Screening And Analysis Of Genes Related To The Regulation Of ENA1 Encoding A Lithium Pump

Lithium is an important trace element and has been widely used for human disease treatment. Lithium has been used for more than 50 years to treat depression and bipolar disorder, a common mental disease, and also has positive effects on cancer, blood disease, bone marrow transplantation and other diseases. However, the pharmaceutical mechanisms of lithium are still not fully understood. Understanding mechanisms how lithium regulates cell processes would be helpful to unearth more cell targets, and therefore enable us to take better advantage of its positive functions and prevent its toxic effects. Saccharomyces cerevisiae is the eukaryotic model organism that has been used to study ion transportation and homeostasis. Recently, the gene deletion library of S. cerevisiae has been widely used to screen and identify targets of different pharmaceuticals and metal ions and the pathways they regulate.Our previous study has identified 6 lithium-tolerant and 108 lithium-sensitive gene mutations by screening the gene deletion library. The ENA1 gene encodes a P-type Na+-ATPase that pumps excessive sodium or lithium ions out of the yeast cell. Yeast cells lacking ENA1 are sensitive to lithium, whereas overexpression of ENA1 increases lithium tolerance of yeast cells. To investigate the cellular effects of these 114 genes, this work has examined the transcription levels of ENA1 and the subcellular localization of Ena1 p in these 114 gene deletion mutants. As a result, we found the transcription level of ENA1 gene is higher than the wild-type in 19 mutants and lower in 82 mutants. We also found 13 mutants in which the transcription level of ENA1 gene has no significant difference with the wild-type. 3 morphological classes of Ena1 p localization patterns are found in these mutants:(1) plasma membrane and vacuolar lumen/membrane;(2) plasma membrane and vacuolar membrane;(3) plasma membrane only. Moreover, we found that two complexes ESCRT and CORVET participating in the sorting and processing of vacuolar proteins are the key factors of Ena1 p transportation in cells. Our results provide a basis for our further understanding the regulatory mechanisms of lithium tolerance in yeast cells.