title: Expression patterns of two potassium channel genes in skeletal muscle cells of patients with familial hypokalemic periodic paralysis.
abstract: BACKGROUND
  Familial hypokalemic periodic paralysis is an autosomal-dominant disorder characterized by episodic attacks of muscle weakness with hypokalemia. The combination of sarcolemmal depolarization and hypokalemia has been attributed to abnormalities of the potassium conductance governing the membrane potential; however, the molecular mechanism that causes hypokalemia has not yet been determined.
  
  
  OBJECTIVE
  To test the hypothesis that the expression patterns of delayed rectifier potassium channel genes in the skeletal muscle cells of patients with familial hypokalemic periodic paralysis differ from those in normal cells.
  
  
  METHODS
  We examined both mRNA and protein levels of two major delayed rectifier potassium channel genes KCNQ3 and KCNQ5 in the skeletal muscle cells from three patients with familial hypokalemic periodic paralysis and three healthy controls.
  
  
  RESULTS
  When normal cells were exposed to 50 mM potassium buffer, which was used to induce depolarization, the KCNQ3 protein level significantly increased in the membrane fraction but decreased in the cytosolic fraction, whereas the opposite was true in patient cells.
  
  
  CONCLUSIONS
  Abnormal subcellular distribution of the KCNQ3 protein was observed in patient cells. Our results suggest that the altered expression of KCNQ3 in patient cells exposed to high extracellular potassium levels could possibly hinder normal function of the channel protein. These findings may provide an important clue to understanding the molecular mechanism of familial hypokalemic periodic paralysis.
authors: Department of Pediatrics, Konyang University School of Medicine, Republic of Korea. hoppdoctor@hanmail.com
authors: June-Bum
authors: JB
authors: Kim
authors: Gyung-Min
authors: GM
authors: Lee
authors: Sung-Jo
authors: SJ
authors: Kim
authors: Dong-Ho
authors: DH
authors: Yoon
authors: Young-Hyuk
authors: YH
authors: Lee
mesh_terms: D000704:Analysis of Variance; D015220:Calcium Channels / Q000235:genetics; D020746:Calcium Channels, L-Type; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D020514:Hypokalemic Periodic Paralysis / Q000235:genetics / Q000473:pathology*; D051656:KCNQ Potassium Channels / Q000235:genetics / Q000378:metabolism*; D051659:KCNQ3 Potassium Channel / Q000235:genetics / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D011188:Potassium / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: C412223:CACNA1S protein, human; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D051656:KCNQ Potassium Channels; D051659:KCNQ3 Potassium Channel; C412231:KCNQ5 protein, human; D012333:RNA, Messenger; D011188:Potassium