Oxidation and nitrosylation of cysteines proximal to the intermediate filament (IF)-binding site of plectin: effects on structure and vimentin binding and involvement in IF collapse

As an intermediate filament (IF)-based cytolinker protein, plectin plays a key role in the maintenance of cellular cytoarchitecture and serves at the same time as a scaffolding platform for signaling cascades. Consisting of six structural repeats (R1-6) and harboring binding sites for different IF proteins and proteins involved in signaling, the plectin C-terminal domain is of strategic functional importance. Depending on the species, it contains at least 13 cysteines, 4 of which reside in the R5 domain. To investigate the structural and biological functions of R5 cysteines, we used cysteine-to-serine mutagenesis and spectroscopic, biochemical, and functional analyses. Urea-induced unfolding experiments indicated that wild-type R5 in the oxidized, disulfide bond-mediated conformation was more stable than its cysteine-free mutant derivative. The binding affinity of R5 for vimentin was significantly higher, however, when the protein was in the reduced, more relaxed conformation. Of the four R5 cysteines, one (Cys4) was particularly reactive as reflected by its ability to form disulfide bridges with R5 Cys1 and to serve as a target for nitrosylation in vitro. Using immortalized endothelial cell cultures from mice, we show that endogenous plectin is nitrosylated in vivo, and we found that NO donor-induced IF collapse proceeds dramatically faster in plectin-deficient compared with wild-type cells. Our data suggest an antagonistic role of plectin in nitrosylation (oxidative stress)-mediated alterations of IF cytoarchitecture and a possible role of R5 Cys4 as a regulatory switch.     

Trauma, dreaming, and psychological distress among Kurdish children.

The authors examined (a) how traumatic events are associated with children's dream structure and content and (b) which dream characteristics might moderate the negative impact of traumatic events on mental health. Participants were 122 Kurdish children (9-17 years old, M = 13.02, SD = 1.66). Their dreams were collected during 1 week using a semistructured dream diary and scored according to the dream atmosphere, the role of the dreamer, bizarreness, narrative quality, fragmentation and resolution, and content such as themes of death, persecution and rejection, hostility, and anxiety. The results substantiated the hypothesis that children exposed to a high level of traumatic events would report dreams characterized by unpleasant atmosphere, fragmented flow, and low levels of bizarre narrative quality. Pleasant dreams containing complete narratives and happy endings moderated the negative impact of traumatic events on children's mental health. The authors argue that dreaming allows cognitive-emotional processing of traumatic events and may thus enhance child well-being in war conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)