Targeting phosphatase regulated cleavage of HIF-1-alpha in ischemic brain injury

描述(申请人提供)：缺氧诱导因子(HIF-1a)诱导的从头基因表达在决定神经元在缺血损伤后存活或死亡方面起着决定性作用。然而，调节HIF适应性和病理效应之间平衡的分子机制仍未解决。我们已经发现，MAP激酶磷酸酶MKP-1在氨基末端反式激活区域附近刺激HIF-1a裂解，并触发BNIP3表达和一系列相关的促凋亡反应。在这个应用中，我们测试了这样的假设，即MKP-1和HIF-1a一起在缺血期间起到分子开关的作用，促进涉及自噬和凋亡信号的基因的表达。我们将使用互补的遗传方法应用于培养和动物缺血损伤模型来研究：1)MKP调节HIF-1a翻译后修饰的机制，2)HIF-1a裂解所需的离散修饰和因素，以及3)这些改变对神经元存活的影响。总之，这些实验集中在一个新的，生理反应的信号节点，它调节HIF-1a的潜在凋亡潜力。在这个网络中识别合适的靶点将使发现旨在抑制或增强转录依赖损伤的小分子成为可能。这一领域的进展将对缺血性和恶性脑疾病产生广泛的影响。

DESCRIPTION (provided by applicant): De novo gene expression induced by the hypoxia inducible factor (HIF-1a) plays a decisive role in determining whether neurons live or die after an ischemic insult. However, the molecular mechanisms regulating the balance between HIF's adaptive and pathological effects remain unsettled. We have discovered that the MAP kinase phosphatase MKP-1 stimulates HIF-1a cleavage near the amino-terminal transactivation domain and triggers both BNIP3 expression and a host of related pro-apoptotic responses. In this application we test the hypothesis that together, MKP-1 and HIF-1a function as a molecular switch during ischemia, promoting the expression of genes involved in autophagy and apoptotic signaling. We will use complimentary genetic approaches applied in culture and animal models of ischemic injury to investigate: 1) the mechanism by which MKP regulates HIF-1a post-translational modification, 2) the discrete modifications and factors required for HIF-1a cleavage, and 3) the effects these changes have on neuron survival. Together, these experiments focus on a novel, physiologically responsive signaling node that modulates HIF-1a's latent apoptotic potential. The identification of suitable targets in this network will enable the discovery of small molecules designed to either inhibit or augment transcription- dependent injury. Progress in this area will have broad implications for both ischemic and malignant brain disorders.