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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

The transcription factor LEF-1 induces an epithelial–mesenchymal transition in MDCK cells independent of β-catenin

Highlights: •The transcription factor LEF-1 induces an EMT in MDCK cells. •A mutant LEF-1 that cannot interact with β-catenin retained the ability. •The nuclear function of β-catenin was not necessary for the LEF-1-induced EMT. •The mRNA levels of Slug, ZEB1, and ZEB2 increased significantly in these cells. -- Abstract: The epithelial–mesenchymal transition (EMT), a key process in the tumor metastatic cascade, is characterized by the loss of cell–cell junctions and cell polarity, as well as the acquisition of migratory and invasive properties. LEF-1 is a member of the lymphoid enhancer-binding factor/T-cell factor (LEF/TCF) family of DNA-binding transcription factors, which interact with nuclear β-catenin and act as central transcriptional mediators of Wnt signaling. To investigate the role of LEF-1 in EMT, we generated stable LEF-1 transfectants using MDCK cells. The transfectants had a spindle-shaped mesenchymal morphology, and enhanced migration and invasiveness relative to control cells. These EMT changes were accompanied by the downregulation of an epithelial marker protein, E-cadherin, and the upregulation of mesenchymal marker proteins, vimentin and N-cadherin. Consistent with these observations, the mRNA levels of Slug, ZEB1, and ZEB2—EMT-related transcription factors—increased significantly. Although the N-terminally deleted mutant LEF-1 cannot interact with β-catenin, it retained the ability to induce EMT. Consistent with these observations, neither the expression of a dominant negative β-catenin/engrailed chimera, nor the expression of a cytoplasmic domain of E-cadherin that sequesters β-catenin from binding to LEF/TCF, reversed LEF-1-induced EMT. Together, these data indicated that the nuclear function of β-catenin was not necessary for the induction of Slug, ZEB1, and ZEB2 expression leading to EMT.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Oxaliplatin antagonizes HIV-1 latency by activating NF-κB without causing global T cell activation

Highlights: • The chemotherapeutic drug oxaliplatin reactivates latent HIV-1 in this cell line model of HIV-1 latency. • Reactivation is synergized when oxaliplatin is used in combination with valproic acid. • Oxaliplatin reactivates latent HIV-1 through activation of NF-kB and does not induce T cell activation. - Abstract: Reactivation of latent HIV-1 is a promising strategy for the clearance of the viral reservoirs. Because of the limitations of current agents, identification of new latency activators is urgently required. Using an established model of HIV-1 latency, we examined the effect of Oxaliplatin on latent HIV-1 reactivation. We showed that Oxaliplatin, alone or in combination with valproic acid (VPA), was able to reactivate HIV-1 without inducing global T cell activation. We also provided evidence that Oxaliplatin reactivated HIV-1 expression by inducing nuclear factor kappa B (NF-κB) nuclear translocation. Our results indicated that Oxaliplatin could be a potential drug candidate for anti-latency therapies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Syndecan-1 responsive microRNA-126 and 149 regulate cell proliferation in prostate cancer

Highlights: • Syndecan-1 is highly expressed in androgen independent prostate cancer cells, PC3. • Syndecan-1 regulates the expression of miR-126 and -149 in prostate cancer cells. • MiR-126 and 149 control cell growth via p21 induction and senescence mechanism. • MiR-126 and 149 promote cell proliferation by suppressing SOX2, NANOG, and Oct4. - Abstract: MicroRNAs (miRNAs) are short (19–24 nt), low molecular weight RNAs that play important roles in the regulation of target genes associated with cell proliferation, differentiation, and development, by binding to the 3′-untranslated region of the target mRNAs. In this study, we examined the expression of miRNA-126 (miR-126) and miR-149 in prostate cancer, and investigated the molecular mechanisms by which they affect syndecan-1 in prostate cancer. Functional analysis of miR-126 and miR-149 was conducted in the prostate cancer cell lines, PC3, Du145, and LNCaP. The expression levels of SOX2, NANOG, Oct4, miR-126 and miR-149 were evaluated by quantitative RT-PCR. After silencing syndecan-1, miR-126, and/or miR-149 in the PC3 cells, cell proliferation, senescence, and p21 induction were assessed using the MTS assay, senescence-associated β-galactosidase (SA-β-Gal) assay, and immunocytochemistry, respectively. Compared to the Du145 and LNCaP cells, PC3 cells exhibited higher expression of syndecan-1. When syndecan-1 was silenced, the PC3 cells showed reduced expression of miR-126 and miR-149 most effectively. Suppression of miR-126 and/or miR-149 significantly inhibited cell growth via p21 induction and subsequently, induced senescence. The mRNA expression levels of SOX2, NANOG, and Oct4 were significantly increased in response to the silencing of miR-126 and/or miR-149. Our results suggest that miR-126 and miR-149 are associated with the expression of syndecan-1 in prostate cancer cells. These miRNAs promote cell proliferation by suppressing SOX2, NANOG, and Oct4. The regulation of these factors by miR-126 and miR-149 is essential for syndecan-1-mediated development of androgen-refractory prostate cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Fibroblast growth factor 10 protects neuron against oxygen–glucose deprivation injury through inducing heme oxygenase-1

Highlights: • FGF10 attenuates OGD induced injury in cortical neuron. • FGF10 reduces OGD triggered ROS level in cortical neuron. • FGF10 induces HO-1 expression upon OGD stimuli in cortical neuron. • Knockdown of HO-1 impairs the neuroprotection of FGF10 in OGD model. - Abstract: Fibroblast growth factors (FGFs) are a family of structurally related heparin-binding proteins with diverse biological functions. FGFs participate in mitogenesis, angiogenesis, cell proliferation, development, differentiation and cell migration. Here, we investigated the potential effect of FGF10, a member of FGFs, on neuron survival in oxygen–glucose deprivation (OGD) model. In primary cultured mouse cortical neurons upon OGD, FGF10 treatment (100 and 1000 ng/ml) attenuated the decrease of cell viability and rescued the LDH release. Tuj-1 immunocytochemistry assay showed that FGF10 promoted neuronal survival. Apoptosis assay with Annexin V + PI by flow cytometry demonstrated that FGF10 treatment reduced apoptotic cell proportion. Moreover, immunoblotting showed that FGF10 alleviated the cleaved caspase-3 upregulation caused by OGD. FGF10 treatment also depressed the OGD-induced increase of caspase-3, -8 and -9 activities. At last, we found FGF10 triggered heme oxygenase-1 (HO-1) protein expression rather than hypoxia-inducible factor-1 (HIF-1), AMP-activated protein kinase (AMPK) signaling and extracellular signal-regulated kinases 1/2 (ERK1/2) signaling. Knockdown of HO-1 by siRNA partly abolished the neuroprotection of FGF10 in OGD model. In summary, our observations provide the first evidence for the neuroprotective function of FGF10 against ischemic neuronal injury and suggest that FGF10 may be a promising agent for treatment of ischemic stroke.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

17β-Estradiol regulates cell proliferation, colony formation, migration, invasion and promotes apoptosis by upregulating miR-9 and thus degrades MALAT-1 in osteosarcoma cell MG-63 in an estrogen receptor-independent manner

In bone, different concentration of estrogen leads to various of physiological processes in osteoblast, such as the proliferation, migration, and apoptosis in an estrogen receptor-dependent manner. But little was known about the estrogen effects on osteosarcoma (OS). In this study, OS cell MG-63 was treated with low (1 nM) or high (100 nM) dose of 17β-Estradiol (E2) with the presence or absence of estrogen receptor α (ERα), for evaluating the E2 effects on proliferation, migration, invasion, colony formation and apoptosis. Consistent with a previous study, high dose of E2 treatment dramatically downregulated expressing level of long non-coding RNA metastasis associated lung adenocarcinoma transcript 1 (MALAT-1). The observation of upregulation of miR-9 after a high dose of E2 treatment indicated the cause of MALAT-1 reduction. Downregulation of MALAT-1 promoted the combination of SFPQ/PTBP2 complex. It was also observed that the proliferation, migration, invasion, colony formation and apoptosis of OS cells were remarkably affected by high dose of E2 treatment, but not by low dose, in an ERα independent manner. Furthermore, the abolishment of the effects on these physiological processes caused by ectopic expression of miR-9 ASOs suggested the necessity of miR-9 in MALAT-1 regulation. Here we found that the high dose of E2 treatment upregulated miR-9 thus posttranscriptionally regulated MALAT-1 RNA level in OS cells, and then the downregulation of MALAT-1 inhibited cell proliferation, migration, invasion and epithelial–mesenchymal transition (EMT) processes in the E2-dose dependent and ER-independent ways. - Highlights: • E2 affects osteosarcoma cell MG-63 in an Estrogen receptor-independent way. • High dose of E2 treatment upregulates miR-9 which target to MALAT-1 RNA. • Upregulated miR-9 degrades MALAT-1 and thus affects combination of SFPQ/PTBP2. • E2 treatment block cell proliferation, colony formation, mobility, and enhance apoptosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

SG2NA enhances cancer cell survival by stabilizing DJ-1 and thus activating Akt

SG2NA in association with striatin and zinedin forms a striatin family of WD-40 repeat proteins. This family of proteins functions as scaffold in different signal transduction pathways. They also act as a regulatory subunit of protein phosphatase 2A. We have shown that SG2NA which evolved first in the metazoan evolution among the striatin family members expresses different isoforms generated out of alternative splicing. We have also shown that SG2NA protects cells from oxidative stress by recruiting DJ-1 and Akt to mitochondria and membrane in the post-mitotic neuronal cells. DJ-1 is both cancer and Parkinson's disease related protein. In the present study we have shown that SG2NA protects DJ-1 from proteasomal degradation in cancer cells. Hence, downregulation of SG2NA reduces DJ-1/Akt colocalization in cancer cells resulting in the reduction of anchorage dependent and independent growth. Thus SG2NA enhances cancer cell survival. Reactive oxygen species enhances SG2NA, DJ-1 and Akt trimerization. Removal of the reactive oxygen species by N-acetyl-cysteine thus reduces cancer cell growth. - Highlights: • Reactive oxygen species (ROS) play potential role in cancer cell proliferation. • It enhances the association between DJ-1 and Akt mediated by SG2NA. • In cancer cells SG2NA stabilizes DJ-1 by inhibiting it from proteosomal degradation. • DJ-1 then activates Akt and cancer cells get their property of enhanced proliferation by sustained activation of Akt. • Further study on this field could lead to new target for cancer therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Niclosamide, an anti-helminthic molecule, downregulates the retroviral oncoprotein Tax and pro-survival Bcl-2 proteins in HTLV-1-transformed T lymphocytes

Adult T cell leukemia and lymphoma (ATL) is a highly aggressive form of hematological malignancy and is caused by chronic infection of human T cell leukemia virus type 1 (HTLV-1). The viral genome encodes an oncogenic protein, Tax, which plays a key role in transactivating viral gene transcription and in deregulating cellular oncogenic signaling to promote survival, proliferation and transformation of virally infected T cells. Hence, Tax is a desirable therapeutic target, particularly at early stage of HTLV-1-mediated oncogenesis. We here show that niclosamide, an anti-helminthic molecule, induced apoptosis of HTLV-1-transformed T cells. Niclosamide facilitated degradation of the Tax protein in proteasome. Consistent with niclosamide-mediated Tax degradation, this compound inhibited activities of MAPK/ERK1/2 and IκB kinases. In addition, niclosamide downregulated Stat3 and pro-survival Bcl-2 family members such as Mcl-1 and repressed the viral gene transcription of HTLV-1 through induction of Tax degradation. Since Tax, Stat3 and Mcl-1 are crucial molecules for promoting survival and growth of HTLV-1-transformed T cells, our findings demonstrate a novel mechanism of niclosamide in inducing Tax degradation and downregulating various cellular pro-survival molecules, thereby promoting apoptosis of HTLV-1-associated leukemia cells. - Highlights: • Niclosamide is a promising therapeutic candidate for adult T cell leukemia. • Niclosamide employs a novel mechanism through proteasomal degradation of Tax. • Niclosamide downregulates certain cellular pro-survival molecules.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

O-GlcNAc regulates NEDD4-1 stability via caspase-mediated pathway

O-GlcNAc modification of cytosolic and nuclear proteins regulates essential cellular processes such as stress responses, transcription, translation, and protein degradation. Emerging evidence indicates O-GlcNAcylation has a dynamic interplay with ubiquitination in cellular regulation. Here, we report that O-GlcNAc indirectly targets a vital E3 ubiquitin ligase enzyme of NEDD4-1. The protein level of NEDD4-1 is accordingly decreased following an increase of overall O-GlcNAc level upon PUGNAc or glucosamine stimulation. O-GlcNAc transferase (OGT) knockdown, overexpression and mutation results confirm that the stability of NEDD4-1 is negatively regulated by cellular O-GlcNAc. Moreover, the NEDD4-1 degradation induced by PUGNAc or GlcN is significantly inhibited by the caspase inhibitor. Our study reveals a regulation mechanism of NEDD4-1 stability by O-GlcNAcylation. - Highlights: • Reduced NEDD4-1 correlates with increased overall O-GlcNAc level. • OGT negatively regulates NEDD4-1 stability. • O-GlcNAc regulates NEDD4-1 through caspase-mediated pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Methionine sulfoxide reductase B3 deficiency stimulates heme oxygenase-1 expression via ROS-dependent and Nrf2 activation pathways

Methionine sulfoxide reductase B3 (MsrB3), which is primarily found in the endoplasmic reticulum (ER), is an important protein repair enzyme that stereospecifically reduces methionine-R-sulfoxide residues. We previously found that MsrB3 deficiency arrests the cell cycle at the G{sub 1}/S stage through up-regulation of p21 and p27. In this study, we report a critical role of MsrB3 in gene expression of heme oxygenase-1 (HO-1), which has an anti-proliferative effect associated with p21 up-regulation. Depletion of MsrB3 elevated HO-1 expression in mammalian cells, whereas MsrB3 overexpression had no effect. MsrB3 deficiency increased cellular reactive oxygen species (ROS), particularly in the mitochondria. ER stress, which is associated with up-regulation of HO-1, was also induced by depletion of MsrB3. Treatment with N-acetylcysteine as an ROS scavenger reduced augmented HO-1 levels in MsrB3-depleted cells. MsrB3 deficiency activated Nrf2 transcription factor by enhancing its expression and nuclear import. The activation of Nrf2 induced by MsrB3 depletion was confirmed by increased expression levels of its other target genes, such as γ-glutamylcysteine ligase. Taken together, these data suggest that MsrB3 attenuates HO-1 induction by inhibiting ROS production, ER stress, and Nrf2 activation. -- Highlights: •MsrB3 depletion induces HO-1 expression. •MsrB3 deficiency increases cellular ROS and ER stress. •MsrB3 deficiency activates Nrf2 by increasing its expression and nuclear import. •MsrB3 attenuates HO-1 induction by inhibiting ROS production and Nrf2 activation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Four nucleocytoplasmic-shuttling proteins and p53 interact specifically with the YB-NLS and are involved in anticancer reagent-induced nuclear localization of YB-1

In cancer cells, anticancer reagents often trigger nuclear accumulation of YB-1, which participates in the progression of cancer malignancy. YB-1 has a non-canonical nuclear localization signal (YB-NLS). Here we found that four nucleocytoplasmic-shuttling RNA-binding proteins and p53 interact specifically with the YB-NLS and co-accumulate with YB-1 in the nucleus of actinomycin D-treated cells. To elucidate the roles of these YB-NLS-binding proteins, we performed a dominant-negative experiment in which a large excess of YB-NLS interacts with the YB-NLS-binding proteins, and showed inhibitory effects on actinomycin D-induced nuclear transport of endogenous YB-1 and subsequent MDR1 gene expression. Furthermore, the YB-NLS-expressing cells were also found to show increased drug sensitivity. Our results suggest that these YB-NLS-associating proteins are key factors for nuclear translocation/accumulation of YB-1 in cancer cells. - Highlights: • Four nucleocytoplasmic-shuttling proteins and p53 associate with YB-NLS. • They showed nuclear co-accumulation with YB-1 in actinomycin D-treated cells. • Overexpression of YB-NLS was carried out to take YB-NLS-binding proteins from YB-1. • YB-NLS inhibited actinomycin D-induced nuclear localization of endogenous YB-1. • YB-NLS suppressed actinomycin D-induced expression of MDR1.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

5-Aminolevulinic acid with sodium ferrous citrate induces autophagy and protects cardiomyocytes from hypoxia-induced cellular injury through MAPK-Nrf-2-HO-1 signaling cascade

Background: Hypoxia causes cardiac disease via oxidative stress and mitochondrial dysfunction. 5-Aminolevulinic acid in combination with sodium ferrous citrate (ALA/SFC) has been shown to up-regulate heme oxygenase-1 (HO-1) and decrease macrophage infiltration and renal cell apoptosis in renal ischemia injury mice. However, its underlying mechanism remains largely unknown. The aim of this study was to investigate whether ALA/SFC could protect cardiomyocytes from hypoxia-induced apoptosis by autophagy via HO-1 signaling. Materials & methods: Murine atrial cardiomyocyte HL-1 cells were pretreated with ALA/SFC and then exposed to hypoxia. Results: ALA/SFC pretreatment significantly attenuated hypoxia-induced cardiomyocyte apoptosis, reactive oxygen species production, and mitochondrial injury, while it increased cell viability and autophagy levels. HO-1 expression by ALA/SFC was associated with up-regulation and nuclear translocation of Nrf-2, whereas Nrf-2 siRNA dramatically reduced HO-1 expression. ERK1/2, p38, and SAPK/JNK pathways were activated by ALA/SFC and their specific inhibitors significantly reduced ALA/SFC-mediated HO-1 upregulation. Silencing of either Nrf-2 or HO-1and LY294002, inhibitor of autophagy, abolished the protective ability of ALA/AFC against hypoxia-induced injury and reduced ALA/SFC-induced autophagy. Conclusion: Taken together, our data suggest that ALA/SFC induces autophagy via activation of MAPK/Nrf-2/HO-1 signaling pathway to protect cardiomyocytes from hypoxia-induced apoptosis. - Highlights: • ALA/SFC attenuates hypoxia-induced cardiomyocyte apoptosis, reactive oxygen species production, and mitochondrial injury. • ALA/SFC increases the heme oxygenase-1 expression via Nrf-2 and ERK1/2, p38, and SAPK/JNK pathways. • ALA/SFC induces autophagy and inhibition of autophagy prevent ALA/SFC-mediated suppression of hypoxia-induced injury.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

MicroRNA-1297 inhibits prostate cancer cell proliferation and invasion by targeting the AEG-1/Wnt signaling pathway

MicroRNAs (miRNAs) have been known to be implicated in tumorigenic programs. miR-1297 has been reported to be dysregulated and involved in cancer progression in many types of human cancers. However, the expression level and the role of miR-1297 in prostate cancer remain unclear. Herein, we aimed to investigate the potential role and molecular mechanism of miR-1297 in prostate cancer progression. We found that miR-1297 was significantly downregulated in human prostate cancer specimens as well as in several prostate cancer cell lines. In addition, functional experiments demonstrated that overexpression of miR-1297 remarkably inhibited prostate cancer cell proliferation and invasion whereas miR-1297 suppression significantly promoted prostate cancer cell proliferation and invasion. Bioinformatics analysis showed that the Astrocyte elevated gene-1 (AEG-1), a well-known oncogene, is a predicted target of miR-1297. Dual-luciferase reporter assay showed that miR-1297 was able to directly target the 3’-untranslated region of AEG-1. In addition, RT-qPCR and Western blot analysis showed that miR-1297 regulated the mRNA and protein expression levels of AEG-1. We also showed that miR-1297 was able to regulate the Wnt signaling pathway. Moreover, rescue assays indicated that AEG-1 contributed to miR-1297-endowed effects on cell proliferation and invasion as well as Wnt signaling pathway. Taken together, these findings suggest that miR-1297 inhibits prostate cancer proliferation and invasion by targeting AEG-1, thereby providing novel insight into understanding the pathogenesis of prostate cancer. Thus, miR-1297 may be a novel potential therapeutic candidate to treat prostate cancer. - Highlights: • miR-1297 is decreased in prostate cancer. • miR-1297 inhibits prostate cancer cell proliferation and invasion. • miR-1297 targets and inhibits AEG-1. • miR-1297 regulates AEG-1/Wnt signaling pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Bmi-1 plays a critical role in the protection from acute tubular necrosis by mobilizing renal stem/progenitor cells

The regeneration of injured tubular cell occurs primarily from intrinsic renal stem/progenitor cells (RSCs) labeled with CD24 and CD133 after acute tubular necrosis (ATN). Bmi-1 plays a crucial role in regulating self-renewal, differentiation and aging of multiple adult stem cells and progenitor cells. Bmi-1 was rapidly elevated in the induction of adult kidney regeneration by renal injury. To determine whether Bmi-1 maintained mobilization of RSCs in the protection from ATN, glycerol-rhabdomyolysis-induced ATN were performed in wild type (WT) and Bmi-1-deficient (Bmi-1{sup −/−}) mice. Their ATN phenotypes were analyzed; CD24 and CD133 double positive (CD24{sup +}CD133{sup +}) cells were measured; and the levels of serum urea nitrogen (SUN) and serum creatinine (SCr) were detected. We found that CD24{sup +}CD133{sup +} RSCs were mobilized in WT ATN mice with the increased expression of Bmi-1; Bmi-1 deficiency led to increased tubular cast formation and necrosis, elevated levels of SUN and SCr, decreased tubular proliferation, and immobilized ratio of RSCs in ATN. These findings indicated that Bmi-1 played a critical role in the protection from ATN by maintaining mobilization of RSCs and would be a novel therapeutic target for preventing the progression of ATN.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Functional characterization of Brassica napus DNA topoisomerase Iα-1 and its effect on flowering time when expressed in Arabidopsis thaliana

Previous studies have shown that DNA topoisomerase Iα (AtTOP1α) has specific developmental functions during growth and development in Arabidopsis thaliana. However, little is known about the roles of DNA topoisomerases in the closely related and commercially important plant, rapeseed (Brassica napus). Here, the full-length BnTOP1α-1 coding sequence was cloned from the A2 subgenome of the Brassica napus inbred line L111. We determine that all BnTOP1α paralogs showed differing patterns of expression in different organs of L111, and that when expressed in tobacco leaves as a fusion protein with green fluorescent protein, BnTOP1α-1 localized to the nucleus. We further showed that ectopic expression of BnTOP1α-1 in the A. thaliana top1α-7 mutant fully complemented the early flowering phenotype of the mutant. Moreover, altered expression levels in top1α-7 seedlings of several key genes controlling flowering time were restored to wild type levels by ectopic expression of BnTOP1α-1. These results provide valuable insights into the roles of rapeseed DNA topoisomerases in flowering time, and provide a promising target for genetic manipulation of this commercially significant process in rapeseed. - Highlights: • BnTOP1α-1 was cloned from the A2 subgenome of Brassica napus inbred line L111. • BnTOP1α-1 rescued the early flowering phenotype of the Attop1α-7 mutant. • BnTOP1α-1 rescued the altered expression of flowering time genes in the Attop1α-mutant. • The functions of BnTOP1α-1 and AtTOP1α are likely conserved.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Netrin-1 promotes metastasis of gastric cancer by regulating YAP activity

Yes-associated protein (YAP) is a major downstream molecular of the Hippo pathway, which plays important role in cancer development. Netrin-1 conveys oncogenic activity in many types of malignant tumors. However, the downstream signaling of netrin-1 mediating its oncogenic effects in gastric cancer (GC) is not well defined. Here, we aim to investigate the role of netrin-1 in metastasis potential of GC by regulating YAP. In this study, we showed that netrin-1 inhibition significantly decreased migration and invasion abilities of GC cells, while netrin-1 overexpression effectively reversed this effect. We also demonstrated that netrin-1 upregulated YAP expression via its transmembrane receptor neogenin. Furthermore, our in vitro and in vivo results showed that the effect of netrin-1 on GC cells migration and invasion abilities was regulated by YAP. Collectively, our results defined netrin-1 as a positive regulator of malignant tumor metastasis in GC by activating the YAP signaling, with potential implications for new approaches to GC therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Glucagon-like peptide-1 contributes to increases ABCA1 expression by downregulating miR-758 to regulate cholesterol homeostasis

Abnormal regulation of lipid metabolism is associated with type 2 diabetes mellitus (T2DM). GLP-1 as a new treatment for T2DM, has unique effects in modulating cholesterol homeostasis. However, the mechanism of this effect is largely missing. The aim of this study was to determine the effects of GLP-1 on cholesterol-induced lipotoxicity in hepatocytes and examine the underlying mechanisms. The cell viability was determined, and caspase-3 was used to detect the effects of GLP-1 on cholesterol-induced apoptosis. The alterations of miR-758 and ATP-binding cassette transporter A1 (ABCA1) resulting from cholesterol incubation or GLP-1 were detected by qRT-PCR and Western blot assays. Overexpression of miR-758 abrogated the GLP-1-mediated ABCA1 expression, and conversely, down-regulation of miR-758 aggravated GLP-1's action and revealed significant promotion effects. BODIPY-Cholesterol efflux assay revealed that treatment with miR-758 inhibitor significantly enhanced ABCA1-dependent cholesterol efflux, resulting in reduced total cholesterol. Furthermore, Oil red O staining and cholesterol measurement were used to detect lipid accumulation. As a result, cholesterol significantly attenuated cell viability, promoted cell apoptosis, and facilitated lipid accumulation, and these effects were reversed by GLP-1. This study provides evidence that, in HepG2 cells, GLP-1 may affect cholesterol homeostasis by regulating the expression of miR-758 and ABCA1. These data can inform the development of biomarkers for miR-758, and potentially other drugs, on the key pathways of lipid metabolism.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

GLP-1 receptor agonist liraglutide exerts central action to induce β-cell proliferation through medulla to vagal pathway in mice

Highlights: • ICV injected GLP-1RA liraglutide and GLP-1 induce pancreatic β-cell proliferation. • This effect is induced by single shot liraglutide at low dose not touching feeding. • This effect is inhibited by atropine and hence possibly mediated by vagal efferent. • ICV liraglutide activates dorsal vagal complex (DVC), suggesting DVC-vagal reflex. • This pathway may serve to counteract β-cell reduction in diabetic patients. Endogenous GLP-1 and GLP-1 receptor agonists (GLP-1RAs) regulate glucose metabolism via common and distinct mechanisms. Postprandial release of GLP-1 is modest and it is degraded by DPP-4 within 2 min, and hence it cannot enter the brain in substantial amount. In contrast, DPP-4-resistant GLP-1RAs are administered at 10 times higher concentration than endogenous GLP-1 level, which enables them to reach several brain regions including ARC and AP, the areas implicated in glucose metabolism. Hence, some of the effects of GLP-1RAs observed clinically and experimentally, including pancreatic β-cell proliferation, are thought to involve the brain. However, the effects of centrally acting GLP-1/GLP-1RAs on glucose metabolism and underlying neural mechanism are unclear. This study aimed to establish the link of central GLP-1/GLP-1RA action to pancreatic β-cell proliferation. Both subcutaneous (SC) and intracerebroventricular (ICV) injections of liraglutide increased the number of pancreatic β-cells expressing Ki67 and PCNA, proliferation markers, in C57BL/6J mice. This effect was induced by single ICV administration of liraglutide at relatively low dose that was incapable of suppressing food intake. These SC and ICV liraglutide-induced effects were inhibited by 50% and 70%, respectively, by pretreatment with atropine, a muscarinic receptor blocker. ICV liraglutide induced c-Fos expression in the area postrema (AP), nucleus tractus solitaries (NTS), and dorsal motor nucleus of the vagus (DMX) of the brain stem. These results demonstrate that central action of liraglutide induces pancreatic β-cell proliferation via the pathway involving the brain stem AP/NTS/DMX area and vagus nerve. This route is highly sensitive to GLP-1/GLP-1RA. Hence, this brain-pancreatic β-cell pathway may operate in type 2 diabetic patients treated with GLP-RAs and serve to counteract the reduction of β-cell mass.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

IGF-1 resist oxidative damage to HaCaT and depigmentation in mice treated with H2O2

Vitiligo, an acquired pigmentary disorder of the skin, is characterized by a chronic and progressive loss of melanocyte from the epidermis and follicular reservoir. Growth factor of surrounding cells impacted on melanocytes survival. In this study, lower level of IGF-1 in the lesion was found than that in the donor area of vitiligo patients. IGF-1 improved activation of Nrf2, and inhibited ROS generation and endoplasmic reticulum dilation in HaCaT. C57BL/6 mice were treated with 5% H{sub 2}O{sub 2}, and combined with 50 μg/kg of IGF-1 pre-treatment or not once every day for 50 consecutive days. After 50 days, IGF-1 obviously ameliorated depigmentation of mice skin and reduced hair follicle length, skin thickness and Tyrosinase induced by H{sub 2}O{sub 2.} Moreover, IGF-1 significantly suppressed CD8{sup +} T cells infiltration in mice skin, inhibited the production of IL-2 and IFN-γ, and decreased the expression of CXCL10 and CXCR3. Thus, the results indicated that IGF-1 could resist oxidative damage to HaCaT, suppress CD8{sup +} T cells infiltration and pro-inflammatory cytokines secretion, and suppresses the thinning of epidermal layer in vivo. It suggests that IGF-1 inhibits oxidative damage to HaCaT and immunosuppressive effects on CD8{sup +} T cells proliferation and activation to resist depigmentation induced by H{sub 2}O{sub 2}. This disclosed its multiple roles in the vitiligo, and shed a light on developing the application potential for IGF-1 in vitiligo.

60 APPLIED LIFE SCIENCES↗