Intracellular interaction of myosin light chain kinase with macrophage migration inhibition factor (MIF) in endothelium.

The endothelial cell Ca2+/calmodulin (CaM)-dependent myosin light chain kinase isoform (EC MLCK) is a multifunctional contractile effector involved in vascular barrier regulation, leukocyte diapedesis, apoptosis, and angiogenesis. The EC MLCK isoform and its splice variants contain a unique N-terminal sequence not present in the smooth muscle MLCK isoform (SM MLCK), which allows novel upregulation of MLCK activation by signaling cascades including p60src. The yeast two-hybrid assay system using the entire EC MLCK1 N-terminus (922 aa) as bait, identified additional stable MLCK binding partners including the 12 KDa macrophage migration inhibitory factor (MIF).

Endothelial cell myosin light chain kinase (MLCK) regulates TNFalpha-induced NFkappaB activity.

Tumor necrosis factor (TNFalpha-) generates both apoptotic and survival signals with endothelial cell (EC) survival dependent on nuclear factor kappa-B (NFkappaB) activation, a regulator of anti-apoptotic genes. We previously demonstrated that increased EC contractility, rearrangement of the actin cytoskeleton, and increased myosin light chain (MLC) phosphorylation occurs as a consequence of TNFalpha-induced activation of EC MLC kinase (EC MLCK) and is required for bovine lung EC apoptosis. As the association between MLCK and pro-survival signals such as NFkappaB activation is unknown, we studied the role of MLCK in the regulation of NFkappaB-dependent transactivation in bovine pulmonary artery EC.

Differential regulation of human lung epithelial and endothelial barrier function by thrombin.

Lung epithelial and endothelial barrier dysfunction is critical to the physiologic derangement observed in acute lung injury, but remains poorly understood. We utilized human alveolar epithelial (A549) and endothelial cells (EC) to study cytoskeletal remodeling, myosin light chain (MLC) phosphorylation and barrier regulation evoked by the edemagenic agent, thrombin. Thrombin-challenged human EC monolayers demonstrated increased MLC phosphorylation, actin stress fiber formation and loss of barrier integrity reflected by decreased transmonolayer electrical resistance (TER).

Myosin II in retinal pigmented epithelial cells: evidence for an association with membranous vesicles.

The goal of this study was to further characterize and identify possible functions for a cytoplasmic myosin II protein which we have isolated from retinal pigmented epithelial (RPE) cells. The nucleotide and deduced amino acid sequences are highly identical to non-muscle myosin heavy chain II-A (NMMHC II-A). However, this RPE myosin displays characteristics that are atypical of other myosins, including an affinity for carbohydrate and a C-terminal sequence extension, suggesting it may have a specialized function.

Loss of adhesion-regulated proteinase production is correlated with invasive activity in oral squamous cell carcinoma.

Background: Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity. However, the cellular and biochemical factors that underlie locoregional and distant spread of the disease are poorly understood. Invasion of OSCC requires multiple cellular events including dissolution of cell-cell junctions, basement membrane attachment, extracellular matrix proteolysis, and migration.

Receptor-bound uPA is reversibly protected from inhibition by low molecular weight inhibitors.

Urokinase-type plasminogen activator (uPA) plays a ubiquitous role in cell migration and invasiveness. Amiloride, a competitive inhibitor of uPA, can inhibit endothelial cell (EC) outgrowth during angiogenesis. To address the question of whether amiloride blocked angiogenesis by inhibiting uPA, we undertook a study of uPA expression in sprouting EC in vitro and the effects of amiloride on both enzymatic and morphogenetic activity.