A Terrain Elevation Map Generation Method Based on Self-Attention Mechanism and Multifeature Sketch.

To address the issues of low efficiency in manual terrain feature map annotating and poor realism in terrain elevation map generation, this paper proposes a terrain elevation map generation method based on self-attention mechanism and multifeature sketch. Firstly, the proposed method extracts features from a terrain elevation map using an adaptive feature enhancement method. Afterwards, our method adds a self-attention mechanism to the generator and discriminator of conditional generative adversarial network to capture the global spatial features and generates a realistic terrain elevation map. Finally, a level of detail method is used to visualize the three-dimensional terrain, and an interactive terrain editing tool for roaming interaction is implemented. Experimental data show that the proposed method performs well in subjective visual performance and objective criteria and has obvious advantages over other current typical methods.

Neuroprotection Effect of Astragaloside IV from 2-DG-Induced Endoplasmic Reticulum Stress.

OBJECTIVE: Astragaloside IV shows neuroprotective activity, but its mechanism remains unclear. To investigate whether astragaloside IV protects from endoplasmic reticulum stress (ERS), we focus on the regulation of glycogen synthase kinase-3ß (GSK-3ß) and mitochondrial permeability transition pore (mPTP) by astragaloside IV in neuronal cell PC12. METHODS AND RESULTS: PC12 cells treated with different concentrations of ERS inductor 2-deoxyglucose (2-DG) (25-500 µM) showed a significant increase of glucose-regulated protein 78 (GRP 78) and GRP 94 expressions and a decrease of tetramethylrhodamine ethyl ester (TMRE) fluorescence intensity and mitochondrial membrane potential (∆Ψm), with the peak effect seen at 50 µM, indicating that 2-DG induces ERS and the mPTP opening. Similarly, 50 µM of astragaloside IV increased the GSK-3ß phosphorylation at Ser9 most significantly. Next, we examined the neuroprotection of astragaloside IV by dividing the PC12 cells into control group, 2-DG treatment group, astragaloside IV plus 2-DG treatment group, and astragaloside IV only group. PC12 cells treated with 50 µM 2-DG for different time courses (0-36 hr) showed a significant increase of Cleaved-Caspase-3 with the peak at 6 hr. 2-DG significantly induced cell apoptosis and increased the green fluorescence intensity of Annexin V-FITC, and these effects were reversed by astragaloside IV. Such a result indicates that astragaloside IV protected neural cell survival from ERS. 2-DG treatment significantly increased the expressions of inositol-requiring ER-to-nucleus signal kinase 1 (IRE1), phosphor-protein kinase R-like ER kinase (p-PERK), but not affect the transcription factor 6 (ATF6) expression. 2-DG treatment significantly decreased the phosphorylation of GSK-3ß and significantly reduced the TMRE fluorescence intensity and ∆Ψm, following mPTP open. Astragaloside IV significantly inhibited the above effects caused by 2-DG, except the upregulation of ATF6 protein. Taken together, astragaloside IV significantly inhibited the ERS caused by 2-DG. CONCLUSION: Our data suggested that astragaloside IV protects PC12 cells from ERS by inactivation of GSK-3ß and preventing the mPTP opening. The GRP 78, GRP 94, IRE1, and PERK signaling pathways but not ATF6 are responsible for GSK-3ß inactivation and neuroprotection by astragaloside IV.

Zn2+ and mPTP mediate resveratrol-induced myocardial protection from endoplasmic reticulum stress.

Resveratrol displays cardioprotective activity; however, its mechanism of action remains unclear. In the current study, resveratrol-induced myocardial protection from endoplasmic reticulum stress (ERS) was investigated, focusing on the roles of Zn2+ and the mitochondrial permeability transition pore (mPTP). We found, using the MTT/LDH kit, that 2-DG-induced ERS significantly decreased H9c2 cell viability. Resveratrol markedly inhibited the expression of endoplasmic reticulum chaperone GRP 78/94 and ERS-related apoptosis proteins CHOP, Caspase12, and JNK induced by 2-DG. The zinc ion chelator TPEN, and ERK/GSK-3ß inhibitors PD98059 and SB216763 and their siRNAs blocked resveratrol function. The AKT inhibitor LY294002 and siRNA did not alter the action of resveratrol. In addition, resveratrol significantly increased the phosphorylation of ERK and GSK-3ß. Resveratrol prevented 2-DG-induced mPTP opening and increased intracellular Zn2+ concentration indicated by TMRE and Newport Green DCF fluorescence intensity, which were further abrogated by ERK/GSK-3ß inhibitors and siRNAs. Our data suggested that resveratrol protected cardiac cells from ERS by mobilizing intracellular Zn2+ and preventing mPTP opening through the ERK/GSK-3ß but not PI3K/AKT signaling pathway.

Tauroursodeoxycholic acid inhibits endoplasmic reticulum stress, blocks mitochondrial permeability transition pore opening, and suppresses reperfusion injury through GSK-3ß in cardiac H9c2 cells.

This study investigates whether inhibition of endoplasmic reticulum (ER) stress prevents opening of the mitochondrial permeability transition pore (mPTP) and evaluates the corresponding signaling pathways involved in this process. Exposure of cardiac H9c2 cells to 800 µM H2O2 for 20 min opened mPTP in response to oxidative stress, as demonstrated by quenching of tetramethylrhodamine ethyl ester (TMRE) fluorescence. Oxidative stress-induced mPTP opening was rescued by the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) in a dose-dependent manner at low concentrations. The PI3K and PKG inhibitors LY294002 and KT5823 inhibited the effect of TUDCA on mPTP opening, suggesting the involvement of PI3K/Akt and PKG signaling pathways. TUDCA significantly increased glycogen synthase kinase 3 (GSK-3ß) phosphorylation at Ser-9, with peak effect at 30 µM TUDCA. The level of GRP78 (ER chaperone) expression was significantly upregulated by 30 µM TUDCA. TUDCA-induced increases in Akt and GSK-3ß phosphorylation were inhibited by LY294002, whereas KT5823 suppressed TUDCA-induced increases in VASP and GSK-3ß phosphorylation. Oxidative stress severely affected cell morphology and ultrastructure. TUDCA prevented H2O2-induced ER swelling and mitochondrial damage. TUDCA boosted the viability of cells disrupted by ischemia/reperfusion (I/R), indicating that TUDCA eased reperfusion injury. However, TUDCA did not improve the viability of cells expressing the constitutively active GSK-3ß mutant (GSK-3ß-S9A-HA) that were subjected to I/R, suggesting an essential role of GSK-3ß inactivation in TUDCA-mediated cardioprotection against reperfusion damage. These data indicate that ER stress inhibition prevents mPTP opening and attenuates reperfusion injury through GSK-3ß inactivation. The PI3K/Akt and PKG pathways may mediate GSK-3ß inactivation.