Project description:High-level production of pharmaceutical proteins in industrial microorganism is often limited due to the increased cellular stress from misfolded proteins or protein aggregates. Here, we explore the feasibility of applying a yeast Alzheimer’s disease (AD) model with accumulation of amyloid-β peptides (Aβ42), which presents similar phenotypes of cellular stress. We utilize the suppressors of Aβ42 cytotoxicity as potential metabolic engineering targets to improve industrial protein production. The transcriptomics analyses provide new insights towards developing synthetic yeast cell factories for biosynthesis of valuable pharmaceutical proteins.
Project description:ABSTRACT: Sphingolipid synthesis is initiated by condensation of serine with palmitoyl-CoA to produce 3-ketodihydrosphinganine (3-KDS), which is subsequently reduced by a 3-KDS reductase to dihydrosphinganine (DHS). Serine palmitoyltransferase was recently shown to be essential for plant viability, but the 3-KDS reductase step of sphingolipid synthesis has not been investigated in plants. Arabidopsis thaliana contains two genes (At3g06060/TSC10A and At5g19200/TSC10B) that encode proteins with significant homology to the yeast 3-KDS reductase, Tsc10p. Heterologous expression, in yeast, of either A. thaliana gene restored 3-KDS reductase activity to the yeast tsc10Δ mutant, thereby identifying both as bona fide 3-KDS reductase genes. Consistent with previous evidence that sphingolipids have essential functions in plants, double mutant progeny lacking both genes were not recovered. Although the 3-KDS reductase genes are functionally redundant and ubiquitously expressed in A. thaliana, 3-KDS reductase activity was reduced to approximately 10% of wild-type levels in the loss-of-function tsc10a mutant, leading to an altered sphingolipid profile compared to wild-type plants. Interestingly, this perturbation of sphingolipid biosynthesis in the A. thaliana tsc10a mutant leads to significant alterations in the leaf ionome, including increases in Na, K and Rb (a K analogue), and decreases in Mg, Ca, Fe, and Mo. Reciprocal grafting revealed that these changes in the leaf ionome are driven by the root, and are associated with both increases in root suberin, and elevation of expression in the root of genes involved in Fe homoeostasis, including the Fe-transporter IRT1. Keywords: genomic hybridization bulked segregant analysis
Project description:ABSTRACT: Sphingolipid synthesis is initiated by condensation of serine with palmitoyl-CoA to produce 3-ketodihydrosphinganine (3-KDS), which is subsequently reduced by a 3-KDS reductase to dihydrosphinganine (DHS). Serine palmitoyltransferase was recently shown to be essential for plant viability, but the 3-KDS reductase step of sphingolipid synthesis has not been investigated in plants. Arabidopsis thaliana contains two genes (At3g06060/TSC10A and At5g19200/TSC10B) that encode proteins with significant homology to the yeast 3-KDS reductase, Tsc10p. Heterologous expression, in yeast, of either A. thaliana gene restored 3-KDS reductase activity to the yeast tsc10Δ mutant, thereby identifying both as bona fide 3-KDS reductase genes. Consistent with previous evidence that sphingolipids have essential functions in plants, double mutant progeny lacking both genes were not recovered. Although the 3-KDS reductase genes are functionally redundant and ubiquitously expressed in A. thaliana, 3-KDS reductase activity was reduced to approximately 10% of wild-type levels in the loss-of-function tsc10a mutant, leading to an altered sphingolipid profile compared to wild-type plants. Interestingly, this perturbation of sphingolipid biosynthesis in the A. thaliana tsc10a mutant leads to significant alterations in the leaf ionome, including increases in Na, K and Rb (a K analogue), and decreases in Mg, Ca, Fe, and Mo. Reciprocal grafting revealed that these changes in the leaf ionome are driven by the root, and are associated with both increases in root suberin, and elevation of expression in the root of genes involved in Fe homoeostasis, including the Fe-transporter IRT1. Keywords: genomic hybridization bulked segregant analysis Hybridizations from a set of Bulk Segregant analysis. An F2 population from 7113 in the col-0 background crossed to Ler-0 was analyzed. This series contains the 3 hybs from Ler used to identify Single Feature Polymorphisms, the 3 hybs of Col-0 they were compared to, and 1 hyb for each pool from the BSA mapping(low Ca/Mg Pool and wild type pools).
Project description:Studies of aging and longevity are revealing how diseases that shorten life can be controlled to improve the quality of life and lifespan itself. Two strategies under intense study to accomplish this goal are rapamycin treatment and calorie restriction. New strategies are being discovered including one that uses low-dose myriocin treatment. Myriocin inhibits the first enzyme in sphingolipid synthesis in all eukaryotes and we showed recently that low-dose myriocin treatment increases yeast lifespan at least in part by down-regulating the sphingolipid-controlled Pkh1/2-Sch9 (ortholog of mammalian S6 kinase) signaling pathway. Here we show that myriocin treatment has global influences and modulates the evolutionarily conserved Snf1/AMPK, PKA and TORC1 signaling pathways to enhance yeast lifespan. These extensive affects of myriocin rival those of rapamycin and calorie restriction. Our studies in yeast along with other studies in mammals reveal the potential of myriocin or related compounds to lower the incidence of age-related diseases in humans. No-myriocin-treated cells and myriocin-treated cells; three biological replicates in each treatment
Project description:Sphingolipids are essential components of eukaryotic cells with important functions in membrane biology and cellular signaling. Their levels are tightly controlled and coordinated with the abundance of other membrane lipids. How sphingolipid homeostasis is achieved is not yet well understood. Studies performed primarily in yeast showed that the phosphorylation states of several enzymes and regulators of sphingolipid synthesis are important, although a global understanding for such regulation is lacking. Here, we used high-resolution mass-spectrometry-based proteomics and phosphoproteomics, in combination with data from a chemical genetic screen, to analyze the cellular response to sphingolipid synthesis inhibition. Our dataset reveals that changes in protein phosphorylation, rather than protein abundance, dominate the response to blocking sphingolipid synthesis. We identified Ypk1 signaling as a major pathway that is activated under these conditions, and we confirmed and identified Ypk1 targets. We also revealed key aspects of the cellular response to sphingolipid deprivation, including nodes that intersect with sterol metabolism and modification of lipid transport. Our data provide a rich resource for on-going mechanistic studies of key elements of the cellular response to the depletion of sphingolipid levels and the maintenance of sphingolipid homeostasis.
Project description:The cleavage of sphingoid base phosphates by sphingosine-1-phosphate (S1P) lyase to produce phosphoethanolamine and a fatty aldehyde is the final degradative step in the sphingolipid metabolic pathway. We have studied mice with an inactive S1P lyase gene and have found that, in addition to the expected increase of sphingoid base phosphates, other sphingolipids (including sphingosine, ceramide, and sphingomyelin) were substantially elevated in the serum and /or liver of these mice. This latter increase is consistent with a reutilization of the sphingosine backbone for sphingolipid synthesis due to its inability to exit the sphingolipid metabolic pathway. Furthermore, the S1P lyase deficiency resulted in changes in the levels of serum and liver lipids not directly within the sphingolipid pathway, including phospholipids, triacyglycerol, diacylglycerol, and cholesterol. Even though lipids in serum and lipid storage were elevated in liver, adiposity was reduced in the S1P lyase-deficient mice. Microarray analysis of lipid metabolism genes in liver showed that the S1P lyase deficiency caused widespread changes in their expression pattern. These results demonstrate that S1P lyase is a key regulator of the levels of multiple sphingolipid substrates and reveal functional links between the sphingolipid metabolic pathway and other lipid metabolic pathways that may be mediated by shared lipid substrates and changes in gene expression programs. The disturbance of lipid homeostasis by altered sphingolipid levels may be relevant to metabolic diseases. Experiment Overall Design: RNA samples from liver for three sphingosine-1-phosphate lyase knock-out and three WT mice.
Project description:rs07-05_sphingolipids-cold - sphingo-1 - The cold choc response seems to be partly triggered by Sphingolipid species. To date no gene response as been associated to sphingolipid signaling pathway in plant. Our aim is to identify among the cold induced genes the ones regulated by sphingolipids and to try to define a sphingolipid pathway specific group of genes. - 7ml of 5 days-old cells suspensions were incubated in presence of different sphingolipid pathway inhibitors, 30 min to 2 hours depending in the coumpound (all were resuspended in DMSO and control were done with DMSO). Then a 30 min cold choc was applied before cells were harvested and frozen in cold nitrogen. RNA were then extracted. FB1 and DMS were from Alexis , Myr from Cayman, TSP from matreya. 6 dye-swap - treated vs untreated comparison
Project description:Studies of aging and longevity are revealing how diseases that shorten life can be controlled to improve the quality of life and lifespan itself. Two strategies under intense study to accomplish this goal are rapamycin treatment and calorie restriction. New strategies are being discovered including one that uses low-dose myriocin treatment. Myriocin inhibits the first enzyme in sphingolipid synthesis in all eukaryotes and we showed recently that low-dose myriocin treatment increases yeast lifespan at least in part by down-regulating the sphingolipid-controlled Pkh1/2-Sch9 (ortholog of mammalian S6 kinase) signaling pathway. Here we show that myriocin treatment has global influences and modulates the evolutionarily conserved Snf1/AMPK, PKA and TORC1 signaling pathways to enhance yeast lifespan. These extensive affects of myriocin rival those of rapamycin and calorie restriction. Our studies in yeast along with other studies in mammals reveal the potential of myriocin or related compounds to lower the incidence of age-related diseases in humans.
Project description:Lipid intermediates derived from sphingolipid metabolism are crucial regulators of mitochondrial function from yeast to humans. Among these intermediates, trans-2-hexadecenal (t-2hex) within the sphingolipid degradation pathway exhibits remarkable efficiency in inducing mitochondria-mediated cell death. In yeast cell cultures, the addition of t-2-hex triggers complete disintegration of the mitochondrial network, leading to subsequent cell death. This effect is particularly pronounced in yeast cells lacking the activity of the t-2-hex degrading enzyme, Hfd1. However, the molecular mechanisms of t-2-hex induction of mitochondrial dysfunction are completely unknown. In this project, we want to exploit the unprecedented power of yeast genetics to unveil novel genetic determinants involved in t-2-hex's pro-apoptotic function. To accomplish this, we employed the SATAY method, which combines saturated transposon mutagenesis with high-throughput sequencing to functionally explore the yeast genome. In our screening approach, hfd1 mutant cells harboring a plasmid-encoded inducible MiniDs transposon were induced by galactose, resulting in extensive integration of the transposon throughout the yeast genome. Cells with the plasmid excised and the transposon genomically integrated were pooled together, creating a high-density transposon library comprising approximately 2.3E+06 independent insertion mutants. Subsequently, the pooled mutant library was subjected to treatment with the mitochondria-mediated death inducer, t-2-hexadecenal. As a control, cells were also incubated with the solvent dimethyl sulfoxide (DMSO), in which hexadecenal is dissolved. Following the treatments, cells were collected for genomic DNA extraction and digestion, using restriction enzymes with frequent four-base pair recognition sites. The resulting library fragments were circularized using T4 DNA ligase, and the transposon-genome junctions were selectively amplified through PCR with outward-facing primers specific to the transposon. Finally, the pooled and purified amplicons were subjected to massive sequencing on an Illumina MiSeq platform. The obtained sequences were then aligned to the reference genome of Saccharomyces cerevisiae, allowing for the mapping of transposon insertions and the calculation of transposon counts per gene. This project enabled the identification of genes required for the resistance and toxicity to t-2hex.