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Elucidating the Critical Functions of Yap1 in the Embryonic Development and Regeneration of the Biliary System

阐明 Yap1 在胆道系统胚胎发育和再生中的关键功能

基本信息

批准号：
9906522
负责人：
Laura Maria Molina
金额：
$ 5.05万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-04-01 至 2022-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9906522
关键词：
3-Dimensional Accounting Adult Affect Age-Months Alagille Syndrome Biliary Biological Birth Cell Fraction Cell Proliferation Cell Survival Cells Child Childhood Cholestasis Clinical Data Defect Dependovirus Development Developmental Biology Disease model Duct (organ) structure Embryo Embryonic Development Epithelial Cells Etiology Event Experimental Designs Failure Fibrosis Foundations Future Generations Goals Growth Hepatic Hepatocyte Image Immunofluorescence Immunologic Impairment Inherited Injections Intrahepatic bile duct Knockout Mice Learning Life Life Expectancy Liver Liver Regeneration Manuscripts Medical Mentorship Microscopy Modeling Molecular Morbidity - disease rate Morphogenesis Mus Natural regeneration Organogenesis Pathology Patients Phenotype Physicians Process Proteins Publications Quality of life Regenerative Medicine Research Training Role Savings Scientist Serotyping Signal Transduction Sleeping Beauty Structure System Tail Techniques Technology TimeLine Tissue Engineering Tissues Training Veins base bile duct biliary tract career cell regeneration cell type cholestatic injury cholestatic liver disease hepatocyte injury improved insight intrahepatic liver development liver imaging liver transplantation mortality mouse model notch protein novel novel therapeutics oval cell polarized cell postnatal prevent progenitor regenerative regenerative therapy repaired restoration stem cells targeted treatment transdifferentiation

项目摘要

PROJECT SUMMARY/ABSTRACT Cholestatic liver diseases are devastating illnesses of the biliary system, accounting for ~45% of pediatric and 10% of adult liver transplants annually. Currently no targeted therapies are available, and there is a significant unmet clinical need to improve patient survival. Biliary epithelial cells (BECs) possess significant regenerative capacity, but after severe cholestatic injury hepatocytes (liver parenchymal cells) are able to transdifferentiate into BECs to repair damaged bile ducts in both adult and pediatric models of disease. Hepatocytes are thus an untapped reservoir for promotion of biliary repair. Recently, Yes-associated protein 1 (Yap1) has emerged as a critical regulator of bile duct formation and liver regeneration. However, little is known about the mechanisms by which Yap1 drives biliary differentiation during embryonic development or hepatocyte-derived BEC regeneration. We have developed a novel Foxa3-Cre Yap1 knockout (KO) mouse model in which Yap1 is fully deleted from liver progenitor cells before induction of the biliary lineage, resulting in failure of bile duct formation and severe cholestatic injury. A recent model of Alagille syndrome showing similar defects in biliary development described extensive de novo generation of bile ducts derived from hepatocytes by 4 months. However, 4-month-old Yap1- deficient livers show no evidence of hepatocyte-derived biliary regeneration. Based on these observations, our overarching hypothesis is that Yap1 is indispensable for functional bile duct formation regardless of their origin, whether from hepatoblasts during embryonic liver development or from transdifferentiating hepatocytes in the setting of severe cholestatic injury. To investigate, we propose the following specific aims, which will yield novel mechanistic insights into Yap1 signaling, with significant implications for regenerative medicine and tissue engineering technologies aimed at promoting biliary repair and regeneration. Specific Aim 1: We will determine the ontogeny of Yap1 activity during normal liver organogenesis, and investigate the timeline of bile duct development in Yap1 KO mice using immunofluorescence and 3D whole-liver microscopy. We will thus identify the specific defects in 3D bile duct morphogenesis caused by Yap1 deletion. Specific Aim 2: Based on our preliminary data showing lack of hepatocyte-to-BEC transdifferentiation in Yap1 KO mice, we hypothesize that restoration of Yap1 expression to Yap1-negative hepatocytes will selectively allow these cells to transdifferentiate and restore a critical biliary mass to ameliorate ongoing cholestatic injury. We will use lineage- tracing to determine whether any hepatocyte-derived bile ducts are present in adult Yap1 KO mice. We will then use two complementary approaches to selectively deliver a tagged wild-type Yap1 construct to a small number of hepatocytes in Yap1 KO mice and trace their fate to assess their capacity for transdifferentiation into BECs and de novo bile duct formation. Contribution to Training: This proposal combines research training in liver pathology, developmental biology, and state-of-the-art biological imaging with world-class clinical training, providing a strong foundation for a productive career as an academic physician scientist.

项目总结/文摘