Role of Beta-Catenin Signaling in Liver Regeneration

β-连环蛋白信号传导在肝脏再生中的作用

• 批准号: 8642778
• 负责人: Satdarshan Singh Monga
• 金额: $ 38.25万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8642778
• 关键词: Acetaminophen; Acute Liver Failure; Address; Adult; Ammonia; Appearance; CYP2E1 gene; Cell Proliferation; Cells; Central Vein; Chief Cell; Clinical; Cyclic AMP-Dependent Protein Kinases; Cyclin D1; Cytochrome P450; Data; Development; Endothelial Cells; Epidermal Growth Factor Receptor; Exhibits; Felis catus; Funding; GC 1 compound; Gene Expression; Glutamate-Ammonia Ligase; Goals; Hepatic; Hepatic Stellate Cell; Hepatocyte; Homeostasis; In Vitro; Injury; Kinetics; Knock-out; Knockout Mice; Kupffer Cells; Liver; Liver Regeneration; Liver diseases; Medicine; Metabolic; Modeling; Molecular; Mus; Natural regeneration; Operative Surgical Procedures; Partial Hepatectomy; Pathway interactions; Patients; Phase Transition; Pre-Clinical Model; Primary carcinoma of the liver cells; Process; Progress Reports; Receptor Protein-Tyrosine Kinases; Regenerative Medicine; Research Proposals; Role; S Phase; Signal Transduction; Source; Staging; Therapeutic; Thyroid Gland; Tissues; Toxic effect; Transgenic Organisms; Treatment Efficacy; Triiodothyronine; Xenobiotics; analog; autocrine; base; beta catenin; cancer therapy; cell type; clinically relevant; efficacy testing; gene function; glucose metabolism; in vivo; insight; liver cell proliferation; liver injury; meetings; mouse model; novel; overexpression; paracrine; progenitor; public health relevance; receptor; stellate cell; toxicant; treatment strategy

DESCRIPTION (provided by applicant): We have made significant progress in determining the role of ?-catenin in hepatic development, zonation, liver regeneration (LR) & liver injury. Wnt/??-catenin signaling is an important contributor in hepatic zonation regulating the expression of glutamine synthetase (GS) and cytochrome P450's like CYP2E1 & 1A2 in hepatocytes around central vein. We have shown ?-catenin signaling as one of the key mechanisms essential for initiation of LR. Hepatocyte-specific ?-catenin knockout mice (Hep??-cat KO) lack zonation and show delay in LR after partial hepatectomy (PHx) due to decreased expression of cyclin-D1. In addition, ?-catenin overexpression promotes LR in mice and in acetaminophen toxicity patients. Several additional key questions emerge from the previous studies & form the basis of current proposal. What are the upstream effectors and their cell sources that regulate ?-catenin activation in normal liver for zonation and during LR for hepatocyte proliferation and who is ?-catenin signaling turned off once LR is accomplished. Lastly, are there clinically relevant molecules that can be used to induce??-catenin signaling to provide proof-of-principle that ?-catenin activation can have implications in treatment of end stage liver disease (ESLD). We hypothesize that Wnts from varying cell sources act in autocrine or paracrine mechanisms to direct ?-catenin activation to in turn instruct hepatic zonation and hepatocyte proliferation during LR, and their elucidation will have broad therapeutic impact. Based on our preliminary studies in mice where Wnt co-receptors LRP5/6 have been deleted from hepatocytes (Hep-LRP5/6 KO) that lack zonation and show delay in LR, ?-catenin appears to be under exclusive control of Wnt signaling in vivo in liver. Also, mice with hepatocyte-specific deletion of Wntless (Wls), essential for Wnt secretion from a cell, do not show impaired zonation or initiation of LR, but displayed prolonged LR after PHx. In specific aim 1, we will determine cellular origin & molecular identity of upstream effectors of ?-catenin in liver zonation and during LR process. This will be done by characterizing these two processes in mice that conditionally lack Wls in various cells of the liver including hepatocytes, sinusoidal endothelial cells, Kupffer cells and stellate cells using cell-specific Cre transgenic lines and floxed-Wls mice that exist in our lab. n specific aim 2, we will determine the mechanism of termination of ?-catenin signaling following accomplishment of hepatocyte proliferation during LR after PH. Hep-Wls KO mice exhibit continued expression of cyclin-D1, cell proliferation at 72-96h after PHx & decreased Wnt5a, an inhibitory Wnt. We will investigate how Wnt5a inhibits ?-catenin signaling in hepatocytes both in vitro and in vivo. We will also use Hep-Wnt5a KO mice to conclusively address if Wnt5a indeed terminates ?-catenin signaling and eventually LR after PHx. In aim 3, we propose to study the therapeutic efficacy of Wnt stimulation to augment LR in murine models of ALF. Our preliminary data shows that ?-catenin activation can promote LR. We identify triiodothyronine (T3) to stimulate ?-catenin signaling in PKA-dependent manner to induce hepatocyte proliferation. We will conclusively address the relevance of PKA-dependent ?-catenin activation in T3-induced hepatocyte proliferation using Hep-LRP5/6 KO mice. We will directly evaluate efficacy of T3 and its thyroid receptor- ? selective analogue GC-1, in inducing LR in acetaminophen-induced liver injury and 90% PH models of acute liver failure. Thus our proposed studies will further our understanding of cellular and molecular basis of LR and investigate the utility of ?-catenin stimulation as a way to treat ESLD using clinically relevant agents.

描述（由申请人提供）：我们在确定肝发育，分区，肝脏再生（LR）和肝损伤中的作用方面取得了重大进展。 Wnt/?? - catenin信号传导是调节肝分散的重要因素，它调节谷氨酰胺合成酶（GS）和细胞色素P450的表达，例如CYP2E1和1A2，在中静脉周围的肝细胞中。我们已经表明？ - 阳极肽信号传导是启动LR所必需的关键机制之一。肝细胞特异性？-Catenin基因敲除小鼠（HEP ?? - CAT KO）缺乏分区，由于Cyclin-D1的表达降低，部分肝切除术（PHX）后LR显示出LR的延迟。此外，？ - 蛋白质过表达可促进小鼠和对乙酰氨基酚毒性患者的LR。以前的研究和构成了当前建议的基础，出现了几个其他关键问题。在正常肝脏中和LR期间，用于肝细胞增殖的正常肝脏中的上游效应子及其细胞来源是什么？ - 一旦完成LR，肝细胞增殖的LR是什么？最后，是否存在可用于诱导catenin信号传导的临床相关分子，以提供原则上的证明？ - 蛋白质激活可能对治疗终阶段肝病（ESLD）具有影响。我们假设来自不同细胞源的Wnts在自分泌或旁分泌机制中作用着引导？ - 蛋白质激活在LR期间指导肝分区和肝细胞增殖，并且它们的阐明将具有广泛的治疗影响。根据我们在小鼠中的初步研究，Wnt共受体LRP5/6已从肝细胞（Hep-LRP5/6 KO）中删除，这些肝细胞缺乏分区并显示LR的延迟，？ - catenin似乎是在肝脏中Vivo中的Wnt信号的独家控制下。同样，具有肝细胞特异性缺失的小鼠（WLS）（WLS），对于细胞的Wnt分泌至关重要，不会显示LR的分区或启动受损，但在PHX后显示长时间LR。在特定的目标1中，我们将确定肝脏分区和LR过程中上游效应子的细胞起源和分子身份。这将通过表征小鼠中的这两个过程来完成，这些过程在肝脏的各种细胞中缺乏WL，包括肝细胞，正弦内皮细胞，kupffer细胞和星状细胞使用细胞特异性CRE转基因系和我们实验室中存在的Floxed WLS小鼠。 n特定的目标2，我们将确定在pH后LR期间完成肝细胞增殖后终止的机理。 HEP-WLS KO小鼠在PHX和Wnt5a（抑制性Wnt）后72-96H表现出持续表达细胞周期蛋白-D1，细胞增殖。我们将研究Wnt5a如何抑制？ - 肝细胞中的蛋白质信号在体外和体内。我们还将使用HEP-WNT5A KO小鼠最终解决WNT5A是否确实终止了？ - phx之后的卡丁蛋白信号传导以及最终LR。在AIM 3中，我们建议研究Wnt刺激在ALF鼠模型中增加LR的治疗功效。我们的初步数据表明？ - 蛋白酶激活可以促进LR。我们以PKA依赖性方式识别三碘甲状腺素（T3）以刺激？ - 蛋白质信号传导，以诱导肝细胞增殖。我们将最终解决PKA依赖性？ - 蛋白蛋白激活在T3诱导的肝细胞增殖中使用HEP-LRP5/6 KO小鼠的相关性。我们将直接评估T3及其甲状腺受体的功效？选择性模拟GC-1，在对乙酰氨基酚诱导的肝损伤和急性肝衰竭的90％pH模型中诱导LR。因此，我们提出的研究将进一步理解LR的细胞和分子基础，并研究-Catenin刺激的实用性，以此作为使用临床相关剂治疗ESLD的一种方式。