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Sch9 regulates intracellular protein ubiquitination by controlling stress responses.

Qie B, Lyu Z, Lyu L, Liu J, Gao X, Liu Y, Duan W, Zhang N, Du L, Liu K - Redox Biol (2015)

Bottom Line: In this study, we found that the overall level of ubiquitinated proteins dramatically decreased as yeast cell grew from log to stationary phase.Deletion of SCH9, a gene encoding a key protein kinase for longevity control, decreased the level of ubiquitinated proteins in log phase and this effect could be reversed by restoring Sch9 function.Our results revealed for the first time how Sch9 regulates the level of ubiquitinated proteins and provides new insight into how Sch9 controls longevity.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Science, Sichuan University, Chengdu, Sichuan 610064, China.

No MeSH data available.


Related in: MedlinePlus

sch9Δ cells are resistant to ubiquitination due to decreased intracellular oxidation. (A) The mRNA levels of stress response genes (GPX1, HSP104, HSP12, TSA2 and CTT1) were tested by qPCR and normalized by the levels of actin (ACT1) mRNA in log phase cells (OD600 nm=0.5). (B) Microscopy of DCF fluorescence on WT cells (TB50a) transformed with empty vector (WT+vector), SCH9 deletion mutant cells (TS120-2d) transformed with empty vector (sch9Δ+vector) or pRS416−SCH9 (sch9Δ+Sch9) at log phase (OD600 nm=0.5) after treated with or without 0.5 mM H2O2 for 1 h. Bars: 100 µm. (C) Spectrofluorimeter analysis of DCF-stained cells (*P <0.05, **P<0.01).
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f0020: sch9Δ cells are resistant to ubiquitination due to decreased intracellular oxidation. (A) The mRNA levels of stress response genes (GPX1, HSP104, HSP12, TSA2 and CTT1) were tested by qPCR and normalized by the levels of actin (ACT1) mRNA in log phase cells (OD600 nm=0.5). (B) Microscopy of DCF fluorescence on WT cells (TB50a) transformed with empty vector (WT+vector), SCH9 deletion mutant cells (TS120-2d) transformed with empty vector (sch9Δ+vector) or pRS416−SCH9 (sch9Δ+Sch9) at log phase (OD600 nm=0.5) after treated with or without 0.5 mM H2O2 for 1 h. Bars: 100 µm. (C) Spectrofluorimeter analysis of DCF-stained cells (*P <0.05, **P<0.01).

Mentions: Previous gene chip studies have shown that sch9Δ cells have enhanced expression of stress response genes [36]. By using quantitative PCR we found that the mRNA level of several stress response genes, including GPX1 (Phospholipid hydroperoxide glutathione peroxidase), HSP104 (disaggregase), HSP12 (12 kD small heat shock protein), TSA2 (Stress inducible cytoplasmic thioredoxin peroxidase) and CTT1 (Cytosolic catalase T) increased 2–30 fold in sch9Δ cells (Fig. 4A). Consistently, the catalase activity of Ctt1 elevated ~50% upon SCH9 deletion while adding Sch9 back decreased the catalase activity of Ctt1 back to a level similar to that in WT cells (Fig. S2A and B). These results suggest that sch9Δ cells have stronger capability of ROS scavenging and protein refolding and therefore may generate less damaged proteins as substrates for ubiquitination.


Sch9 regulates intracellular protein ubiquitination by controlling stress responses.

Qie B, Lyu Z, Lyu L, Liu J, Gao X, Liu Y, Duan W, Zhang N, Du L, Liu K - Redox Biol (2015)

sch9Δ cells are resistant to ubiquitination due to decreased intracellular oxidation. (A) The mRNA levels of stress response genes (GPX1, HSP104, HSP12, TSA2 and CTT1) were tested by qPCR and normalized by the levels of actin (ACT1) mRNA in log phase cells (OD600 nm=0.5). (B) Microscopy of DCF fluorescence on WT cells (TB50a) transformed with empty vector (WT+vector), SCH9 deletion mutant cells (TS120-2d) transformed with empty vector (sch9Δ+vector) or pRS416−SCH9 (sch9Δ+Sch9) at log phase (OD600 nm=0.5) after treated with or without 0.5 mM H2O2 for 1 h. Bars: 100 µm. (C) Spectrofluorimeter analysis of DCF-stained cells (*P <0.05, **P<0.01).
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f0020: sch9Δ cells are resistant to ubiquitination due to decreased intracellular oxidation. (A) The mRNA levels of stress response genes (GPX1, HSP104, HSP12, TSA2 and CTT1) were tested by qPCR and normalized by the levels of actin (ACT1) mRNA in log phase cells (OD600 nm=0.5). (B) Microscopy of DCF fluorescence on WT cells (TB50a) transformed with empty vector (WT+vector), SCH9 deletion mutant cells (TS120-2d) transformed with empty vector (sch9Δ+vector) or pRS416−SCH9 (sch9Δ+Sch9) at log phase (OD600 nm=0.5) after treated with or without 0.5 mM H2O2 for 1 h. Bars: 100 µm. (C) Spectrofluorimeter analysis of DCF-stained cells (*P <0.05, **P<0.01).
Mentions: Previous gene chip studies have shown that sch9Δ cells have enhanced expression of stress response genes [36]. By using quantitative PCR we found that the mRNA level of several stress response genes, including GPX1 (Phospholipid hydroperoxide glutathione peroxidase), HSP104 (disaggregase), HSP12 (12 kD small heat shock protein), TSA2 (Stress inducible cytoplasmic thioredoxin peroxidase) and CTT1 (Cytosolic catalase T) increased 2–30 fold in sch9Δ cells (Fig. 4A). Consistently, the catalase activity of Ctt1 elevated ~50% upon SCH9 deletion while adding Sch9 back decreased the catalase activity of Ctt1 back to a level similar to that in WT cells (Fig. S2A and B). These results suggest that sch9Δ cells have stronger capability of ROS scavenging and protein refolding and therefore may generate less damaged proteins as substrates for ubiquitination.

Bottom Line: In this study, we found that the overall level of ubiquitinated proteins dramatically decreased as yeast cell grew from log to stationary phase.Deletion of SCH9, a gene encoding a key protein kinase for longevity control, decreased the level of ubiquitinated proteins in log phase and this effect could be reversed by restoring Sch9 function.Our results revealed for the first time how Sch9 regulates the level of ubiquitinated proteins and provides new insight into how Sch9 controls longevity.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Science, Sichuan University, Chengdu, Sichuan 610064, China.

No MeSH data available.


Related in: MedlinePlus