Role of soluble adenylyl cyclase in ischemia-reperfusion-induced brain injury

缺血性中风是一种急性神经退行性疾病，是导致死亡和残疾的主要原因之一。越来越多的证据表明，细胞凋亡在脑缺血再灌注后神经元死亡中起重要作用。在几种信号通路中，cAMP-PKA信号在调节对不同应激刺激（包括缺血性损伤）的凋亡反应中起重要作用。到目前为止，它被完全归因于G蛋白反应性跨膜腺苷酸环化酶（tmAC）的活性。除了tmAC之外，哺乳动物细胞还具有cAMP的第二来源，即普遍表达的可溶性腺苷酸环化酶（sAC）。最近，我们证明了这种环化酶是冠状动脉内皮细胞凋亡的重要调节因子。此外，我们还发现这种环化酶的活性形式也在大鼠皮层中表达。sAC是否参与神经元细胞凋亡尚不清楚。本课题旨在探讨sAC在脑缺血再灌注诱导的细胞凋亡中的作用。为此目的，将首先对暴露于模拟缺血-再灌注的原代大鼠胚胎细胞培养物以及人神经母细胞瘤培养物进行体外研究。最后，将进行野生型或sAC敲除小鼠的体内研究。

Ischemic stroke is an acute neurodegenerative disorder that is one of the leading causes of death and disability. Increasing evidence suggest that apoptosis contributes significantly in the neuronal death under cerebral ischemia-reperfusion. Within several signaling pathways, cAMP-PKA signaling plays an essential role in modulating the apoptotic response to different stress stimuli including ischemic insult. Until now, it was attributed exclusively to the activity of the G-protein-responsive transmembrane adenylyl cyclase (tmAC). Aside from the tmAC, mammalian cells possess a second source of cAMP, the ubiquitously expressed soluble adenylyl cyclase (sAC). Recently, we demonstrated that this cyclase is an essential modulator of mitochondria-dependent apoptosis in coronary endothelial cells. Furthermore, we found that the active form of this cyclase is also expressed in rat cortex. Whether sAC contributes in apoptosis of neuronal cells is unknown. To investigate the role of sAC in cerebral apoptosis induced by ischemia-reperfusion is the aim of the proposed project. For this purpose, first in vitro studies with primary rat embryonic cell culture as well as with human neuroblastoma culture exposed to simulated ischemia-reperfusion will be performed. Finally, in vivo studies with wild type or sAC-knockout mice will be curried out.