Project description:Ssz1p plays multifunctional roles in diverse cellular activities including forming a ribosome-associated complex to assist new protein synthesis and activating pleiotropic drug resistance (PDR) pathway. Here we report a novel function of SSZ1 to maintain cellular robustness when it is overexpressed. We found overexpression of SSZ1 can suppress the death phenotype of the double mutant Δire1Δscj1 and the temperature sensitivity (TS) phenotype of scj1-1Δire1. Microarray analyses showed that overexpression of SSZ1 induced up-regulation of the genes involved in the PDR pathway and the cell wall integrity (CWI) pathway, but not the unfolded protein response (UPR) pathway. However, overexpression of PDR1 and PDR5 cannot significantly suppress the TS phenotype of scj1-1Δire1, and overexpression of SSZ1 cannot up-regulate the gene expression of lacZ under the control of the unfolded protein response element in SSZ1OEΔire1 compared with that in Δire1. We infer that the suppression is not through the PDR pathway or through the UPR pathway. It may be through regulating downstream genes of the CWI pathway. Moreover, the peptide-binding domain of Ssz1p is necessary for its suppression of TS phenotype of scj1-1Δire1.
Project description:Membrane integrity at the endoplasmic reticulum (ER) is tightly regulated and its disturbance is implicated in metabolic diseases. Using an engineered sensor that activates the unfolded protein response (UPR) exclusively when normal ER membrane lipid composition is compromised, we identified pathways beyond lipid metabolism that are necessary to maintain ER integrity in yeast and in C. elegans. To systematically validate yeast mutants that disrupt ER membrane homeostasis, we identified a lipid bilayer stress (LBS) sensor in the UPR transducer protein Ire1, located at the interface of the amphipathic and transmembrane helices. Furthermore, transcriptome and chromatin immunoprecipitation (ChIP) analyses pinpoint the UPR as a broad-spectrum compensatory response wherein LBS and proteotoxic stress deploy divergent transcriptional UPR programs. Together, these findings reveal the UPR program as the sum of two independent stress responses, an insight that could be exploited for future therapeutic intervention.
Project description:CID 70698683 is a novel broad-spectrum antiviral compound. To understand the broad-spectrum antiviral mechanism, the cellular gene expression changes by the treatment of CID70698683 was measured.
Project description:CID 70698683 is a novel broad-spectrum antiviral compound. To understand the broad-spectrum antiviral mechanism, the cellular gene expression changes by the treatment of CID70698683 was measured. HEp-2 cells grown in 6-well plates were treated with 5 microM of CID 70698683 for overnight and the cellular RNA was extracted (Treatment group). For control, DMSO was used instead of CID 70698683 (final concentration of 0.25%). Three replicates per group used.
Project description:The unfolded protein response (UPR) is a network of intracellular signaling pathways that supports the ability of the secretory pathway to maintain equilibrium between the load of proteins entering the endoplasmic reticulum (ER) and the protein folding capacity of the ER lumen. Current evidence suggests that human pathogenic fungi rely heavily on this pathway for virulence, but there is limited understanding of the mechanisms involved. The best known functional output of the UPR is transcriptional upregulation of mRNAs involved in ER homeostasis. However, this does not take into account mechanisms of translational regulation that involve differential recruitment of mRNAs to ribosomes. In this study, a global analysis of transcript-specific translational regulation was performed in the pathogenic mold Aspergillus fumigatus to determine the nature and scope of the translational response to ER stress.