Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.17 (CaMKII)
 4,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Filamin is a dimeric muscle phosphoprotein that cross-links actin filaments. We have found that purified chicken gizzard filamin is phosphorylated in vitro at serine residues by the Ca2+/calmodulin-dependent protein kinase II (CaM kinase II). Up to 0.9 mol of phosphate can be incorporated into 1 mol of filamin dimer. Phosphorylation by CaM kinase II increases filamin's critical actin filament gelling concentration and diminishes the amount of actin sedimented by filamin at low G-force. The modulation of filamin function by CaM kinase II requires ATP, Ca2+, and calmodulin, and it is abolished when CaM kinase II is inactivated with heat. Protein phosphatase 2A removed the phosphate added by CaM kinase II and restored filamin's actin filament cross-linking activity to the untreated basal level. In cosedimentation experiments, phosphorylation reduces the binding of filamin to actin filaments. The Kd for binding of filamin to actin filaments increases approximately 2-fold, from 3.2 to 6.9 microM, following CaM kinase II-mediated phosphorylation. Phosphorylation by CaM kinase II, therefore, regulates the binding of filamin to actin filaments.
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PMID:Actin filament cross-linking by chicken gizzard filamin is regulated by phosphorylation in vitro. 775 5

Thrombin-induced endothelial cell barrier dysfunction is tightly linked to Ca(2+)-dependent cytoskeletal protein reorganization. In this study, we found that thrombin increased Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II) activities in a Ca(2+)- and time-dependent manner in bovine pulmonary endothelium with maximal activity at 5 min. Pretreatment with KN-93, a specific CaM kinase II inhibitor, attenuated both thrombin-induced increases in monolayer permeability to albumin and decreases in transendothelial electrical resistance (TER). We next explored potential thrombin-induced CaM kinase II cytoskeletal targets and found that thrombin causes translocation and significant phosphorylation of nonmuscle filamin (ABP-280), which was attenuated by KN-93, whereas thrombin-induced myosin light chain phosphorylation was unaffected. Furthermore, a cell-permeable N-myristoylated synthetic filamin peptide (containing the COOH-terminal CaM kinase II phosphorylation site) attenuated both thrombin-induced filamin phosphorylation and decreases in TER. Together, these studies indicate that CaM kinase II activation and filamin phosphorylation may participate in thrombin-induced cytoskeletal reorganization and endothelial barrier dysfunction.
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PMID:Regulation of endothelial cell barrier function by calcium/calmodulin-dependent protein kinase II. 1129 May 23

In this study we have examined the interaction of CD44 (a major hyaluronan (HA) receptor) with a RhoA-specific guanine nucleotide exchange factor (leukemia-associated RhoGEF (LARG)) in human head and neck squamous carcinoma cells (HNSCC-HSC-3 cell line). Immunoprecipitation and immunoblot analyses indicate that CD44 and the LARG protein are expressed in HSC-3 cells and that these two proteins are physically associated as a complex. HA-CD44 binding induces LARG-specific RhoA signaling and phospholipase C epsilon (PLC epsilon) activity. In particular, the activation of RhoA-PLC epsilon by HA stimulates inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, and the up-regulation of Ca2+/calmodulin-dependent kinase II (CaMKII), leading to phosphorylation of the cytoskeletal protein, filamin. The phosphorylation of filamin reduces its interaction with filamentous actin, promoting tumor cell migration. The CD44-LARG complex also interacts with the EGF receptor (EGFR). Most importantly, the binding of HA to the CD44-LARG-EGFR complex activates the EGFR receptor kinase, which in turn promotes Ras-mediated stimulation of a downstream kinase cascade including the Raf-1 and ERK pathways leading to HNSCC cell growth. Using a recombinant fragment of LARG (the LARG-PDZ domain) and a binding assay, we have determined that the LARG-PDZ domain serves as a direct linker between CD44 and EGFR. Transfection of the HSC-3 cells with LARG-PDZcDNA significantly reduces LARG association with CD44 and EGFR. Overexpression of the LARG-PDZ domain also functions as a dominant-negative mutant (similar to the PLC/Ca2+-calmodulin-dependent kinase II (CaMKII) and EGFR/MAPK inhibitor effects) to block HA/CD44-mediated signaling events (e.g. EGFR kinase activation, Ras/RhoA co-activation, Raf-ERK signaling, PLC epsilon-mediated inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, CaMKII activity, filamin phosphorylation, and filamin-actin binding) and to abrogate tumor cell growth/migration. Taken together, our findings suggest that CD44 interaction with LARG and EGFR plays a pivotal role in Rho/Ras co-activation, PLC epsilon-Ca2+ signaling, and Raf/ERK up-regulation required for CaMKII-mediated cytoskeleton function and in head and neck squamous cell carcinoma progression.
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PMID:Hyaluronan-CD44 interaction with leukemia-associated RhoGEF and epidermal growth factor receptor promotes Rho/Ras co-activation, phospholipase C epsilon-Ca2+ signaling, and cytoskeleton modification in head and neck squamous cell carcinoma cells. 1656 89

Phosphatidylinositol bisphosphate (PIP2) regulates epithelial sodium channel (ENaC) open probability. In turn, myristoylated alanine-rich C kinase substrate (MARCKS) protein or MARCKS-like protein 1 (MLP-1) at the plasma membrane regulates the delivery of PIP2 to ENaC. MARCKS and MLP-1 are regulated by changes in cytosolic calcium; increasing calcium promotes dissociation of MARCKS from the membrane, but the calcium-regulatory mechanisms are unclear. However, it is known that increased intracellular calcium can activate calmodulin and we show that inhibition of calmodulin with calmidazolium increases ENaC activity presumably by regulating MARCKS and MLP-1. Activated calmodulin can regulate MARCKS and MLP-1 in two ways. Calmodulin can bind to the effector domain of MARCKS or MLP-1, inactivating both proteins by causing their dissociation from the membrane. Mutations in MARCKS that prevent calmodulin association prevent dissociation of MARCKS from the membrane. Calmodulin also activates CaM kinase II (CaMKII). An inhibitor of CaMKII (KN93) increases ENaC activity, MARCKS association with ENaC, and promotes MARCKS movement to a membrane fraction. CaMKII phosphorylates filamin. Filamin is an essential component of the cytoskeleton and promotes association of ENaC, MARCKS, and MLP-1. Disruption of the cytoskeleton with cytochalasin E reduces ENaC activity. CaMKII phosphorylation of filamin disrupts the cytoskeleton and the association of MARCKS, MLP-1, and ENaC, thereby reducing ENaC open probability. Taken together, these findings suggest calmodulin and CaMKII modulate ENaC activity by destabilizing the association between the actin cytoskeleton, ENaC, and MARCKS, or MLP-1 at the apical membrane.
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PMID:Calmodulin and CaMKII modulate ENaC activity by regulating the association of MARCKS and the cytoskeleton with the apical membrane. 2613 60