Activation of endothelial cells to pathological status by down-regulation of connexin43.
OBJECTIVE
We investigated the effects of connexin43 (Cx43) down-regulation on endothelial function.


RESULTS
We used two different sequences of Cx43-specific small interference RNA (siRNA) to reduce de novo synthesis of Cx43 in human aortic endothelial cells and then examined the expression profiles, proliferation activity and viability, and angiogenic potential. The involvement of mitogen-activated protein kinase signalling pathways was analysed. In parallel, the effect of inhibition of gap-junctional communication by connexin-mimetic peptides was evaluated. During the down-regulation of Cx43 by the siRNA, the cells exhibited impaired gap-junctional communication, proliferation, viability, and angiogenic potential. In addition, plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor were up-regulated. Furthermore, c-jun N-terminal kinase (JNK) and its downstream target c-jun were activated, while caspase-3, p38, and extracellular signal-regulated kinase remained unchanged. Inhibition of JNK by SP600125 blocked the siRNA-induced increased expression of PAI-1 and partially recovered the impaired angiogenic potential. Short-term inhibition of Cx43 channels by connexin-mimetic peptides did not activate JNK.


CONCLUSIONS
Down-regulation of Cx43 inhibits gap-junctional communication and activates endothelial cells to pathological status, as characterized by up-regulation of coagulatory molecules and impairment of proliferation, viability, and angiogenesis. The processes are associated with activation of JNK signalling pathways and rectified by inhibition of the activation. These results suggest that inadequate expression of Cx43 per se impairs endothelial function by the activation of stress-activated protein kinase.
Wang
Hsueh-Hsiao
HH
Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan.
Kung
Chang-I
CI
Tseng
Yuen-Yi
YY
Lin
Yi-Chun
YC
Chen
Chi-Hau
CH
Tsai
Cheng-Ho
CH
Yeh
Hung-I
HI
D000873:Anthracenes / Q000494:pharmacology; D002450:Cell Communication / Q000187:drug effects; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D017630:Connexins / Q000494:pharmacology; D015536:Down-Regulation; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D018919:Neovascularization, Physiologic; D009842:Oligopeptides; D010455:Peptides / Q000494:pharmacology; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D013997:Time Factors; D014841:von Willebrand Factor / Q000378:metabolism
D000873:Anthracenes; D018031:Connexin 43; D017630:Connexins; C514423:Gap 26 peptide; D009842:Oligopeptides; D010455:Peptides; D017395:Plasminogen Activator Inhibitor 1; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; C051321:SERPINE1 protein, human; C455880:gap 27 peptide; D014841:von Willebrand Factor; C432165:pyrazolanthrone; D048031:JNK Mitogen-Activated Protein Kinases