Circular RNA circESYT2 serves as a microRNA-665 sponge to promote the progression of hepatocellular carcinoma through ENO2

Circular RNAs (circRNAs) have emerged as crucial regulators in tumor progression, yet their specific role in hepatocellular carcinoma (HCC) remains largely uncharacterized. In this study, we utilized high-transcriptome sequencing to identify the upregulation of circESYT2 (hsa_circ_002142) in HCC tissues. Functional experiments carried out in vivo and in vitro revealed that circESYT2 played a significant role in maintaining the growth and metastatic behaviors of HCC. Through integrative analysis, we identified enolase 2 (ENO2) as a potential target regulated by circESYT2 through the competitive endogenous RNA sponge mechanism. Additional gain- or loss-of-function experiments indicated that overexpression of circESYT2 led to a tumor-promoting effect, which could be reversed by transfection of microRNA-665 (miR-665) mimic or ENO2 knockdown in HCC cells. Furthermore, the direct interaction between miR-665 and circESYT2 and between miR-665 and ENO2 was confirmed using RNA immunoprecipitation, FISH, RNA pull-down, and dual-luciferase reporter assays, highlighting the involvement of the circESYT2/miR-665/ENO2 axis in promoting HCC progression. These findings shed light on the molecular characteristics of circESYT2 in HCC tissues and suggest its potential as a biomarker or therapeutic target for HCC treatment.

Tumor-derived Exosomal ENO2 Modulates Polarization of Tumor-associated Macrophages through Reprogramming Glycolysis to Promote Progression of Diffuse Large B-cell Lymphoma

Macrophages can be polarized into functional classically activated (M1) or alternatively activated (M2) phenotype. Tumor-associated macrophages (TAMs) mainly exhibit M2 phenotype. Previous works determined that up-regulation of enolase 2 (ENO2) in diffuse large B-cell lymphoma (DLBCL) cells can promote macrophages to an M2-like phenotype, thereby consequently promoting the progression of DLBCL. Exosomes are a subset of extracellular vesicles, carrying various bioactive molecules, mediate signals transduction and regulate immune cells. In our study, we investigated the role and related mechanisms of DLBCL-derived exosomal ENO2 in regulating macrophage polarization during DLBCL progression via bioinformatics analysis and a series of experiments. The results of bioinformatics analysis indicated that high expression of ENO2 was positively correlated with DLBCL progression and macrophages M2/M1 ratio. ENO2 protein levels were increased in the exosomes of the sera of DLBCL patients and DLBCL cells. Moreover, the DLBCL-derived exosomes were assimilated by macrophages and then regulated macrophage polarization. The results of in vitro and in vivo experiments showed that DLBCL-derived exosomal ENO2 modulated macrophages polarization (increased M2 phenotype and decreased M1 phenotype), thereby promoting DLBCL proliferation, migration, and invasion. We then revealed that the modulation of macrophages polarization by DLBCL-derived exosomal ENO2 depended on glycolysis and was promoted through GSK3β/β-catenin/c-Myc signaling pathway. These findings suggested that DLBCL-derived exosomal ENO2 accelerated glycolysis via GSK3β/β-catenin/c-Myc signaling pathway to ultimately promote macrophages to an M2-like phenotype, which can promote the proliferation, migration and invasion of DLBCL, suggesting that exosomal ENO2 may be a promising therapeutic target and prognostic biomarker for DLBCL.

ALDOC- and ENO2- driven glucose metabolism sustains 3D tumor spheroids growth regardless of nutrient environmental conditions: a multi-omics analysis

BACKGROUND

Metastases are the major cause of cancer-related morbidity and mortality. By the time cancer cells detach from their primary site to eventually spread to distant sites, they need to acquire the ability to survive in non-adherent conditions and to proliferate within a new microenvironment in spite of stressing conditions that may severely constrain the metastatic process. In this study, we gained insight into the molecular mechanisms allowing cancer cells to survive and proliferate in an anchorage-independent manner, regardless of both tumor-intrinsic variables and nutrient culture conditions.

METHODS

3D spheroids derived from lung adenocarcinoma (LUAD) and breast cancer cells were cultured in either nutrient-rich or -restricted culture conditions. A multi-omics approach, including transcriptomics, proteomics, and metabolomics, was used to explore the molecular changes underlying the transition from 2 to 3D cultures. Small interfering RNA-mediated loss of function assays were used to validate the role of the identified differentially expressed genes and proteins in H460 and HCC827 LUAD as well as in MCF7 and T47D breast cancer cell lines.

RESULTS

We found that the transition from 2 to 3D cultures of H460 and MCF7 cells is associated with significant changes in the expression of genes and proteins involved in metabolic reprogramming. In particular, we observed that 3D tumor spheroid growth implies the overexpression of ALDOC and ENO2 glycolytic enzymes concomitant with the enhanced consumption of glucose and fructose and the enhanced production of lactate. Transfection with siRNA against both ALDOC and ENO2 determined a significant reduction in lactate production, viability and size of 3D tumor spheroids produced by H460, HCC827, MCF7, and T47D cell lines.

CONCLUSIONS

Our results show that anchorage-independent survival and growth of cancer cells are supported by changes in genes and proteins that drive glucose metabolism towards an enhanced lactate production. Notably, this finding is valid for all lung and breast cancer cell lines we have analyzed in different nutrient environmental conditions. broader Validation of this mechanism in other cancer cells of different origin will be necessary to broaden the role of ALDOC and ENO2 to other tumor types. Future in vivo studies will be necessary to assess the role of ALDOC and ENO2 in cancer metastasis.

Lower circulating neuron-specific enolase concentrations in adults and adolescents with severe mental illness

BACKGROUND

Both neurodegenerative and neurodevelopmental abnormalities have been suggested to be part of the etiopathology of severe mental illness (SMI). Neuron-specific enolase (NSE), mainly located in the neuronal cytoplasm, may indicate the process as it is upregulated after neuronal injury while a switch from non-neuronal enolase to NSE occurs during neuronal maturation.

METHODS

We included 1132 adult patients with SMI [schizophrenia (SZ) or bipolar spectrum disorders], 903 adult healthy controls (HC), 32 adolescent patients with SMI and 67 adolescent HC. Plasma NSE concentrations were measured by enzyme immunoassay. For 842 adults and 85 adolescents, we used total grey matter volume (TGMV) based on T1-weighted magnetic resonance images processed in FreeSurfer v6.0. We explored NSE case-control differences in adults and adolescents separately. To investigate whether putative case-control differences in NSE were TGMV-dependent we controlled for TGMV.

RESULTS

We found significantly lower NSE concentrations in both adult (p < 0.001) and adolescent patients with SMI (p = 0.007) compared to HC. The results remained significant after controlling for TGMV. Among adults, both patients with SZ spectrum (p < 0.001) and bipolar spectrum disorders (p = 0.005) had lower NSE than HC. In both patient subgroups, lower NSE levels were associated with increased symptom severity. Among adults (p < 0.001) and adolescents (p = 0.040), females had lower NSE concentrations than males.

CONCLUSION

We found lower NSE concentrations in adult and adolescent patients with SMI compared to HC. The results suggest the lack of progressive neuronal injury, and may reflect abnormal neuronal maturation. This provides further support of a neurodevelopmental rather than a neurodegenerative mechanism in SMI.

Identification of cerebral spinal fluid protein biomarkers in Niemann-Pick disease, type C1

BACKGROUND

Niemann-Pick disease, type C1 (NPC1) is an ultrarare, recessive, lethal, lysosomal disease characterized by progressive cerebellar ataxia and cognitive impairment. Although the NPC1 phenotype is heterogeneous with variable age of onset, classical NPC1 is a pediatric disorder. Currently there are no therapies approved by the FDA and therapeutics trials for NPC1 are complicated by disease rarity, heterogeneity, and the relatively slow rate of neurological decline. Thus, identification of disease relevant biomarkers is necessary to provide tools that can support drug development efforts for this devastating neurological disease.

METHODS

Proximal extension assays (O-link® Explore 1536) were used to compare cerebrospinal fluid (CSF) samples from individuals with NPC1 enrolled in a natural history study and non-NPC1 comparison samples. Relative expression levels of 1467 proteins were determined, and candidate protein biomarkers were identified by evaluating fold-change and adjusted Kruskal-Wallis test p-values. Selected proteins were orthogonally confirmed using ELISA. To gain insight into disease progression and severity we evaluated the altered protein expression with respect to clinically relevant phenotypic aspects: NPC Neurological Severity Score (NPC1 NSS), Annual Severity Increment Score (ASIS) and age of neurological onset.

RESULTS

This study identified multiple proteins with altered levels in CSF from individuals with NPC1 compared to non-NPC1 samples. These included proteins previously shown to be elevated in NPC1 (NEFL, MAPT, CHIT1, CALB1) and additional proteins confirmed by orthogonal assays (PARK7, CALB2/calretinin, CHI3L1/YKL-40, MIF, CCL18 and ENO2). Correlations with clinically relevant phenotypic parameters demonstrated moderate negative (p = 0.0210, r = -0.41) and possible moderate positive (p = 0.0631, r = 0.33) correlation of CSF CALB2 levels with age of neurological onset and ASIS, respectively. CSF CHI3L1 levels showed a moderate positive (p = 0.0183, r = 0.40) correlation with the concurrent NPC1 NSS. A strong negative correlation (p = 0.0016, r = -0.648) was observed between CSF CCL18 and age of neurological onset for childhood/adolescent cases. CSF CCL18 levels also showed a strong positive correlation (p = 0.0017, r = 0.61) with ASIS.

CONCLUSION

Our study identified and validated multiple proteins in CSF from individuals with NPC1 that are candidates for further investigation in a larger cohort. These analytes may prove to be useful as supportive data in therapeutic trials.

TRIAL REGISTRATIONS

NCT00344331, NCT00001721, NCT02931682.

Mediation of PKM2-dependent glycolytic and non-glycolytic pathways by ENO2 in head and neck cancer development

BACKGROUND

Enolase 2 (ENO2) is a crucial glycolytic enzyme in cancer metabolic process and acts as a "moonlighting" protein to play various functions in diverse cellular processes unrelated to glycolysis. ENO2 is highly expressed in head and neck squamous cell carcinoma (HNSCC) tissues relative to normal tissues; however, its impact and underlying regulatory mechanisms in HNSCC malignancy remain unclear.

METHODS

Molecular alterations were examined by bioinformatics, qRT-PCR, western blotting, immunofluorescence, immunohistochemistry, immunoprecipitation, and ChIP-PCR assays. Metabolic changes were assessed by intracellular levels of ATP and glucose. Animal study was used to evaluate the therapeutic efficacy of the ENO inhibitor.

RESULTS

ENO2 is required for HNSCC cell proliferation and glycolysis, which, surprisingly, is partially achieved by controlling PKM2 protein stability and its nuclear translocation. Mechanistically, loss of ENO2 expression promotes PKM2 protein degradation via the ubiquitin-proteasome pathway and prevents the switch of cytoplasmic PKM2 to the nucleus by inactivating AKT signaling, leading to a blockade in PKM2-mediated glycolytic flux and CCND1-associated cell cycle progression. In addition, treatment with the ENO inhibitor AP-III-a4 significantly induces HNSCC remission in a preclinical mouse model.

CONCLUSION

Our work elucidates the signaling basis underlying ENO2-dependent HNSCC development, providing evidence to establish a novel ENO2-targeted therapy for treating HNSCC.

Integrative transcriptomic and TMT-based proteomic analysis reveals the mechanism by which AtENO2 affects seed germination under salt stress

Seed germination is critical for plant survival and agricultural production and is affected by many cues, including internal factors and external environmental conditions. As a key enzyme in glycolysis, enolase 2 (ENO2) also plays a vital role in plant growth and abiotic stress responses. In our research, we found that the seed germination rate was lower in the AtENO2 mutation (eno2^- ) than in the wild type (WT) under salt stress in Arabidopsis thaliana, while there was no significant difference under normal conditions. However, the mechanisms by which AtENO2 regulates seed germination under salt stress remain limited. In the current study, transcriptome and proteome analyses were used to compare eno2^- and the WT under normal and salt stress conditions at the germination stage. There were 417 and 4442 differentially expressed genes (DEGs) identified by transcriptome, and 302 and 1929 differentially expressed proteins (DEPs) qualified by proteome under normal and salt stress conditions, respectively. The combined analysis found abundant DEGs and DEPs related to stresses and hydrogen peroxide removal were highly down-regulated in eno2^- . In addition, several DEGs and DEPs encoding phytohormone transduction pathways were identified, and the DEGs and DEPs related to ABA signaling were relatively greatly up-regulated in eno2^- . Moreover, we constructed an interactive network and further identified GAPA1 and GAPB that could interact with AtENO2, which may explain the function of AtENO2 under salt stress during seed germination. Together, our results reveal that under salt stress, AtENO2 mainly affects the expression of genes and proteins related to the phytohormone signal transduction pathways, stress response factors, and reactive oxygen species (ROS), and then affects seed germination. Our study lays the foundation for further exploration of the molecular function of AtENO2 under salt stress at the seed germination stage in Arabidopsis thaliana.

Overexpression of let-7d explains down-regulated KDM3A and ENO2 in the pathogenesis of preeclampsia

Pre‐eclampsia (PE) is the leading cause of maternal death; however, the causative molecular basis remains largely unknown. Recent studies have revealed the important role microRNAs (miRNAs) play in PE. We aimed to explore the effects of let‐7d on trophoblast proliferation, migration, invasion and apoptosis in PE and its underlying mechanism. Placental tissues were collected from PE patients and healthy pregnant women, and it was found that let‐7d expression was increased, while KDM3A and ENO2 expression was decreased in PE tissues and cells. Bioinformatics analysis indicated the interaction among let‐7d, KDM3A and ENO2, confirmed by dual luciferase reporter gene assay; ChIP experiment identified methylated modification to ENO2 by KDM3A. With gain‐ and loss‐function method, silencing of let‐7d increased KDM3A expression and enhanced the binding between KDM3A and ENO2. Furthermore, overexpression of let‐7d suppressed cell proliferation, migration and invasion of trophoblasts, and induced apoptosis of trophoblasts, while these capacities were restored upon additional treatment of overexpressed ENO2. PE rat models were established to explore the effects of let‐7d and ENO2 on PE in vivo. The results established that the silencing of let‐7d alleviated the tissue injury and PE‐related symptoms when reducing urine protein, TUNEL‐positive cells and increasing ENO2, and KDM3A expression in rats. Cumulatively, let‐7d suppressed cell progression of trophoblasts, and induced apoptosis through the down‐regulation of KDM3A to promote ENO2 methylation, thereby promoting progression of PE. Such an epigenetic network of let‐7d, KDM3A and ENO2 in the pathogenesis of PE might provide novel insight into targeted therapy against this disorder.

AtENO2 functions in the development of male gametophytes in Arabidopsis thaliana

Pollen fertility is an important factor affecting the seed setting rate and seed yield of plants. The Arabidopsis thaliana enolase gene ENO2 (AtENO2) can affect the pollen morphology, germination, and pollen tube growth. AtENO2 encodes two proteins AtENO2 and AtMBP-1. To examine the effect of AtENO2 protein on pollen development, the 2nd ATG of the AtENO2 coding sequence for AtMBP-1 was mutated by site-directed mutagenesis, and transgenic plants expressing only AtENO2 but not AtMBP-1 were obtained. Phenotypic analysis indicated that AtENO2 was essential in the pollen development. The mechanisms of AtENO2 on pollen development were analyzed. AtENO2 can affect development of the pollen intine, and the mechanism may be that AtENO2 regulated the methyl esterification of pectin in pollen intine through ARF3 and AtPMEI-pi. The -734 ∼ -573 sequence of AtENO2 promoter is the main transcriptional regulatory region of AtENO2 affecting pollen development. The functional cis-acting element may be GTGANTG10(GTGA), and the trans-acting factors may be KAN, AS2 and ARF3/ETT. Moreover, the deletion of AtENO2 can cause significant difference in the expression of multiple genes related to pollen exine development. These results are useful for further studying the function of AtENO2 and exploring the mechanism of plant pollen development.

Co-opting of nonATP-generating glycolytic enzymes for TBSV replication

Positive-strand RNA viruses build viral replication organelles (VROs) with the help of co-opted host factors. The energy requirement of intensive viral replication processes is less understood. Previous studies on tomato bushy stunt virus (TBSV) showed that tombusviruses hijack two ATP-producing glycolytic enzymes to produce ATP locally within VROs. In this work, we performed a cDNA library screen with Arabidopsis thaliana proteins and the TBSV p33 replication protein. The p33 - plant interactome contained highly conserved glycolytic proteins. We find that the glycolytic Hxk2 hexokinase, Eno2 phosphopyruvate hydratase and Fba1 fructose 1,6-bisphosphate aldolase are critical for TBSV replication in yeast or in a cell-free replicase reconstitution assay. The recruitment of Fba1 is important for the local production of ATP within VROs. Altogether, our data support the model that TBSV recruits and compartmentalizes possibly most members of the glycolytic pathway. This might allow TBSV to avoid competition with the host for ATP.

Identification of VEGFA-centric temporal hypoxia-responsive dynamic cardiopulmonary network biomarkers

AIMS

Hypoxia, a pathophysiological condition, is profound in several cardiopulmonary diseases (CPD). Every individual's lethality to a hypoxia state differs in terms of hypoxia exposure time, dosage units and dependent on the individual's genetic makeup. Most of the proposed markers for CPD were generally aim to distinguish disease samples from normal samples. Although, as per the 2018 GOLD guidelines, clinically useful biomarkers for several cardio pulmonary disease patients in stable condition have yet to be identified. We attempt to address these key issues through the identification of Dynamic Network Biomarkers (DNB) to detect hypoxia induced early warning signals of CPD before the catastrophic deterioration.

MATERIALS AND METHODS

The human microvascular endothelial tissues microarray datasets (GSE11341) of lung and cardiac expose to hypoxia (1% O₂) for 3, 24 and 48 h were retrieved from the public repository. The time dependent differentially expressed genes were subjected to tissue specificity and promoter analysis to filtrate the noise levels in the networks and to dissect the tissue specific hypoxia induced genes. These filtered out genes were used to construct the dynamic segmentation networks. The hypoxia induced dynamic differentially expressed genes were validated in the lung and heart tissues of male rats. These rats were exposed to hypobaric hypoxia (simulated altitude of 25,000 or PO₂ - 282 mm of Hg) progressively for 3, 24 and 48 h.

KEY FINDINGS

To identify the temporal key genes regulated in hypoxia, we ranked the dominant genes based on their consolidated topological features from tissue specific networks, time dependent networks and dynamic networks. Overall topological ranking described VEGFA as a single node dynamic hub and strongly communicated with tissue specific genes to carry forward their tissue specific information. We named this type of VEGFAcentric dynamic networks as "V-DNBs". As a proof of principle, our methodology helped us to identify the V-DNBs specific for lung and cardiac tissues namely V-DNB^L and V-DNB^C respectively.

SIGNIFICANCE

Our experimental studies identified VEGFA, SLC2A3, ADM and ENO2 as the minimum and sufficient candidates of V-DNB^L. The dynamic expression patterns could be readily exploited to capture the pre disease state of hypoxia induced pulmonary vascular remodelling. Whereas in V-DNB^C the minimum and sufficient candidates are VEGFA, SCL2A3, ADM, NDRG1, ENO2 and BHLHE40. The time dependent single node expansion indicates V-DNB^C could also be the pre disease state pathological hallmark for hypoxia-associated cardiovascular remodelling. The network cross-talk and expression pattern between V-DNB^L and V-DNB^C are completely distinct. On the other hand, the great clinical advantage of V-DNBs for pre disease predictions, a set of samples during the healthy condition should suffice. Future clinical studies might further shed light on the predictive power of V-DNBs as prognostic and diagnostic biomarkers for CPD.

Specific activation of glycolytic enzyme enolase 2 in BRAF V600E-mutated colorectal cancer

The BRAF V600E mutation occurs in approximately 10% of patients with metastatic colorectal cancer (CRC) and constitutes a distinct subtype of the disease with extremely poor prognosis. To address this refractory disease, we investigated the unique metabolic gene profile of BRAF V600E‐mutated tumors via in silico analysis using a large‐scale clinical database. We found that BRAF V600E‐mutated tumors exhibited a specific metabolic gene expression signature, including some genes that are associated with poor prognosis in CRC. We discovered that BRAF V600E‐mutated tumors expressed high levels of glycolytic enzyme enolase 2 (ENO2), which is mainly expressed in neuronal tissues under physiological conditions. In vitro experiments using CRC cells demonstrated that BRAF V600E‐mutated cells exhibited enhanced dependency on ENO2 compared to BRAF wild‐type cancer cells and that knockdown of ENO2 led to the inhibition of proliferation and migration of BRAF V600E‐mutated cancer cells. Moreover, inhibition of ENO2 resulted in enhanced sensitivity to vemurafenib, a selective inhibitor of BRAF V600E. We identified AP‐1 transcription factor subunit (FOSL1) as being involved in the transcription of ENO2 in CRC cells. In addition, both MAPK and PI3K/Akt signaling were suppressed upon inhibition of ENO2, implying an additional oncogenic role of ENO2. These results suggest the crucial role of ENO2 in the progression of BRAF V600E‐mutated CRC and indicate the therapeutic implications of targeting this gene.

Enolase2 and enolase1 cooperate against neuronal injury in stroke model

Stroke is one of the leading causes of death in adults worldwide. However, the mechanism causing neuronal death remains poorly understood. Our previous report showed that enolase1 (ENO1), a key glycolytic enzyme, alleviates cerebral ischemia-induced neuronal injury. It remained unclear whether enolase2 (ENO2) affects neuronal injury in stroke models. Here, we examined the effects of ENO2 in several stroke models. The results showed that the expression level of ENO2 was downregulated after 3 h of cerebral ischemia by middle cerebral artery occlusion (MCAO) in the mouse model. ENO2 was expressed in mouse brain and cultured hippocampus neurons. Overexpression of ENO2 in cultured hippocampus neurons did not affect neuronal injury in our oxygen-glucose deprivation (OGD) model. Interestingly, double knock-down (KD) of ENO1 and ENO2 increased neuronal injury while either KD of ENO1 or ENO2 failed to increase neuronal injury in OGD. Deletion of ENO1 did not affect anoxia-starvation (AS)-induced worm death in C. elegans. These findings demonstrated that ENO2 and ENO1 work together against neuronal injury in these stroke models.

Quantitative Proteomics Reveals that GmENO2 Proteins Are Involved in Response to Phosphate Starvation in the Leaves of Glycine max L

Soybean (Glycine max L.) is a major crop providing important source for protein and oil for human life. Low phosphate (LP) availability is a critical limiting factor affecting soybean production. Soybean plants develop a series of strategies to adapt to phosphate (Pi) limitation condition. However, the underlying molecular mechanisms responsible for LP stress response remain largely unknown. Here, we performed a label-free quantification (LFQ) analysis of soybean leaves grown under low and high phosphate conditions. We identified 267 induced and 440 reduced differential proteins from phosphate-starved leaves. Almost a quarter of the LP decreased proteins are involved in translation processes, while the LP increased proteins are accumulated in chlorophyll biosynthetic and carbon metabolic processes. Among these induced proteins, an enolase protein, GmENO2a was found to be mostly induced protein. On the transcriptional level, GmENO2a and GmENO2b, but not GmENO2c or GmENO2d, were dramatically induced by phosphate starvation. Among 14 enolase genes, only GmENO2a and GmENO2b genes contain the P1BS motif in their promoter regions. Furthermore, GmENO2b was specifically induced in the GmPHR31 overexpressing soybean plants. Our findings provide molecular insights into how soybean plants tune basic carbon metabolic pathway to adapt to Pi deprivation through the ENO2 enzymes.

Krüppel-like factor 12 suppresses bladder cancer growth through transcriptionally inhibition of enolase 2

Krüppel-like factors (KLFs) are transcription factors and play important roles in bladder cancer (BC). Clarifying the function of KLFs will provide new strategies for clinical treatment of BC. In this study, we found that Krüppel-like factor 12 (KLF12) was decreased in BC tissues and cells. Knockdown of KLF12 by siRNA dramatically elevated the proliferation and colony formation of BC cells. By contrast, overexpressing KLF12 suppressed the cell viability and the number of clones. Overexpression of KLF12 also regulated cell cycle progression, apoptosis and migration of BC cells. Furthermore, KLF12 bound to the promoter of enolase 2 (ENO2) and transcriptionally inhibited the expression of ENO2, which was highly expressed in BC tissues. KLF12 suppressed, while ENO2 promoted glycolysis. Lastly, ENO2 overexpression and knockdown promoted and suppressed the proliferation and migration of BC cells, respectively. These results suggest that KLF12 acts as a tumor suppressor by negatively regulated ENO2. Targeting ENO2 is a promising treatment strategy for this malignancy.

Overexpression of enolase 2 is associated with worsened prognosis and increased glycikolysis in papillary renal cell carcinoma

Papillary renal cell carcinoma (pRCC) is characterized with underlying genetic disorders and the role enolase 2 (ENO2) in ccRCC is unknown. An in silico exploratory analysis using multiple public genetic datasets was used to establish association between ENO2 expression and clinicopathological parameters. Associations of interest were validated using 49 pRCC samples using immunohistochemistry. In vitro and in vivo assays were carried out to validate findings in tissue. ENO2 was overexpressed and prognostic in pRCC. ENO2 expression was significantly higher in younger patients and in CpG island methylator phenotype subtype. ENO2-overexpressed cases showed significant enrichment in glycolysis. Overexpression of ENO2 significantly increased proliferation and silencing of ENO2 significantly inhibited growth of ACHN cells. Glycolytic genes HK1, HK 2, and lactate dehydrogenase A were decreased when ENO2 was silenced in ACHN. Glycolytic inhibitor TT-232 showed minimal inhibitory effect on ACHN cells yet showed synergistic effect in the presence of ENO2 silencing. ENO2 significantly increased and decreased extracellular glucose, respectively in ACHN cells. Xenograft mouse model showed ENO2 silencing and TT-232 combination treatment showed synergistic effect in ACHN tumors. ENO2 is associated with worsened prognosis in pRCC and is related to glycolysis. ENO2-targeted therapy can be of therapeutic potential.

ENO2 Affects the Seed Size and Weight by Adjusting Cytokinin Content and Forming ENO2-bZIP75 Complex in Arabidopsis thaliana

Arabidopsis thaliana ENO2 (AtENO2) encodes two proteins AtENO2 (enolase) and AtMBP-1 (c-Myc binding protein 1-like). The loss of AtENO2 function causes the constitutive developmental defects which are correlated with reduced enolase activity, but not AtMBP-1 transcript abundance. However, the regulation mechanism of AtENO2 on the seed properties is still not clear. In this study, we found that the mutation of AtENO2 reduced the seed size and weight. The level of glucose in seed was significantly elevated but that of starch was decreased in AtENO2 mutants compared to WT plants. We also found that AtENO2 mutation reduced the content of cytokinin which resulted in smaller cotyledons. The RNA-seq data showed that there were 1892 differentially expressed genes and secondary metabolic pathways were significantly enriched. Instead of AtMBP-1, AtENO2 protein interacted with AtbZIP75 which may mediate the secondary metabolism. Therefore, ENO2 alters the size and weight of seeds which is not only regulated by the content of cytokinin and secondary metabolism, but may be affected by the interaction of ENO2 and bZIP57. These results are helpful to understand the novel function of AtENO2 which provide a foundation for further exploration of the key candidate genes for crop breeding.

NCS-1 Deficiency Affects mRNA Levels of Genes Involved in Regulation of ATP Synthesis and Mitochondrial Stress in Highly Vulnerable Substantia nigra Dopaminergic Neurons

Neuronal Ca²⁺ sensor proteins (NCS) transduce changes in Ca²⁺ homeostasis into altered signaling and neuronal function. NCS-1 activity has emerged as important for neuronal viability and pathophysiology. The progressive degeneration of dopaminergic (DA) neurons, particularly within the Substantia nigra (SN), is the hallmark of Parkinson's disease (PD), causing its motor symptoms. The activity-related Ca²⁺ homeostasis of SN DA neurons, mitochondrial dysfunction, and metabolic stress promote neurodegeneration and PD. In contrast, NCS-1 in general has neuroprotective effects. The underlying mechanisms are unclear. We analyzed transcriptional changes in SN DA neurons upon NCS-1 loss by combining UV-laser microdissection and RT-qPCR-approaches to compare expression levels of a panel of PD and/or Ca²⁺-stress related genes from wildtype and NCS-1 KO mice. In NCS-1 KO, we detected significantly lower mRNA levels of mitochondrially coded ND1, a subunit of the respiratory chain, and of the neuron-specific enolase ENO2, a glycolytic enzyme. We also detected lower levels of the mitochondrial uncoupling proteins UCP4 and UCP5, the PARK7 gene product DJ-1, and the voltage-gated Ca²⁺ channel Cav2.3 in SN DA neurons from NCS-1 KO. Transcripts of other analyzed uncoupling proteins (UCPs), mitochondrial Ca²⁺ transporters, PARK genes, and ion channels were not altered. As Cav channels are linked to regulation of gene expression, metabolic stress and degeneration of SN DA neurons in PD, we analyzed Cav2.3 KO mice, to address if the transcriptional changes in NCS-1 KO were also present in Cav.2.3 KO, and thus probably correlated with lower Cav2.3 transcripts. However, in SN DA neurons from Cav2.3 KO mice, ND1 mRNA as well as genomic DNA levels were elevated, while ENO2, UCP4, UCP5, and DJ-1 transcript levels were not altered. In conclusion, our data indicate a possible novel function of NCS-1 in regulating gene transcription or stabilization of mRNAs in SN DA neurons. Although we do not provide functional data, our findings at the transcript level could point to impaired ATP production (lower ND1 and ENO2) and elevated metabolic stress (lower UCP4, UCP5, and DJ-1 levels) in SN DA neurons from NCS-1 KO mice. We speculate that NCS-1 is involved in stimulating ATP synthesis, while at the same time controlling mitochondrial metabolic stress, and in this way could protect SN DA neurons from degeneration.

Impact of fliD and virulence plasmid pSEV on response of chicken embryo fibroblasts to Salmonella Enteritidis

Salmonella Enteritidis is the main serovar of poultry origin in humans, but its complex interaction with certain avian cells is still not fully understood. Previously we identified several genes significantly induced in chicken embryo fibroblasts (CEFs) by the wild-type strain S. Enteritidis 11 (SE 11). In the present study, we raised the question whether virulence-attenuated mutants of this strain would induce altered expression of the newly identified fibroblast genes associated with immune and non-immune functions of CEFs. Gene expression was evaluated by real-time PCR following challenge by the parental strain SE 11 and its virulence attenuated mutants lacking flagellin gene fliD only or fliD and the serovar-specific virulence plasmid pSEV. As a result, deletion mutants induced a lower expression of all immune genes, but an increased expression of the non-immune genes G0S2 and ENO2 relative to the parental strain. Our data indicate the importance of flagella and pSEV in modulation of virulence and host response in this model. We demonstrated, for the first time ever, an increased induction of survival genes G0S2 and ENO2 by virulence-attenuated mutants of S. Enteritidis.

Transformation by different oncogenes relies on specific metabolic adaptations

Metabolic adaptations are emerging as common traits of cancer cells and tumor progression. In vitro transformation of NIH 3T3 cells allows the analysis of the metabolic changes triggered by a single oncogene. In this work, we have compared the metabolic changes induced by H-RAS and by the nuclear resident mutant of histone deacetylase 4 (HDAC4). RAS-transformed cells exhibit a dominant aerobic glycolytic phenotype characterized by up-regulation of glycolytic enzymes, reduced oxygen consumption and a defect in complex I activity. In this model of transformation, glycolysis is strictly required for sustaining the ATP levels and the robust cellular proliferation. By contrast, in HDAC4/TM transformed cells, glycolysis is only modestly up-regulated, lactate secretion is not augmented and, instead, mitochondrial oxygen consumption is increased. Our results demonstrate that cellular transformation can be accomplished through different metabolic adaptations and HDAC4/TM cells can represent a useful model to investigate oncogene-driven metabolic changes besides the Warburg effect.

HyCCAPP as a tool to characterize promoter DNA-protein interactions in Saccharomyces cerevisiae

Currently available methods for interrogating DNA-protein interactions at individual genomic loci have significant limitations, and make it difficult to work with unmodified cells or examine single-copy regions without specific antibodies. In this study, we describe a physiological application of the Hybridization Capture of Chromatin-Associated Proteins for Proteomics (HyCCAPP) methodology we have developed. Both novel and known locus-specific DNA-protein interactions were identified at the ENO2 and GAL1 promoter regions of Saccharomyces cerevisiae, and revealed subgroups of proteins present in significantly different levels at the loci in cells grown on glucose versus galactose as the carbon source. Results were validated using chromatin immunoprecipitation. Overall, our analysis demonstrates that HyCCAPP is an effective and flexible technology that does not require specific antibodies nor prior knowledge of locally occurring DNA-protein interactions and can now be used to identify changes in protein interactions at target regions in the genome in response to physiological challenges.

Quercetin Impacts Expression of Metabolism- and Obesity-Associated Genes in SGBS Adipocytes

Obesity is characterized by the rapid expansion of visceral adipose tissue, resulting in a hypoxic environment in adipose tissue which leads to a profound change of gene expression in adipocytes. As a consequence, there is a dysregulation of metabolism and adipokine secretion in adipose tissue leading to the development of systemic inflammation and finally resulting in the onset of metabolic diseases. The flavonoid quercetin as well as other secondary plant metabolites also referred to as phytochemicals have anti-oxidant, anti-inflammatory, and anti-diabetic effects known to be protective in view of obesity-related-diseases. Nevertheless, its underlying molecular mechanism is still obscure and thus the focus of this study was to explore the influence of quercetin on human SGBS (Simpson Golabi Behmel Syndrome) adipocytes’ gene expression. We revealed for the first time that quercetin significantly changed expression of adipokine (Angptl4, adipsin, irisin and PAI-1) and glycolysis-involved (ENO2, PFKP and PFKFB4) genes, and that this effect not only antagonized but in part even overcompensated the effect mediated by hypoxia in adipocytes. Thus, these results are explained by the recently proposed hypothesis that the protective effect of quercetin is not solely due to its free radical-scavenging activity but also to a direct effect on mitochondrial processes, and they demonstrate that quercetin might have the potential to counteract the development of obesity-associated complications.

Neuron-Specific Enolase as a Biomarker: Biochemical and Clinical Aspects

Neuron-specific enolase (NSE) is known to be a cell specific isoenzyme of the glycolytic enzyme enolase. In vertebrate organisms three isozymes of enolase, expressed by different genes, are present: enolase α is ubiquitous; enolase β is muscle-specific and enolase γ is neuron-specific. The expression of NSE, which occurs as γγ- and αγ-dimer, is a late event in neural differentiation, thus making it a useful index of neural maturation.NSE is a highly specific marker for neurons and peripheral neuroendocrine cells. As a result of the findings of NSE in specific tissues under normal conditions, increased body fluids levels of NSE may occur with malignant proliferation and thus can be of value in diagnosis, staging and treatment of related neuroendocrine tumours (NETs).NSE is currently the most reliable tumour marker in diagnosis, prognosis and follow-up of small cell lung cancer (SCLC), even though increased levels of NSE have been reported also in non-small cell lung cancer (NSCLC). The level of NSE correlates with tumour burden, number of metastatic sites and response to treatment.NSE can be also useful at diagnosis of NETs and gastroenteropancreatic (GEP)-NETs.Raised serum levels of NSE have been found in all stages of neuroblastoma, although the incidence of increased concentration is greater in widespread and metastatic disease. Moreover, NSE determination in cord blood offers an early postnatal possibility of confirming the diagnosis of neuroblastoma in newborns.NSE has been demonstrated to provide quantitative measures of brain damage and/or to improve the diagnosis and the outcome evaluation in ischaemic stroke, intracerebral hemorrhage, seizures, comatose patients after cardiopulmonary resuscitation for cardiac arrest and traumatic brain injury.Increased NSE serum levels have also been found associated with melanoma, seminoma, renal cell carcinoma, Merkel cell tumour, carcinoid tumours, dysgerminomas and immature teratomas, malignant phaechromocytoma, Guillain-Barré syndrome and Creutzfeldt-Jakob disease.

Comparative gene expression profiling analysis of lymphoblastoid cells reveals neuron-specific enolase gene (ENO2) as a susceptibility gene of heroin dependence

Heroin dependence is a complex mental disorder resulting from interactions between genetic and environmental factors. Identifying the susceptibility genes of heroin dependence is the basis for understanding the pathogenesis of heroin dependence. Using a total gene expression microarray, we detected 924 differentially expressed gene transcripts in lymphoblastoid cell lines (LCLs) between 19 male heroin-dependent individuals and 20 male control subjects, including 279 upregulated and 645 downregulated gene transcripts in heroin-dependent individuals. We verified the reduced expression of the neuron-specific enolase gene (ENO2) in heroin-dependent individuals using real-time quantitative polymerase chain reaction and Western blot analysis. We further compared the allele and genotype frequencies of three single nucleotide polymorphisms (SNPs, rs11064464, rs3213433 and rs10849541) of the ENO2 gene between 532 male heroin-dependent individuals and 369 male controls. No significant differences in the allele or genotype frequencies of these three SNPs were detected between these two groups. Nevertheless, we identified a haplotype (T-C-G) derived from these three SNPs significantly underrepresented in heroin-dependent individuals compared with the control group (72.7% versus 75.9%, P<0.032), while two other rare haplotypes (C-A-G and T-C-A) significantly overrepresented in heroin-dependent individuals compared with the control group (P<0.001). Further study, however, did not detect significant differences of the plasma concentration of neuron-specific enolase between these two groups. Our data suggest that the ENO2 gene might be associated with heroin dependence, and reduced ENO2 gene expression may confer increased risk to heroin dependence.

Identification of mitochondrial dysfunction in Hutchinson-Gilford progeria syndrome through use of stable isotope labeling with amino acids in cell culture

Hutchinson-Gilford progeria syndrome (HGPS) is a rare segmental premature aging disorder that recapitulates some biological and physical aspects of physiological aging. The disease is caused by a sporadic dominant mutation in the LMNA gene that leads to the expression of progerin, a mutant form of lamin A that lacks 50 amino acids and retains a toxic farnesyl modification in its carboxy-terminus. However, the mechanisms underlying cellular damage and senescence and accelerated aging in HGPS are incompletely understood. Here, we analyzed fibroblasts from healthy subjects and HGPS patients using SILAC (stable isotope labeling with amino acids in cell culture). We found in HGPS cells a marked downregulation of mitochondrial oxidative phosphorylation proteins accompanied by mitochondrial dysfunction, a process thought to provoke broad organ decline during normal aging. We also found mitochondrial dysfunction in fibroblasts from adult progeroid mice expressing progerin (Lmna(G609G/G609G) knock-in mice) or prelamin A (Zmpste24-null mice). Analysis of tissues from these mouse models revealed that the damaging effect of these proteins on mitochondrial function is time- and dose-dependent. Mitochondrial alterations were not observed in the brain, a tissue with extremely low progerin expression that seems to be unaffected in HGPS. Remarkably, mitochondrial function was restored in progeroid mouse fibroblasts treated with the isoprenylation inhibitors FTI-277 or pravastatin plus zoledronate, which are being tested in HGPS clinical trials. Our results suggest that mitochondrial dysfunction contributes to premature organ decline and aging in HGPS. Beyond its effects on progeria, prelamin A and progerin may also contribute to mitochondrial dysfunction and organ damage during normal aging, since these proteins are expressed in cells and tissues from non-HGPS individuals, most prominently at advanced ages.

BIOLOGICAL SIGNIFICANCE

Mutations in LMNA or defective processing of prelamin A causes premature aging disorders, including Hutchinson-Gilford progeria syndrome (HGPS). Most HGPS patients carry in heterozygosis a de-novo point mutation (c.1824C>T: GGC>GGT; p.G608G) which causes the expression of the lamin A mutant protein called progerin. Despite the importance of progerin and prelamin A in accelerated aging, the underlying molecular mechanisms remain largely unknown. To tackle this question, we compared the proteome of skin-derived dermal fibroblast from HGPS patients and age-matched controls using quantitative stable isotope labeling with amino acids in cell culture (SILAC). Our results show a pronounced down-regulation of several components of the mitochondrial ATPase complex accompanied by up-regulation of some glycolytic enzymes. Accordingly, functional studies demonstrated mitochondrial dysfunction in HGPS fibroblasts. Moreover, our expression and functional studies using cellular and animal models confirmed that mitochondrial dysfunction is a feature of progeria which develops in a time- and dose-dependent manner. Finally, we demonstrate improved mitochondrial function in progeroid mouse cells treated with a combination of statins and aminobisphosphonates, two drugs that are being evaluated in ongoing HGPS clinical trials. Although further studies are needed to unravel the mechanisms through which progerin and prelamin A provoke mitochondrial abnormalities, our findings may pave the way to improved treatments of HGPS. These studies may also improve our knowledge of the mechanisms leading to mitochondrial dysfunction during normal aging, since both progerin and prelamin A have been found to accumulate during normal aging.