Disease relevance of Mylk

• The data also indicate that inhibition of epithelial MLCK may be an effective non-immunosuppressive therapy for treatment of immune-mediated intestinal disease [1].
• The effects of giardiasis on epithelial permeability in vivo remain unknown, and the role of T cells and myosin light chain kinase (MLCK) in altered intestinal barrier function is unclear [2].
• When added to contracting solution at the peak of a contracture, anti-MLCK Fab elicited a relaxation that was complete in about 120 minutes despite the presence of Ca2+ [3].
• Rapid response of cardiac obscurin gene cluster to aortic stenosis: differential activation of Rho-GEF and MLCK and involvement in hypertrophic growth [4].

Psychiatry related information on Mylk

• Phosphorylation of the regulatory light chain by myosin light chain kinase (MLCK) regulates the motor activity of smooth muscle and nonmuscle myosin II [5].

High impact information on Mylk

• In spreading and migrating cells we find local periodic contractions of lamellipodia that depend on matrix rigidity, fibronectin binding and myosin light chain kinase (MLCK) [6].
• A specific precipitating antibody against chicken gizzard myosin light chain kinase (MLCK) has been produced in rabbits [7].
• Indirect immunofluorescent microscopy of non-muscle tissue culture cells revealed MLCK to be localized in the spindle apparatus and midbody of mitotic cells and on the stress fibers and in the nucleolus of interphase cells [7].
• In myofibrils isolated from skeletal and cardiac muscle, anti-MLCK decorated the actin-containing I bands of the sarcomere [7].
• These results are consistent with the suggestion that MLCK and calmodulin are intermediates in the regulation of cell motility by calcium [7].

Biological context of Mylk

• We sequenced a 180-kb bacterial artificial chromosome clone containing the 24 first exons of Mylk; the complete mouse gene is expected to span >200 kb [8].
• Transcription of the telokin gene is restricted to smooth muscle cells throughout development, making this gene an excellent model for unraveling the mechanisms that regulate gene expression in smooth muscle tissues [9].
• Gel mobility shift assays demonstrated that purified TEF protein can specifically bind to an AT-rich region within the core of the telokin promoter [9].
• To identify proteins that bind to the telokin promoter, the AT-rich/CArG core of the promoter was used as a probe to perform a Southwestern screen of a mouse bladder cDNA library [9].
• Genetic knockout of long myosin light chain kinase (MLCK) or treatment of wild-type mice with a highly specific peptide MLCK inhibitor prevented epithelial MLC phosphorylation, tight junction disruption, protein leak, and diarrhea following T cell activation [1].

Anatomical context of Mylk

• No difference in the Ca2+ force relationship occurred in telokin WT and knockout (KO) aortas, presumably reflecting the normally approximately 5-fold lower telokin content in aorta vs. ileum smooth muscle [10].
• HFH-1 strongly represses telokin promoter activity when overexpressed in A10 vascular smooth muscle cells [11].
• We propose a model in which the smooth muscle specificity of the telokin promoter is regulated by interactions between positive- and negative-acting members of the hepatocyte nuclear factor-3/forkhead family of transcription factors [11].
• The localization of HFH-1 mRNA to the epithelial cell layer of mouse bladder and stomach implicates HFH-1 in repressing telokin expression in epithelial cells [11].
• The purpose of this study was to characterize myosin light chain kinase (MLCK) expression in cardiac and skeletal muscle [12].

Associations of Mylk with chemical compounds

• Mechanistic studies using nontransformed human duodenal epithelial monolayers (SCBN) determined the effects of Giardia on myosin light chain (MLC) phosphorylation, transepithelial fluorescein isothiocyanate-dextran fluxes, cytoskeletal F-actin, tight junctional zonula occludens-1 (ZO-1), and MLCK [2].
• Ca2+ desensitization of contractile force by 8-Br-cGMP was attenuated by 50% in telokin KO intestinal smooth muscle [10].
• The MLCK210 knockout mice are less susceptible to ALI induced by i.p. injection of the endotoxin lipopolysaccharide and show enhanced survival during subsequent mechanical ventilation [13].
• Ex vivo responses of aortic rings to vasoconstrictor and vasodilator agonists were not modified in MLCK210 null mice [14].
• Carbachol treatment produces the same amount of force development and RLC phosphorylation, with much smaller increases in [Ca(2+)](i) and MLCK activation [15].

Physical interactions of Mylk

• HFH-1 does not disrupt serum response factor binding to an adjacent CArG box within the telokin promoter, implying that HFH-1 must compete with other unidentified trans-activators to mediate repression [11].
• Results from gel mobility shift assays demonstrated that Hoxa10-1, Hoxa10-2, and Hoxb8 bind directly to multiple sites in the telokin promoter [16].
• Gel mobility shift assays demonstrate that GATA-6 binds to a consensus site adjacent to the CArG box in the telokin promoter [17].

Enzymatic interactions of Mylk

• 208-kDa MLCK phosphorylates 20-kDa myosin light chains in a Ca2+/calmodulin-dependent manner, consistent with it being a member of the MLCK family [18].

Regulatory relationships of Mylk

• HFH-1 inhibits telokin promoter activity, by binding to a forkhead consensus site located within an AT-rich region of the telokin promoter [11].
• On the other hand, Hoxb8 inhibited the activity of the telokin, SM22alpha, and smooth muscle alpha-actin promoters [16].
• This analysis revealed that GATA-6 strongly repressed telokin promoter activity [17].
• GATA-6 did not interfere with the serum-response factor-stimulated promoter activity but blocked myocardin-induced activation of the telokin promoter [17].

Other interactions of Mylk

• Furthermore, when overexpressed in 10T1/2 cells, TEF significantly increased the activity of a telokin promoter-reporter gene; this activation was further augmented by elevated intracellular calcium levels [9].
• In addition, we have demonstrated that fetal human astroglia have the enzyme MLCK and calmodulin [19].
• The increase in telokin expression correlated with an increase in the expression of several other smooth muscle-restricted proteins, including smooth muscle myosin and alpha-actin [20].
• Deletion of MLCK210 did not affect systolic blood pressure and heart rate or echocardiographic measurements [14].
• The presence and spatial distribution of MLCK at various stages of preimplantation development of the mouse suggest that it could play a crucial role in the regulation of the contractile events involved in the initial differentiation that occurs during formation of the mouse blastocyst [21].

Analytical, diagnostic and therapeutic context of Mylk

• Using a complementary chemical biology approach, we developed a new class of small-molecule MLCK inhibitor based on the pharmacologically privileged aminopyridazine and found that a single i.p. injection of the inhibitor protected WT mice against ALI and death from mechanical ventilation complications [13].
• Gel mobility shift and chromatin immunoprecipitation assays revealed that Elk-1 binds to a nonconsensus binding site in the telokin promoter and Elk-1 binding is dependent on serum response factor (SRF) binding to a nearby CArG box [22].
• Northern blot, Western blot, and histochemical studies show that the 220-kDa MLCK is widely expressed during development as well as in several adult smooth muscle and nonmuscle tissues [23].
• We also show by immunoblotting and immunohistochemistry of various mouse tissues that the antibody used in this study has cross-reactivity to MLCK of various muscle and non-muscle tissues of the mouse [21].
• MLCK levels and activity are increased in various animal models of disease and in human clinical disease samples [24].

References