Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of yeast grown in gastric or duodenal medium to identify promoters that could be used to down-regulate genes used in the release of therapeutic proteins

ABSTRACT: The use of yeast as a delivery system is an attractive option for the oral administration of therapeutic agents. We recently developed mutants of Saccharomyces cerevisiae capable of lysis upon conditional down-regulation of the expression of the cell wall genes PKC1 and SRB1. The lysis mechanism of the mutant is based on the use of the MET3 promoter, which, upon addition of methionine and cysteine, blocks transcription of SRB1 and PKC1. This strain has the potential to be an integral part of an oral yeast delivery system, in which there is lysis of yeasts in the human gut, followed by release of recombinant proteins for therapeutic use. In order to provide proof-of-principle, the system was evaluated testing the cells viability and lysis performance under conditions, which simulate those found in the human stomach and the duodenum. Upon incubation of yeast cells in these conditions, lysis could be induced and was accompanied by release of GFP reporter protein into the medium. However, the conditional lysis mechanism based on the MET3 promoter is not applicable in vivo. Therefore, alternative promoters suitable for in-vivo down-regulation of SRB1 and PKC1 were identified by a microarray experiments. The transcripts of genes ANB1, TIR1, and MF(ALPHA)2 were significantly reduced upon exposure of the yeast cells to conditions of the two gut compartments. Their promoters could be used to down-regulate SRB1/VIG9 and PKC1 in vivo to achieve lysis of the yeast in the gut to release cargo therapeutic proteins.

ORGANISM(S): Saccharomyces cerevisiae

SUBMITTER: Andy Hayes

PROVIDER: E-MEXP-2127 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Conditional cell-wall mutants of Saccharomyces cerevisiae as delivery vehicles for therapeutic agents in vivo to the GI tract.

Omara Walid A M WA Rash Bharat M BM Hayes Andrew A Wickham Martin S J MS Oliver Stephen G SG Stateva Lubomira I LI

Journal of biotechnology 20100329 2

Strains of Saccharomyces cerevisiae capable of lysis upon conditional down-regulation of cell-wall biogenesis genes (SRB1 and PKC1) have been reported. Here, we show that they lyse and release recombinant protein not only under laboratory conditions, but (more importantly) under conditions found in the human stomach and duodenum. These findings provide proof that, in principle, such conditional lysis strains could be used as an integral part of a system for the oral delivery of therapeutic prote ...[more]

PMID: 20356564

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Project description:The yeast proteins Pkh1 and Pkh2 are functional counterparts of the mammalian 3-phosphoinositide-dependent protein kinase 1 (PDK1). Cells carrying simultaneous deletion in both genes, PKH1 and PKH2 are not viable, at least in some genetic backgrounds (Casamayor et al., 1999; Inagaki et al., 1999). Consequently, a different strategy is needed to study the function of these apparently redundant gene products. The approach that has been successfully used to dissect the functions of these proteins consist in the use of a strain that combine the disruption of PKH2 with the temperature sensitive pkh1D398G allele (Inagaki et al., 1999). Since Pkh1 and Pkh2 phosphorylate Pkc1 in vitro in its activation loop (Thr983), and the cell lysis defects of the pkh1D398G pkh2 strain at the restrictive temperature are partially restored by constitutive activation of the Pkc1-Slt2 MAPK pathway, it has been suggested that the Pkh activity is important for maintenance of the cell wall integrity in S. cerevisiae (Inagaki et al., 1999; Friant et al., 2001). We considered it necessary that a different genetic strategy would be convenient in order to carry out specific studies about the functions of the Pkh proteins. In order to avoid incubation at temperatures that activate the Slt2 pathway, and induce cellular lysis, we decided to use a strategy based on the use of a regulatable promoter. We replaced 487 bp located immediately upstream the start PKH2 codon by a cassette containing the doxycycline-repressed promoter tetO7. In this strain (MB002) the PKH2 expression could be switched off by addition of doxycycline. In order to deplete the cell for the Pkh activity, we disrupted both, the PKH1 and PKH3 coding regions, obtaining the new SDP8 strain. Our results show that the long term depletion of Pkh results in a cell transcriptional response that include overexpression of genes typically induced in response to oxidative stress, as well as up-regulation of chaperons and genes that induce the unfolded protein response.

Dataset Information

Transcription profiling of yeast grown in gastric or duodenal medium to identify promoters that could be used to down-regulate genes used in the release of therapeutic proteins

Publications

Conditional cell-wall mutants of Saccharomyces cerevisiae as delivery vehicles for therapeutic agents in vivo to the GI tract.

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