Activating Transcription Factor 3 Diminishes Ischemic Cerebral Infarct and Behavioral Deficit by Downregulating Carboxyl-Terminal Modulator Protein.

Activating transcription factor 3 (ATF3) is a stress-induced transcription factor and a familiar neuronal marker for nerve injury. This factor has been shown to protect neurons from hypoxic insult in vitro by suppressing carboxyl-terminal modulator protein (CTMP) transcription, and indirectly activating the anti-apoptotic Akt/PKB cascade. Despite prior studies in vitro, whether this neuroprotective pathway also exists in the brain in vivo after ischemic insult remains to be determined. In the present study, we showed a rapid and marked induction of ATF3 mRNA throughout ischemia-reperfusion in a middle cerebral artery (MCA) occlusion model. Although the level of CTMP mRNA was quickly induced upon ischemia, its level showed only a mild increase after reperfusion. With the gain-of-function approach, both pre- and post-ischemic administration of Ad-ATF3 ameliorated brain infarct and neurological deficits. Whereas, with the loss-of-function approach, ATF3 knockout (KO) mice showed bigger infarct and worse functional outcome after ischemia. In addition, these congenital defects were rescued upon reintroducing ATF3 to the brain of KO mice. ATF3 overexpression led to a lower level of CTMP and a higher level of p-Akt(473) in the ischemic brain. On the contrary, ATF3 KO resulted in upregulation of CTMP and downregulation of p-Akt(473) instead. Furthermore, post-ischemic CTMP siRNA knockdown led to smaller infarct and better behaviors. CTMP siRNA knockdown increased the level of p-Akt(473), but did not alter the ATF3 level in the ischemic brain, upholding the ATF3→CTMP signal cascade. In summary, our proof-of-principle experiments support the existence of neuroprotective ATF3→CTMP signal cascade regulating the ischemic brain. Furthermore, these results suggest the therapeutic potential for both ATF3 overexpression and CTMP knockdown for stroke treatment.

Carboxyl-terminal modulator protein (CTMP) deficiency mitigates denervation-induced skeletal muscle atrophy.

Denervated skeletal muscles show decreased Akt activity and phosphorylation, resulting in atrophy. Akt inhibits downstream transcription of atrophy-associated ubiquitin ligases like muscle ring-finger protein 1 (MuRF-1). In addition, reduced Akt signaling contributes to aberrant protein synthesis in muscles. In ALS mice, we recently found that carboxyl-terminator modulator protein (CTMP) expression is increased and correlated with reduced Akt signaling in atrophic skeletal muscle. CTMP has also been implicated in promoting muscle degeneration and catabolism in an in vitro muscle atrophy model. The present study examined whether sciatic nerve injury (SNI) stimulated CTMP expression in denervated skeletal muscle during muscle atrophy. We hypothesized that CTMP deficiency would reduce neurogenic atrophy and reverse Akt signaling downregulation. Compared to the unaffected contralateral muscle, wild-type (WT) gastrocnemius muscle had a significant increase in CTMP (p < 0.05). Furthermore, denervated CTMP knockout (CTMP-KO) gastrocnemius weighed more than WT muscle (p < 0.05). Denervated CTMP-KO gastrocnemius also showed higher Akt and downstream glycogen synthase kinase 3ß (GSK3ß) phosphorylation compared to WT muscle (p < 0.05) as well as ribosomal proteins S6 and 4E-BP1 phosphorylation (p < 0.001 and p < 0.05, respectively). Moreover, CTMP-KO mice showed significantly lower levels of E3 ubiquitin ligase MuRF-1 and myostatin than WT muscle (p < 0.05). Our findings suggest that CTMP is essential to muscle atrophy after denervation and it may act by reducing Akt signaling, protein synthesis, and increasing myocellular catabolism.

Carboxyl-terminal modulator protein facilitates tumor metastasis in triple-negative breast cancer.

Currently, the survival rate for breast cancer is more than 90%, but once the cancer cells metastasize to distal organs, the survival rate is dramatically reduced, to less than 30%. Triple-negative breast cancer accounts for 15-20% of all breast cancers. Triple-negative breast cancer (TNBC) is associated with poor prognostic and diagnostic outcomes due to the limiting therapeutic strategies, relative to non-TNBC breast cancers. Therefore, the development of targeted therapy for TNBC metastasis remains an urgent issue. In this study, high Carboxyl-terminal modulator protein (CTMP) is significantly associated with recurrence and disease-free survival rate in TNBC patients. Overexpression of CTMP promotes migration and invasion abilities in BT549 cells. Down-regulating of CTMP expression inhibits migration and invasion abilities in MDA-MB-231 cells. In vivo inoculation of high-CTMP cells enhances distant metastasis in mice. The metastasis incidence rate is decreased in mice injected with CTMP-downregulating MDA-MB-231 cells. Gene expression microarray analysis indicates the Akt-dependent pathway is significantly enhanced in CTMP overexpressing cells compared to the parental cells. Blocking Akt activation via Akt inhibitor treatment or co-expression of the dominant-negative form of Akt proteins successfully abolishes the CTMP mediating invasion in TNBC cells. Our findings suggest that CTMP is a potential diagnostic marker for recurrence and poor disease-free survival in TNBC patients. CTMP promotes TNBC metastasis via the Akt-activation-dependent pathway.

High Expression of ACOT2 Predicts Worse Overall Survival and Abnormal Lipid Metabolism: A Potential Target for Acute Myeloid Leukemia.

Acyl-CoA thioesterase (ACOT) plays a considerable role in lipid metabolism, which is closely related to the occurrence and development of cancer, nevertheless, its role has not been fully elucidated in acute myeloid leukemia (AML). To explore the role of ACOT2 in AML and to provide a potential therapeutic target for AML, the expression pattern of ACOT was investigated based on the TNMplot, Gene Expression Profiling Interactive Analysis (GEPIA), and Cancer Cell Line Encyclopedia (CCLE) database, and diagnostic value, prognostic value, and clinical phenotype of ACOT were explored based on data from The Cancer Genome Atlas (TCGA). Functional annotation and enrichment analysis of the common targets between ACOT2 coexpressed and AML-related genes were further performed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) analyses. The protein-protein interaction (PPI) network of ACOT2 coexpressed genes and functional ACOT2-related metabolites association network were constructed based on GeneMANIA and Human Metabolome Database. Among ACOTs, ACOT2 was highly expressed in AML compared to normal control subjects according to TNMplot, GEPIA, and CCLE database, which was significantly associated with poor overall survival (OS) in AML (P=0.003). Moreover, ACOT2 exhibited excellent diagnostic efficiency for AML (AUC: 1.000) and related to French-American-British (FAB) classification and cytogenetics. GO, KEGG, and GSEA analyses of 71 common targets between ACOT2 coexpressed and AML-related genes revealed that ACOT2 is closely related to ACOT1, ACOT4, enoyl-acyl carrier protein reductase, mitochondrial (MECR), puromycin-sensitive aminopeptidase (NPEPPS), SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1), and long-chain fatty acid-CoA ligase 1 (ACSL1) in PPI network, and plays a significant role in lipid metabolism, that is, involved in fatty acid elongation and biosynthesis of unsaturated fatty acids. Collectively, the increase of ACOT2 may be an important characteristic of worse OS and abnormal lipid metabolism, suggesting that ACOT2 may become a potential therapeutic target for AML.

ACOT7 protects epidermal stem cells against lipid peroxidation.

Epidermal stem cells (ESCs) are critical for skin regeneration and repair. Previous studies have shown that ESCs are susceptible to oxidative stress, which in turn leads to lipid peroxidation and affects skin repair. Our study aims to explore how ESCs resist lipid peroxidation. By performing proteomics analysis, we found that the expression of Acyl-CoA thioesterase 7 (ACOT7) was positively correlated with the concentration of transferrin. Overexpression adenovirus vectors of ACOT7 were constructed and transfected into ESCs. Levels of lipid peroxidation by flow cytometry, cell viabilities, and MDA levels were measured. The results revealed that ACOT7 could inhibit lipid peroxidation, reduce the level of malondialdehyde (MDA), and improve the survival rate of ESCs induced by H2O2, Erastin, and RSL3. Our data suggest that ACOT7 has an effect on protecting ESCs against iron-dependent lipid peroxidation.

Heterologous Expression of Jatropha curcas Fatty Acyl-ACP Thioesterase A (JcFATA) and B (JcFATB) Affects Fatty Acid Accumulation and Promotes Plant Growth and Development in Arabidopsis.

Plant fatty acyl-acyl carrier protein (ACP) thioesterases terminate the process of de novo fatty acid biosynthesis in plastids by hydrolyzing the acyl-ACP intermediates, and determine the chain length and levels of free fatty acids. They are of interest due to their roles in fatty acid synthesis and their potential to modify plant seed oils through biotechnology. Fatty acyl-ACP thioesterases (FAT) are divided into two families, i.e., FATA and FATB, according to their amino acid sequence and substrate specificity. The high oil content in Jatropha curcas L. seed has attracted global attention due to its potential for the production of biodiesel. However, the detailed effects of JcFATA and JcFATB on fatty acid biosynthesis and plant growth and development are still unclear. In this study, we found that JcFATB transcripts were detected in all tissues and organs examined, with especially high accumulation in the roots, leaves, flowers, and some stages of developing seeds, and JcFATA showed a very similar expression pattern. Subcellular localization of the JcFATA-GFP and JcFATB-GFP fusion protein in Arabidopsis leaf protoplasts showed that both JcFATA and JcFATB localized in chloroplasts. Heterologous expression of JcFATA and JcFATB in Arabidopsis thaliana individually generated transgenic plants with longer roots, stems and siliques, larger rosette leaves, and bigger seeds compared with those of the wild type, indicating the overall promotion effects of JcFATA and JcFATB on plant growth and development while JcFATB had a larger impact. Compositional analysis of seed oil revealed that all fatty acids except 22:0 were significantly increased in the mature seeds of JcFATA-transgenic Arabidopsis lines, especially unsaturated fatty acids, such as the predominant fatty acids of seed oil, 18:1, 18:2, and 18:3. In the mature seeds of the JcFATB-transgenic Arabidopsis lines, most fatty acids were increased compared with those in wild type too, especially saturated fatty acids, such as 16:0, 18:0, 20:0, and 22:0. Our results demonstrated the promotion effect of JcFATA and JcFATB on plant growth and development, and their possible utilization to modify the seed oil composition and content in higher plants.

Mitochondrial protein LETM1 and its-mediated CTMP are potential therapeutic targets for endometrial cancer.

Leucine zipper/EF hand-containing transmembrane-1 (LETM1) is an important mitochondrial protein, while its function in endometrial cancer remains unknown. This study aimed to explore the function of LETM1 in endometrial cancer and reveal the underlying mechanisms involving carboxy-terminal modulator protein (CTMP). Immunohistochemistry was performed to detect the expression of LETM1 and CTMP in normal, atypical hyperplastic and endometrial cancer endometrial tissues. LETM1 and CTMP were silenced in two endometrial cancer cell lines (ISK and KLE), which were verified by western blot. Cell viability, colony number, migration and invasion were detected by cell counting kit-8, colony formation, wound healing and trans-well assays, respectively. A xenograft mouse model was established to determine the antitumor potential of LETM1/CTMP silencing in vivo . In addition, CTMP was overexpressed to evaluate its regulatory relationship with LETM1 in endometrial cancer cells. The expression of LETM1 and CTMP proteins were higher in endometrial cancer tissues than atypical hyperplastic tissues and were higher in atypical hyperplastic tissues than normal tissues. LETM1 and CTMP were also upregulated in ISK and KLE cells. Silencing of LETM1 or CTMP could decrease the viability, colony number, migration and invasion of endometrial cancer cells and the weight and volume of tumor xenografts. In addition, CTMP was downregulated by LETM1 silencing in KLE cells, and its overexpression enhanced the malignant characteristics of si-LETM1-transfected KLE cells. Silencing of LETM1 inhibits the malignant progression of endometrial cancer through downregulating CTMP.

Acyl-Coa Thioesterases: A Rheostat That Controls Activated Fatty Acids Modulates Dengue Virus Serotype 2 Replication.

During infection with dengue viruses (DENVs), the lipid landscape within host cells is significantly altered to assemble membrane platforms that support viral replication and particle assembly. Fatty acyl-CoAs are key intermediates in the biosynthesis of complex lipids that form these membranes. They also function as key signaling lipids in the cell. Here, we carried out loss of function studies on acyl-CoA thioesterases (ACOTs), a family of enzymes that hydrolyze fatty acyl-CoAs to free fatty acids and coenzyme A, to understand their influence on the lifecycle of DENVs. The loss of function of the type I ACOTs 1 (cytoplasmic) and 2 (mitochondrial) together significantly increased DENV serotype 2 (DENV2) viral replication and infectious particle release. However, isolated knockdown of mitochondrial ACOT2 significantly decreased DENV2 protein translation, genome replication, and infectious virus release. Furthermore, loss of ACOT7 function, a mitochondrial type II ACOT, similarly suppressed DENV2. As ACOT1 and ACOT2 are splice variants, these data suggest that functional differences and substrate specificities due to the location (cytosol and mitochondria, respectively) of these proteins may account for the differences in DENV2 infection phenotype. Additionally, loss of mitochondrial ACOT2 and ACOT7 expression also altered the expression of several ACOTs located in multiple organelle compartments within the cell, highlighting a complex relationship between ACOTs in the DENV2 virus lifecycle.

A dual cellular-heterogeneous catalyst strategy for the production of olefins from glucose.

Living systems provide a promising approach to chemical synthesis, having been optimized by evolution to convert renewable carbon sources, such as glucose, into an enormous range of small molecules. However, a large number of synthetic structures can still be difficult to obtain solely from cells, such as unsubstituted hydrocarbons. In this work, we demonstrate the use of a dual cellular-heterogeneous catalytic strategy to produce olefins from glucose using a selective hydrolase to generate an activated intermediate that is readily deoxygenated. Using a new family of iterative thiolase enzymes, we genetically engineered a microbial strain that produces 4.3 ± 0.4 g l-1 of fatty acid from glucose with 86% captured as 3-hydroxyoctanoic and 3-hydroxydecanoic acids. This 3-hydroxy substituent serves as a leaving group that enables heterogeneous tandem decarboxylation-dehydration routes to olefinic products on Lewis acidic catalysts without the additional redox input required for enzymatic or chemical deoxygenation of simple fatty acids.

Differential protein expression during growth on model and commercial mixtures of naphthenic acids in Pseudomonas fluorescens Pf-5.

Naphthenic acids (NAs) are carboxylic acids with the formula (Cn H2n+Z O2 ) and are among the most toxic, persistent constituents of oil sands process-affected waters (OSPW), produced during oil sands extraction. Currently, the proteins and mechanisms involved in NA biodegradation are unknown. Using LC-MS/MS shotgun proteomics, we identified proteins overexpressed during the growth of Pseudomonas fluorescens Pf-5 on a model NA (4'-n-butylphenyl)-4-butanoic acid (n-BPBA) and commercial NA mixture (Acros). By day 11, >95% of n-BPBA was degraded. With Acros, a 17% reduction in intensity occurred with 10-18 carbon compounds of the Z family -2 to -14 (major NA species in this mixture). A total of 554 proteins (n-BPBA) and 631 proteins (Acros) were overexpressed during growth on NAs, including several transporters (e.g., ABC transporters), suggesting a cellular protective response from NA toxicity. Several proteins associated with fatty acid, lipid, and amino acid metabolism were also overexpressed, including acyl-CoA dehydrogenase and acyl-CoA thioesterase II, which catalyze part of the fatty acid beta-oxidation pathway. Indeed, multiple enzymes involved in the fatty acid oxidation pathway were upregulated. Given the presumed structural similarity between alkyl-carboxylic acid side chains and fatty acids, we postulate that P. fluorescens Pf-5 was using existing fatty acid catabolic pathways (among others) during NA degradation.

Thioesterase superfamily member 1 undergoes stimulus-coupled conformational reorganization to regulate metabolism in mice.

In brown adipose tissue, thermogenesis is suppressed by thioesterase superfamily member 1 (Them1), a long chain fatty acyl-CoA thioesterase. Them1 is highly upregulated by cold ambient temperature, where it reduces fatty acid availability and limits thermogenesis. Here, we show that Them1 regulates metabolism by undergoing conformational changes in response to ß-adrenergic stimulation that alter Them1 intracellular distribution. Them1 forms metabolically active puncta near lipid droplets and mitochondria. Upon stimulation, Them1 is phosphorylated at the N-terminus, inhibiting puncta formation and activity and resulting in a diffuse intracellular localization. We show by correlative light and electron microscopy that Them1 puncta are biomolecular condensates that are inhibited by phosphorylation. Thus, Them1 forms intracellular biomolecular condensates that limit fatty acid oxidation and suppress thermogenesis. During a period of energy demand, the condensates are disrupted by phosphorylation to allow for maximal thermogenesis. The stimulus-coupled reorganization of Them1 provides fine-tuning of thermogenesis and energy expenditure.

Ligand-induced transition in conformations of vicinal cysteine disulfides in proteins.

Vicinal cysteine disulfides are thought to be associated with specific conformations of cysteine disulfides due to the restricted rotation of single bonds in an eight-membered cyclic disulfide loop. Conformations of vicinal cysteine disulfides are analyzed using χ1 , χ2 , χ3 , χ2 ', χ1 ' torsion angles in the crystal structures of proteins retrieved from Protein Data Bank (PDB). 85% of vicinal disulfides have (+, -)LHStaple conformation with trans configuration of the peptide bond and 9% have (-, -)RHStaple conformation with cis configured peptide bond. Conformational analysis of dipeptide Cys-Cys vicinal disulfide by density functional theory (DFT) further supported (+, -)LHStaple, (-, -)RHStaple, and (+, +)RHStaple as the preferred conformations of vicinal disulfides. Interestingly, the rare conformations of vicinal disulfides are observed in the ligand-bound forms of proteins and have higher disulfide strain energy. Conformations of vicinal disulfides in palmitoyl protein thioesterase 1, AChBP, and α7 nicotinic receptor are changed from preferred (+, -)LHStaple to rare (+, -)AntiLHHook/(+, -)AntiRHHook/(+, +)RHStaple conformation due to binding of ligands. Surprisingly, ligands are proximal to the vicinal disulfides in protein complexes that exhibited rare conformations of vicinal disulfides. The report has identified (+, -) LHStaple/(-, -) RHStaple as the hallmark conformations of vicinal disulfides and unraveled ligand-induced transition in conformations of vicinal cysteine disulfides in proteins.

ACOT4 accumulation via AKT-mediated phosphorylation promotes pancreatic tumourigenesis.

The acyl-CoA thioesterase (ACOT) family catalyses the hydrolysis of acyl-CoA thioesters to their corresponding non-esterified fatty acid and coenzyme A (CoA). Increasing evidence suggests that cancer cells generally have altered lipid metabolism in different aspects. However, the roles of the ACOT family in cancer, especially in pancreatic ductal carcinoma (PDAC), are largely unknown. In the present study, we mined data to determine the clinical significance of all eleven ACOT genes among nine major solid tumour types from TCGA database and found that the expression of ACOT4 in PDAC was negatively correlated with patient survival, establishing ACOT4 as a potential biomarker of PDAC. Depletion of ACOT4 attenuated the proliferation and tumour formation of PDAC cells. Using mass spectrometry, HSPA1A was found to associate with ACOT4. Furthermore, we found that phosphorylation of ACOT4 at S392 by AKT decreased the binding of ACOT4 to HSPA1A, resulting in ACOT4 accumulation. The ACOT4 elevation promotes pancreatic tumourigenesis by producing excessive CoA to support tumour cell metabolism. Thus, our study expands the relationship between AKT signalling and lipid metabolism and establishes a functional role of ACOT4 in PDAC.

Cloning of the gene encoding acyl-CoA thioesterase 11 and its functional characterization in hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × Pelteobagrus vachelli ♂) under heat stress.

Members of the ACOT (acyl-CoA thioesterase) family hydrolyze fatty acyl-CoA to form free fatty acids (FFAs) and coenzyme A (CoA). These enzymes play important roles in fatty acid metabolism. Here, we report the cloning and functional analysis of acot11ß in hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × P. vachelli ♂). The open reading frame of acot11ß was found to be 594 bp in length, encoding 198 amino acids. We determined the transcript levels of acot11ß in ten tissues of hybrid yellow catfish by qRT-PCR and found that it was highly expressed in the liver, so we chose the liver for further analysis. We determined the transcript levels of acot11ß in hybrid yellow catfish under heat stress conditions, and analyzed the changes in serum biochemical parameters, liver biochemical parameters, and transcript levels of lipid metabolism-related genes. Healthy yellow catfish were subjected to heat stress at 35 °C for 96 h, and the experimental results were compared with those from fish in a control group (28 °C). The levels of glucose (GLU), total cholesterol (TC), and triglyceride (TG) in serum were significantly increased in the heat-stressed group compared with the control group (P < 0.05). Acute heat stress led to decreased liver glycogen contents, but significantly increased TC and TG contents in the liver (P < 0.05). The transcript levels of acot11ß, acc, and fas were significantly reduced, while that of pparα was significantly increased in hybrid yellow catfish exposed to heat stress (P < 0.05). Our results indicate that acot11ß plays an important role in regulating lipid metabolism in hybrid yellow catfish, and this metabolic process is greatly affected by temperature. These results may be useful for developing effective strategies to prevent or reduce metabolic disorders of yellow catfish caused by high temperature.

Allosteric regulation of thioesterase superfamily member 1 by lipid sensor domain binding fatty acids and lysophosphatidylcholine.

Nonshivering thermogenesis occurs in brown adipose tissue to generate heat in response to cold ambient temperatures. Thioesterase superfamily member 1 (Them1) is transcriptionally up-regulated in brown adipose tissue upon exposure to the cold and suppresses thermogenesis in order to conserve energy reserves. It hydrolyzes long-chain fatty acyl-CoAs that are derived from lipid droplets, preventing their use as fuel for thermogenesis. In addition to its enzymatic domains, Them1 contains a C-terminal StAR-related lipid transfer (START) domain with unknown ligand or function. By complementary biophysical approaches, we show that the START domain binds to long-chain fatty acids, products of Them1's enzymatic reaction, as well as lysophosphatidylcholine (LPC), lipids shown to activate thermogenesis in brown adipocytes. Certain fatty acids stabilize the START domain and allosterically enhance Them1 catalysis of acyl-CoA, whereas 18:1 LPC destabilizes and inhibits activity, which we verify in cell culture. Additionally, we demonstrate that the START domain functions to localize Them1 near lipid droplets. These findings define the role of the START domain as a lipid sensor that allosterically regulates Them1 activity and spatially localizes it in proximity to the lipid droplet.

Analysis of plasma metabolic profile, characteristics and enzymes in the progression from chronic hepatitis B to hepatocellular carcinoma.

Hepatitis B virus (HBV) infection is an important factor causing hepatocellular carcinoma (HCC). The aim of this study was to investigate the metabolic characteristics and related metabolic enzyme changes during the progression from chronic hepatitis B (CHB) to liver cirrhosis (LC) and, ultimately, to HCC. An untargeted metabolomics assay was performed in plasma from 50 healthy volunteers, 43 CHB patients, 67 LC patients, and 39 HCC patients. A total of 24 differential metabolites (DMs) were identified. Joint pathway analysis suggested striking changes in amino acid metabolism and lipid metabolism from CHB to HCC. The panel of L-serine, creatine and glycine distinguished LC from CHB, and L-serine, cystathionine, creatine and linoleic acid distinguished HCC from LC. Bioinformatic analysis of publicly available data showed that differential metabolite profile-associated enzyme genes, including alanine-glyoxylate aminotransferase-2 (AGXT2), D-amino-acid oxidase (DAO), and cystathionine gamma-lyase (CTH), were downregulated, while bisphosphoglycerate mutase (BPGM), cystathionine-ß-synthase (CBS), phosphoserine phosphatase (PSPH) and acyl-CoA thioesterase 7 (ACOT7) were upregulated, in HCC, all of which correlated with a poor prognosis for HCC patients. Our results indicated that serum metabolites and related enzymes are of considerable significance for the diagnosis and prognosis of HCC and can provide a theoretical basis and therapeutic index for future diagnosis and treatment.

Interaction between ACOT7 and LncRNA NMRAL2P via Methylation Regulates Gastric Cancer Progression.

PURPOSE: Gastric cancer (GC) has a very poor prognosis when diagnosed at a late stage. Acyl-CoA thioesterase 7 (ACOT7) is a major isoform of the acyl coenzyme family that catalyzes the hydrolysis of fatty acyl-CoAs into unesterified free fatty acid and coenzyme A. The purpose of this study was to investigate the expression levels of ACOT7 in GC and mechanisms related therewith. MATERIALS AND METHODS: Screening of systematic biology studies revealed ACOT7 as a key gene in GC, as well as involvement of the long non-coding RNA NMRAL2P in ACOT7 expression. In this study, GC tissues and adjacent tissue samples were obtained from 10 GC patients at the Department of Gastrointestinal Surgery. GES1 and SGC-7901 cells were collected and treated to silence ACOT7 and overexpress NMRAL2P. The expressions of ACOT7 and NMRAL2P were detected by real-time quantitative PCR and Western blot. Additionally, cell proliferation, apoptosis, migration, and invasion were examined. RESULTS: ACOT7 was upregulated in gastric tumor tissues and GC cell lines. ACOT7 gene silencing induced a less malignant phenotype and was closely correlated to reduced cell proliferation and migration, altered cell cycle, and increased apoptosis. Furthermore, NMRAL2P was downregulated in tumor tissues and GC cell lines. NMRAL2P overexpression induced a more malignant phenotype and significantly inhibited the expression of ACOT7. Importantly, NMRAL2P indirectly methylated ACOT7 by binding to DNMT3b, thereby suppressing ACOT7 expression. CONCLUSION: NMRAL2P activation suppresses ACOT7 expression in GC. Thus, ACOT7 could be a promising target for the treatment of GC.

Fatty Acyl Synthetases and Thioesterases in Plant Lipid Metabolism: Diverse Functions and Biotechnological Applications.

Plants use fatty acids to synthesize acyl lipids for many different cellular, physiological, and defensive roles. These roles include the synthesis of essential membrane, storage, or surface lipids, as well as the production of various fatty acid-derived metabolites used for signaling or defense. Fatty acids are activated for metabolic processing via a thioester linkage to either coenzyme A or acyl carrier protein. Acyl synthetases metabolically activate fatty acids to their thioester forms, and acyl thioesterases deactivate fatty acyl thioesters to free fatty acids by hydrolysis. These two enzyme classes therefore play critical roles in lipid metabolism. This review highlights the surprisingly complex and varying roles of fatty acyl synthetases in plant lipid metabolism, including roles in the intracellular trafficking of fatty acids. This review also surveys the many specialized fatty acyl thioesterases characterized to date in plants, which produce a great diversity of fatty acid products in a tissue-specific manner. While some acyl thioesterases produce fatty acids that clearly play roles in plant-insect or plant-microbial interactions, most plant acyl thioesterases have yet to be fully characterized both in terms of their substrate specificities and their functions. The biotechnological applications of plant acyl thioesterases and synthetases are also discussed, as there is significant interest in these enzymes as catalysts for the sustainable production of fatty acids and their derivatives for industrial uses.

Off-Loading Mechanism of Products in Polyunsaturated Fatty Acid Synthases.

Marine microorganisms de novo biosynthesize polyunsaturated fatty acids such as docosahexaenoic acid and eicosapentaenoic acid by polyunsaturated fatty acid (PUFA) synthases composed of three or four polypeptides in a manner similar to fatty acid synthases (FASs). FASs usually possess thioesterase (TE) domains to release free fatty acids from acyl carrier protein (ACP)-tethered intermediates. Here, we investigated the off-loading mechanism with microalgal and bacterial PUFA synthases through in vivo and in vitro experiments. The in vitro experiments with acyltransferase (AT)-like domains and acyl-ACP substrates clearly demonstrated that the AT-like domains catalyzed the hydrolysis of acyl-ACPs to yield free fatty acids.

Production of adipic acid by short- and long-chain fatty acid acyl-CoA oxidase engineered in yeast Candida tropicalis.

In this study, to produce adipic acid, mutant strains of Candida tropicalis KCTC 7212 deficient of AOX genes encoding acyl-CoA oxidases which are important in the ß-oxidation pathway were constructed. Production of adipic acid in the mutants from the most favorable substrate C12 methyl laurate was significantly increased. The highest level of production of adipic acid was obtained in the C. tropicalis ΔAOX4::AOX5 mutant of 339.8 mg L-1 which was about 5.4-fold higher level compared to the parent strain. The C. tropicalis ΔAOX4::AOX5 mutant was subjected to fed-batch fermentation at optimized conditions of agitation rate of 1000 rpm, pH 5.0 and methyl laurate of 3% (w/v), giving the maximum level of adipic acid of 12.1 g L-1 and production rate of 0.1 g L-1 h-1.