The Study On The Roles Of Ceramide And P53 In The Apoptosis Induced By AngⅡ

Objectives: The mortality and morbidity of cardiovascular disease isincreasing, so more studies is to clear the pathogenesis of cardiovascular disease. Itis known that the endothelial cells (EC), which line the lumen of the blood vessels,are not passive bystanders but are active responders to stimuli like activatedleukocytes and cytokines. The dysfunction of EC can provoke the progression ofcardiovascular disease. Angiotensinâ…¡(Angâ…¡), as the main active peptide ofthe RAS, regulates both cellular and physiological responses in the cardiovascularsystem. However, Angâ…¡is also implicated in pathophysiological processesassociated with vascular injury and repair. Ceramide belongs to a family of lipidsknown as sphingolipids, characterized by a sphingoid backbone and distinct headgroups. Recently, more and more studys indicated that ceramide is a cellular lipidsecond messenger and is retained in the cytoplasm but enters the nucleus inresponse to various stimuli. It plays roles in cell proliferation,differentiate,growthinhibiting,especially in the inducing cellular apoptosis. As the "guard gene", p53 istranscriptional activator and makes roles in retaining the integrity of cytogene,repairing impaired DNA,normal running of cell cycle. Wild type p53 can inhibitecell proliferation and inversion, but inducing apoptosis. Ceramide and p53 areurging apoptosis fatrors, causing apoptosis in endothelial cell. It's biological effectsmake important roles in cardiovascular system. As a result, the purpose of thepresent study is to elucidate the role of ceramide and p53 in the apoptosis of ECinduced by Angâ…¡.Methods: (1) The EC was treated with Angâ…¡alone. The apoptosis rateswere measured by Tunel. In addition, ceramide,p53,AT1 and AT2 were evaluatedfor their influence on the apoptosis of EC induced by Angâ…¡. The role of ceramideand p53 in apoptosis of EC induced by Angâ…¡was evaluated.(2) After EC was induced with Angâ…¡and ceramide, the protein and gene expression of p53 were measured with Western blotting and reversetranscription-polymerase chain reaction (RT-PCR), and the roles and interrelationsof ceramide and p53 in Angâ…¡were also observed.Results: (1) Angâ…¡can induce the apoptosis of EC in time- anddose-dependent manner. PD123319, inhibitor of AT₂, and fumonisin B1, inhibitor ofceramide, could decrease the apoptosis rate of EC induced by Angâ…¡, but Losartan,inhibitor of AT₁, couldn't. Fumonisin B1 can inhibite Angâ…¡-induced apoptosis.(2) RT-PCR and western Blot assay demonstrated that Fumonisin B1 caninhibite the expression of p53 induced by Angâ…¡in EC. With more and moreceramide, the expression of p53 was also down-regulated.Conclusions: In the process of apoptosis induced by Angâ…¡, Angâ…¡caninduces the activation of ceramide by binding with AT₂, ceramide plays animportant role. Ceramide lies the upper stream of p53. Ceramide induces theapoptosis not by p53.