The Role of HNF4alpha in Cell Proliferation

描述（由申请人提供）：肝细胞核因子（HNF）41是胎儿和成人肝脏形态和功能所需的一种重要核受体，调节许多参与各种代谢过程、血液稳态和上皮结构的肝脏特异性基因。这种高度保守的核受体具有N-末端和C-末端结构域不同的各种同种型。这些是通过使用两个替代启动子和3'剪接事件产生的。有证据表明，这些剪接变异体在肝脏发育中发挥不同的作用。P1亚型（HNF 411/12）仅在胚胎、出生后和成年肝脏中表达，而P2亚型（HNF 417/18）仅在胎儿肝脏中表达。这些异构体如何调节细胞从增殖到分化的转变还有待阐明。最近，我们已经表明，HNF 411上调细胞周期蛋白依赖性激酶抑制剂p21，细胞周期抑制剂，我们还表明，癌蛋白c-Myc废除这种活动。其他人已经显示HNF 41与TCF/LEF相互作用，TCF/LEF是Wnt/2-连环蛋白途径的下游。这一途径的功能障碍与肝癌和其他癌症有关。我们的目标是破译HNF 41在细胞周期调控中的作用，并研究不同HNF 41亚型在该过程中的作用。我们将在我们的研究中结合分子和高通量技术，如共免疫沉淀（co-IP），细胞增殖测定，表达谱阵列和染色质免疫沉淀测序（ChIP-Seq）技术。我们将使用永生化的癌细胞系和小鼠胚胎干细胞（mES），我们将分化成肝谱系。ES细胞可以像癌细胞一样无限增殖，但它们也可以分化成任何专门的细胞类型。简而言之，它们模仿正常发育。另一方面，癌细胞系提供了一个系统来检查破坏微妙的增殖-分化平衡的病理后果。这两个系统将提供互补的方法来解决肝脏发育和疾病中细胞增殖和细胞分化之间的基本二分法。

DESCRIPTION (provided by applicant): Hepatocyte nuclear factor (HNF) 41, an important nuclear receptor required for the morphology and function of the fetal and adult livers, regulates many liver-specific genes involved in various metabolic processes, blood homeostasis, and epithelium architecture. This highly conserved nuclear receptor has various isoforms that differ in the N-terminal and C- terminal domains. These are generated by the use of two alternative promoters and 3' splicing events. There has been evidence suggesting that these splice variants play different roles in liver development. The P1 isoforms (HNF411/12) are expressed exclusively in lat embryo, postnatal and adult livers while the P2 isoforms (HNF417/18) are expressed only in the fetal liver. How these isoforms regulate the transition from proliferating to differentiating cells is yet to be elucidated. Recently, we have shown that HNF411 upregulates cyclin dependent kinase inhibitor p21, a cell cycle inhibitor; we have also shown that the oncoprotein c-Myc abolishes this activity. Others have shown HNF41 interacts with TCF/LEF which is the downstream of the Wnt/2-catenin pathway. Dysfunction in this pathway is associated with liver and other cancers. Our goal is to decipher the role of HNF41 in cell cycle regulation and to investigate the role of the different HNF41 isoforms in that process. We will incorporate molecular and high throughput technology such as co-immunoprecipitiation (co-IP), cell proliferation assays, expression profiling arrays, and chromatin immunoprecipitation sequencing (ChIP-Seq) techniques in our study. We will use both immortalized cancer cell lines and mouse embryonic stem (mES) cells that we will differentiate into the hepatic lineage. ES cells can proliferate indefinitely, just like cancer cells, but they also can differentiate into any specialized cell type. In short, they mimic normal development. Cancer cell lines, on the other hand, provide a system to examine the pathological consequences of disrupting the delicate proliferation-differentiation balance. These two systems will provide complementary approaches to address the fundamental dichotomy between cell proliferation and cell differentiation in liver development and disease.