Enforcement and Enlargement of the Saccharomyces cerevisiae Endoplasmic Reticulum through Artificial Evocation of the Unfolded Protein Response

Upon dysfunction of the Endoplasmic Reticulum (ER), eukaryotic cells provoke a gene expression program, namely, the Unfolded Protein Response (UPR), leading to an increase in the size and function of the ER. In the yeast Saccharomyces cerevisiae, the UPR is modulated by the Hac1i protein, which is a transcription factor produced by ER stress. When the UPR is artificially triggered under non-stress conditions by artificial expression of the Hac1i protein, S. cerevisiae cells carry an enforced and enlarged ER, which allows us to obtain commercially valuable materials such as secretory proteins and functional lipids abundantly.