Cirrhosis and portal hypertension are the cause of significant morbidity, mortality, and healthcare expenditures. Since hepatic fibrosis and pathological angiogenesis are processes that are mutually dependent and since liver endothelial cell (LEC) invasion is a requisite step for angiogenesis, studies of the detailed molecular mechanisms governing LEC invasion are of great importance. LEC invasion is modulated by mechanisms involving localized cell volume regulation and osmotically driven membrane shape changes. Aquaporin-1 (AQP1) is an integral membrane water channel that is dramatically overexpressed in LEC during cirrhosis and facilitates invasion through the cirrhotic microenvironment. The precise mechanisms responsible for the overexpression of AQP1 in LEC during cirrhosis remain largely uninvestigated. Based on selected background rationale and novel preliminary data, we propose the central hypothesis that local osmotic fluctuation during cirrhosis drives AQP1 overexpression by altering levels of the osmotically sensitive, AQP1 regulatory miRNAs, miR-666 and miR-708, thereby promoting dynamic membrane blebbing, LEC invasion, and angiogenesis during cirrhosis. To accomplish our overall objective, we will employ complementary molecular, cell biologic, an in vivo approaches to establish the mechanism of AQP1 overexpression and the effect of AQP1 regulatory miRNAs on LEC invasion, angiogenesis, and cirrhosis.
Aim I will focus on how local osmolality silences miR- 666 and miR-708 to subsequently increase AQP1 in LEC.
Aim II investigates the effects of miR-666 and miR- 708 on the angiogenic phenotype of LEC.
Aim III tests the effects of miR-666 and miR-708 overexpression on angiogenesis and fibrosis in vivo. The results will mechanistically extend the preliminary findings and provide novel information regarding the osmotically sensitive, miRNA-based mechanisms, controlling AQP1 overexpression and may ultimately produce the foundation for anti-angiogenic therapies targeting AQP1 and its molecular regulators in cirrhosis.

Public Health Relevance

Most forms of chronic liver disease ultimately result in the formation of dense scarring within the liver, known as cirrhosis. In conjunction with this scarring abnormal blood vessel development occurs and is thought to promote further injury and scarring. This project is intended to study the underlying mechanisms that control abnormal blood vessel development and ultimately to generate therapeutic targets to slow or reverse the process of liver scarring.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08DK100575-02
Application #
8732650
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Podskalny, Judith M,
Project Start
2013-09-13
Project End
2018-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
2
Fiscal Year
2014
Total Cost
$147,042
Indirect Cost
$10,892
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
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Huebert, Robert C; Shah, Vijay H (2014) Sinusoidal endothelial cells direct traffic at the intersection of regeneration and fibrosis. Hepatology 60:754-6
de Assuncao, Thiago M; Lomberk, Gwen; Cao, Sheng et al. (2014) New role for Kruppel-like factor 14 as a transcriptional activator involved in the generation of signaling lipids. J Biol Chem 289:15798-809