K+ channels and the cAMP-PKA pathway modulate TGF-beta1-induced migration of rat vascular myofibroblasts.
Our previous studies have indicated that TGF-beta1 exerts its effect on the expression of A-type potassium channels (I(A)) in rat vascular myofibroblasts by activation of protein kinase C during the phenotypic transformation of vascular fibroblasts to myofibroblasts. In the present study, patch-clamp whole-cell recording and transwell-migration assays were used to examine the effects of TGF-beta1- and phorbol 12-myristate 13-acetate (PMA)-induced expression of I(A) channels on myofibroblast migration and its modulation by the protein kinase A (PKA) pathway. Our results reveal that incubation of fibroblasts with TGF-beta1 or PMA up-regulates the expression of I(A) channels and increases myofibroblast migration. Blocking I(A) channel expression by 4-aminopyridine (4-AP) significantly inhibits TGF-beta1- and PMA-induced myofibroblast migration. Incubation of fibroblasts with forskolin does not result in increased expression of I(A) channels but does cause a slight increase in fibroblast migration at higher concentrations. In addition, forskolin increases the TGF-beta1- and PMA-induced myofibroblast migration but inhibits TGF-beta1- and PMA-induced the expression of I(A) channels. Whole-cell current recordings showed that forskolin augments the delayed rectifier outward K(+) (I(K)) current amplitude of fibroblasts, but not the I(A) of myofibroblasts. Our results also indicate that TGF-beta1- and PMA-induced expression of I(A) channels might be related to increase TGF-beta1- or PMA-induced myofibroblast migration. Promoting fibroblast and myofibroblast migration via the PKA pathway does not seem to involve the expression of I(A) channels, but the modulation of I(K) and I(A) channels might be implicated.
Institute of Brain Science, School of Life Sciences and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, China.
Ya-Rong
YR
Liu
Wen-Lei
WL
Ye
Xi-Min
XM
Zeng
Wen-Hua
WH
Ren
Yu-Qiu
YQ
Zhang
Yan-Ai
YA
Mei
D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D005576:Colforsin / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015290:Second Messenger Systems / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D053773:Transforming Growth Factor beta1; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D013755:Tetradecanoylphorbol Acetate