8%, n=8, p=0.415) or brain specific JNK3 (54 kDa band: 109 ± 17.1%, n=8, p=0.609; 45 kDa band: 106 ± 13.9%, n=8, p=0.682). However, analysis of total levels (phosphorylated and nonphosphorylated) of JNK isoforms showed no significant changes in the total expression of any JNK isoform, including JNK2. This suggests that elevated levels of pJNK2 in epilepsy arise from activation by upstream signaling pathways, not from increased protein expression of JNK2. Conclusions: In summary, our results show that JNK2 is selectively hyperactivated in chronic epilepsy. Given our previous observation that overall JNK inhibition reduces seizure frequency, this investigation suggests that selective JNK2 inhibition may be a potential antiepileptic strategy. Funding: NIH NS050229
Basic Mechanisms