Myosin Light Chain Kinase / Actin Interaction in Phorbol Dibutyrate–Stimulated Smooth Muscle Cells

Abstract

Abstract. Previous work has suggested that in addition to its kinase activity, myosin light chain kinase (MLCK) exhibits non-kinase properties within its N-terminus that could influence cytoskeletal organization of smooth muscle cells (A. Nakamura et al. Biochem Biophys Res Commun. 2008;369:135-143). Myosin ATPase activity measurements indicate that the 26 -41 peptide of MLCK significantly decreases ATPase activity as the concentration of this peptide increases. Sliding velocity of actin-filaments on myosin and stress responses in skinned smooth muscle tissue are also inhibited. Peptide-mediated uptake and the microinjection technique in cells indicate that the peptide was necessary for actin-filament stabilization. Fluorescence resonance energy transfer analysis indicated that in the presence of MLCK, α-actin but not β-actin remodeled during phorbol 12,13-dibutyrate (PDBu)-induced contractions. PDBu also induced podosomes in the cell. When MLCK expression was down-regulated by introduction of RNAi for MLCK by lentivirus vector into the cells, we failed to observe the podosome induction upon PDBu stimulation. Rescue experiments indicate that the non-kinase activity of MLCK plays an important role in maintaining actin stress fibers and in the PDBu-induced reorganization of actin-filaments in smooth muscle cells.

Pharmacological activation of ERβ by arctigenin maintains the integrity of intestinal epithelial barrier in inflammatory bowel diseases

“…Long and short MLCK, could regulate the cytoskeletal organization through kinase pathway or non-kinase pathway within its N-terminus. 51 The up-regulation of long-MLCK expression was associated with the disruption of intestinal barrier and the progression of IBD. 52 MLCK-mediated phosphorylation of MLC at Ser-19 and Thr-18 sites induced cytoskeletal contraction, which was accompanied by the dysfunction of TJ and the disruption of endothelial barrier.…”

“…In addition to various junctions, the cytoskeletal organization of epithelial cells also plays an important role in the permeability of intestinal epithelial barrier and the pathogenesis of IBD, and MLCK/MLC are deeply involved. Long and short MLCK, could regulate the cytoskeletal organization through kinase pathway or non‐kinase pathway within its N‐terminus . The up‐regulation of long‐MLCK expression was associated with the disruption of intestinal barrier and the progression of IBD .…”

Na+/Ca2+ Exchanger 1/2 Double-Heterozygote Knockout Mice Display Increased Nitric Oxide Component and Altered Colonic Motility

“…A decline in the intracellular Ca 2+ concentration and/or desensitization of the contractile proteins to intracellular Ca 2+ are crucial for relaxation in gastrointestinal smooth muscles (6,32). NO is the primary neurotransmitter involved in mediating the relaxation response in the smooth muscle of several gastrointestinal tissues.…”

Calix[4]arene C-99 inhibits myosin ATPase activity and changes the organization of contractile filaments of myometrium

“…The abilityofcalix [4]arenestopenetrateinsidethecell wasshownbyotherauthorsusingfluorescentderivativesofsomecalix [4]arenes [11,12]. Similarresultsconcerningtheeffectofsome compoundsontheintegrityofactomyosincomplex havebeendescribedinpublisheddata.Inparticular, theabilityoftapsigargin [13]andphorbolester [14] to affect actin and myosin association was shown by the method of confocal microscopy on the culture of А7r5SMcells;thatisaccompaniedbytransformationofactinfilamentsintodiscreteperipheralcorpusclesandbydiffuselocalizationofmyosin.Such effect is a result of penetration of these compounds to A7r5 cell cytoplasm.…”