A spun carbon nanotube fiber functions as a torsional actuator in almost all available environmental media such as air, water, organic solvents, and electrolyte solutions. The Ampere's Law among helically aligned carbon nanotubes explains the simultaneous occurrence of lengthwise contraction and rotary torsion upon applying a low current. The produced stress is over 100 times that of the strongest natural skeletal muscle with high reversibility and good stability. The use of torsional fibers for electric motors is demonstrated.

Activation of b-catenin, the central effector of the canonical wingless-type (Wnt) pathway, has been implicated in hepatocellular carcinoma (HCC). However, the transcription regulation mechanism of the b-catenin gene in HCC remains unknown. Here we report that human zinc finger protein 191 (ZNF191) is a potential regulator of b-catenin transcription. ZNF191, a Krüppel-like protein, specifically interacts with the TCAT motif, which constitutes the HUMTH01 microsatellite in the tyrosine hydroxylase (TH) gene ex vivo. We demonstrate that ZNF191 is significantly overexpressed in human HCC specimens and is associated with growth of human HCC cells. Global profiling of gene expression in ZNF191 knockdown human hepatic L02 cells revealed that the important Wnt signal pathway genes b-catenin and cyclin D1 messenger RNAs (mRNAs) are significantly downregulated. In agreement with transcription level, b-catenin and cyclin D1 proteins are also down-regulated in transient and stable ZNF191 knockdown L02 and hepatoma Hep3B cell lines. Moreover, significant correlation between ZNF191 and b-catenin mRNA expression was detected in human HCCs. Promoter luciferase assay indicated that ZNF191 can increase transcription activity of the full-length b-catenin (CTNNB1) promoter, and nucleotide (nt)-1407/-907 of the CTNNB1 promoter exhibited the maximum transcriptional activity. Electrophoretic mobility shift assay showed that purified ZNF191 protein can directly bind to the CTNNB1 promoter, and the binding region is located at nt-1254/-1224. Finally, we demonstrate that the key binding sequence of ZNF191 in vivo is ATTAATT. Conclusion: ZNF191 can directly bind to the CTNNB1 promoter and activate the expression of b-catenin and its downstream target genes such as cyclin D1 in hepatoma cell lines. This study uncovers a new molecular mechanism of transcription regulation of the b-catenin gene in HCC.

The mechanisms underlying human parturition are still not understood, yet we need this knowledge to combat preterm birth. Fetal membranes express abundant 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), which converts inert cortisone to active cortisol. We examined whether cortisol regeneration in the amnion might play a role in human parturition through regulation of lysyl oxidase (LOX), a collagen cross-linking enzyme, thereby contributing to the rupture of fetal membranes. By using cultured human primary amnion fibroblasts, we demonstrated that, in addition to the induction of the key enzymes involved in prostaglandin E2 (PGE2) synthesis, cortisol stimulated 11β-HSD1 and inhibited LOX reciprocally. These results were reproduced in human amnion tissue explants after cortisol treatment. Cortisone also inhibited LOX expression, which was abolished by the inhibition of 11β-HSD1. Despite the inhibition of LOX by PGE2, inhibition of the PGE2 pathway failed to block the inhibition of LOX by cortisol. However, inhibition of glucocorticoid receptor and mutation of a negative glucocorticoid response element in LOX promoter abolished the inhibition of LOX by cortisol. Chromatin immunoprecipitation assay revealed that cortisol increased GR binding to the LOX promoter. Moreover, increased cortisol and 11β-HSD1 abundance and decreased LOX abundance were observed in human amnion tissue after the labor-initiated spontaneous rupture of membranes. These data highlight a crucial role for local cortisol regeneration by 11β-HSD1 in the down-regulation of LOX expression via glucocorticoid receptor binding to a negative glucocorticoid response element to its promoter in the amnion, which may contribute to rupture of fetal membranes at parturition.

SummaryProtein ubiquitination plays an important role in initiating the DNA damage response. Following DNA damage, E2 ubiquitin conjugating enzymes are crucial for catalyzing substrate ubiquitination that recruits downstream DNA repair factors to DNA lesions. To identify novel E2 conjugating enzymes important for initiating the DNA-damage-induced ubiquitination cascade, we screened most of the known E2 enzymes and found that RAD6A and RAD6B function together with RNF168 in the ionizing radiation (IR)-induced DNA damage response. Similarly to RNF168-deficient cells, RAD6A-or RAD6B-deficient cells exhibit a reduction in DNA-damage-induced protein ubiquitination. Correspondingly, DNA-damage-induced foci formation of DNA damage repair proteins, such as BRCA1 and 53BP1, is impaired in the absence of RAD6A or RAD6B. Moreover, the RNF168-RAD6 complex targeted histone H1.2 for ubiquitination in vitro and regulated DNA-damage-induced histone H1.2 ubiquitination in vivo. Collectively, these data demonstrate that RNF168, in complex with RAD6A or RAD6B, is activated in the DNA-damage-induced protein ubiquitination cascade.