Acyl-CoA synthases catalyze the initial reaction in fatty acid metabolism, by forming a thioester with CoA. Has some preference toward medium-chain substrates. Plays a role in adipodyte differentiation.
Adipogenesis is the process by which undifferentiated precursor cells differentiate into fat laden adipocytes. The nuclear proteins peroxisome proliferator-activated receptors (PPARs) play a central role in adipocyte differentiation. The goals of this study were to identify novel PPARgamma responsive genes and to determine their role in regulating human adipocyte differentiation. Affymetrix profiling of gene expression in human adipocytes identified about 1000 genes that were significantly up-regulated subsequent to induction of differentiation. PPARgamma expression was reduced prior to induction of differentiation using a novel, chemically modified antisense oligonucleotide. Affymetrix microarray profiling of these cells identified 278 statistically significantly down-regulated genes. Eight genes were found to contain previously documented PPARgamma recognition element (PPRE) in their upstream nucleotide (promoter) sequence. Four of these genes are novel and have not previously been characterized. Chromatin immuno-precipitation experiments confirmed the binding of PPARgamma to the PPRE of three of these genes. The ortholog of one of these genes, hypothetical protein FLJ 20920, has previously been reported to be involved in the control of body fat composition in Caenorhabditis elegans. Inhibition of expression of this protein was found to also inhibit differentiation of human adipocytes. MAST/MEME algorithm analysis was used to identify novel commonly occurring sequence motifs in the 5' upstream region of transcripts for subset of down-regulated genes, which were grouped according to their sequence similarities. A number of clusters were identified and the largest cluster contained similar motifs from 26 genes with the literature supporting 7 of the 26 genes as being involved in fatty acid metabolism or PPARgamma interaction.
Acyl-coenzyme A synthetases (ACSs) catalyze the fundamental, initial reaction in fatty acid metabolism. "Activation" of fatty acids by thioesterification to CoA allows their participation in both anabolic and catabolic pathways. The availability of the sequenced human genome has facilitated the investigation of the number of ACS genes present. Using two conserved amino acid sequence motifs to probe human DNA databases, 26 ACS family genes/proteins were identified. ACS activity in either humans or rodents was demonstrated previously for 20 proteins, but 6 remain candidate ACSs. For two candidates, cDNA was cloned, protein was expressed in COS-1 cells, and ACS activity was detected. Amino acid sequence similarities were used to assign enzymes into subfamilies, and subfamily assignments were consistent with acyl chain length preference. Four of the 26 proteins did not fit into a subfamily, and bootstrap analysis of phylograms was consistent with evolutionary divergence. Three additional conserved amino acid sequence motifs were identified that likely have functional or structural roles. The existence of many ACSs suggests that each plays a unique role, directing the acyl-CoA product to a specific metabolic fate. Knowing the full complement of ACS genes in the human genome will facilitate future studies to characterize their specific biological functions.
Catalysis of the joining of two substances, or two groups within a single molecule, with the concomitant hydrolysis of the diphosphate bond in ATP or a similar triphosphate.
The chemical reactions and pathways involving fatty acids, aliphatic monocarboxylic acids liberated from naturally occurring fats and oils by hydrolysis.
Protein involved in the biochemical reactions with fatty acids. Fatty acids are long chain organic acids of the general formula CH3(CnHx)COOH. They are constituents of lipids and can be saturated or unsaturated. The esterified forms are important both as energy storage molecules and structural molecules.
Protein involved in the biochemical reactions of lipids. Lipids are a diverse class of compounds which are insoluble in water but soluble in organic solvents. They include fats, oils, triacylglycerols, fatty acids, glycolipids, phospholipids and steroids.
Enzyme that catalyzes the joining of two molecules coupled with the breakdown of a pyrophosphate bond in ATP or a similar triphosphate. Sometimes the terms "synthase", "synthetase" or "carboxylase" are also used for this class of enzymes.
A reference proteome is a set of protein sequences derived from a complete proteome which constitutes a defined standard for a particular user community. Reference proteomes are manually defined according to a number of criteria. They cover the proteomes of well- studied model organisms and other proteomes of interest for biomedical and biotechnological research. Reference proteomes have been selected to provide broad coverage of the tree of life, and constitute a representative cross-section of the taxonomic diversity to be found within UniProtKB.