foxo is required for resistance to amino acid starvation in Drosophila

Genome ◽  
2008 ◽  
Vol 51 (8) ◽  
pp. 668-672 ◽  
Author(s):  
Jamie M. Kramer ◽  
Jennifer D. Slade ◽  
Brian E. Staveley
Keyword(s):  
Amino Acid ◽  
Insulin Signalling ◽  
Amino Acid Starvation ◽  
Reproductive Capacity ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Insulin Signalling Pathway ◽  
Evolutionarily Conserved ◽  
Sense And Respond

The ability of an organism to alter its metabolism, growth, and reproductive capacity in response to fluctuations in food availability has likely been an important factor in the course of evolution. The insulin signalling pathway is an evolutionarily conserved mechanism used by metazoan animals to sense and respond to changes in nutrient intake. During conditions of starvation the level of circulating insulin is low. Under conditions of low insulin, the foxo family of transcription factors are activated. Studies in Drosophila suggest that Drosophila foxo may alter the transcriptional profile of cells to allow for maximum survival of the fly during starvation. We have tested this ability in transgenic flies containing a luciferase reporter gene under the control of foxo response elements. We show that foxo activity is increased during amino acid starvation and reduced in the presence of amino acids. In addition, we find that loss of function of foxo leads to reduced survival under conditions of amino acid starvation in both larvae and adult flies. These data provide direct evidence that foxo is activated during amino acid starvation and is critical for optimal survival under these conditions.

scholarly journals Contribution of microRNA-30d to the prevention of the thyroid cancer progression: mechanism and implications

2020 ◽  
Author(s):  
Yuan Shao ◽  
Shaoqiang Zhang ◽  
Xiaoxia Wang ◽  
Xin Sun ◽  
Jie Wu ◽  
...  
Keyword(s):  
Thyroid Cancer ◽  
Cancer Progression ◽  
Endocrine Tumor ◽  
Luciferase Reporter ◽  
Tunel Staining ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Gene Assay ◽  
Low Expression

Abstract Background Thyroid cancer is a major endocrine tumor and represents an emerging health problem worldwide. MicroRNAs (miRNAs) have been addressed to be associated with the pathogenesis and progression of thyroid cancer. However, it remains largely unknown what functions miR-30d may exert on thyroid cancer. This study herein aimed to identify the functional significance and mechanism of miR-30d in the progression of thyroid cancer. Methods The expression of miR-30d and ubiquitin-specific protease 22 (USP22) in cancerous tissues of patients with thyroid cancer was measured using RT-qPCR and Western blot analysis. In response to the gain- or loss-of-function of miR-30d and USP22, cell apoptosis was evaluated by flow cytometry and TUNEL staining in combination with the measurement of apoptosis-related proteins. The interactions among miR-30d, USP22, SIRT1, FOXO3a and PUMA were explored using a series of assays, including dual-luciferase reporter gene assay, Co-IP and ChIP assay. The effects of miR-30d and USP22 on thyroid tumorigenesis were finally validated in vivo. Results MiR-30b presented aberrant low expression in thyroid cancer tissues and this low expression correlated with poor prognosis of thyroid cancer patients. miR-30d promoted apoptosis of thyroid cancer cells through targeting USP22, an up-regulated gene in thyroid cancer. USP22 could enhance the stability of SIRT1 by inducing deubiquitination which consequently contributed to FOXO3a deacetylation-induced PUMA repression. It was verified that this regulatory mechanism was responsible for the pro-apoptotic effect of miR-30d by the in vivo tumorigenicity assay. Conclusion To conclude, the progression of thyroid cancer can be suppressed by miR-30d-mediated inhibition of USP22, provides a promising therapeutic target for thyroid cancer treatment.

scholarly journals miR-373-3p inhibits EMT via regulation of TGFβR2 in choriocarcinoma

2019 ◽  
Author(s):  
yanjie lu ◽  
Xiaoru Li ◽  
Yanzhen Zuo ◽  
qian xu ◽  
lei liu ◽  
...  
Keyword(s):  
Western Blot ◽  
Untranslated Region ◽  
Bioinformatic Analysis ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Early Metastasis ◽  
Choriocarcinoma Cells ◽  
Jar Cells

Abstract Background: Previous studies have indicated that early metastasis is a major cause of mortality in patients with choriocarcinoma. However, what determines whether early metastasis of choriocarcinoma has occurred is unknown. The emerging role of miRNA in regulating cancer development and progression has been recognized. MiR-373-3p has been shown to play pivotal roles in tumorigenesis and metastasis. However, whether miR-373-3p functions to promote choriocarcinoma metastasis is not clear. The purpose of this study is to determine the function of miR-373-3p in the progression of choriocarcinoma. Methods: In this study, we first compared EMT-related markers, which are inversely correlated with miR-373-3p expression, in trophoblast and choriocarcinoma cell lines. Using PCR and western blot, the upregulation of miR‑373‑3p was observed to inhibit EMT progression. Similarly, gain-and loss-of-function studies revealed that ectopic miR-373-3p overexpression inhibited the metastasis of choriocarcinoma cells. Results: Our results revealed that miR-373-3p functions as an inhibitor in JEG-3 and JAR cells; this is due to its mediation of the TGF-β signalling pathway, which is responsible for EMT. The bioinformatic analysis and dual‑luciferase reporter gene assays were employed to verify that miR‑373‑3p might interact with the 3' untranslated region of TGFβR2 mRNA. Further western blot results showed miR‑373‑3 preversed the increases of TGFβR2 and inhibited EMT. Conclusions: In light of our observations, miR‑373‑3p upregulation partly accounts for TGFβR2 downregulation and leads to a restraint of EMT and metastasis. MiR‑373‑3p may, therefore, serve as a valuable target in potential anticancer strategies to treat choriocarcinoma.

scholarly journals ELK4 promotes the development of gastric cancer by inducing M2 polarization of macrophages through regulation of the KDM5A-PJA2-KSR1 axis

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Lei Zheng ◽  
Hongmei Xu ◽  
Ya Di ◽  
Lanlan Chen ◽  
Jiao Liu ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Transcriptional Activation ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
M2 Polarization ◽  
Lysine Specific Demethylase ◽  
Dependent Inhibition ◽  
Kinase Suppressor Of Ras ◽  
The Stability

Abstract Background We tried to elaborate the molecular mechanism of ETS-like transcription factor 4 (ELK4) affecting gastric cancer (GC) progression through M2 polarization of macrophages mediated by lysine-specific demethylase 5A (KDM5A)-Praja2 (PJA2)-kinase suppressor of ras 1 (KSR1) axis. Methods GC expression dataset was obtained from GEO database, and the downstream regulatory mechanism of ELK4 was predicted. Tumor-associated macrophages (TAMs) were isolated from GC tissues. The interaction among ELK4, KDM5A, PJA2 and KSR1 was analyzed by dual luciferase reporter gene, ChIP and Co-IP assays. The stability of KSR1 protein was detected by cycloheximide (CHX) treatment. After TAMs were co-cultured with HGC-27 cells, HGC-27 cell biological processes were assessed through gain- and loss-of function assays. Tumorigenicity was detected by tumorigenicity test in nude mice. Results In GC and TAMs, ELK4, KDM5A and KSR1 were highly expressed, while PJA2 was lowly expressed. M2 polarization of macrophages promoted the development of GC. ELK4 activated KDM5A by transcription and promoted macrophage M2 polarization. KDM5A inhibited the expression of PJA2 by removing H3K4me3 of PJA2 promoter, which promoted M2 polarization of macrophages. PJA2 reduced KSR1 by ubiquitination. ELK4 promoted the proliferative, migrative and invasive potentials of GC cells as well as the growth of GC xenografts by regulating KSR1. Conclusion ELK4 may reduce the PJA2-dependent inhibition of KSR1 by transcriptional activation of KDM5A to promote M2 polarization of macrophages, thus promoting the development of GC.

Inactivation of a Frameshift TSH Receptor Variant Val711Phefs*18 is Due to Acquisition of a Hydrophobic Degron

2020 ◽  
Vol 106 (1) ◽  
pp. e265-e272
Author(s):  
Chiho Sugisawa ◽  
Makoto Ono ◽  
Kenichi Kashimada ◽  
Tomonobu Hasegawa ◽  
Satoshi Narumi
Keyword(s):  
Amino Acid ◽  
Congenital Hypothyroidism ◽  
Fluorescent Protein ◽  
Transmembrane Domain ◽  
Tsh Receptor ◽  
Hek293 Cells ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Tail Region

Abstract Context Inactivating variants of thyrotropin (thyroid-stimulating hormone; TSH) receptor (TSHR) cause congenital hypothyroidism. More than 60 such variants have been reported so far, most of which were located in the extracellular or transmembrane domain. Objective We report the identification and characterization of a frameshift TSHR variant in the intracytoplasmic C-tail region. Methods Sequencing of TSHR was performed in a patient with congenital hypothyroidism. The functionality of the identified variants was assessed by expressing TSHR in HEK293 cells and measuring TSH-dependent activation of the cAMP–response element-luciferase reporter. A series of systematic mutagenesis experiments were performed to characterize the frameshifted amino acid sequence. Results The proband was heterozygous for a known TSHR variant (p.Arg519His) and a novel frameshift TSHR variant (p.Val711Phefs*18), which removed 54 C-terminal residues and added a 17–amino acid frameshifted sequence. The loss of function of Val711Phefs*18-TSHR was confirmed in vitro, but the function of Val711*-TSHR was found to be normal. Western blotting showed the low protein expression of Val711Phefs*18-TSHR. Fusion of the frameshift sequence to green fluorescent protein or luciferase induced inactivation of them, indicating that the sequence acted as a degron. A systematic mutagenesis study revealed that the density of hydrophobic residues in the frameshift sequence determined the stability. Eight additional frameshift TSHR variants that covered all possible shifted frames in C-tail were created, and another frameshift variant (Thr748Profs*27) with similar effect was found. Conclusions We characterized a naturally occurring frameshift TSHR variant located in C-tail, and provided a unique evidence that hydrophobicity in the C-terminal region of the receptor affects protein stability.

scholarly journals Identification of the ASPM-miR-26b-5p network associated with the aggressive traits of HCC cells

2020 ◽  
Author(s):  
Hong-Guang Li ◽  
Heng-Jun Gao ◽  
Fang-Feng Liu ◽  
Jun Liu
Keyword(s):  
Tumor Model ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Luciferase Reporter Gene Assay ◽  
Gene Assay ◽  
Hcc Cells

Abstract Background: Even though earlier reports have revealed that abnormal spindle-like microcephaly associated (ASPM) exert essential roles in diverse malignancies, its relationship between specific microRNAs (miRNAs) in regulation of hepatocellular carcinoma (HCC) progression has never been elaborated. Methods: Bioinformatics analysis detected differentially expressed genes in HCC and normal. qRT-PCR was performed to detect expression of miR-26b-5p in HCC tissues and cells. HCC cells were transfected with plasmids and their proliferative ability and colony formation were detected with loss-of-function assay. The invasion of HCC cells was determined using Transwell assay. The expression of ASPM was detected by western blotting. Luciferase reporter gene assay was performed to detect the interaction between miR-26b-5p and ASPM. ASMP silencing cells were injected into mice to establish xenograft tumor model.Results: Herein, we proved that ASPM was upregulated in HCC and higher level of ASPM was significantly associated with worse survival in HCC patients. ASPM silencing restrained HCC cell proliferation, migration and invasion capacities in vitro. In vivo, downregulation of ASPM also suppressed HCC cells growth. Mechanistic analyses illustrated that ASPM was a directly target of miR-26b-5p. The expression of ASPM was negatively modulated by miR-26b-5p. Rescues assays displayed that miR-26b-5p inhibited HCC cells growth and invasion via modulating the expression of ASPM. Conclusions: Our work validated that miR-26b-5p restrained the aggressiveness of HCC cells through targeting ASPM.

scholarly journals PQLC2 recruits the C9orf72 complex to lysosomes in response to cationic amino acid starvation

2019 ◽  
Vol 219 (1) ◽  
Author(s):  
Joseph Amick ◽  
Arun Kumar Tharkeshwar ◽  
Gabriel Talaia ◽  
Shawn M. Ferguson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Starvation ◽  
Cationic Amino Acid Transporter ◽  
Cationic Amino Acid ◽  
Binding Partner ◽  
Sensing Mechanism ◽  
Cationic Amino Acids ◽  
Sense And Respond ◽  
Amino Acid Sensing

The C9orf72 protein is required for normal lysosome function. In support of such functions, C9orf72 forms a heterotrimeric complex with SMCR8 and WDR41 that is recruited to lysosomes when amino acids are scarce. These properties raise questions about the identity of the lysosomal binding partner of the C9orf72 complex and the amino acid–sensing mechanism that regulates C9orf72 complex abundance on lysosomes. We now demonstrate that an interaction with the lysosomal cationic amino acid transporter PQLC2 mediates C9orf72 complex recruitment to lysosomes. This is achieved through an interaction between PQLC2 and WDR41. The interaction between PQLC2 and the C9orf72 complex is negatively regulated by arginine, lysine, and histidine, the amino acids that PQLC2 transports across the membrane of lysosomes. These results define a new role for PQLC2 in the regulated recruitment of the C9orf72 complex to lysosomes and reveal a novel mechanism that allows cells to sense and respond to changes in the availability of cationic amino acids within lysosomes.

scholarly journals SOX2 knockdown slows cholangiocarcinoma progression through inhibition of transcriptional activation of lncRNA PVT1

2020 ◽  
Vol 477 (18) ◽  
pp. 3527-3540
Author(s):  
Aijun Yu ◽  
Luwen Zhao ◽  
Qingmin Kang ◽  
Jian Li ◽  
Kai Chen ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
High Rate ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Nude Mouse Model ◽  
Mortality And Morbidity ◽  
Gene Assay

Cholangiocarcinoma (CCA) has accounted for a high rate of mortality and morbidity in the recent years. Long non-coding RNAs (lncRNAs) play an important role in different cellular environments, including cancer. As such, they have been used as potential targets during CCA therapy. The objective of this study was to investigate the effects of lncRNA PVT1 on CCA and its mechanisms behind lncRNA PVT1 regulation. The interactions among SOX2, lncRNA PVT1, miR-186 and SEMA4D were verified by chromatin immunoprecipitation, RNA immunoprecipitation and dual luciferase reporter gene assay. Gain- and loss-of-function experiments were conducted to explore the modulatory effects of SOX2, lncRNA PVT1, miR-186 and SEMA4D on cell viability, migration and invasion of CCA by CCK-8 and Transwell assays. In vivo effects of lncRNA PVT1 or SEMA4D were studied in a nude mouse model. MiR-186 was poorly expressed while SOX2, lncRNA PVT1 and SEMA4D were highly expressed in CCA cells. SOX2 induced the transcriptional activation of lncRNA PVT1 expression to promote proliferation, migration and invasion of CCA cells. LncRNA PVT1 bound to miR-186 and miR-186 was found to target SEMA4D. The overexpression of lncRNA PVT1 and SEMA4D, as well as the inhibition of miR-186 led to elevated CCA cell proliferation, migration and invasion. In vivo experiments confirmed the inhibitory role of lncRNA PVT1 knockdown or SEMA4D knockdown in CCA. All in all, SOX2 down-regulated miR-186 through the transcriptional activation of lncRNA PVT1, whereas elevating SEMA4D expression, thus promoting the progression of CCA.

scholarly journals Promotion of viral internal ribosomal entry site-mediated translation under amino acid starvation

2012 ◽  
Vol 93 (5) ◽  
pp. 951-962 ◽  
Author(s):  
Maria Licursi ◽  
Yumiko Komatsu ◽  
Theerawat Pongnopparat ◽  
Kensuke Hirasawa
Keyword(s):  
Amino Acid ◽  
Internal Ribosomal Entry Site ◽  
Amino Acid Starvation ◽  
Encephalomyocarditis Virus ◽  
Initiation Factor ◽  
Luciferase Reporter ◽  
Eukaryotic Initiation Factor ◽  
Entry Site ◽  
Ribosomal Entry ◽  
Cellular Stresses

Cap-dependent and internal ribosomal entry site (IRES)-mediated translation are regulated differently within cells. Viral IRES-mediated translation often remains active when cellular cap-dependent translation is severely impaired under cellular stresses induced by virus infection. To investigate how cellular stresses influence the efficiency of viral IRES-mediated translation, we used a bicistronic luciferase reporter construct harbouring IRES elements from the following viruses: encephalomyocarditis virus (EMCV), foot-and-mouth disease virus (FMDV), hepatitis C virus (HCV) or human rhinovirus (HRV). NIH3T3 cells transfected with these bicistronic reporter constructs were subjected to different cellular stresses. Increased translation initiation was only observed under amino acid starvation when EMCV or FMDV IRES elements were present. To identify cellular mechanisms that promoted viral IRES-mediated translation, we tested the involvement of eukaryotic initiation factor 4E-binding protein (4E-BP), general control non-depressed 2 (GCN2) and eukaryotic initiation factor 2B (eIF2B), as these are known to be modulated under amino acid starvation. Knockdown of 4E-BP1 impaired the promotion of EMCV and FMDV IRES-mediated translation under amino acid starvation, whereas GCN2 and eIF2B were not involved. To further investigate how 4E-BP1 regulates translation initiated by EMCV and FMDV IRES elements, we used a phosphoinositide kinase-3 inhibitor (LY294002), an mTOR inhibitor (Torin1) or leucine starvation to mimic 4E-BP1 dephosphorylation induced by amino acid starvation. 4E-BP1 dephosphorylation induced by the treatments was not sufficient to promote viral IRES-mediated translation. These results suggest that 4E-BP1 regulates EMCV and FMDV IRES-mediated translation under amino acid starvation, but not via its dephosphorylation.

scholarly journals LncRNA MYLK-AS1 facilitates tumor progression and angiogenesis by targeting miR-424-5p/E2F7 axis and activating VEGFR-2 signaling pathway in hepatocellular carcinoma

2020 ◽  
Author(s):  
Fei Teng ◽  
Ju-Xiang Zhang ◽  
Qi-Meng Chang ◽  
Xu-Bo Wu ◽  
Wei-Guo Tang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Tumor Progression ◽  
Underlying Mechanism ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Tumor Tissues ◽  
Vegfr2 Signaling

Abstract BackgroundLong non-coding RNA is essential for the metastasis, invasion, angiogenesis and progression of hepatocellular carcinoma (HCC). However, their specific mechanisms are still controversial. Here, we found that Lnc-MYLK-AS1 is a potential oncogene. We systematically analyzed the clinical significance and mechanism of Lnc-MYLK-AS1 in HCC metastasis, invasion and angiogenesis.MethodsDetermine research goals through bioinformatics analysis. The expression of MYLK-AS1 in matched tumor and non-tumor tissues of 156 HCC patients was detected by quantitative reverse transcription PCR. The in vitro and in vivo biological functions of MYLK-AS1 were examined through the loss of function and function gain experiments. The use of dual luciferase reporter gene analysis, quantitative PCR, Western blotting, and fluorescence in situ hybridization (FISH) clarified the underlying mechanism of this competitive endogenous RNA (ceRNA). ResultsMYLK-AS1 is up-regulated in HCC cell lines and tumor tissues, which is related to tumor progression and enhancement of angiogenesis. Overexpression of MYLK-AS1 promotes the proliferation, metastasis, invasion, and angiogenesis of HCC cells, while down-regulation of MYLK-AS1 can reverse these effects in vivo and in vitro. Dual analysis of luciferase and RNA immunoprecipitation showed that microRNA miR-424-5p is the direct target of MYLK-AS1, and MYLK-AS1 acts as ceRNA, which can regulate angiogenesis in HCC. Mechanism studies have shown that miR-424-5p specifically targets E2F transcription factor 7 (E2F7), while the complex MYLK-AS1/miR-424-5p activates VEGFR2 signaling through E2F7, thereby promoting tumor proliferation and angiogenesis.ConclusionThe up-regulation of MYLK-AS1 is related to tumor cell proliferation, increased angiogenesis and poor prognosis in HCC patients. MYLK-AS1 regulates E2F7 expression and VEGFR2 signaling by acting as a ceRNA of miR-424-5p.

scholarly journals Overexpressed microrna-129-5p reverses CCl4-Induced hepatic fibrosis by suppressing PEG3 expression and the NF-κB signaling pathway

2020 ◽  
Author(s):  
Shengtao Sun ◽  
Yunxia Ma ◽  
Yinfeng Li
Keyword(s):  
Signaling Pathway ◽  
Hepatic Fibrosis ◽  
Gene Expression Regulation ◽  
Function Analysis ◽  
Luciferase Reporter ◽  
Tunel Staining ◽  
Loss Of Function ◽  
Luciferase Reporter Gene ◽  
Related Factors ◽  
Gene Assay

AbstractHepatic fibrosis is a pathological process resulting from liver damage, which leads to the extracellular matrix (ECM) proteins accumulation in the liver. Considering that microRNA (miR)-129-5p has a vital effect in the gene expression regulation about fibrosis through transcriptional profiling, this study speculated whether miR-129-5p had potential to influence the progression of hepatic fibrosis. The hepatic fibrosis rat models induced by C-C motif chemokine ligand 4 (CCl4) were established. The pathological changes of the liver tissues were assayed with hematoxylin-eosin (HE) staining. Subsequently, gain- and loss-of-function analysis with miR-129-5p antagomir or shRNA against PEG3 was conducted to further investigate the molecular regulatory mechanism of miR-129-5p, with detection of the expression of NF-κB signaling pathway-related proteins and apoptosis-related factors. The serum samples of rats were analyzed by serological index analysis. The targeting of miR-129-5p to PEG3 was verified by dual-luciferase reporter gene assay. The detection of apoptosis in rats was measured by TUNEL staining. MiR-129-5p was poorly-expressed and PEG3 was highly-expressed in hepatic fibrosis. miR-129-5p could reduce the expression of PEG3. Next, upregulated miR-129-5p or downregulated PEG3 led to less obvious histological changes of liver cirrhosis and lowered apoptosis rate. Further, miR-129-5p regulated the activation of NF-κB signaling pathway via PEG3. The hepatic fibrosis induced by CCl4 can be reversed by upregulated miR-129-5p or downregulated PEG3 expression.

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