In preparations of synaptic terminals (synaptosomes) isolated from rat brain, the activity of phospholipase A2 (PLA2), a phospholipid hydrolase that serves a central function in signal transduction, was inhibited in a Ca(2+)-dependent manner by incubation with 60 mM K+ or with the Ca(2+)-selective ionophore ionomycin. Reversal by alkaline phosphatase treatment suggested that this inhibitory eff...

As its name implies, calcium/calmodulin-dependent protein kinase II (CaMKII) is calcium dependent. In its basal state, the activity of CaMKII is extremely low. Regulation of intracellular calcium levels allows the neuron to link activity with phosphorylation by CaMKII. This review will briefly summarize our current understanding of the intramolecular mechanisms of activity regulation and their ...

Neuronal dendritic and axonal arbors grow to a characteristic size and then stabilize their structures. Activity-dependent stop-growing signals may limit neuronal process elaboration. We tested whether endogenous calcium/calmodulin-dependent protein kinase II (CaMKII) activity in postsynaptic optic tectal cells is required to restrict the elaboration of neuronal processes in the Xenopus tadpole...

In GN4 rat liver epithelial cells, angiotensin II (Ang II) and other agonists which activate phospholipase C stimulate tyrosine kinase activity in a calcium-dependent, protein kinase C (PKC)-independent manner. Since Ang II also produces a proliferative response in these cells, we investigated downstream signaling elements traditionally linked to growth control by tyrosine kinases. First, Ang I...

While plasticity is typically associated with persistent modifications of synaptic strengths, recent studies indicated that modulations of dendritic excitability may form the other part of the engram and dynamically affect computational processing and output of neuronal circuits. However it remains unknown whether modulation of dendritic excitability is controlled by synaptic changes or whether...

Jessica A. Loweth,1,2 Dongdong Li,2 James J. Cortright,2 Georgia Wilke,2 Okunola Jeyifous,3 Rachael L. Neve,4 K. Ulrich Bayer,5 and Paul Vezina1,2 1Committee on Neurobiology, and Departments of 2Psychiatry and Behavioral Neuroscience and 3Neurobiology, The University of Chicago, Chicago, Illinois 60637, 4Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and 5Department of P...

While CaMKII has long been known to be essential for synaptic plasticity and learning, recent work points to new dimensions of CaMKII function in the nervous system, revealing that CaMKII also plays an important role in synaptic organization. Ca(2+)-triggered autophosphorylation of CaMKII not only provides molecular memory by prolonging CaMKII activity during long-term plasticity (LTP) and lear...

CaMKII is an abundant synaptic protein strongly implicated in plasticity. Overexpression of autonomous (T286D) CaMKII in CA1 hippocampal cells enhances synaptic strength if T305/T306 sites are not phosphorylated, but decreases synaptic strength if they are phosphorylated. It has generally been thought that spine size and synaptic strength covary; however, the ability of CaMKII and its various p...