Investigation of Astrocytic Cebpd-Regulated Mirnas and Their Effects on Angiogenesis during Neuroinflammation

Rationale: In Alzheimer’s disease (AD), large populations of endothelial cells undergo angiogenesis due to brain hypoxia and inflammation. Substantial evidence from epidemiologic, pathologic, and clinical reports suggests that vascular factors are critical for the pathogenesis of AD. However, the detailed regulation between inflammation and angiogenesis in AD has not been well elucidated. Preliminary results: CCAAT/enhancer binding delta (CEBPD) was found to be overexpressed in astrocytes in AD mice. Our previous study showed that astrocytic CEBPD contributes to angiogenesis in amyloid precursor protein transgenic (AppTg) mice. CEBPD is a transcription factor and shows a modulating effect on a group of miRNAs in astrocytes. Among them, the attenuated miR-29 and miR-22 were predicted to associate the increases of pentrxin 3 (PTX3) and a known pro-angiogenic factor G protein signaling-2 (RGS2), respectively. An interesting result showed that euPTX3 (purified recombinant PTX3 protein from mammal cells) could induce the tube formation of HUVEC, which suggests that PTX3 is a novel pro-angiogenic factor. Moreover, miRNAs have been identified in microvesicles (MVs) derived from tissue cells, thus supporting the idea that MVs may serve as physiological carriers of miRNAs. These observations raise our interests to dissect the involvement of the suppression of miR-29 and miR-22 in response to astrocytic CEBPD activation in angiogenesis during neuroinflammation. Hypothesis: Activation of astrocytic CEBPD contributes to the angiogenesis through miRNAs-mediated regulation in AD.Specific Aims: Based on our preliminary results, several experiments are proposed to study the functional role of CEBPD in inflammatory microenvironments and to investigate the sequential regulation of the angiogenesis features in AD. First, we will investigate the effect of CEBPD-miR-29 axis on PTX3 posttranscriptional regulation in astrocytes. Second, we will dissect the PTX3-transduced signaling pathways in endothelia cells. Third, we will verify and assess the attenuation of microvesicle-mediated miR-22 (MVs-miR22) in response to astrocytic CEBPD activation and the consequent effects in endothelial cells through the MVs-miR-22/RGS2 axis-mediated regulation. Novelty and application: In this proposal, our objective is to explore and verify the roles of astrocytic CEBPD in angiogenesis. We believe that insight into the communication between astrocytes and endothelial cells can provide more knowledge to improve or even overcome angiogenesis-associated diseases. In the future, CEBPD-based animal models for neuroinflammation research can be established and constitute a useful platform. We also aim to apply these novel targets to further translational applications in the treatment of patients with AD.