acyl-CoA Binding Protein Gene Research Articles

Identification of acyl-CoA-binding protein gene in Triticeae species reveals that TaACBP4A-1 and TaACBP4A-2 positively regulate powdery mildew resistance in wheat

Plant acyl-CoA-binding proteins (ACBPs), which contain the conserved ACB domain, participate in multiple biological processes, however, there are few reports on wheat ACBPs. In this study, the ACBP genes from nine different species were identified comprehensively. The expression patterns of TaACBP genes in multiple tissues and under various biotic stresses were determined by qRT-PCR. The function of selected TaACBP genes was studied by virus-induced gene silencing. A total of 67 ACBPs were identified from five monocotyledonous and four dicotyledonous species and divided into four classes. Tandem duplication analysis of the ACBPs suggested that tandem duplication events occurred in Triticum dicoccoides, but there was no tandem duplication event in wheat ACBP genes. Evolutionary analysis suggested that the TdACBPs may have experienced gene introgression during tetraploid evolution, while TaACBP gene loss events occurred during hexaploid wheat evolution. The expression pattern showed that all the TaACBP genes were expressed, and most of them were responsive to induction by Blumeria graminis f. sp. tritici or Fusarium graminearum. Silencing of TaACBP4A-1 and TaACBP4A-2 increased powdery mildew susceptibility in the common wheat BainongAK58. Furthermore, TaACBP4A-1, which belonged to class III, physically interacted with autophagy-related ubiquitin-like protein TaATG8g in yeast cells. This study provided a valuable reference for further investigations into the functional and molecular mechanisms of the ACBP gene family.

Molecular Characterization of the Acyl-CoA-Binding Protein Genes Reveals Their Significant Roles in Oil Accumulation and Abiotic Stress Response in Cotton.

Members of the acyl-CoA-binding protein (ACBP) gene family play vital roles in diverse processes related to lipid metabolism, growth and development, and environmental response. Plant ACBP genes have been well-studied in a variety of species including Arabidopsis, soybean, rice and maize. However, the identification and functions of ACBP genes in cotton remain to be elucidated. In this study, a total of 11 GaACBP, 12 GrACBP, 20 GbACBP, and 19 GhACBP genes were identified in the genomes of Gossypium arboreum, Gossypium raimondii, Gossypium babardense, and Gossypium hirsutum, respectively, and grouped into four clades. Forty-nine duplicated gene pairs were identified in Gossypium ACBP genes, and almost all of which have undergone purifying selection during the long evolutionary process. In addition, expression analyses showed that most of the GhACBP genes were highly expressed in the developing embryos. Furthermore, GhACBP1 and GhACBP2 were induced by salt and drought stress based on a real-time quantitative PCR (RT-qPCR) assay, indicating that these genes may play an important role in salt- and drought-stress tolerance. This study will provide a basic resource for further functional analysis of the ACBP gene family in cotton.

DNA G-quadruplex structure participates in regulation of lipid metabolism through acyl-CoA binding protein.

G-quadruplex structure (G4) is a type of DNA secondary structure that widely exists in the genomes of many organisms. G4s are believed to participate in multiple biological processes. Acyl-CoA binding protein (ACBP), a ubiquitously expressed and highly conserved protein in eukaryotic cells, plays important roles in lipid metabolism by transporting and protecting acyl-CoA esters. Here, we report the functional identification of a G4 in the promoter of the ACBP gene in silkworm and human cancer cells. We found that G4 exists as a conserved element in the promoters of ACBP genes in invertebrates and vertebrates. The BmACBP G4 bound with G4-binding protein LARK regulated BmACBP transcription, which was blocked by the G4 stabilizer pyridostatin (PDS) and G4 antisense oligonucleotides. PDS treatment with fifth instar silkworm larvae decreased the BmACBP expression and triacylglycerides (TAG) level, resulting in reductions in fat body mass, body size and weight and growth and metamorphic rates. PDS treatment and knocking out of the HsACBP G4 in human hepatic adenocarcinoma HepG2 cells inhibited the expression of HsACBP and decreased the TAG level and cell proliferation. Altogether, our findings suggest that G4 of the ACBP genes is involved in regulation of lipid metabolism processes in invertebrates and vertebrates.

Two typical acyl-CoA-binding proteins (ACBPs) are required for the asexual development and virulence of Phytophthora sojae

Being found in all eukaryotes investigated, acyl-CoA-binding proteins (ACBPs) participate in lipid metabolism via specifically binding acyl-CoA esters with high affinity. The structures and functions of ACBP family proteins have been extensively described in yeasts, fungi, plants and mammals, but not oomycetes. In the present study, seven ACBP genes named PsACBP1-7 were identified from the genome of Phytophthora sojae, an oomycete pathogen of soybean. CRISPR-Cas9 knockout mutants targeting PsACBP1 and PsACBP2 were created for phenotypic assays. PsACBP1 knockout led to defects in sporangia production and virulence. PsACBP2 knockout mutants exhibited impaired vegetative growth, zoospore production, cyst germination and virulence. Moreover, Nile red staining of PsACBP2 knockout and over-expression lines showed that PsACBP2 is involved in the formation of lipid bodies in P. sojae. Our results demonstrate that two ACBP genes are differently required for growth and development, and both are essential for virulence in P. sojae.

Evolution of Acyl-CoA-binding protein gene family in plants provides insights into potential functions of grapevine (Vitis vinifera L.)

BACKGROUND: Grapevine was one of the most important perennial fruit crops worldwide. Acyl-CoA-binding proteins (ACBPs) in eudicots and monocots show conservation in an acyl-CoA-binding domain (ACB domain) which binds acyl-CoA esters. OBJECTIVE: The information and data provided in the present study contributes to understand the evolutionary processes and potential functions of this gene family in grapevine growth and development, and responses to abiotic stress. METHODS: Using the complete grapevine genome sequences, we investigated the number grapevine ACBP genes, the exon-intron structure, phylogenetic relationships and synteny with the Arabidopsis ACBP gene family. Furthermore, the expression profiles of VvACBP genes based on public microarray data in different tissues, and the expression patterns responding to different exogenous hormones as well as abiotic and biotic stresses were presented. The qRT-PCR was used to verify the microarray data under drought stress treatments. Finally, the leaf relative water content (RWC), leaf chlorophyll content, and enzymatic activities were measured to further examine the tolerance to drought stress in grapevine. RESULTS: The six grapevine ACBPs were identified. Their distribution into various groups differed from Arabidopsis and rice. Synteny analysis demonstrated that several VvACBP genes were found in corresponding syntenic blocks of Arabidopsis, suggesting that these genes arose before the divergence of the respective lineages. Sequence alignment and structural annotation provided an overview of variations that might contribute to functional divergence from Arabidopsis ACBPs. Expressional analyses suggested that both conserved and variant biological functions exist in ACBPs across different species. The expression pattern of these genes were similar in the microarray and qRT-PCR analyses. Gene structure organization and expression characteristics of VvACBPs resembled those of their Arabidopsis orthologous, although species-specific differences also exist. Differential regulation of genes suggested functional diversification among isoforms. The biochemical and physiological data showed the tolerance to drought stress of grapevine. CONCLUSIONS: These findings provided insight into evolution of ACBP gene family in plants and a solid foundation for a deeper understanding of the complex molecular responses of grapevine to stress.

Abstract 3248: Over-expression of 1-ACBP, B-ACBP and PBR genes in mast cells infiltrating oesophageal squamous cell tumors

Abstract Oesophageal cancer ranks as the sixth most common malignancy in the world, and recent evidence has shown that its incidence is increasing. ACBPs (Acyl-coA binding proteins) act as intracellular carrier-proteins for medium to long chain acyl-coA, mediating fatty acid transport to the mitochondrion for ß-oxidation. ACBPs are also believed to be putative ligands of PBR (peripheral benzodiazepine receptor), and bound to this receptor facilitate mitochondrial membrane permeabilization giving the notion that favours apoptosis. The main aim of the study was to establish the expression patterns of 1-ACBP, B-ACBP, and PBR in oesophageal cancer, and to link their roles with the disease. Probes specific to the genes encoding 1-ACBP, B-ACBP, and PBR were PCR amplified and cloned into pGEM-T easy vectors using gene specific primers. The cloned products were sequenced and screened against the GENBANK database (NCBI) to verify the identity and orientation of cloned products within the vector. Antisense and sense probes were then generated using T7 or SP6 RNA polymerase after digestion with either Pst1 or Apa1, respectively. In situ hybridization and quantitative real-time PCR methods were performed to determine localization and the expression levels of the three genes in oesophageal cancer. All three genes illustrated substantial up-regulation within the malignant tissue sections as compared to normal oesophageal sections, all three transcripts localized specifically to plasma cells and lymphocytes in diseased and normal tissue section. In the diseased tissue B-ACBP and 1-ACBP mRNA localized to endothelial cells of blood vessels in the submucosa. B-ACBP also localized to the nucleus of squamous epithelial cells. PBR localization was indicated in tumour islands of invasive tissue sections. Quantitative RT-PCR also indicated that the expression levels of PBR were higher as compared to the ACBP genes expression in tumours. These results show that 1-ACBP, B-ACBP and PBR play a role in the pathogenesis of oesophageal tumours and also suggest the interaction between these genes with the immune system and that was also confirmed using bioinformatics analysis. Citation Format: Zodwa Dlamini. Over-expression of 1-ACBP, B-ACBP and PBR genes in mast cells infiltrating oesophageal squamous cell tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3248.

The ACBP gene family in Rhodnius prolixus: Expression, characterization and function of RpACBP-1

The acyl-CoA-binding proteins (ACBP) constitute a family of conserved proteins that bind acyl-CoA with high affinity and protect it from hydrolysis. Thus, ACBPs may have essential roles in basal cellular lipid metabolism. The genome of the insect Rhodnius prolixus encodes five ACBP genes similar to those described for other insect species. The qPCR analysis revealed that these genes have characteristic expression profiles in insect organs, suggesting that they have specific roles in insect physiology. Recombinant RpACBP-1 was able to bind acyl-CoA in an in vitro gel-shift assay. Moreover, heterologous RpACBP-1 expression in acb1Δ mutant yeast rescued the multi-lobed vacuole phenotype, indicating that RpACBP-1 acts as a bona fide acyl-CoA-binding protein. RpACBP-1 knockdown using RNAi caused triacylglycerol accumulation in the insect posterior midgut and a reduction in the number of deposited eggs. The amount of stored triacylglycerol was reduced in flight muscle, and the incorporation of fatty acids in cholesteryl esters was increased in the fat body. These results showed that RpACBP-1 participates in several lipid metabolism steps in R. prolixus.

Construction of Overexpression Vector of ACBP Gene in Zygosaccharomyces rouxii

The Zygosaccharomyces rouxii is a kind of fermentation yeast which yield flavoring substance in the production of soy sauce. In order to the overexpression of the target protein in wild type strains, we choose PYEs2.0 as the original carrier, the acyl-coA binding protein (ACBP) and GFP gene have been cloned in the multiple cloning site. The screening of labeled URA3 gene was replaced by KanMX gene which anti G418. The vector was obtained through the screening of G418 at the concentration of 25 ug/ml.

Molecular cloning and characterization of acyl-CoA binding protein (ACBP) gene from shrimp Penaeus monodon exposed to salinity stress

Acyl-CoA binding protein (ACBP), a protein present ubiquitously in wide range of organisms play significant role in transport of acyl groups for macromolecular biosynthesis involved in various functional and regulatory processes. In crustaceans, ACBP has functional role in growth, reproduction and temperature tolerance. In the present study, two suppression subtractive hybridization (SSH) cDNA libraries were performed using gut tissues of shrimp Penaeus monodon exposed to low (3ppt) and high (55ppt) salinity stress conditions. SSH library resulted in identification of differentially expressed genes that belonged to various functional classes such as the nucleic acid regulation and replication, defence proteins, allergen protein, signal transduction pathways, apoptosis, energy and metabolism, cell cycle regulation and hypothetical proteins. ACBP was identified as one of the differentially expressed gene in both the SSH libraries of shrimp P. monodon subjected to low and high salinity stress. The full-length cDNA of P. monodon ACBP gene was isolated and the sequence revealed 273bp open reading frame encoding 90 amino acids with molecular mass of 10kDa and pI 6.8. The ORF showed presence of four phosphorylation sites, with absence of signal peptide sequence and glycosylation sites. The deduced amino acid sequence of ACBP exhibited high sequence identity (92%) with ACBP class of protein identified from Fenneropenaeus chinensis. Real time PCR analysis of shrimps subjected to 3ppt salinity conditions after 2weeks revealed an increase in expression of ACBP transcripts, in the gut (28.08-folds), gills (11.71-folds) and in the muscle tissues (1.70-folds). Whereas, shrimps exposed to 55ppt salinity conditions after 2weeks exhibited increased ACBP transcript levels in the gut (11.95-folds), gills (1.052-folds) and muscle tissues (7.35-folds). The significant increase in expression levels of ACBP in various tissues of shrimps suggests a functional role of this gene in salinity stress tolerance and adaptation.

Molecular properties of the class III subfamily of acyl-coenyzme A binding proteins from tung tree (Vernicia fordii)

Acyl-CoA binding proteins (ACBPs) have been identified in most branches of life, and play various roles in lipid metabolism, among other functions. Plants contain multiple classes of ACBP genes. The most diverse group is the class III proteins. Tung tree (Vernicia fordii) contains two such genes, designated VfACBP3A and VfACBP3B. The two proteins are significantly different in length and sequence. Analysis of tung ACBP3 genes revealed significant evolution, suggesting relatively ancient divergence of the two genes from a common ancestor. Phylogenetic comparisons of multiple plant class III proteins suggest that this group is the most evolutionarily dynamic class of ACBP. Both tung ACBP3 genes are expressed at similar levels in most tissues tested, but ACBP3A is stronger in leaves. Three-dimensional modeling predictions confirmed the presence of the conserved four α-helix bundle acyl-CoA binding (ACB); however, other regions of these proteins likely fold much differently. Acyl-CoA binding assays revealed different affinities for different acyl-CoAs, possibly contradicting the redundancy of function suggested by the gene expression studies. Subcellular targeting of transiently-expressed plant ACBP3 proteins contradicted earlier studies, and suggested that at least some class III ACBPs may be predominantly targeted to endoplasmic reticulum membranes, with little or no targeting to the apoplast.

Mice with targeted disruption of the acyl-CoA binding protein display attenuated urine concentrating ability and diminished renal aquaporin-3 abundance

The acyl-CoA binding protein (ACBP) is a small intracellular protein that specifically binds and transports medium to long-chain acyl-CoA esters. Previous studies have shown that ACBP is ubiquitously expressed but found at particularly high levels in lipogenic cell types as well as in many epithelial cells. Here we show that ACBP is widely expressed in human and mouse kidney epithelium, with the highest expression in the proximal convoluted tubules. To elucidate the role of ACBP in the renal epithelium, mice with targeted disruption of the ACBP gene (ACBP(-/-)) were used to study water and NaCl balance as well as urine concentrating ability in metabolic cages. Food intake and urinary excretion of Na(+) and K(+) did not differ between ACBP(-/-) and (+/+) mice. Interestingly, however, water intake and diuresis were significantly higher at baseline in ACBP(-/-) mice compared with that of (+/+) mice. Subsequent to 20-h water deprivation, ACBP(-/-) mice exhibited increased diuresis, reduced urine osmolality, elevated hematocrit, and higher relative weight loss compared with (+/+) mice. There were no significant differences in plasma concentrations of renin, corticosterone, and aldosterone between mice of the two genotypes. After water deprivation, renal medullary interstitial fluid osmolality and concentrations of Na(+), K(+), and urea did not differ between genotypes and cAMP excretion was similar. Renal aquaporin-1 (AQP1), -2, and -4 protein abundances did not differ between water-deprived (+/+) and ACBP(-/-) mice; however, ACBP(-/-) mice displayed increased apical targeting of pS256-AQP2. AQP3 abundance was lower in ACBP(-/-) mice than in (+/+) control animals. Thus we conclude that ACBP is necessary for intact urine concentrating ability. Our data suggest that the deficiency in urine concentrating ability in the ACBP(-/-) may be caused by reduced AQP3, leading to impaired efflux over the basolateral membrane of the collecting duct.

Acyl-CoA binding protein gene ablation induces pre-implantation embryonic lethality in mice.

Unique among the intracellular lipid binding proteins, acyl-CoA binding protein (ACBP) exclusively binds long-chain fatty acyl-CoAs (LCFA-CoAs). To test if ACBP is an essential protein in mammals, the ACBP gene was ablated by homologous recombination in mice. While ACBP heterozygotes appeared phenotypically normal, intercrossing of the heterozygotes did not produce any live homozygous deficient (null) ACBP((-/-)) pups. Heterozygous and wild type embryos were detected at all post-implantation stages, but no homozygous ACBP-null embryos were obtained-suggesting that an embryonic lethality occurred at a pre-implantation stage of development, or that embryos never formed. While ACBP-null embryos were not detected at any blastocyst stage, ACBP-null embryos were detected at the morula (8-cell), cleavage (2-cell), and zygote (1-cell) pre-implantation stages. Two other LCFA-CoA binding proteins, sterol carrier protein-2 (SCP-2) and sterol carrier protein-x (SCP-x) were significantly upregulated at these stages. These findings demonstrate for the first time that ACBP is an essential protein required for embryonic development and its loss of function may be initially compensated by concomitant upregulation of two other LCFA-CoA binding proteins, but only at the earliest pre-implantation stages. The fact that ACBP is the first known intracellular lipid binding protein whose deletion results in embryonic lethality suggests its vital importance in mammals.

Serotonin regulates an acyl-CoA-binding protein (ACBP) gene expression in the midgut of Rhodnius prolixus

Acyl-CoA esters have many intracellular functions, acting as energy source, substrate for metabolic processes and taking part in cell signaling. The acyl-CoA-binding protein (ACBP), a highly conserved 10 kDa intracellular protein, binds long- and medium-chain acyl-CoA esters with very high affinity, directing them to specific metabolic routes and protecting them from hydrolysis. An ACBP gene sequence was identified in the genome of Rhodnius prolixus. This ACBP gene ( RpACBP-1) was expressed in all analyzed tissues and quantitative PCR showed that expression was highest in posterior midgut. In this tissue, ACBP gene expression increased in the first day after blood meal (∼10-fold) and then decreased to unfed levels in the seventh day after meal. Injection of serotonin (5-hydroxytryptamine; 5-HT), a neuroamine released in the hemolymph after the start of feeding, increased the expression of this gene in the midgut of unfed females, reaching levels similar to those observed in fed insects. This effect of injected 5-HT was inhibited by spiperone, an antagonist of 5-HT mammalian receptors, that was also able to block the physiological increase in RpACBP-1 expression observed after feeding. Injection of cholera toxin or dibutyryl-cAMP also resulted in the stimulation of this gene expression. These data reveal a transcriptional regulatory mechanism in R. prolixus, that is triggered by 5-HT. In this way, a novel role for 5-HT is proposed, as a regulator of ACBP gene expression and, consequently, taking part in the control of lipid metabolism.

Effect of medium‐ and long‐chain fatty acid diets on PPAR and SREBP‐1 expression and glucose homeostasis in ACBP‐overexpressing transgenic rats

Acyl-CoAs are important intermediates and regulators of lipid metabolism. Binding proteins like acyl-CoA binding protein (ACBP) can influence their regulatory functions. ACBP has also been shown to exert direct effects on gene regulation in vitro. As the physiological relevance of ACBP in the regulation of lipid metabolism under high fat diets is unclear, we investigated the influence of such diets on the metabolic responses in ACBP-overexpressing rats. A transgenic rat line overexpressing the ACBP gene was used to study the effects of 4 weeks of feeding with medium- (MC) or long-chain (LC) fatty acid-containing diets. Glucose tolerance tests were performed. Expression of transcription factors was measured by quantitative RT-PCR and protein levels of AMP-activated protein kinase were determined by western blotting. Transgenic animals fed the MC diet had an improved glucose tolerance and lower serum insulin levels compared with controls. Their liver PPARgamma (by 43%) and SREBP-1 (by 35%) mRNA levels were found to be decreased, while adipose tissue PPARgamma expression was increased by 31%. Tg animals fed the LC diet did not exhibit changes in glucose or insulin levels but exhibited increased mRNA levels of liver PPARs and SREBP-1 (1.5-3.5 times) and decreased protein levels of AMPKalpha (by 48%). Our results demonstrate that ACBP overexpression affects metabolic responses to diets with distinct difference in their fatty acid chain lengths. The molecular regulatory mechanism behind these effects seems to be an ACBP-induced tissue-specific regulation of expression of PPARs and SREBP.

Association of acyl‐CoA‐binding protein (ACBP) single nucleotide polymorphisms and type 2 diabetes in two German study populations

The human acyl-CoA-binding protein (ACBP) is a potential candidate gene of type 2 diabetes (T2D), since it plays a central role in determining the intracellular concentration of activated fatty acids which contribute to insulin resistance. The aim of our study was to evaluate whether single nucleotide polymorphisms (SNPs) of the ACBP gene are associated with risk of T2D. Genotyping of eight SNPs (rs2084202, rs3731607, rs8192501, rs8192504, rs2244135, rs2276596, rs8192506, rs2289948) was performed in 192 incident T2D subjects and 384 matched controls of the European Prospective Investigation into Cancer and Nutrition-Potsdam cohort. A putative promoter SNP (rs2084202) of splice variant ACBP 1c showed decreased risk of T2D (odds ratio (OR) 0.63, 95% CI 0.41-0.96). The haplotype, that contained the mutant base of rs2084202 showed similar evidence for the association with disease risk as single SNP rs2084202. In a second population-based study, Cooperative Health Research in the Augsburg Region of 226 individuals with T2D and 863 control subjects a borderline significant association between rs2084202 and T2D (OR 0.72, 95% CI 0.51-1.01) was observed. In summary, we obtained evidence from two Caucasian study populations that the minor allele of ACBP rs2084202 might be associated with reduced risk of T2D.

ACBP – a PPAR and SREBP modulated housekeeping gene

The acyl-CoA binding protein (ACBP) is a 10 kD intracellular lipid binding protein that binds and transports acyl-CoA esters. The protein is expressed in most cell types at low levels; however, expression differs markedly between different cell types with expression being particularly high in e.g. cells with a high turnover of fatty acids. We show here that the relatively high basal promoter activity of the rat ACBP gene in fibroblasts and hepatoma cells relies on sequences between -331 to -182 and on the Sp1 and NF-Y sites at -172 and -143, respectively. The basal transcription is modulated by members of the PPAR and SREBP families. In adipocytes, PPARgamma is in part responsible for the induction during adipocyte differentiation, but other transcription factors appear to play a role as well. In hepatocytes, SREBP-1c is the main regulator of ACBP in response to changes in insulin levels during fasting/refeeding. PPARalpha counteracts this effect by stimulating ACBP expression during fasting. In addition, PPARalpha mediates the induction of ACBP expression in response to peroxisome proliferators. PPARalpha and PPARgamma do not require sequences upstream of -182 for transactivation; however, SREBP-1c requires the synergistic action of sequences in intron 1 for transactivation of the ACBP promoter.

Isolation and characterization of a cDNA encoding a membrane bound acyl-CoA binding protein from Agave americana L. epidermis

A cDNA encoding an acyl-CoA binding protein (ACBP) homologue has been cloned from a cDNA library made from mRNA isolated from epidermis of young leaves of Agave americana L. The derived amino acid sequence reveals a protein corresponding to the membrane-associated form of ACBPs only previously described in Arabidopsis and rice. Northern blot analysis showed that the A. americana ACBP gene is mainly expressed in the epidermis of mature zone of the leaves. The epidermis of A. americana leaves have a well developed cuticle with the highest amounts of the cuticular components waxes, cutin and cutan suggesting a potential role of the protein in cuticle formation.

Evolution of the acyl-CoA binding protein (ACBP)

Acyl-CoA-binding protein (ACBP) is a 10 kDa protein that binds C12-C22 acyl-CoA esters with high affinity. In vitro and in vivo experiments suggest that it is involved in multiple cellular tasks including modulation of fatty acid biosynthesis, enzyme regulation, regulation of the intracellular acyl-CoA pool size, donation of acyl-CoA esters for beta-oxidation, vesicular trafficking, complex lipid synthesis and gene regulation. In the present study, we delineate the evolutionary history of ACBP to get a complete picture of its evolution and distribution among species. ACBP homologues were identified in all four eukaryotic kingdoms, Animalia, Plantae, Fungi and Protista, and eleven eubacterial species. ACBP homologues were not detected in any other known bacterial species, or in archaea. Nearly all of the ACBP-containing bacteria are pathogenic to plants or animals, suggesting that an ACBP gene could have been acquired from a eukaryotic host by horizontal gene transfer. Many bacterial, fungal and higher eukaryotic species only harbour a single ACBP homologue. However, a number of species, ranging from protozoa to vertebrates, have evolved two to six lineage-specific paralogues through gene duplication and/or retrotransposition events. The ACBP protein is highly conserved across phylums, and the majority of ACBP genes are subjected to strong purifying selection. Experimental evidence indicates that the function of ACBP has been conserved from yeast to humans and that the multiple lineage-specific paralogues have evolved altered functions. The appearance of ACBP very early on in evolution points towards a fundamental role of ACBP in acyl-CoA metabolism, including ceramide synthesis and in signalling.

Identification of new acyl-CoA binding protein transcripts in human and mouse

The ubiquitously expressed acyl-CoA binding protein (ACBP) is involved in lipid metabolism and is regulated by hormones and feeding status via transcription factors such as sterol regulatory element-binding protein 1 and peroxisome proliferator-activated receptor-γ (PPARγ). In humans, two transcripts encoding proteins of 86 and 104 amino acids are known, whereas in mouse only one protein of 86 amino acids is described. We identified new transcripts in human and mouse tissues, that had been generated by alternative first exon usage. Quantitative RT-PCR analyses showed a high expression of the new human transcript, ACBP-1c, in adipose tissue. By promoter reporter gene assays, specific regulation of this transcript by PPARγ2 was revealed, implicating the usage of an alternative promoter that contains a PPARγ responsive element. Subcellular localizations of the known human proteins and the new variant showed an occurrence in cytoplasma and nucleus. Reported studies concerning ACBP gene regulation should be re-evaluated with respect to a new ACBP gene model. Given the fact that the new variant is highly expressed in adipose tissue and a PPARγ target, it might be relevant for diseases like diabetes and obesity.

Isolation and Characterization of a Humoral Factor That Stimulates Transcription of the Acyl-CoA-binding Protein in the Pheromone Gland of the Silkmoth, Bombyx mori

Acyl-CoA binding protein (ACBP) is a highly conserved 10-kDa intracellular lipid-binding protein that binds straight-chain (C14-C22) acyl-CoA esters with high affinity and is expressed in a wide variety of species ranging from yeast to mammals. Functionally, ACBP can act as an acyl-CoA carrier or as an acyl-CoA pool maker within the cell. Much work on the biochemical properties regarding the ACBP has been performed using various vertebrate and plant tissues, as well as different types of cells in culture, the regulatory mechanisms underlying ACBP gene expression have remained poorly understood. By exploiting the unique sex pheromone production system in the moth pheromone gland (PG), we report that transcription of a specific ACBP termed pheromone gland ACBP is triggered by a hemolymph-based humoral factor. Following purification and structure elucidation by means of high resolution electrospray ionization mass spectrometry and NMR analyses, in conjunction with stereochemical analyses using acid hydrolysates, the humoral factor was identified to be beta-D-glucosyl-O-L-tyrosine. Examination of the hemolymph titers during development revealed that the amount of beta-D-glucosyl-O-L-tyrosine dramatically rose prior to eclosion and reached a maximum of 5 mg/ml (about 1 mg/pupa) on the day preceding eclosion, which was consistent with the effective dose of beta-D-glucosyl-O-L-tyrosine in stimulating pheromone gland ACBP transcription in vivo. Furthermore, in vitro assays using trimmed PG indicated that beta-D-glucosyl-O-L-tyrosine acts directly on the PG. These results provide the first evidence that transcription of some ACBPs can be triggered by specific humoral factors.