The small GTPase Rho is implicated in cytoskeletal rearrangements including stress fiber and focal adhesion formation and in the transcriptional activation of c-fos serum response element. In vitro, Rho-kinase, which is activated by Rho, phosphorylates not only myosin light chain (MLC) (thereby activating myosin ATPase) but also myosin phosphatase, thus inactivating myosin phosphatase. Rho-kinase is involved in the formation of stress fibers and focal adhesions in fibroblasts. Here we show that the expression of constitutively active Rho-kinase increased the level of MLC phosphorylation. The activity of Rho-kinase was necessary for maintaining the vinculin-containing focal adhesions, whereas organized actin stress fibers were not necessary for this. The microinjection of constitutively active Rho-kinase into fibroblasts induced the formation of focal adhesions to some extent under the conditions where organized actin stress fibers were disrupted. The expression of constitutively active Rhokinase also stimulated the transcriptional activity of c-fos serum response element. These results suggest that Rho-kinase has distinct roles in divergent pathways downstream of Rho, which include MLC phosphorylation leading to stress fiber formation, focal adhesion formation, and gene expression.
The epitaxial growth of pentacene on hydrogen-terminated Si͑111͒ is reported. Reflection high energy electron diffraction ͑RHEED͒ revealed that the crystal packing resembles that in the bulk crystal even at a monolayer thickness, which was maintained in multilayers. A ripening effect was clearly observed by atomic force microscopy ͑AFM͒. These results are important to obtain oriented crystalline films of pentacene combined with silicon microdevices with reduced defect densities.
Changes in the state of water and ATPase activity during dehydration procedures of white croaker myofibrils were investigated in the presence of various amino acids by monitoring the desorption isotherm profile and myofibrillar Ca-ATPase activity.Amino acids were classified into four groups by their effect on myofibrillar Ca-ATPase inactivation; (1) amino acids exerting marked suppressive effect on inactivation such as Na-Glu and Na-Asp, (2) those exerting moderate suppressive effect such as Gly and Ala, (3) those exerting little or no effect on inactivation such as Val, Leu, and Ile, and (4) those accelerating the inactivation including hydrophobic amino acids.The addition of acidic amino acids exhibiting a remarkable suppressive effect on ATPase inactivation increased the content of monolayer and multilayer water adsorption of myofibrils.
Kheper is a novel member of the ZFH (zinc-finger and homeodomain protein)/deltaEF1 family in zebrafish. kheper transcripts are first detected in the epiblast of the dorsal blastoderm margin at the early gastrula stage and kheper is expressed in nearly all the neuroectoderm at later stages. kheper expression was expanded in noggin RNA-injected embryos and also in swirl mutant embryos and was reduced in bmp4 RNA-injected embryos and chordino mutant embryos, suggesting that kheper acts downstream of the neural inducers Noggin and Chordino. Overexpression of Kheper elicited ectopic expansion of the neuroectoderm-specific genes fkd3, hoxa-1, and eng3, and the ectopic expression of hoxa-1 was not inhibited by BMP4 overexpression. Kheper interacted with the transcriptional corepressors CtBP1 and CtBP2. Overexpression of a Kheper mutant lacking the homeodomain or of a VP16-Kheper fusion protein disturbed the development of the neuroectoderm and head structures. These data underscore the role of Kheper in the development of the neuroectoderm and indicate that Kheper acts as a transcriptional repressor.
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