Activation and Regulation Mechanisms of the RAF Kinase Family

BRAF是RAF家族蛋白激酶的一员，在MAPK信号通路中起作用，该通路控制广泛的 细胞事件如增殖和分化。BRAF是人体内最常见的突变激酶 癌的此外，当存在突变时，缺乏BRAF突变的肿瘤取决于BRAF活性 在上游通路成员中，如RAS或生长因子受体。因此，BRAF代表了一个重要的 用于癌症治疗靶点。尽管进行了30年的深入研究， BRAF机制的一部分为BRAF治疗打开了大门。然而，目前临床上的BRAF抑制剂， 维罗非尼和达拉菲尼限于I类突变体BRAFV 600 E。维罗非尼和达拉非尼， ATP竞争性抑制剂可以矛盾地激活非BRAFV 600 E和野生型BRAF，这表明 BRAF具有独立于其激酶活性的功能。非恶性肿瘤的治疗策略 BRAFV 600 E突变和野生型BRAF仍然缺乏。我们知识上的差距导致了 ATP竞争性BRAF药物。拟议的工作围绕着三个问题， 以及健康和疾病状态的监管。问题1：BRAF结构元件和ATP结合如何介导 非BRAFV 600 E和野生型BRAF？Q2：什么是作用机制？ 我们的小组开发的第一个BRAF变构抑制剂，以及抑制剂如何靶向催化和非- 开发BRAF的催化功能？问题3：哪些因素有助于RAF的职能不重叠 异构体，尽管它们的结构相似？PI及其团队将通过以下方式解决这些问题： 多学科方法，包括X射线晶体学，结合动力学，磷酸化蛋白质组学，活细胞 成像、化学生物学和计算方法。我们的发现不仅有助于更好地理解 RAF激酶家族复杂的生化机制，也提供了新的分子基础 靶向BRAF驱动的肿瘤的治疗方法。

BRAF, a member of the RAF family protein kinases, works in the MAPK signaling pathway, which controls broad cellular events like proliferation and differentiation. BRAF is the most frequently mutated kinase in human cancers. Furthermore, tumors lacking BRAF mutations are contingent on BRAF activity when there are mutations in upstream pathway members, such as RAS or growth factor receptors. Thus, BRAF represents an important target for cancer therapy. Despite three decades of intense research, only recently has a sufficient understanding of BRAF's mechanism creaked open the door to BRAF therapy. However, the current clinical BRAF inhibitors, vemurafenib and dabrafenib, are limited to the class I mutant BRAFV600E. Vemurafenib and dabrafenib, the two ATP-competitive inhibitors, can paradoxically activate non-BRAFV600E and wild-type BRAF, suggesting that BRAF has functions that are independent of its kinase activity. Therapeutic strategies for tumors with non- BRAFV600E mutations and wild-type BRAF are still lacking. Gaps in our knowledge contributed to the limitations of ATP-competitive BRAF drugs. The proposed work centers around three questions regarding RAF activation and regulation in health and disease states. Q1: how BRAF structural elements and ATP binding mediate the catalytic-independent functions of non-BRAFV600E and wild-type BRAF? Q2: what is the mechanism of action of the first BRAF allosteric inhibitor developed by our group and how can inhibitors targeting the catalytic and non- catalytic functions of BRAF be developed? Q3: What factors contribute to the non-overlapping functions of RAF isoforms, despite their structural similarity? The PI and her team will address these questions through multidisciplinary approaches, including X-ray crystallography, binding kinetics, phosphoproteomics, live cell imaging, chemical biology, and computational methods. Our findings will not only facilitate a better understanding of the complex biochemical mechanisms of the RAF kinase family, also provide a molecular basis for novel therapeutic approaches targeting BRAF-driven tumors.