Mechanism and inhibition of SREBP-dependent cholesterol/lipid metabolism

描述（由申请人提供）：基因表达程序的异常控制与许多全球重大疾病的发病机制有关，包括心血管疾病（CVD）、肥胖和糖尿病。甾醇调节元件结合蛋白（SREBP）转录因子家族的成员控制参与胆固醇/脂质代谢、膜合成和脂肪储存的基因。异常的SREBP活性与代谢综合征相关的疾病有关，如胰岛素抵抗、肥胖、LDL-C和甘油三酯升高、心血管疾病和非酒精性脂肪肝疾病。此外，SREBPs还通过调控膜合成参与了癌细胞的增殖和包膜病毒的复制。我们之前已经定义了SREBPs激活基因的分子要求，证明了Mediator共激活物复合物的MED15亚基和CBP/p300乙酰转移酶的核心作用。虽然大多数旨在改变基因表达程序的治疗方法针对上游信号通路或核易位检查点，但我们的研究提供了支持另一种方法的机制见解，该方法旨在直接抑制SREBP转激活域（tad）与MED15和CBP/p300核共激活子的相互作用。本研究的目的是阐明SREBP转录激活因子与共激活因子相互作用的机制，并开发这些相互作用的特异性小分子抑制剂。通过结合结构和生物物理方法以及高通量小分子筛选，我们建议使用结构见解来指导针对心血管和其他疾病的新型治疗方法的开发。在初步工作中，我们已经能够鉴定出能够破坏SREBP-TAD与MED15结合的小分子抑制剂，从而导致其靶基因（如脂肪酸合成酶（FASN））的下调。从这些研究中出现的抑制剂将通过药物化学进行优化。具体目标1：从结构和功能上表征SREBP与共激活子MED15和CBP/p300的相互作用。特异性目标2：发现并表征SREBP-TAD与共激活剂相互作用的体外小分子抑制剂，以开发针对异常胆固醇/脂质代谢的治疗方法。特异性目标3：使用细胞培养和小鼠模型对已鉴定的SREBP/共激活剂抑制剂进行功能表征。

DESCRIPTION (provided by applicant): Aberrant control of gene expression programs is contributing to the pathogenesis of a number of globally significant diseases, including cardiovascular disease (CVD), obesity, and diabetes. Members of the sterol regulatory element-binding protein (SREBP) family of transcription factors controls genes involved in cholesterol/lipid metabolism, membrane synthesis, and fat storage. Aberrant SREBP activity has been linked to conditions associated with metabolic syndrome, such as insulin resistance, obesity, elevated LDL-C and triglycerides, cardiovascular pathologies, and non-alcoholic fatty liver disease. Furthermore, SREBPs have been implicated in cancer cell proliferation and replication of enveloped viruses through regulation of membrane synthesis. We have previously defined the molecular requirements for gene activation by SREBPs, demonstrating a central role for the MED15 subunit of the Mediator co-activator complex and the CBP/p300 acetyltransferases. While most therapeutic approaches aimed at altering gene expression programs target upstream signaling pathways or nuclear translocation checkpoints, our studies have provided mechanistic insights supporting an alternative approach, which is aimed at directly inhibiting the interaction of the SREBP transactivation domains (TADs) with MED15 and CBP/p300 co-activators in the nucleus. The goal of the proposed research is to elucidate the mechanisms by which the SREBP transcriptional activators interact with co-activators, and to develop specific small-molecule inhibitors of these interactions. Through a combination of structural and biophysical methods in conjunction with high-throughput screening of small molecules, we propose to use structural insights to guide the development of new classes of therapeutics against cardiovascular and other diseases. In preliminary work, we have already been able to identify small-molecule inhibitors capable of disrupting SREBP-TAD binding to MED15, resulting in concomitant down-regulation of its target genes, such as fatty acid synthase (FASN). Inhibitors emerging from these studies will be optimized with medicinal chemistry. We will pursue the following specific aims: Specific Aim 1: Characterize structurally and functionally the SREBP interaction with co-activators MED15 and CBP/p300. Specific Aim 2: Discover and characterize in vitro small-molecule inhibitors of the SREBP-TAD interaction with co-activators to develop therapeutics against aberrant cholesterol/lipid metabolism. Specific Aim 3: Functionally characterize identified SREBP/co-activator inhibitors using both cell culture and mouse models.