Project description:Arabidopsis seeds expressing the castor fatty acid hydroxylase accumulate hydroxylated fatty acids up to 17% of total fatty acids in seed triacylglycerols, however total seed oil is also reduced up to 50%. Investigations into the cause of the reduced oil phenotype through in vivo [14C]acteate and [3H]2O metabolic labeling of developing seeds surprisingly revealed that the rate of de novo fatty acid synthesis within the transgenic seeds was approximately half that of control seeds. Addition of castor phospholipid:diacylglycerol acyltransferase (PDAT) increased hydroxylated fatty acid content of the seed oil, increased the rate of fatty acid synthesis, and mostly restored seed oil levels. RNAseq analysis indicated no changes in expression of fatty acid synthesis genes in hydroxylase-expressing plants. Transcript profiles of Arabidopsis developing seeds of three lines, at three stages of development were generated by deep sequencing, in triplicate, using Illumina.
Project description:Arabidopsis seeds expressing the castor fatty acid hydroxylase accumulate hydroxylated fatty acids up to 17% of total fatty acids in seed triacylglycerols, however total seed oil is also reduced up to 50%. Investigations into the cause of the reduced oil phenotype through in vivo [14C]acteate and [3H]2O metabolic labeling of developing seeds surprisingly revealed that the rate of de novo fatty acid synthesis within the transgenic seeds was approximately half that of control seeds. Addition of castor phospholipid:diacylglycerol acyltransferase (PDAT) increased hydroxylated fatty acid content of the seed oil, increased the rate of fatty acid synthesis, and mostly restored seed oil levels. RNAseq analysis indicated no changes in expression of fatty acid synthesis genes in hydroxylase-expressing plants.
Project description:Sesamin, a special compound present in sesame and sesame oil, has been reported the role in regulating blood lipids and improving liver function, while the underlying mechanisms remain unclear. This study aims to explore its potential mechanisms in regulating lipid metabolism. HepG2 cells were treated with oleic acid to establish an in vitro high-fat cell model to simulate impaired hepatocytes under lipid metabolism disorders.Differentially expressed genes during the sesame intervention were screened by RNA sequencing (RNA seq) and validated using real-time quantitative PCR and Western blot.The data showed that sesamin significantly upregulated the mRNA levels of genes involved in fatty acid metabolism processes such as ETFB, ACAT2, FADS2, FABP1, ACOT1, and those involved in cholesterol metabolism processes such as FDPS, PCSK9, and DHCR7, and downregulated the mRNA levels of CYP24A1 and GGT5 involved in fatty acid metabolism, as well as MVK involved in cholesterol synthesis. Sesamin significantly down-regulated the protein levels of NOTCH1, CD36, SOX4, and FABP1. In summary, sesamin alleviates lipid accumulation in HepG2 by regulating lipid metabolism, with potential mechanisms involving steroid biosynthesis, unsaturated fatty acid biosynthesis, fat digestion and absorption, fatty acid metabolism, Notch signaling pathway, and PPAR signaling pathway.
Project description:Global analyses of protein profiling during seed development in soybean is paramount to understand the metabolic processes that correspond to the differential protein accumulation and hence seed quality in soybean. Using high throughput tandem mass tag (TMT) based tagging techniques, we identified 4,172 proteins in three stages namely early, mid, and late seed filling. We mapped the identified metabolic pathways associated with seed filling. An elevated level of several kinases was observed from the early to mid-stages of seed filling, indicating that protein phosphorylation was a major event that occurred during this period. The early to late stages of seed filling was characterized by an increased level of proteins associated with the cell wall, oil, and vacuolar-related processes. Twenty-five seed storage protein genes located on 12 different chromosomes were identified. Among the seed storage proteins, 7S (B-subunit) and 11S (Gy3, Gy4, Gy5) exhibited steadily increased abundance from early to late-stage seed development, whereas, 2S albumin exhibited decreased abundance during the same period. An increased abundance of proteases, senescence-associated proteins and, oil synthesis proteins was observed from the mid to late stages of seed filling. The mid to late stages of seed filling were also characterized by a lower abundance of transferases, transporters, Kunitz family trypsin, and protease inhibitors. Two enzymes associated with methionine synthesis exhibited lower abundance from early to late stages. This study unveiled the expression of several key enzymes/proteins associated with amino acid and protein syntheses and their accumulation during seed development which will assist scientists and breeders to develop new value-added soybeans with improved protein quality.
Project description:Metabolic remodeling is one of the earliest events that occur during the early differentiation of embryonic stem cells (ESCs), but how these metabolic changes are regulated and participate in the cell differentiation is still largely undissected. Here, we define the fatty acid metabolism as a key player in definitive endoderm (DE) differentiation from human ESCs. During DE differentiation, lipogenesis is decreased while fatty acid β oxidation is enhanced. This dynamic is due to the phosphorylation of lipogenic enzyme acetyl-CoA carboxylase (ACC), which is mediated by AMP-activated protein kinase (AMPK) and inhibits the de novo fatty acid synthesis. More importantly, inhibition of fatty acid synthesis by either its inhibitors or AMPK agonist, significantly promotes the human endoderm differentiation, while blockade of the fatty acid oxidation by genetic manipulation or chemical antagonists impairs the differentiation. The de novo fatty acid synthesis inhibition and fatty acid β oxidation maintaining contribute to the accumulation of cellular acetyl-CoA, which is the essential substrate for protein acetylation. Further study reveals that SMAD3 acetylation and the subsequent subcellular localization exhibit significant change upon interfering fatty acid metabolism. Mechanistically, the accumulation of cellular acetyl-CoA guarantees the acetylation of key transcription factor SMAD3, which further causes the nuclear localization and activation of SMAD signaling pathway to promote DE differentiation. Thus, our current study reveals a fatty acid synthesis/oxidation shift during early differentiation and presents an instructive role of fatty acid metabolism in regulating human early endoderm differentiation.
Project description:Metabolic remodeling is one of the earliest events that occur during the early differentiation of embryonic stem cells (ESCs), but how these metabolic changes are regulated and participate in the cell differentiation is still largely undissected. Here, we define the fatty acid metabolism as a key player in definitive endoderm (DE) differentiation from human ESCs. During DE differentiation, lipogenesis is decreased while fatty acid β oxidation is enhanced. This dynamic is due to the phosphorylation of lipogenic enzyme acetyl-CoA carboxylase (ACC), which is mediated by AMP-activated protein kinase (AMPK) and inhibits the de novo fatty acid synthesis. More importantly, inhibition of fatty acid synthesis by either its inhibitors or AMPK agonist, significantly promotes the human endoderm differentiation, while blockade of the fatty acid oxidation by genetic manipulation or chemical antagonists impairs the differentiation. The de novo fatty acid synthesis inhibition and fatty acid β oxidation maintaining contribute to the accumulation of cellular acetyl-CoA, which is the essential substrate for protein acetylation. Further study reveals that SMAD3 acetylation and the subsequent subcellular localization exhibit significant change upon interfering fatty acid metabolism. Mechanistically, the accumulation of cellular acetyl-CoA guarantees the acetylation of key transcription factor SMAD3, which further causes the nuclear localization and activation of SMAD signaling pathway to promote DE differentiation. Thus, our current study reveals a fatty acid synthesis/oxidation shift during early differentiation and presents an instructive role of fatty acid metabolism in regulating human early endoderm differentiation.
Project description:To address the molecular basis for atherogenic diet-induced liver injury, we performed microarray analysis using livers at early (6 weeks) and pre-cirrhosis stages (24 weeks) in the development of steatohepatitis. The Atherogenic diet up-regulated the gene expression for fatty acid synthesis, inflammatory cytokines, oxidative stress, and fibrosis, and with down-regulation of fatty acid beta-oxidation. The addition of a high-fat component to the Atherogenic diet up-regulated the gene expression for fatty acid synthesis and transport pathways and down-regulated some of the antioxidant genes. Keywords: time-course
Project description:Fatty acid synthesis is closely linked to nutrient availability and cellular energetic status. The committed step in fatty acid synthesis is the acetyl CoA carboxylase. Eukaryotes have two genes encoding acetyl CoA carboxylases, one encoding a cytosolic enzyme and another coding for a mitochondrial enzyme. They catalyze the synthesis of malonyl CoA in the cytosol and the mitochondria, respectively. While cytosolic malonyl CoA is the precursor for fatty acid synthesis, mitochondrial malonyl CoA controls the transfer of fatty acyl group into the mitochondria by inhibiting carnitine/palmitoyl transferase activity and thus, regulates β-oxidation. In Saccharomyces cerevisiae, β-oxidation is restricted to the peroxisomes, raising the question of the function of the mitochondrial isoform (HFA1). In this study, we replaced the cytosolic Acc1 with Hfa1 expressed in the cytosol by removing the mitochondrial leader peptide, under control of the HFA1 promoter. We studied fatty acid synthesis and transcription profiles in this strain during starvation for carbon or nitrogen, using glucose or ethanol as the carbon source. Under all the conditions studied, the key sensor of energetic status, Snf1, was activated, indicating active inhibition of fatty acid synthesis. The pool size of fatty acids was smaller when Acc1 was replaced with truncated Hfa1 for fatty acid synthesis. Yet, the transcription profiles were similar in both the cases. These results point towards the conclusion that Hfa1 is either catalytically less efficient or it is more sensitive to inhibition by Snf1. Gene expression from a strain of Saccharomyces cerevisiae where cytosolic fatty acid synthesis occurs by mitochondrial acetyl CoA carboxylase (without its mitochondrial leader peptide) is compared with that in a reference strain while growing in chemostats on carbon or nitrogen starvation using glucose or ethanol as the carbon source.
Project description:Purpose: To elucidate the physiological and molecular mechanisms underlying seed development, we conducted a genome-wide transcriptional profiling of developing seeds of ‘Sarsyun’ at four different time points (21, 28, 35, and 42 DAF). 34,423 contigs from four different developing seeds (21, 28, 35, and 42 DAF) were analyzed for transcript abundance and changes to the timing of transcript abundance in relation to the accumulation of seed storage products. Most genes involved in seed photosynthesis and carbohydrate metabolism were highly expressed at 21 or 28 DAF and were subsequently downregulated. Expression of genes coding for oleosins and fatty acid synthesis and elongation markedly increased at 28 DAF through 35 DAF, respectively, remaining high thereafter. Expression of major storage protein genes increased at 28 or 35 DAF. Overall, our results showed that dynamic changes to transcript abundance of most genes in relation to seed storage products occurred between 28 and 35 DAF.