Alpha-synuclein functions in the nucleus to protect against hydroxyurea-induced replication stress in yeast

Abstract

Hydroxyurea (HU) inhibits ribonucleotide reductase (RNR), which catalyzes the rate-limiting synthesis of deoxyribonucleotides for DNA replication. HU is used to treat HIV, sickle-cell anemia and some cancers. We found that, compared with vector control cells, low levels of alpha-synuclein (α-syn) protect S. cerevisiae cells from the growth inhibition and reactive oxygen species (ROS) accumulation induced by HU. Analysis of this effect using different α-syn mutants revealed that the α-syn protein functions in the nucleus and not the cytoplasm to modulate S-phase checkpoint responses: α-syn up-regulates histone acetylation and RNR levels, maintains helicase minichromosome maintenance protein complexes (Mcm2-7) on chromatin and inhibits HU-induced ROS accumulation. Strikingly, when residues 2-10 or 96-140 are deleted, this protective function of α-syn in the nucleus is abolished. Understanding the mechanism by which α-syn protects against HU could expand our knowledge of the normal function of this neuronal protein.

Limelight on Alpha-Synuclein: Pathological and Mechanistic Implications in Neurodegeneration

“…ASYN was reported to colocalize with histone 3, in vivo, and to form a tight 2 : 1 complex with purified histones, in vitro, which dramatically accelerated the rate of ASYN fibrillization [246]. Although it has been described that ASYN directly inhibits histone 3 acetylation [259], it was proposed that different expression levels of the protein or the presence of specific cellular stressors may shift effects of ASYN from inhibiting histone acetylation to promoting acetylation [266] (Fig. 4, 1A).…”

“…It was initially proposed that the C-terminal region of the protein is required for its nuclear translocation [248,264] but two recent studies have demonstrated that this event is driven by the N-domain of the protein [265,266]. Regardless of which mechanisms are involved in ASYN nuclear translocation, several factors have been proposed to play a role in this process.…”

“…4, 1A). The interaction between ASYN and histones may also decrease the pool of free histones available for DNA binding, leading to destabilization of nucleosomes and to subsequent transcription deregulation [246,266,268].…”

Triclabendazole protects yeast and mammalian cells from oxidative stress: Identification of a potential neuroprotective compound

“…Cells were periodically removed to determine the number of viable cells in culture. Previous studies have shown that α-syn significantly shortens the CLS of yeast [17] and induces ROS to accumulate [18]. …”

Molecular Chaperones, Alpha-Synuclein, and Neurodegeneration

“…Maybe α-syn inhibits oxidative stress during heme and hemoglobin synthesis in RBC progenitor cells and this function is also required in RBCs. Perhaps not surprising, antioxidant functions of α-syn have been reported [30,37–43]. …”