The role of PRDM1 in epigenetic regulation and tumor suppression

描述(申请人提供)：PRDM蛋白家族自近20年前被发现以来一直是一个谜。17个人的PRDM蛋白含有一个PR结构域，与赖氨酸甲基转移酶的SET结构域家族有密切的同源性。尽管有这些相似之处，但除了PRDM9，没有PRDM蛋白具有很好的特征酶活性。PRDM家族的成员在发育过程中发挥着重要的作用，其中许多是重要的肿瘤抑制基因或癌基因，特别是PRDM1作为白血病和淋巴瘤的抑制基因，以及PRDM16作为白血病的癌基因。PR结构域通常对肿瘤抑制或肿瘤发生至关重要，但其作用机制尚不清楚。我已经确定PRDM1是一种以组蛋白H3为靶点的精氨酸甲基转移酶。突变一个关键的活性部位残基会降低PRDM1在培养中抑制癌细胞生长的能力。这是一个完全意想不到的活性，因为所有已知的精氨酸甲基转移酶属于一个单一的蛋白家族，与PR或SET结构域几乎没有相似性。这增加了精氨酸甲基化是PRDM蛋白更广泛的功能的可能性，并且这种活性可能对它们在发育和疾病中的作用至关重要。本研究旨在揭示PRDM1甲基转移酶活性抑制肿瘤的分子机制。在指导部分，我将研究PRDM1活性在淋巴瘤细胞模型中的生物学效应，并检验染色质修饰是PRDM1的主要生物学功能的假设。在该奖项的独立部分，我将检验PRDM1通过招募或排斥特定的染色质结合蛋白来调节组蛋白修饰的生物学效应的假设，并确定PRDM1是否甲基化额外的非组蛋白。这项工作的最终目的是确定其他PRDM蛋白是否也甲基化精氨酸，以及这种活性是否参与调节癌症途径。指导部分的培训将集中在分子和细胞生物学的技术上。这些技能将补充我在化学、质谱学和细胞信号方面的本科和研究生培训。发现PRDM1作为第一个非规范的精氨酸甲基转移酶，为未来的工作开辟了无数的途径，并为我的独立研究提供了一个独特的方向。该奖项提供的培训将有助于实现我的长期目标，即建立一个研究计划，调查信号传递过程和表观遗传学如何建立细胞识别，以及它们的失调如何导致疾病。

DESCRIPTION (provided by applicant): The PRDM protein family has been an enigma since its discovery almost twenty years ago. The seventeen human PRDM proteins contain a PR domain with close homology to the SET domain family of lysine methyltransferase enzymes. Despite this similarity, with the exception of PRDM9, no PRDM proteins have well-characterized enzymatic activity. Members of the PRDM family have critical roles during development and many are important tumor suppressors or oncogenes, notably PRDM1 as a suppressor of leukemia and lymphoma, and PRDM16 as an oncogene in leukemia. The PR domain is often critical for tumor suppression or oncogenesis but its mechanism of action is unknown. I have identified PRDM1 as an arginine methyltransferase targeting histone H3 at arginine 17. Mutating a key active site residue reduces the ability of PRDM1 to suppress cancer cell growth in culture. This is a completely unexpected activity because all known arginine methyltransferases belong to a single protein family with little similarity to the PR or SET domains. It raises the possibiliy that arginine methylation is a broader function of the PRDM proteins and that this activity may be critical for their roles in development and disease. This proposal aims to uncover the molecular mechanisms of tumor suppression by PRDM1 methyltransferase activity. In the mentored portion I will investigate the biological effects of PRDM1 activity in cellular models of lymphoma, and test the hypothesis that chromatin modification is the primary biological function of PRDM1. In the independent portion of the award I will test the hypothesis that histone modification by PRDM1 mediates biological effects by recruiting or repelling specific chromatin-binding proteins, and determine whether PRDM1 methylates additional non-histone proteins. The final aim of this work is to determine whether other PRDM proteins also methylate arginine and whether this activity participates in regulating cancer pathways. Training during the mentored portion will focus on techniques in molecular and cell biology. These skills will complement my undergraduate and graduate training in chemistry, mass spectrometry and cellular signaling. Discovering PRDM1 as the first non-canonical arginine methyltransferase opens countless avenues for future work and equips me with a unique direction for my independent research. The training provided by this award will be instrumental in achieving my long-term goal of establishing a research program that investigates how signaling processes and epigenetics establish cellular identify, and how their dysregulation leads to disease.