title: High glucose alters apoptosis and proliferation in HEK293 cells by inhibition of cloned BK Ca channel.
abstract: It has been reported that diabetic vascular dysfunction is associated with impaired function of large conductance Ca(2+) -activated K(+) (BK(Ca) ) channels. However, it is unclear whether impaired BK(Ca) channel directly participates in regulating diabetic vascular remodeling by altering cell growth in response to hyperglycemia. In the present study, we investigated the specific role of BK(Ca) channel in controlling apoptosis and proliferation under high glucose concentration (25 mM). The cDNA encoding the α+β1 subunit of BK(Ca) channel, hSloα+β1, was transiently transfected into human embryonic kidney 293 (HEK293) cells. Cloned BK(Ca) currents were recorded by both whole-cell and cell-attached patch clamp techniques. Cell apoptosis was assessed with immunocytochemistry and analysis of fragmented DNA by agarose gel electrophoresis. Cell proliferation was investigated by flow cytometry assays, MTT test, and immunocytochemistry. In addition, the expression of anti-apoptotic protein Bcl-2, intracellular Ca(2+) , and mitochondrial membrane potential (Δψm) were also examined to investigate the possible mechanisms. Our results indicate that inhibition of cloned BK(Ca) channels might be responsible for hyperglycemia-altered apoptosis and proliferation in HEK-hSloα+β1 cells. However, activation of BK(Ca) channel by NS1619 or Tamoxifen significantly induced apoptosis and suppressed proliferation in HEK-hSloα+β1 cells under hyperglycemia condition. When rat cerebral smooth muscle cells were cultured in hyperglycemia, similar findings were observed. Moreover, the possible mechanisms underlying the activation of BK(Ca) channel were associated with decreased expression of Bcl-2, elevation of intracellular Ca(2+) , and a concomitant depolarization of Δψm in HEK-hSloα+β1 cells. In conclusion, cloned BK(Ca) channel directly regulated apoptosis and proliferation of HEK293 cell under hyperglycemia condition.
authors.affiliation: Department of Aerospace Physiology, Key Laboratory of Aerospace Medicine of Ministry of Education, Fourth Military Medical University, Xi'an, Shaanxi Province, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chang
authors.forename: Yu-Guang
authors.initials: YG
authors.lastname: Ma
authors.forename: Yun-Ying
authors.initials: YY
authors.lastname: Wang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Song
authors.forename: Quan
authors.initials: Q
authors.lastname: Li
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.forename: Hua-Zhou
authors.initials: HZ
authors.lastname: Zhao
authors.forename: Han-Zhong
authors.initials: HZ
authors.lastname: Feng
authors.forename: Yao-Ming
authors.initials: YM
authors.lastname: Chang
authors.forename: Jin
authors.initials: J
authors.lastname: Ma
authors.forename: Zhi-Bin
authors.initials: ZB
authors.lastname: Yu
authors.forename: Man-Jiang
authors.initials: MJ
authors.lastname: Xie
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001562:Benzimidazoles / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D003001:Cloning, Molecular; D015536:Down-Regulation / Q000187:drug effects; D005822:Genetic Vectors / Q000235:genetics; D005947:Glucose / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051038:Large-Conductance Calcium-Activated Potassium Channel beta Subunits / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013629:Tamoxifen / Q000494:pharmacology; D014162:Transfection
chemical_list: D001562:Benzimidazoles; C494841:KCNMA1 protein, human; C531905:KCNMB1 protein, human; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051038:Large-Conductance Calcium-Activated Potassium Channel beta Subunits; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D013629:Tamoxifen; C086491:NS 1619; C064719:iberiotoxin; D005947:Glucose; D002118:Calcium