title: [Estradiol regulates the expression of small conductance Ca(2)+ activated K(+) channel 3 in rat colonic smooth muscle cells in an estrogen receptor α-dependent manner].
abstract: OBJECTIVE
  To explore the effects and possible mechanism of 17β-estradiol on the expression of small conductance Ca(2+) activated K(+) channel 3 (SK3) in rat colonic smooth muscle cells (SMC).
  
  
  METHODS
  The SMC isolated from male SD rats by enzymolysis were cultured. And double immunofluorescence staining was used to detect the co-expression of SK3 and α-actin. Colonic SMC were cultured with different concentrations of 17β-estradiol for 24 h or with 50 nmol/L 17β-estradiol at different time points respectively. The expressions of SK3 in colonic SMC were measured by real-time quantitative reverse transcription (qRT)-PCR and Western blotting. The effects of estrogen receptor (ER) inhibitor ICI 182780, albumin bovine serum-17β-estradiol (BSA-E2), ERα selective agonist propyl pyrazole triol (PPT) and ERβ selective agonist diarylpropionitrile (DPN) on SK3 expression were observed.
  
  
  RESULTS
  Double immunofluorescence staining showed that SK3 and α-actin co-expressed in cultured colonic SMC. The expression of SK3 of 17β-estradiol at different concentration (10, 50 nmol/L) significantly higher than the control group (protein: 0.217 ± 0.030 and 0.321 ± 0.077 vs 0.103 ± 0.063, mRNA: 1.872 ± 0.606 and 2.967 ± 0.659 vs 0.813 ± 0.202, all P < 0.05). And 50 nmol/L was the most effective in vitro concentration. The peak expression of SK3 appeared at 12 and 24 hour (2.91 and 3.30-fold in protein vs 3.46 and 3.37-fold in mRNA respectively, all P < 0.05). The protein levels of SK3 in ICI 182780 plus 17β-estradiol group was less than 17β-estradiol group (0.111 ± 0.050 vs 0.351 ± 0.084, P < 0.05). But it was not influenced by BSA-E2. The expressions of SK3 in PPT and E2 groups were both higher than control group (0.270 ± 0.071, 0.309 ± 0.052 vs 0.087 ± 0.018, both P < 0.05) . However DPN had no effect on SK3 protein levels.
  
  
  CONCLUSIONS
  SK3 is localized in rat colonic SMC. And 17β-estradiol increases its expression in an ERα-dependent manner.
authors.affiliation: Department of Gastroenterology, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China.
authors.forename: Wei-wei
authors.initials: WW
authors.lastname: Yang
authors.forename: Yu-rong
authors.initials: YR
authors.lastname: Tang
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Qing-e
authors.initials: QE
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003106:Colon / Q000166:cytology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000077267:Fulvestrant; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*
chemical_list: D047628:Estrogen Receptor alpha; C496901:Kcnn3 protein, rat; D051640:Small-Conductance Calcium-Activated Potassium Channels; D000077267:Fulvestrant; D004958:Estradiol