Elevated mature macrophage expression of human ABHD2 gene in vulnerable plaque

Lipidomic QTL in Diversity Outbred mice identifies a novel function for α/β hydrolase domain 2 (Abhd2) as an enzyme that metabolizes phosphatidylcholine and cardiolipin

We and others have previously shown that genetic association can be used to make causal connections between gene loci and small molecules measured by mass spectrometry in the bloodstream and in tissues. We identified a locus on mouse chromosome 7 where several phospholipids in liver showed strong genetic association to distinct gene loci. In this study, we integrated gene expression data with genetic association data to identify a single gene at the chromosome 7 locus as the driver of the phospholipid phenotypes. The gene encodes α/β-hydrolase domain 2 (Abhd2), one of 23 members of the ABHD gene family. We validated this observation by measuring lipids in a mouse with a whole-body deletion of Abhd2. The Abhd2KO mice had a significant increase in liver levels of phosphatidylcholine and phosphatidylethanolamine. Unexpectedly, we also found a decrease in two key mitochondrial lipids, cardiolipin and phosphatidylglycerol, in male Abhd2KO mice. These data suggest that Abhd2 plays a role in the synthesis, turnover, or remodeling of liver phospholipids.

Lipidomic QTL in Diversity Outbred mice identifies a novel function for α/β hydrolase domain 2 ( Abhd2 ) as an enzyme that metabolizes phosphatidylcholine and cardiolipin

We and others have previously shown that genetic association can be used to make causal connections between gene loci and small molecules measured by mass spectrometry in the bloodstream and in tissues. We identified a locus on mouse chromosome 7 where several phospholipids in liver showed strong genetic association to distinct gene loci. In this study, we integrated gene expression data with genetic association data to identify a single gene at the chromosome 7 locus as the driver of the phospholipid phenotypes. The gene encodes α/β-hydrolase domain 2 ( Abhd2 ), one of 23 members of the ABHD gene family. We validated this observation by measuring lipids in a mouse with a whole-body deletion of Abhd2 . The Abhd2 KO mice had a significant increase in liver levels of phosphatidylcholine and phosphatidylethanolamine. Unexpectedly, we also found a decrease in two key mitochondrial lipids, cardiolipin and phosphatidylglycerol, in male Abhd2 KO mice. These data suggest that Abhd2 plays a role in the synthesis, turnover, or remodeling of liver phospholipids.

Vaspin accelerates the proliferation, invasion and metastasis of Triple-Negative breast cancer through MiR-33a-5p/ABHD2

OBJECTIVE

To explore the influence and the underlying mechanism of vaspin (visceral adipose tissue-derived serpin) on the development of triple-negative breast malignancy.

METHODS

First, we analyzed medical records and screened out 22 breast cancer patients with different BMI according to inclusion and exclusion criterion, and measured serum vaspin of those patients. Then we studied the effects of vaspin on TNBC cell lines by using EdU assay, colony formation, transwell and wound-healing assay. Later, we used bioinformatics analysis to identify downstream effectors and verify with qRT-PCR, luciferase assay, western blot, etc. RESULTS: We found the vaspin level was positively correlated with BMI in breast malignant patients and vaspin could significantly enhance the proliferation, infiltration and transferring of triple-negative breast cancer cells by restraining the expression of miR-33a-5p. By using bioinformatic analysis and luciferase assay, we identified miR-33a-5p directly regulating ABHD2.

CONCLUSION

Vaspin, as a cancer-promoting cytokine, may inhibit miR-33a-5p thus increasing the level of ABHD2 to promote the development of the triple-negative breast cancer.

Many or too many progesterone membrane receptors? Clinical implications

Several receptors for nongenomically initiated actions of progesterone (P4) exist, namely membrane-associated P4 receptors (MAPRs), membrane progestin receptors (mPRs), receptors for neurosteroids [GABA_A receptor (GABA_AR), NMDA receptor, sigma-1 and -2 receptors (S1R/S2R)], the classical genomic P4 receptor (PGR), and α/β hydrolase domain-containing protein 2 (ABHD2). Two drugs related to this field have been approved: brexanolone (Zulresso™) for the treatment of postpartum depression, and ganaxolone (Ztalmy™) for the treatment of CDKL5 deficiency disorder. Both are derivatives of P4 and target the GABA_AR. Several other indications are in clinical testing. CT1812 (Elayta™) is also being tested for the treatment of Alzheimer's disease (AD) in Phase 2 clinical trials, targeting the P4 receptor membrane component 1 (PGRMC1)/S2R complex. In this Review, we highlight emerging knowledge on the mechanisms of nongenomically initiated actions of P4 and its derivatives.

Whole Blood Metabolite Profiles Reflect Changes in Energy Metabolism in Heart Failure

A variety of atherosclerosis and cardiovascular disease (ASCVD) phenotypes are tightly linked to changes in the cardiac energy metabolism that can lead to a loss of metabolic flexibility and to unfavorable clinical outcomes. We conducted an association analysis of 31 ASCVD phenotypes and 97 whole blood amino acids, acylcarnitines and derived ratios in the LIFE-Adult (n = 9646) and LIFE-Heart (n = 5860) studies, respectively. In addition to hundreds of significant associations, a total of 62 associations of six phenotypes were found in both studies. Positive associations of various amino acids and a range of acylcarnitines with decreasing cardiovascular health indicate disruptions in mitochondrial, as well as peroxisomal fatty acid oxidation. We complemented our metabolite association analyses with whole blood and peripheral blood mononuclear cell (PBMC) gene-expression analyses of fatty acid oxidation and ketone-body metabolism related genes. This revealed several differential expressions for the heart failure biomarker N-terminal prohormone of brain natriuretic peptide (NT-proBNP) in peripheral blood mononuclear cell (PBMC) gene expression. Finally, we constructed and compared three prediction models of significant stenosis in the LIFE-Heart study using (1) traditional risk factors only, (2) the metabolite panel only and (3) a combined model. Area under the receiver operating characteristic curve (AUC) comparison of these three models shows an improved prediction accuracy for the combined metabolite and classical risk factor model (AUC = 0.78, 95%-CI: 0.76–0.80). In conclusion, we improved our understanding of metabolic implications of ASCVD phenotypes by observing associations with metabolite concentrations and gene expression of the mitochondrial and peroxisomal fatty acid oxidation. Additionally, we demonstrated the predictive potential of the metabolite profile to improve classification of patients with significant stenosis.

α/β-Hydrolase Domain (ABHD) Inhibitors as New Potential Therapeutic Options against Lipid-Related Diseases

Much of the experimental evidence in the literature has linked altered lipid metabolism to severe diseases such as cancer, obesity, cardiovascular pathologies, diabetes, and neurodegenerative diseases. Therefore, targeting key effectors of the dysregulated lipid metabolism may represent an effective strategy to counteract these pathological conditions. In this context, α/β-hydrolase domain (ABHD) enzymes represent an important and diversified family of proteins, which are involved in the complex environment of lipid signaling, metabolism, and regulation. Moreover, some members of the ABHD family play an important role in the endocannabinoid system, being designated to terminate the signaling of the key endocannabinoid regulator 2-arachidonoylglycerol. This Perspective summarizes the research progress in the development of ABHD inhibitors and modulators: design strategies, structure-activity relationships, action mechanisms, and biological studies of the main ABHD ligands will be highlighted.

miR-140-3p Inhibits Cutaneous Melanoma Progression by Disrupting AKT/p70S6K and JNK Pathways through ABHD2

Because cutaneous melanoma (CM) is one of the most lethal human tumors, major treatment advances are vital. miR-140-3p has been suggested to act as a suppressor in a range of malignant tumors, implying its possible use as a biomarker for effective antineoplastic treatment. However, the potential role of miR-140-3p in CM and the underlying mechanism remain unclear. In the present study, we identified lower levels of miR-140-3p in both CM tissues and cell lines; this downregulation was strongly associated with worse CM survival. Additionally, overexpression of miR-140-3p significantly inhibited cell proliferation, migration, and invasion in CM cells with different cell line origins. Importantly, by means of both bioinformatics analysis and luciferase reporter assay, we revealed abhydrolase domain containing 2 (ABHD2) to be a target of miR-140-3p in CM cells. Upregulation of ABHD2 reversed the tumor-suppressive effects of miR-140-3p in CM cells. Furthermore, miR-140-3p-targeted ABHD2 played a role in both activation of JNK signaling and inhibition of the AKT/p70S6K pathway in CM cells. Finally, in vivo results strongly suggested the suppressive effects of miR-140-3p on CM growth and metastasis. Collectively, our findings highlight a novel antineoplastic function for miR-140-3p in CM through ABHD2.

ABHD2 Inhibitor Identified by Activity-Based Protein Profiling Reduces Acrosome Reaction

ABHD2 is a serine hydrolase that belongs to the subgroup of the α,β-hydrolase fold-containing proteins, which is involved in virus propagation, immune response, and fertilization. Chemical tools to selectively modulate the activity of ABHD2 in an acute setting are highly desired to investigate its biological role, but are currently lacking. Here, we report a library-versus-library screening using activity-based protein profiling (ABPP) to evaluate in parallel the selectivity and activity of a focused lipase inhibitor library against ABHD2 and a panel of closely related ABHD proteins. This screen resulted in the rapid identification of novel inhibitors for ABHD2. The selectivity of the inhibitor was further investigated in native mouse testis proteome by competitive ABPP, revealing a highly restricted off-target profile. The progesterone-induced acrosome reaction was reduced in a dose-dependent manner by the newly identified inhibitor, which provides further support for the key-role of ABHD2 in the P4-stimulated acrosome reaction. On this basis, the ABHD2 inhibitor is an excellent starting point for further optimization of ABHD2 inhibitors that can modulate sperm fertility and may lead to novel contraceptives.

Regulation of MFGE8 by the intergenic coronary artery disease locus on 15q26.1

BACKGROUND AND AIMS

A recently identified locus for coronary artery disease (CAD) tagged by rs8042271 is in a region of tight linkage disequilibrium (LD) between 2 genes (MFGE8, ABHD2) previously linked to atherosclerosis. Here we have explored the regulatory framework of this region to identify its functional relationship to CAD.

METHODS

The CAD Associated Region between MFGE8 and ABHD2 (CARMA) was investigated by bioinformatic approaches and transcriptional reporter assays to prioritize target genes and identify putative causal variants. Findings were integrated with publicly available gene expression datasets. MFGE8 silencing was performed in cell models relevant to CAD.

RESULTS

The regulatory potential of CARMA is disseminated sparsely over the entire region. CARMA contains multiple eQTL that regulate MFGE8 in coronary artery and coronary artery smooth muscle cell (CoSMC). SNPs that predict the expression of MFGE8 in artery are concordantly associated with higher risk of CAD (pval = 0.0014). Targeting CARMA by CRISPR/Cas9 in a cellular model increased MFGE8 expression. MFGE8 silencing was found to reduce CoSMC and monocyte (THP-1) but not endothelial cell proliferation.

CONCLUSIONS

These findings support a mechanistic link between a GWAS identified CAD risk locus and atherosclerosis. The intergenic locus CARMA regulates MFGE8 in a haplotype dependent manner. Individuals genetically susceptible to increased MFGE8 expression exhibit greater CAD risk. Suppressing MFGE8 expression reduced SMC and THP-1 proliferation. These data support an atherogenic contribution of CARMA/MFGE8 that may be linked to cell proliferation and/or improved survival of CAD relevant cell types.

2-Arachidonoylglycerol: A signaling lipid with manifold actions in the brain

2-Arachidonoylglycerol (2-AG) is a signaling lipid in the central nervous system that is a key regulator of neurotransmitter release. 2-AG is an endocannabinoid that activates the cannabinoid CB₁ receptor. It is involved in a wide array of (patho)physiological functions, such as emotion, cognition, energy balance, pain sensation and neuroinflammation. In this review, we describe the biosynthetic and metabolic pathways of 2-AG and how chemical and genetic perturbation of these pathways has led to insight in the biological role of this signaling lipid. Finally, we discuss the potential therapeutic benefits of modulating 2-AG levels in the brain.

Joint Analysis of Nuclear and Mitochondrial Variants in Age-Related Macular Degeneration Identifies Novel Loci TRPM1 and ABHD2/RLBP1

Purpose

Presently, 52 independent nuclear single nucleotide polymorphisms (nSNPs) have been associated with age-related macular degeneration (AMD) but their effects do not explain all its variance. Genetic interactions between the nuclear and mitochondrial (mt) genome may unearth additional genetic loci previously unassociated with AMD risk.

Methods

Joint effects of nSNPs and selected mtSNPs were analyzed by two degree of freedom (2df) joint tests of association in the International AMD Genomics Consortium (IAMDGC) dataset (17,832 controls and 16,144 advanced AMD cases of European ancestry). Subjects were genotyped on the Illumina HumanCoreExome array. After imputation using MINIMAC and the 1000 Genomes Project Phase I reference panel, pairwise linkage disequilibrium pruning, and quality control, 3.9 million nSNPs were analyzed for interaction with mtSNPs chosen based on association in this dataset or publications: A4917G, T5004C, G12771A, and C16069T.

Results

Novel locus TRPM1 was identified with genome-wide significant joint effects (P < 5.0 × 10⁻⁸) of two intronic TRPM1 nSNPs and AMD-associated nonsynonymous MT-ND2 mtSNP A4917G. Stratified analysis by mt allele identified an association only in 4917A (major allele) carriers (P = 4.4 × 10⁻⁹, odds ratio [OR] = 0.90, 95% confidence interval [CI] = 0.87–0.93). Intronic and intergenic ABHD2/RLBP1 nSNPs demonstrated genome-wide significant joint effects (2df joint test P values from 1.8 × 10⁻⁸ to 4.9 × 10⁻⁸) and nominally statistically significant interaction effects with MT-ND5 synonymous mtSNP G12771A. Although a positive association was detected in both strata, the association was stronger in 12771A subjects (P = 0.0020, OR = 2.17, 95% CI = 1.34–3.60).

Conclusions

These results show that joint tests of main effects and gene–gene interaction reveal associations at some novel loci that were missed when considering main effects alone.

Endocannabinoid Turnover

In this review, we consider the biosynthetic, hydrolytic, and oxidative metabolism of the endocannabinoids anandamide and 2-arachidonoylglycerol. We describe the enzymes associated with these events and their characterization. We identify the inhibitor profile for these enzymes and the status of therapeutic exploitation, which to date has been limited to clinical trials for fatty acid amide hydrolase inhibitors. To bring the review to a close, we consider whether point block of a single enzyme is likely to be the most successful approach for therapeutic exploitation of the endocannabinoid system.

Molecular characterization of human ABHD2 as TAG lipase and ester hydrolase

Alterations in lipid metabolism have been progressively documented as a characteristic property of cancer cells. Though, human ABHD2 gene was found to be highly expressed in breast and lung cancers, its biochemical functionality is yet uncharacterized. In the present study we report, human ABHD2 as triacylglycerol (TAG) lipase along with ester hydrolysing capacity. Sequence analysis of ABHD2 revealed the presence of conserved motifs G²⁰⁵XS²⁰⁷XG²⁰⁹ and H¹²⁰XXXXD¹²⁵. Phylogenetic analysis showed homology to known lipases, Drosophila melanogaster CG3488. To evaluate the biochemical role, recombinant ABHD2 was expressed in Saccharomyces cerevisiae using pYES2/CT vector and His-tag purified protein showed TAG lipase activity. Ester hydrolase activity was confirmed with pNP acetate, butyrate and palmitate substrates respectively. Further, the ABHD2 homology model was built and the modelled protein was analysed based on the RMSD and root mean square fluctuation (RMSF) of the 100 ns simulation trajectory. Docking the acetate, butyrate and palmitate ligands with the model confirmed covalent binding of ligands with the Ser²⁰⁷ of the GXSXG motif. The model was validated with a mutant ABHD2 developed with alanine in place of Ser²⁰⁷ and the docking studies revealed loss of interaction between selected ligands and the mutant protein active site. Based on the above results, human ABHD2 was identified as a novel TAG lipase and ester hydrolase.

Abhydrolase domain containing 2, an androgen target gene, promotes prostate cancer cell proliferation and migration

BACKGROUND

The androgen receptor (AR) plays a key role in the development of prostate cancer. AR signalling mediates the expression of androgen-responsive genes, which are involved in prostate cancer development and progression. Our previous chromatin immunoprecipitation study showed that the region of abhydrolase domain containing 2 (ABHD2) includes a functional androgen receptor binding site. In this study, we demonstrated that ABHD2 is a novel androgen-responsive gene that is overexpressed in human prostate cancer tissues.

METHODS

The expression levels of ABHD2 in androgen-sensitive cells were evaluated by quantitative reverse transcription polymerase chain reaction and western-blot analyses. LNCaP and VCaP cells with ABHD2 overexpression or short interfering RNA (siRNA) knockdown were used for functional analyses. ABHD2 expression was examined in clinical samples of prostate cancer by immunohistochemistry.

RESULTS

We showed that ABHD2 expression is increased by androgen in LNCaP and VCaP cells. This androgen-induced ABHD2 expression was diminished by bicalutamide. While stable expression of ABHD2 affected the enhancement of LNCaP cell proliferation and migration, siRNA-mediated ABHD2 knockdown suppressed cell proliferation and migration. In addition, the siRNA treatment significantly repressed the tumour growth derived from LNCaP cells in athymic mice. Immunohistochemical analysis of ABHD2 expression in tumour specimens showed a positive correlation of ABHD2 immunoreactivity with high Gleason score and pathological N stage. Moreover, patients with high immunoreactivity of ABHD2 showed low cancer-specific survival rates and a resistance to docetaxel-based chemotherapy.

CONCLUSION

ABHD2 is a novel androgen-regulated gene that can promote prostate cancer growth and resistance to chemotherapy, and is a novel target for diagnosis and treatment of prostate cancer.

A comprehensive 1,000 Genomes-based genome-wide association meta-analysis of coronary artery disease

Existing knowledge of genetic variants affecting risk of coronary artery disease (CAD) is largely based on genome-wide association studies (GWAS) analysis of common SNPs. Leveraging phased haplotypes from the 1000 Genomes Project, we report a GWAS meta-analysis of 185 thousand CAD cases and controls, interrogating 6.7 million common (MAF>0.05) as well as 2.7 million low frequency (0.005<MAF<0.05) variants. In addition to confirmation of most known CAD loci, we identified 10 novel loci, eight additive and two recessive, that contain candidate genes that newly implicate biological processes in vessel walls. We observed intra-locus allelic heterogeneity but little evidence of low frequency variants with larger effects and no evidence of synthetic association. Our analysis provides a comprehensive survey of the fine genetic architecture of CAD showing that genetic susceptibility to this common disease is largely determined by common SNPs of small effect size.

Associations of ABHD2 genetic variations with risks for chronic obstructive pulmonary disease in a Chinese Han population

The human α/β hydrolase domain-containing protein 2 gene (ABHD2) plays a critical role in pulmonary emphysema, a major subset of the clinical entity known as chronic obstructive pulmonary disease (COPD). Here, we evaluated genetic variation in the ABHD2 gene in a Chinese Han population of 286 COPD patients and 326 control subjects. The rs12442260 CT/CC genotype was associated with COPD (P < 0.001) under a dominant model. In the former-smoker group, the rs12442260 TT genotype was associated with a decreased risk of developing COPD after adjusting for age, gender and pack-years (P = 0.012). Rs12442260 was also associated with pre-FEV1 (the predicted bronchodilator forced expiratory volume in the first second) in controls (P = 0.027), but with FEV1/ forced vital capacity (FVC) ratios only in COPD patients (P = 0.012) under a dominant model. Results from the current study suggest that ABHD2 gene polymorphisms contribute to COPD susceptibility in the Chinese Han population.

Mammalian alpha beta hydrolase domain (ABHD) proteins: Lipid metabolizing enzymes at the interface of cell signaling and energy metabolism

Dysregulation of lipid metabolism underlies many chronic diseases such as obesity, diabetes, cardiovascular disease, and cancer. Therefore, understanding enzymatic mechanisms controlling lipid synthesis and degradation is imperative for successful drug discovery for these human diseases. Genes encoding α/β hydrolase fold domain (ABHD) proteins are present in virtually all reported genomes, and conserved structural motifs shared by these proteins predict common roles in lipid synthesis and degradation. However, the physiological substrates and products for these lipid metabolizing enzymes and their broader role in metabolic pathways remain largely uncharacterized. Recently, mutations in several members of the ABHD protein family have been implicated in inherited inborn errors of lipid metabolism. Furthermore, studies in cell and animal models have revealed important roles for ABHD proteins in lipid metabolism, lipid signal transduction, and metabolic disease. The purpose of this review is to provide a comprehensive summary surrounding the current state of knowledge regarding mammalian ABHD protein family members. In particular, we will discuss how ABHD proteins are ideally suited to act at the interface of lipid metabolism and signal transduction. Although, the current state of knowledge regarding mammalian ABHD proteins is still in its infancy, this review highlights the potential for the ABHD enzymes as being attractive targets for novel therapies targeting metabolic disease.

Lipases and Related Molecules in Cancer

Lipases are enzymes that catalyze the hydrolysis of lipids. Based on protein structures and sequences, lipases can be classified into different protein families. The majority of conventional mammalian lipases are members of the protein super-families of serine esterases and alpha-beta hydrolases. Differential expression of lipases and related alpha-beta hydrolases in tumor cells has been observed. The physiological or patho-physiological functions of these tumor related enzymes are largely unknown. However, lipases are not only involved in energy metabolism but also in the metabolism of bioactive molecules, e.g. phosphatidic acid or arachidonic acid, suggesting that tumor-specifically expressed lipases might be interesting targets for the development of future treatment strategies. Moreover, independent of the patho-physiological function, tumor associated lipases can serve as targets for immunological treatment strategies. In addition, lipases with exclusive expression in single tumor entities can serve as potential diagnostic targets.

Alpha/beta hydrolase 1 is upregulated in D5 dopamine receptor knockout mice and reduces O2- production of NADPH oxidase

Renal dopamine receptors have been shown to play a critical role in ROS-dependent hypertension. D5 dopamine receptor deficient (D5-/-) mice are hypertensive and have increased systemic oxidative stress which is manifested in the kidney and the brain. To further investigate the underlying mechanisms of hypertension in D5-/- mice, we used RNA arrays to compare mRNA levels of kidneys from wildtype and D5-/- mice. Our data show, that the mRNA level of alpha/beta hydrolase 1 (ABHD1) is significantly upregulated in D5-/- mice. Additionally, overexpression of ABHD1 in a new established renal proximal tubule cell line reduced the amount of O(2)(-) produced by the NADPH oxidase. Therefore the upregulation of ABHD1 in D5-/- mice could be an answer to the increased oxidative stress. While oxidative stress is an important factor for the development of hypertension, ABHD1 could play a protective role in the pathogenesis of hypertension.

Estrogenic status modulates the effect of soy on hepatic responses to 7,12-dimethylbenz(a)anthracene (DMBA)

We examined the influence of estradiol (E2) status and soy protein isolate (SPI) intake on the hepatic responses altered by 7,12-dimethylbenz(a)anthracene (DMBA, a polycyclic aromatic hydrocarbon [PAH]). Sprague-Dawley rats were ovariectomized (OVX) at PND50 and infused with E2 or vehicle for 14 d and gavaged with 50 mg/kg DMBA or vehicle 24 h before sacrifice at PND64. Rats were fed an AIN-93G diet made with SPI or casein as sole protein source throughout the study. Basal AhR protein levels were reduced (P<0.05) by SPI feeding irrespective of the E2 status. However, DMBA increased (P<0.05) AhR-induced CYP1A1 gene expression in OVX, SPI-fed rats, but reduced (P<0.05) CYP1A1 in OVX+E2, SPI-fed rats. Chromatin-immunoprecipitation demonstrated lower (P<0.05) DMBA-mediated recruitment of estrogen receptor alpha to the CYP1A1 promoter by SPI feeding in the presence of E2, suggesting an estrogen-like action of SPI on DMBA-mediated signaling in the absence of E2. Further, microarray analysis (Rat 230-2.0 Affymetrix-GeneChip) revealed 231 genes common to SPI+DMBA and SPI+E2+DMBA (normalized to E2) treatments. AhR-activated genes (CYP1A1, CYP1A2, and NQO1) were down-regulated by SPI+E2+DMBA compared to SPI+DMBA. Unique interactions among SPI, DMBA and E2 altered the expression profile of 316 genes, not observed by either treatment alone. Our data suggest that although E2 status does not effect soy-mediated AhR degradation, it modulates the effects of soy on many genes, including CYP1A1.