Genome-wide screen reveals important roles for ESCRT proteins in drug/ion resistance of fission yeast

Abstract

To study sodium homeostasis, we performed a genome-wide screen for deletion strains that show resistance to NaCl. We identified 34 NaCl-resistant strains. Among them, the largest group that consists of 10 genes related to membrane trafficking and 7 out of 10 genes are ESCRT proteins which are involved in cargo transportation into luminal vesicles within the multivesicular body. All of the ESCRT related mutants which showed sodium resistance also showed defects in vacuole fusion. To further understand the role of the ESCRT pathway in various ion homeostasis, we examined sensitivity of these ESCRT mutants to various cation salts other than NaCl, including KCl, LiCl, CaCl2, CoCl2, MgCl2, NiSO4 and MnCl2. While these ESCRT mutants showed resistance to LiCl, CoCl2 and MgCl2, they showed sensitivity to KCl, CaCl2, NiSO4 and MnCl2. Then we examined sensitivity of these ESCRT mutants to various drugs which are known to inhibit the growth of fission yeast cells. While these ESCRT mutants were more or equally sensitive to most of the drugs tested as compared to the wild-type cells, they showed resistance to some drugs such as tamoxifen, fluorouracil and amiodarone. These results suggest that the ESCRT pathway plays important roles in drug/ion resistance of fission yeast.

Resistance to Chemotherapeutic 5-Fluorouracil Conferred by Modulation of Heterochromatic Integrity through Ino80 Function in Fission Yeast

“…Several genome-scale chemogenomic analyses have been performed to look at 5-FU responsiveness in fission yeast [ 16 , 41 , 42 , 43 ], but none of these null mutants of Ino80 complex subunit genes were observed to exhibit resistance against the drug. Ino80 complex, an ATP-dependent nucleosome-remodeling complex, was shown recently to regulate the integrity of constitutive heterochromatin, which encompassed the centromere of the fission yeast to confer stable kinetochore attachment to spindle microtubules for proper chromosome segregation during the M-phase of the cell cycle [ 44 ].…”

A two–tiered system for selective receptor and transporter protein degradation

“…g . mutant growth is sensitive to MnCl 2 and steady–state CPY maturation is reduced [ 52 – 54 ] ( S1 Fig ). When studying these vps36 Δ cells after methionine addition, we found that Mup1-GFP follows a similar trajectory from the plasma membrane to vacuole lumen ( Fig 1B ), albeit with two important exceptions: (1) Large Mup1-GFP and FM4-64 –positive puncta appeared adjacent to vacuole membranes, a hallmark phenotype of ESCRT deletion mutants (VPS class E) [ 55 ], confirming ILV formation was blocked at endosomes in these cells, and (2) Mup1-GFP aberrantly accumulates on vacuole membranes on route to the lumen ( Fig 1B and 1C ), which is not a trafficking intermediate of the MVB pathway.…”

The search for Schizosaccharomyces fission yeasts in environmental metatranscriptomes

“…Signatures of Schizosaccharomycetes have been found in metagenomic surveys of marine environments in the past (e.g., Porites astreoides coral from the Caribbean Sea in Wegley et al, 2007, and Avicennia marina mangroves from the Red Sea in Simões et al, 2015). These observations are remarkable, as fission yeast is not known to be especially salt tolerant (e.g., Yang et al, 2018).…”