Methylammonium lead iodide perovskite, CH 3 NH 3 PbI 3 (MAPbI 3 ), has made great progress in its efficiency as used in solid-state solar cells during recent years. Meanwhile, the degradation of its performance in moisture has attracted great attentions, but the specific mechanismis not yet fully established. The water effects on the detailed structure and properties of the perovskite CH 3 NH 3 PbI 3 have been carefully explored based on first-principles calculations. The results reveals that the water adsorption energy on the CH 3 NH 3 PbI 3 (001) surface is about 0.30 eV, while the water can easily penetrate into the surface in the form of molecular state owing to the huge interspace of CH 3 NH 3 PbI 3 , which can further corrode down the whole structure gradually. More importantly, the deformation of the structure greatly affects the electronic structure, which decreases the optical absorption. Such work paves an important way to understand the initial degradation progress of the perovskite structure under the humidity condition, which should help to optimize the structure to prevent the penetration of water in the system. The conversion of solar energy into electricity has attracted great attentions because of the increasing energy demands of future generations without negatively impacting the global environment. 1-2 On the other hand, dye-sensitized solar cells (DSCs) based on nanocrystalline metal oxides like TiO 2 3-4 are a promising photovoltaic device for a renewable energy source. In recent years, new organic-inorganic hybrid perovskite compounds (MAPbX 3 , X=halogen; MA=CH 3 NH 3 ) 5-11 have been used as light harvesters for solid-state DSCs. These MAPbX 3 compounds stand out for their low cost, wide light absorption, ferroelectric properties and high efficiency. 12-18 In fact, since the first reported perovskite solar cell with power conversion efficiency (PCE) of 3.81% by Kojima and co-workers in 2009, 19 the amazing growth rate of PCE about these perovskite materials has been made in the following years. In 2011, Park et al. fabricated MAPbI 3 perovskite solar cells with PCE of 6.54%. 20 Then Kim et al. achieved a PCE of up to 9.7% based on spiro-MeOTAD as hole transport materials in 2012. 21 In 2013, Noh et al. demonstrated highly efficient solar cells of a PCE of 12.3% as a result of tunable composition for MAPb(I 1-x Br x ) 3 . 22 In 2014, Grätzel and co-workers reported an efficiency of 17.01% by controlling the size of MAPbI 3 cuboids during their growth. 23 Up to now, the PCE of perovskite-based solar cells reaches to nearly 20%. 7 Although the methylammonium lead iodide MAPbI 3 perovskite shows an outstanding performance and tantalizing prospect in solar cells, there are deficiencies needed to overcome at the same time. One vital problems is that MAPbI 3 perovskite films are extremely sensitive to moisture in air. 7-8, 24-27 Many experiments have demonstrated that the effect of moisture on MAPbI 3 plays a crucial role in the performance of perovskite solar cells. 22, 28-30 In spite of various...

By flow cytometry, a conformational change in mouse cytochrome c (cyt c) of apoptotic and necrotic T hybridoma cells was detected using a monoclonal antibody (mAb) that recognizes the region around amino acid residue 44 on a non-native form of the protein. The conformational change in cyt c is an early event in apoptosis, which can be identified in pre-apoptotic cells that are negative for other indicators of apoptosis. Since the mAb did not bind fixed and permeabilized live cells and did not immunoprecipitate soluble cyt c extracted with detergent from dead cells, it appears to recognize cyt cbound in a detergent-sensitive complex to other cellular components. Coincidentally, the mAb was also shown by competitive enzyme-linked immunosorbent assay to bind cyt c associated with synthetic phosphatidic acid vesicles. This suggests that the conformational change of cyt c in dying cells could be due to its association with intracellular membranes that are, perhaps, altered in cell death. By immunofluorescent confocal microscopy, conformationally altered cyt c in post-apoptotic T hybridoma cells showed a punctate distribution, indicating that it remained associated with mitochondria. Furthermore, the heavy membrane fraction of post-apoptotic cells but not of live cells was functional in caspase activation. This suggests that membrane-bound cyt c is the relevant caspase coactivation factor in the T hybridoma cells.

Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer cells. Here we show that p53/TGF-β signalling inhibits the REGγ–20S proteasome pathway by repressing REGγ expression. Smad3 and p53 interact on the REGγ promoter via the p53RE/SBE region. Conversely, mutant p53 binds to the REGγ promoter and recruits p300. Importantly, mutant p53 prevents Smad3/N-CoR complex formation on the REGγ promoter, which enhances the activity of the REGγ–20S proteasome pathway and contributes to mutant p53 gain of function. Depletion of REGγ alters the cellular response to p53/TGF-β signalling in drug resistance, proliferation, cell cycle progression and proteasome activity. Moreover, p53 mutations show a positive correlation with REGγ expression in cancer samples. These findings suggest that targeting REGγ–20S proteasome for cancer therapy may be applicable to human tumours with abnormal p53/Smad protein status. Furthermore, this study demonstrates a link between p53/TGF-β signalling and the REGγ–20S proteasome pathway, and provides insight into the REGγ/p53 feedback loop.