Cell cycle-dependent expression of potassium channels and cell proliferation in rat mesenchymal stem cells from bone marrow.
OBJECTIVE
Recently, our team has demonstrated that voltage-gated delayed rectifier K(+) current (IK(DR)) and Ca(2+)-activated K(+) current (I(KCa)) are present in rat bone marrow-derived mesenchymal stem cells; however, little is known of their physiological roles. The present study was designed to investigate whether functional expression of IK(DR) and I(KCa) would change with cell cycle progression, and whether they could regulate proliferation in undifferentiated rat mesenchymal stem cells (MSCs).


METHODS
Membrane potentials and ionic currents were recorded using whole-cell patch clamp technique, cell cycling was analysed by flow cytometry, cell proliferation was assayed with DNA incorporation method and the related genes were down-regulated by RNA interference (RNAi) and examined using RT-PCR.


RESULTS
It was found that membrane potential hyperpolarized, and cell size increased during the cell cycle. In addition, IK(DR) decreased, while I(KCa) increased during progress from G(1) to S phase. RT-PCR revealed that the mRNA levels of Kv1.2 and Kv2.1 (likely responsible for IK(DR)) reduced, whereas the mRNA level of KCa3.1 (responsible for intermediate-conductance I(KCa)) increased with the cell cycle progression. Down-regulation of Kv1.2, Kv2.1 or KCa3.1 with the specific RNAi, targeted to corresponding gene inhibited proliferation of rat MSCs.


CONCLUSIONS
These results demonstrate that membrane potential, IK(DR) and I(KCa) channels change with cell cycle progression and corresponding alteration of gene expression. IK(DR) and intermediate-conductance I(KCa) play an important role in maintaining membrane potential and they participate in modulation of proliferation in rat MSCs.
Deng
X L
XL
Department of Medicine, and Research Centre of Heart, Brain, Hormone and Healthy Ageing, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong.
Lau
C P
CP
Lai
K
K
Cheung
K F
KF
Lau
G K
GK
Li
G R
GR
D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells / Q000166:cytology* / Q000378:metabolism*; D002453:Cell Cycle; D049109:Cell Proliferation; D048429:Cell Size; D002478:Cells, Cultured; D017931:DNA Primers / Q000235:genetics; D008564:Membrane Potentials; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats
D017931:DNA Primers; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D012333:RNA, Messenger; D034741:RNA, Small Interfering