It has long been assumed that p53 suppresses tumor development through induction of apoptosis, possibly with contributions by cell cycle arrest and cell senescence. However, combined deficiency in these three processes does not result in spontaneous tumor formation as observed upon loss of p53, suggesting the existence of additional mechanisms that are critical mediators of p53-dependent tumor suppression function. To define such mechanisms, we performed in vivo shRNA screens targeting p53-regulated genes in sensitized genetic backgrounds. We found that knockdown of Zmat3, Ctsf and Cav1, promoted lymphoma/leukemia development only when PUMA and p21, the critical effectors of p53-driven apoptosis, cell cycle arrest and senescence, were also absent. Notably, loss of the DNA repair gene Mlh1 caused lymphoma in a wild-type background, and its enforced expression was able to delay tumor development driven by loss of p53. Further examination of direct p53 target genes implicated in DNA repair showed that knockdown of Mlh1, Msh2, Rnf144b, Cav1 and Ddit4 accelerated MYC-driven lymphoma development to a similar extent as knockdown of p53. Collectively, these findings demonstrate that extensive functional overlap of several p53-regulated processes safeguards against cancer and that coordination of DNA repair appears to be an important process by which p53 suppresses tumor development.

Temperature-dependent photoluminescence measurements have been carried out in zinc-blende InGaN epilayers grown on GaAs substrates by metalorganic vapor-phase epitaxy. An anomalous temperature dependence of the peak position of the luminescence band was observed. Considering thermal activation and the transfer of excitons localized at different potential minima, we employed a model to explain the observed behavior. A good agreement between the theory and the experiment is achieved. At high temperatures, the model can be approximated to the band-tail-state emission model proposed by Eliseev et al. [Appl. Phys. Lett. 71, 569 (1997)].

Alkaline stress (high pH) severely damages root cells, and consequently, inhibits rice (Oryza sativa L.) seedling growth. In this study, we demonstrate the accumulation of reactive oxygen species (ROS) in root cells under alkaline stress. Seedlings of two rice cultivars with different alkaline tolerances, ‘Dongdao-4’ (moderately alkaline-tolerant) and ‘Jiudao-51’ (alkaline-sensitive), were subjected to alkaline stress simulated by 15 mM sodium carbonate (Na2CO3). Alkaline stress greatly reduced seedling survival rate, shoot and root growth, and root vigor. Moreover, severe root cell damage was observed under alkaline stress, as shown by increased membrane injury, malondialdehyde accumulation, and Evan’s Blue staining. The expression of the cell death-related genes OsKOD1, OsHsr203j, OsCP1, and OsNAC4 was consistently upregulated, while that of a cell death-suppressor gene, OsBI1, was downregulated. Analysis of the ROS contents revealed that alkaline stress induced a marked accumulation of superoxide anions (O2•-) and hydrogen peroxide (H2O2) in rice roots. The application of procyanidins (a potent antioxidant) to rice seedlings 24 h prior to alkaline treatment significantly alleviated alkalinity-induced root damage and promoted seedling growth inhibition, which were concomitant with reduced ROS accumulation. These results suggest that root cell damage, and consequently growth inhibition, of rice seedlings under alkaline stress is closely associated with ROS accumulation. The antioxidant activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase increased under alkaline stress in the roots, probably in response to the cellular damage induced by oxidative stress. However, this response mechanism may be overwhelmed by the excess ROS accumulation observed under stress, resulting in oxidative damage to root cells. Our findings provide physiological insights into the molecular mechanisms of alkalinity-induced damage to root cells, and will contribute to the improvement of alkaline stress tolerance in rice plants.

Osteoarthritis (OA) is one of the most painful and widespread chronic degenerative joint diseases and is characterized by destructed articular cartilage and inflamed joints. Previously, our findings indicated that circular RNA ciRS-7 (ciRS-7)/microRNA 7 (miR-7) axis is abnormally expressed in OA, and regulates proliferation, inflammatory responses, and apoptosis of interleukin-1β (IL-1β)-stimulated chondrocytes. However, its underlying role in OA remains unknown. In this study, we first validated cartilage degradation and defection of autophagy in samples of OA patients. IL-1β initially stimulated autophagy of chondrocytes, and ultimately significantly suppressed autophagy. Upregulated ciRS-7/down-regulated miR-7 aggravated IL-1β-induced cartilage degradation, and restrained autophagy in vitro . Gene sequencing and bioinformatics analysis performed on a control group, IL-1β group, and IL-1β+miR-7-mimics group demonstrated that seven of the most significant mRNA candidates were enriched in the interleukin-17 (IL-17) signaling pathway. Increased IL-17A levels were also observed by qRT-PCR and ELISA. In addition, it was revealed that the ciRS-7/miR-7 axis ameliorated cartilage degradation and defection of autophagy by PI3K/AKT/mTOR activation in IL-1β-induced chondrocytes. Furthermore, an OA model was established in rats with medial meniscus destabilization. miR-7-siRNA-expressing lentiviruses alleviated surgical resection-induced cartilage destruction of OA mice, whereas miR-7 mimics worsened the effects. Thus, these findings revealed that the mechanism of the ciRS-7/miR-7 axis involved regulating OA progression and provided valuable directions for OA treatment.

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Blue and white solution-processed OLEDs with low driving voltages, over 20% maximum external quantum efficiency and moderate efficiency decrease were realized by using interfacial exciplex hosts.