title: A role for long chain myosin light chain kinase (MLCK-210) in microvascular hyperpermeability during severe burns.
abstract: Microvascular leakage has been implicated in the pathogenesis of multiple organ dysfunction during trauma. Previous studies suggest the involvement of myosin light chain (MLC) phosphorylation-triggered endothelial contraction in the development of microvascular hyperpermeability. Myosin light chain kinase (MLCK) plays a key role in the control of MLC-phosphorylation status; thus, it is thought to modulate barrier function through its regulation of intracellular contractile machinery. The aim of this study was to further investigate the endothelial mechanism of MLC-dependent barrier injury in burns, focusing on the long isoform of MLCK (MLCK-210) that has recently been identified as the predominant isoform expressed in vascular endothelial cells. An MLCK-210 knockout mouse model was subjected to third-degree scald burn covering 25% total body surface area. The mesenteric microcirculation was observed using intravital microscopy, and the microvascular permeability was assessed by measuring the transvenular flux of fluorescein isothiocyanate-albumin. In a separate experiment, in vivo mesenteric hydraulic conductivity (Lp) was measured using the modified Landis technique. The injury caused a profound microvascular leakage, as indicated by a 2-fold increase in albumin flux and 4-fold increase in Lp at the early stages, which was associated with a high mortality within the 24-h period. Compared with wild-type control, the MLCK-210-deficient mice displayed a significantly improved survival with a greatly attenuated microvascular hyperpermeability response to albumin and fluid. These results provide direct evidence for a role of MLCK-210 in mediating burn-induced microvascular barrier injury and validate MLCK-210 as a potential therapeutic target in the treatment of burn edema.
authors.affiliation: Division of Research, Department of Surgery, University of California at Davis School of Medicine, Sacramento, California 95817, USA.
authors.forename: Rashell
authors.initials: R
authors.lastname: Reynoso
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Perrin
authors.forename: Jerome W
authors.initials: JW
authors.lastname: Breslin
authors.forename: Dayle A
authors.initials: DA
authors.lastname: Daines
authors.forename: Katherine D
authors.initials: KD
authors.lastname: Watson
authors.forename: D Martin
authors.initials: DM
authors.lastname: Watterson
authors.forename: Mack H
authors.initials: MH
authors.lastname: Wu
authors.forename: Sarah
authors.initials: S
authors.lastname: Yuan
mesh_terms: D000818:Animals; D002056:Burns / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000628:therapy; D002199:Capillary Permeability; D004487:Edema / Q000201:enzymology* / Q000235:genetics / Q000473:pathology / Q000628:therapy; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000473:pathology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism*; D013152:Splanchnic Circulation
chemical_list: D007527:Isoenzymes; D009219:Myosin-Light-Chain Kinase