Long-lasting decrease in neuronal Ca2+/calmodulin-dependent protein kinase II activity in a hippocampal neuronal...

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Epileptiform activity, characterized by spontaneous recurrent seizures (SRSs), is a hallmark of epilepsy.
• Ca2+/calmodulin-dependent protein kinase II (CaM Kinase II) plays critical roles in neuronal function and plasticity.

Purpose of the Study:

• To investigate the activity of CaM Kinase II in an in vitro model of epileptiform activity.
• To determine if CaM Kinase II activity is altered during the induction and maintenance of SRSs.

Main Methods:

• Induction of SRSs in hippocampal neuronal cultures using low Mg2+ media.
• Analysis of endogenous Ca2+/calmodulin-dependent phosphorylation of CaM Kinase II subunits.
• Assay of CaM Kinase II substrate phosphorylation using synthetic peptides (Autocamtide-2, Syntide II).

Main Results:

• A significant, long-lasting decrease in CaM Kinase II activity was observed following SRS induction.
• Reduced phosphorylation of CaM Kinase II alpha and beta subunits correlated with SRS activity.
• Decreased substrate phosphorylation persisted throughout the neurons' lifespan in culture and was not due to enhanced phosphatase activity.

Conclusions:

• CaM Kinase II activity is significantly reduced in hippocampal cultures exhibiting epileptogenesis.
• This diminished CaM Kinase II activity may be a contributing factor to the generation and maintenance of SRSs.
• The findings suggest a potential role for CaM Kinase II dysregulation in epilepsy pathogenesis.