G-Protein ß-Subunit Gene TaGB1-B Enhances Drought and Salt Resistance in Wheat.

In the hexaploid wheat genome, there are three Gα genes, three Gß and twelve Gγ genes, but the function of Gß in wheat has not been explored. In this study, we obtained the overexpression of TaGB1 Arabidopsis plants through inflorescence infection, and the overexpression of wheat lines was obtained by gene bombardment. The results showed that under drought and NaCl treatment, the survival rate of Arabidopsis seedlings' overexpression of TaGB1-B was higher than that of the wild type, while the survival rate of the related mutant agb1-2 was lower than that of the wild type. The survival rate of wheat seedlings with TaGB1-B overexpression was higher than that of the control. In addition, under drought and salt stress, the levels of superoxide dismutase (SOD) and proline (Pro) in the wheat overexpression of TaGB1-B were higher than that of the control, and the concentration of malondialdehyde (MDA) was lower than that of the control. This indicates that TaGB1-B could improve the drought resistance and salt tolerance of Arabidopsis and wheat by scavenging active oxygen. Overall, this work provides a theoretical basis for wheat G-protein ß-subunits in a further study, and new genetic resources for the cultivation of drought-tolerant and salt-tolerant wheat varieties.

Genome-Wide Analysis of the Peptidase M24 Superfamily in Triticum aestivum Demonstrates That TaM24-9 Is Involved in Abiotic Stress Response.

The peptidase M24 (Metallopeptidase 24, M24) superfamily is essential for plant growth, stress response, and pathogen defense. At present, there are few systematic reports on the identification and classification of members of the peptidase M24 proteins superfamily in wheat. In this work, we identified 53 putative candidate TaM24 genes. According to the protein sequences characteristics, these members can be roughly divided into three subfamilies: I, II, III. Most TaM24 genes are complex with multiple exons, and the motifs are relatively conserved in each sub-group. Through chromosome mapping analysis, we found that the 53 genes were unevenly distributed on 19 wheat chromosomes (except 3A and 3D), of which 68% were in triads. Analysis of gene duplication events showed that 62% of TaM24 genes in wheat came from fragment duplication events, and there were no tandem duplication events to amplify genes. Analysis of the promoter sequences of TaM24 genes revealed that cis-acting elements were rich in response elements to drought, osmotic stress, ABA, and MeJA. We also studied the expression of TaM24 in wheat tissues at developmental stages and abiotic stress. Then we selected TaM24-9 as the target for further analysis. The results showed that TaM24-9 genes strengthened the drought and salt tolerance of plants. Overall, our analysis showed that members of the peptidase M24 genes may participate in the abiotic stress response and provided potential gene resources for improving wheat resistance.

[The role of Bmal1 in neuronal radial migration and axonal projection of the embryonic mouse cerebral cortex].

Normal development of the cerebral cortex is a basis for the formation and function of mammalian brains. During this process, the radial migration of cortical neurons, as well as the axon projection into specific layers, are the most important steps regulated by some transcription factors, but the underlying molecular mechanisms are still obscure. BMAL1 (brain and muscle Arnt-like protein 1) is a newly identified transcription factor that plays important roles in the circadian rhythms. It was recently found to regulate the proliferation of hippocampal neuronal progenitor/precursor cells (NPCs), implicating Bmal1 in the brain development. Here we employed both RT-RCR and real-time PCR to explore the expression pattern of the Bmal1 gene in the developing brain. We found BMAl1 is enriched in the brain cortex during the perinatal stages and peaked in P3 mouse brains. Combined with in utero electroporation and interference with RNAi, we found that reducing the expression level of Bmal1 in neurons, the radial migration of embryonic cortical neurons was largely delayed, in a gene dose-effect pattern. Moreover, reducing the level of Bmal1 expression in mouse brains, the axonal projection in the corpus callosum was also disrupted from ipsilateral to the lateral cerebral hemisphere. These findings indicate that BMAL1 is essential for the radial migration of neurons in the cerebral cortex and the axonal projection of the corpus callosum, providing insights into the molecular mechanisms of cerebral cortex development.

Selective 14-3-3γ Upregulation Promotes Beclin-1-LC3-Autophagic Influx via ß-Catenin Interaction in Starved Neurons In Vitro and In Vivo.

Lack of blood or glucose supply is the most common pathological factor in the brain. To cope with such an energy stress, initiating programmed autophagic processes in neurons is required. However, the mechanisms controlling neuronal autophagy during starvation remain far from clear. Here, we report an essential role of 14-3-3γ in starvation-activated neuronal autophagic influx signaling and elucidate the underlying mechanism. Double-fluorescent immunostaining demonstrates that 14-3-3γ protein elevation is well co-localized with Beclin-1 and LC3 elevation in cortical neurons in ischemic brains. Starvation treatment activates autophagic influx and upregulates Beclin-1 and only the γ isoform of 14-3-3 in N2a cells and cultured cortical neurons. Suppressing overall 14-3-3 function by difopein overexpression or knocking-out the γ isoform of 14-3-3 is sufficient to abolish starvation-induced Beclin-1 induction and LC3 activation while overexpressing 14-3-3γ but no other 14-3-3 isoform significantly upregulate Beclin-1-LC3 signaling. Upon starvation, 14-3-3γ binds more p-ß-catenin but less Beclin-1. Finally, overexpressing 14-3-3γ reactivates ß-catenin-suppressed Beclin-1-LC3 signaling in neuronal cells. Taken together, our data reveal that starvation-induced 14-3-3γ is required for ß-catenin-Beclin-1-LC3-autophagy in starved neurons in vitro and in vivo, which may provide insights in the treatment of neurologic diseases such as stoke.

PD-L1 confers glioblastoma multiforme malignancy via Ras binding and Ras/Erk/EMT activation.

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor due to the lack of effective therapeutic drugs. Cancer therapy targeting programmed cell death protein 1 (PD-1) or programmed death ligand-1 (PD-L1) is of revolutionary. However, the role of intrinsic PD-L1, which determines immune-therapy outcomes, remains largely unclear. Here we demonstrated an oncogenic role of PD-L1 via binding and activating Ras in GBM cells. RNA-sequencing transcriptome data revealed that PD-L1 significantly altered gene expression enriched in cell growth/migration/invasion pathways in human GBM cells. PD-L1 overexpression and knockout or knockdown demonstrated that PD-L1 promoted GBM cell proliferation and migration in vitro and in vivo. Mechanistically, PD-L1 prominently activated epithelial mesenchymal transition (EMT) process in a MEK/Erk- but not PI3K/Akt-dependent manner. Further, we identified intracellular interactions of PD-L1 and H-Ras, which led to Ras/Erk/EMT activation. Finally, we demonstrated that PD-L1 overexpression promoted while knockdown abolished GBM development and invasion in orthotopic GBM models of rodents. Taken together, we found that intracellular PD-L1 confers GBM cell malignancy and aggressiveness via binding Ras and activating the downstream Erk-EMT signaling. Thus, these results shed important insights in improving efficacy of immune therapy for GBM as well as other malignant tumors.

Neuroglobin boosts axon regeneration during ischemic reperfusion via p38 binding and activation depending on oxygen signal.

Cerebral ischemia causes severe cell death or injury including axon breakdown or retraction in the brain. Axon regeneration is crucial for the functional recovery of injured neurons or brains after ischemia/reperfusion (I/R); however, this process has been proved extremely difficult in adult brains and there is still no effective therapy for it. Here we reported that neuroglobin (Ngb), a novel oxygen-binding or sensor protein existing predominantly in neurons or brains, functions as a driving factor for axon regeneration during I/R. Ngb was upregulated and accumulated in growth cones of ischemic neurons in primary cultures, rat, and human brains, correlating positively to the elevation of axon-regeneration markers GAP43, neurofilament-200, and Tau-1. Ngb overexpression promoted while Ngb knockdown suppressed axon regeneration as well as GAP43 expression in neurons during oxygen-glucose deprivation/reoxygenation (OGD/Re). By using specific pharmacological inhibitors, we identified p38 MAPK as the major downstream player of Ngb-induced axon regeneration during OGD/Re. Mechanistically, Ngb directly bound to and activated p38 in neurons upon OGD/Re. Serial truncation and point mutation of Ngb revealed that the 7-105 aa fragment of Ngb was required and the oxygen-binding site (His64) of Ngb was the major regulatory site for its p38 interaction/activation. Finally, administration of exogenous TAT-Ngb peptides significantly enhanced axon regeneration in cultured neurons upon OGD/Re. Taken together, Ngb promotes axon regeneration via O2-Ngb-p38-GAP43 signaling during I/R. This novel mechanism suggests potential therapeutic applications of Ngb for ischemic stroke and other related axonopathy.

Advances in Hypoxia-Mediated Mechanisms in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the fifth most common and the third most deadly malignant tumor worldwide. Hypoxia and related oxidative stress are heavily involved in the process of HCC development and its therapies. However, direct and accurate measurement of oxygen concentration and evaluation of hypoxic effects in HCC prove difficult. Moreover, the hypoxia-mediated mechanisms in HCC remain elusive. Here, we summarize recent major evidence of hypoxia in HCC lesions shown by measuring partial pressure of oxygen (pO2), the clinical importance of hypoxic markers in HCC, and recent advances in hypoxia-related mechanisms and therapies in HCC. For the mechanisms, we focus mainly on the roles of oxygen-sensing proteins (i.e., hypoxia-inducible factor and neuroglobin) and hypoxia-induced signaling proteins (e.g., matrix metalloproteinases, high mobility group box 1, Beclin 1, glucose metabolism enzymes, and vascular endothelial growth factor). With respect to therapies, we discuss mainly YQ23, sorafenib, 2-methoxyestradiol, and celastrol. This review focuses primarily on the results of clinical and animal studies.

Piperlongumine selectively kills hepatocellular carcinoma cells and preferentially inhibits their invasion via ROS-ER-MAPKs-CHOP.

Hepatocellular carcinomas (HCC) are highly malignant and aggressive tumors lack of effective therapeutic drugs. Piperlongumine (PL), a natural product isolated from longer pepper plants, is recently identified as a potent cytotoxic compound highly selective to cancer cells. Here, we reported that PL specifically suppressed HCC cell migration/invasion via endoplasmic reticulum (ER)-MAPKs-CHOP signaling pathway. PL selectively killed HCC cells but not normal hepatocytes with an IC50 of 10-20 µM while PL at much lower concentrations only suppressed HCC cell migration/invasion. PL selectively elevated reactive oxygen species (ROS) in HCC cells, which activated or up-regulated downstream PERK/Ire 1α/Grp78, p38/JNK/Erk and CHOP subsequently. Administration of antioxidants completely abolished PL's effects on cell death and migration/invasion. However, pharmacological inhibition of ER stress-responses or MAPKs signaling pathways with corresponding specific inhibitors only reversed PL's effect on cell migration/invasion but not on cell death. Consistently, knocking-down of CHOP by RNA interference only reversed PL-suppressed HCC cell migration. Finally, PL significantly suppressed HCC development and activated the ER-MAPKs-CHOP signaling pathway in HCC xenografts in vivo. Taken together, PL selectively killed HCC cells and preferentially inhibited HCC cell migration/invasion via ROS-ER-MAPKs-CHOP axis, suggesting a novel therapeutic strategy for the highly malignant and aggressive HCC clinically.

Piperlongumine induces apoptotic and autophagic death of the primary myeloid leukemia cells from patients via activation of ROS-p38/JNK pathways.

AIM: To investigate the effects of piperlongumine (PL), an anticancer alkaloid from long pepper plants, on the primary myeloid leukemia cells from patients and the mechanisms of action. METHODS: Human BM samples were obtained from 9 patients with acute or chronic myeloid leukemias and 2 patients with myelodysplastic syndrome (MDS). Bone marrow mononuclear cells (BMMNCs) were isolated and cultured. Cell viability was determined using MTT assay, and apoptosis was examined with PI staining or flow cytometry. ROS levels in the cells were determined using DCFH-DA staining and flow cytometry. Expression of apoptotic and autophagic signaling proteins was analyzed using Western blotting. RESULTS: PL inhibited the viability of BMMNCs from the patients with myeloid leukemias (with IC50 less than 20 µmol/L), but not that of BMMNCs from a patient with MDS. Furthermore, PL (10 and 20 µmol/L) induced apoptosis of BMMNCs from the patients with myeloid leukemias in a dose-dependent manner. PL markedly increased ROS levels in BMMNCs from the patients with myeloid leukemias, whereas pretreatment with the antioxidant N-acetyl-L-cysteine abolished PL-induced ROS accumulation and effectively reduced PL-induced cytotoxicity. Moreover, PL markedly increased the expression of the apoptotic proteins (Bax, Bcl-2 and caspase-3) and autophagic proteins (Beclin-1 and LC3B), and phosphorylation of p38 and JNK in BMMNCs from the patients with myeloid leukemias, whereas pretreatment with the specific p38 inhibitor SB203580 or the specific JNK inhibitor SP600125 partially reversed PL-induced ROS production, apoptotic/autophagic signaling activation and cytotoxicity. CONCLUSION: Piperlongumine induces apoptotic and autophagic death of the primary myeloid leukemia cells from patients via activation of ROS-p38/JNK pathways.

[Progress in autism: de novo mutation and CHD8 functions].

Autism or autism spectrum disorders is the most common central nervous system developmental disorder in children. Until now, there is still no effective drug for autism. The latest breakthrough advance in autism study is the discovery of autism-related gene de novo mutation by the whole exon sequencing. Among multiple de novo gene mutations identified in autism, the chromodomain helicase DNA-binding protein 8 (CHD8) is the most frequently mutated gene, suggesting that CHD8 is an important candidate gene for autism. CHD8 binds to various other proteins such as p53 and beta-catenin to regulate gene expression. The discovery of autism-candidate genes provides novel molecular targets for the diagnosis and treatment of autism.

Piperlongumine inhibits migration of glioblastoma cells via activation of ROS-dependent p38 and JNK signaling pathways.

Piperlongumine (PL) is recently found to kill cancer cells selectively and effectively via targeting reactive oxygen species (ROS) responses. To further explore the therapeutic effects of PL in cancers, we investigated the role and mechanisms of PL in cancer cell migration. PL effectively inhibited the migration of human glioma (LN229 or U87 MG) cells but not normal astrocytes in the scratch-wound culture model. PL did not alter EdU(+)-cells and cdc2, cdc25c, or cyclin D1 expression in our model. PL increased ROS (measured by DCFH-DA), reduced glutathione, activated p38 and JNK, increased IκBα, and suppressed NFκB in LN229 cells after scratching. All the biological effects of PL in scratched LN229 cells were completely abolished by the antioxidant N-acetyl-L-cysteine (NAC). Pharmacological administration of specific p38 (SB203580) or JNK (SP600125) inhibitors significantly reduced the inhibitory effects of PL on LN229 cell migration and NF κ B activity in scratch-wound and/or transwell models. PL prevented the deformation of migrated LN229 cells while NAC, SB203580, or SP600125 reversed PL-induced morphological changes of migrated cells. These results suggest potential therapeutic effects of PL in the treatment and prevention of highly malignant tumors such as glioblastoma multiforme (GBM) in the brain by suppressing tumor invasion and metastasis.

Neuroglobin promotes neurite outgrowth via differential binding to PTEN and Akt.

Neuroglobin, the third mammalian globin with a hexa-coordinated heme, exists predominantly in neurons of the brain. Neuroglobin plays an important role in neuronal death upon ischemia and oxidative stress. The physiological function of neuroglobin remains unclear. Here, we report a novel function of neuroglobin in neurite development. Knocking-down neuroglobin exhibited a prominent neurite-deficient phenotype in mouse neuroblastoma N2a cells. Silencing neuroglobin prevented neurite outgrowth, while ectopic expression of neuroglobin but not homologous cytoglobin promoted neurite outgrowth of N2a cells upon serum withdrawal. In primary cultured rat cerebral cortical neurons, neuroglobin was upregulated and preferentially distributed in neurites during neuronal development. Overexpression of neuroglobin but not cytoglobin in cultured cortical neurons promoted axonal outgrowth, while knocking-down of neuroglobin retarded axonal outgrowth. Neuroglobin overexpression suppressed phosphatase and tensin homolog (PTEN) but increased Akt phosphorylation during neurite induction. Bimolecular fluorescence complementation and glutathione S-transferase pull-down assays revealed that neuroglobin and various mutants (E53Q, E118Q, K119N, H64A, H64L, and Y44D) bound with Akt and PTEN differentially. Neuroglobin E53Q showed a prominent reduced PTEN binding but increased Akt binding, resulting in decreased p-PTEN, increased p-Akt, and increased neurite length. Taken together, we demonstrate a critical role of neuroglobin in neuritogenesis or development via interacting with PTEN and Akt differentially to activate phosphatidylinositol 3-kinase/Akt pathway, providing potential therapeutic applications of neuroglobin for axonopathy in neurological diseases.

Piperlongumine selectively kills glioblastoma multiforme cells via reactive oxygen species accumulation dependent JNK and p38 activation.

Piperlongumine (PL), a natural alkaloid isolated from the long pepper, may have anti-cancer properties. It selectively targets and kills cancer cells but leaves normal cells intact. Here, we reported that PL selectively killed glioblastoma multiforme (GBM) cells via accumulating reactive oxygen species (ROS) to activate JNK and p38. PL at 20µM could induce severe cell death in three GBM cell lines (LN229, U87 and 8MG) but not astrocytes in cultures. PL elevated ROS prominently and reduced glutathione levels in LN229 and U87 cells. Antioxidant N-acetyl-L-cysteine (NAC) completely reversed PL-induced ROS accumulation and prevented cell death in LN229 and U87 cells. In LN229 and U87 cells, PL-treatment activated JNK and p38 but not Erk and Akt, in a dosage-dependent manner. These activations could be blocked by NAC pre-treatment. JNK and p38 specific inhibitors, SB203580 and SP600125 respectively, significantly blocked the cytotoxic effects of PL in LN229 and U87 cells. Our data first suggests that PL may have therapeutic potential for one of the most malignant and refractory tumors GBM.