title: Prolonged K+deficiency increases intracellular ATP, cell cycle arrest and cell death in renal tubular cells.
abstract: Chronic potassium (K+) deficiency can cause renal damage namely hypokalemic nephropathy with unclear pathogenic mechanisms. In the present study, we investigated expression and functional alterations in renal tubular cells induced by prolonged K+deficiency.
  
  
  
  MDCK cells were maintained in normal-K+(CNK) (K+=5.3mmol/L), low-K+(CLK) (K+=2.5mmol/L), or K+-depleted (CKD) (K+=0mmol/L) medium for 10days (n=5 independent cultures/condition). Differentially expressed proteins were identified by a proteomics approach followed by various functional assays.
  
  
  
  Proteomic analysis revealed 46 proteins whose levels significantly differed among groups. The proteomic data were confirmed by Western blotting. Gene Ontology (GO) classification and protein network analysis revealed that majority of the altered proteins participated in metabolic process, whereas the rest involved in cellular component organization/biogenesis, cellular process (e.g., cell cycle, regulation of cell death), response to stress, and signal transduction. Interestingly, ATP measurement revealed that intracellular ATP production was increased in CLK and maximum in CKD. Flow cytometry showed cell cycle arrest at S-phase and G2/M-phase in CLK and CKD, respectively, consistent with cell proliferation and growth assays, which showed modest and marked degrees of delayed growth and prolonged doubling time in CLK and CKD, respectively. Cell death quantification also revealed modest and marked degrees of increased cell death in CLK and CKD, respectively.
  
  
  
  In conclusion, prolonged K+deficiency increased intracellular ATP, cell cycle arrest and cell death in renal tubular cells, which might be responsible for mechanisms underlying the development of hypokalemic nephropathy.
authors.affiliation: Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, and Center for Research in Complex Systems Science, Mahidol University, Bangkok, Thailand.
authors.forename: Kedsarin
authors.initials: K
authors.lastname: Fong-Ngern
authors.affiliation: Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, and Center for Research in Complex Systems Science, Mahidol University, Bangkok, Thailand.
authors.forename: Nardtaya
authors.initials: N
authors.lastname: Ausakunpipat
authors.affiliation: Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, and Center for Research in Complex Systems Science, Mahidol University, Bangkok, Thailand.
authors.forename: Nilubon
authors.initials: N
authors.lastname: Singhto
authors.affiliation: Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, and Center for Research in Complex Systems Science, Mahidol University, Bangkok, Thailand.
authors.forename: Kanyarat
authors.initials: K
authors.lastname: Sueksakit
authors.affiliation: Medical Proteomics Unit, Office for Research and Development, Faculty of Medicine Siriraj Hospital, and Center for Research in Complex Systems Science, Mahidol University, Bangkok, Thailand. Electronic address: thongboonkerd@dr.com.
authors.forename: Visith
authors.initials: V
authors.lastname: Thongboonkerd
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D059447:Cell Cycle Checkpoints; D016923:Cell Death; D049109:Cell Proliferation; D004285:Dogs; D007684:Kidney Tubules / Q000473:pathology*; D061985:Madin Darby Canine Kidney Cells; D011191:Potassium Deficiency / Q000378:metabolism / Q000473:pathology*; D040901:Proteomics / Q000379:methods
chemical_list: D000255:Adenosine Triphosphate
keywords: Hypokalemia; Kidney; Potassium deficiency; Proteomics