Gating the activation and tuning the Ca[2+] frequency response of CaM kinase II Ca[2+] functions as a second messenger for many signaling molecules, including neurotransmitters, hormones and growth factors. One of the central mediators of Ca[2+]/CaM action is the multifunctional CaM kinase II (CaMKII), a ubiquitous Ser/Thr protein kinase that phosphorylates dozens of key cellular proteins and enzymes in the cytosol, plasma membrane, and nucleus. The kinase has been the focus of considerable attention because i) it has a unique architecture with 12 kinase subunits that determine its Ca[2+]/CaM sensing, intracellular targeting, and substrate specificity;ii) it displays a form of molecular memory in which Ca[2+]-dependent autophosphorylation at a Thr residue and/or oxidation at a nearby Met residue switches it to a Ca[2+]-independent (autonomous) state that participates in neuronal memory and other functions;iii) it can respond to the frequency of Ca[2+]-linked stimulation, such as heart rate, and modifies cell function accordingly. Understanding the mechanism and structural basis by which CaMKII decodes the frequency of Ca[2+] spikes is therefore critical to understanding both its physiological and pathological functions. Based on a recent crystal structure and functional analysis of the kinase we hypothesize that the kinase undergoes an equilibrium between a compact structure where its catalytic domains are tightly packed into a central hub composed of its association domain and a more extended structure that is more readily activated by CaM. We will test whether the length of linker sequences between the catalytic and association domains tune the kinase to different frequencies of Ca[2+] spikes and how this is affected by oxidation. We will further examine the effects of gating of the autoinhibitory domain by a pharmacological inhibitor and by a SNP that is associated with increased risk of sudden cardiac arrest. We propose to test its remarkable properties by determining whether the kinase decodes the frequency of Ca[2+] stimuli delivered to cardiomyocytes to increase its autophosphorylation and phosphorylation of its substrates. Finally, we will use our structural and regulatory insights to develop an activator of CaMKII that can be used to evaluate and discover and delineate new CaMKII functions in diverse cell types.

Public Health Relevance

Gating the activation and tuning the Ca[2+] frequency response of CaM kinase II CaM kinase II is a ubiquitous enzyme that mediates the effect of Ca[2+] signaling in essentially every tissue of the body. It has been the focus of considerable attention because it is activated by the frequency of stimuli, such as heartbeat, or specific neuronal stimuli necessary for memory. It responds to increases in both Ca[2+] and oxidation. Understanding the mechanism and structural basis by which CaMKII is tuned to different Ca[2+] spike frequencies is therefore critical to understanding both its physiological and pathological functions in heart, brain and other tissues.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM101277-01
Application #
8276424
Study Section
Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
Program Officer
Nie, Zhongzhen
Project Start
2012-09-30
Project End
2016-08-31
Budget Start
2012-09-30
Budget End
2013-08-31
Support Year
1
Fiscal Year
2012
Total Cost
$246,115
Indirect Cost
$56,115
Name
Allosteros Therapeutics, Inc.
Department
Type
DUNS #
831512020
City
Sunnyvale
State
CA
Country
United States
Zip Code
94089
Pellicena, Patricia; Schulman, Howard (2014) CaMKII inhibitors: from research tools to therapeutic agents. Front Pharmacol 5:21
Stratton, Margaret; Lee, Il-Hyung; Bhattacharyya, Moitrayee et al. (2014) Activation-triggered subunit exchange between CaMKII holoenzymes facilitates the spread of kinase activity. Elife 3:e01610
Stratton, Margaret M; Chao, Luke H; Schulman, Howard et al. (2013) Structural studies on the regulation of Ca2+/calmodulin dependent protein kinase II. Curr Opin Struct Biol 23:292-301