Autocamtide-2-related inhibitory peptide, myristoylated

Transient elevations in Ca2+ have previously been shown to promote focal adhesion disassembly and cell motility through an unknown mechanism. In this study, evidence is provided to show that CaMK-II, a Ca2+/calmodulin dependent protein kinase, influences fibroblast adhesion and motility. TIRF microscopy reveals a dynamic population of CaMK-II at the cell surface in migrating cells. Inhibition of CaMK-II with two mechanistically distinct, membrane permeant inhibitors (KN-93 and myr-AIP) freezes lamellipodial dynamics, accelerates spreading on fibronectin, enlarges paxillin-containing focal adhesions and blocks cell motility. In contrast, constitutively active CaMK-II is not found at the cell surface, reduces cell attachment, eliminates paxillin from focal adhesions and decreases the phospho-tyrosine levels of both FAK and paxillin; all of these events can be reversed with myr-AIP. Thus, both CaMK-II inhibition and constitutive activation block cell motility through over-stabilization or destabilization of focal adhesions, respectively. Coupled with the existence of transient Ca2+ elevations and a dynamic CaMK-II population, these findings provide the first direct evidence that CaMK-II enables cell motility by transiently and locally stimulating tyrosine dephosphorylation of focal adhesion proteins to promote focal adhesion turnover.

Chronic stress and neuronal vulnerability have recently been recognized as factors contributing to cognitive disorders. One way to modify neuronal vulnerability is through mediation of phosphodiesterase 2 (PDE2), an enzyme that exerts its action on cognitive processes via the control of intracellular second messengers, cGMP and, to a lesser extent, cAMP. This study explored the effects of a PDE2 inhibitor, Bay 60-7550, on stress-induced learning and memory dysfunction in terms of its ramification on behavioral, morphologic, and molecular changes. Bay 60-7550 reversed stress-induced cognitive impairment in the Morris water maze, novel object recognition, and location tasks (object recognition test and/or object location test), effects prevented by treatment with 7-NI, a selective inhibitor of neuronal nitric oxide synthase; MK801, a glutamate receptor (NMDAR) inhibitor; myr-AIP, a CaMKII inhibitor; and KT5823, a protein kinase G inhibitor. Bay 60-7550 also ameliorated stress-induced structural remodeling in the CA1 of the hippocampus, leading to increases in dendritic branching, length, and spine density. However, the neuroplasticity initiated by Bay 60-7550 was not seen in the presence of 7-NI, MK801, myr-AIP, or KT5823.

RATIONALE: ;The cellular mechanisms of obesity/hyperlipidemia-induced cardiac remodeling are many and not completely elucidated. Ca;2+;/calmodulin-dependent protein kinase II (CaMKII), a multifunctional serine/threonine kinase, has been reported to be involved in a variety of cardiovascular diseases. However, its role in obesity/hyperlipidemia-induced cardiac remodeling is still unknown.;OBJECTIVE: ;The objective of this study was to demonstrate the role of CaMKII in the pathogenesis of obesity/hyperlipidemia-induced cardiac remodeling both in vitro and in vivo.;METHODS AND RESULTS: ;In cardiac-derived H9C2 cells, palmitate treatment induced cell apoptosis coupled with activation of the mitochondrial apoptotic pathway, and cell hypertrophic and fibrotic responses. All of these alterations were inhibited by pharmacological inhibition of CaMKII with either of two specific inhibitors, Myr-AIP and KN93. In addition, an increased inflammatory response coupled with activation of the MAPKs and NF-κB signaling pathway, exaggerated oxidative stress, ER stress and autophagy were also observed in palmitate-treated H9C2 cells, while pretreatment with CaMKII inhibitors decreased these pathological signals.