RESUMO
Endothelial cell (EC) lifespan controlled by the IL-1 family of cytokines is an important determinant of susceptibility to artery wall disease. Here we show that EC lacking intracellular interleukin-1 receptor antagonist (IL-1ra) have a reduced lifespan compared to controls. Over expression of IL-1ra enhanced proliferation via cyclin dependent kinase 2 activity and retinoblastoma protein phosphorylation. This was not seen in EC lacking IL-1 receptor 1 (IL-1 signalling ability), nor apparent using other stimuli e.g. TNF alpha. These data suggest that IL-1ra has a specific and receptor-dependent function to control the growth and lifespan of EC.
Assuntos
Proliferação de Células , Senescência Celular , Células Endoteliais/citologia , Proteína Antagonista do Receptor de Interleucina 1/metabolismo , Animais , Apoptose , Senescência Celular/genética , Quinase 2 Dependente de Ciclina , Células Endoteliais/metabolismo , Humanos , Proteína Antagonista do Receptor de Interleucina 1/genética , Interleucina-1beta/metabolismo , Camundongos , Camundongos Mutantes , Proteína do Retinoblastoma/metabolismoRESUMO
Migration and proliferation of smooth muscle cells are key to a number of physiological and pathological processes, including wound healing and the narrowing of the vessel wall. Previous work has shown links between inflammatory stimuli and vascular smooth muscle cell proliferation and migration through mitogen-activated protein kinase (MAPK) activation, although the molecular mechanisms of this process are poorly understood. Here we report that tribbles-1, a recently described modulator of MAPK activation, controls vascular smooth muscle cell proliferation and chemotaxis via the Jun kinase pathway. Our findings demonstrate that this regulation takes place via direct interactions between tribbles-1 and MKK4/SEK1, a Jun activator kinase. The activity of this kinase is dependent on tribbles-1 levels, whereas the activation and the expression of MKK4/SEK1 are not. In addition, tribbles-1 expression is elevated in human atherosclerotic arteries when compared with non-atherosclerotic controls, suggesting that this protein may play a role in disease in vivo. In summary, the data presented here suggest an important regulatory role for trb-1 in vascular smooth muscle cell biology.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Sistema de Sinalização das MAP Quinases , Miócitos de Músculo Liso/citologia , Proteínas Serina-Treonina Quinases/fisiologia , Aterosclerose , Biópsia , Movimento Celular , Proliferação de Células , Quimiotaxia , Humanos , Inflamação , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Modelos Biológicos , Músculo Liso Vascular/citologia , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais , Regulação para Cima , CicatrizaçãoRESUMO
Mouse lung endothelial cells (MLEC) and HUVEC were used under serum withdrawal (SW) conditions as a model of endothelial cell (EC) apoptosis. Apoptosis was quantified by time-lapse video microscopy. Mouse lung ECs from caspase-1(-/-) mice had significantly reduced rates of SW-induced apoptosis compared with wild-type mice, specifically implicating caspase-1 in proapoptotic signaling in ECs. SW conditions induced HUVEC apoptosis with concomitant activation of caspase-1. Further studies demonstrated that the caspase-1 inhibitors z-VAD and z-YVAD significantly reduced the rate of SW-induced HUVEC apoptosis. HUVEC, when transfected with caspase-1, showed a highly significant increase in apoptosis. SW was associated with increases in reactive oxygen species production that were significantly inhibited by the antioxidant N-acetyl-L-cysteine, although rates of apoptosis and caspase-1 activation were unaffected. These results demonstrate the involvement of caspase-1 in SW-induced EC apoptosis, independently of reactive oxygen species production.