The lymphatic vascular system is essential for lipid absorption/transport from the digestive system, maintenance of tissue fluid homeostasis, and immune surveillance. It is also involved in many pathological processes such as inflammatory disease and tumor metastasis, as well as lymphedema, in which the drainage of lymphatic fluid from the interstitial tissue is insufficient, causing the tissues to swell. Lymphedema is most commonly attributed to impaired lymphangiogenesis or lymphatic-valve deficiency; however, the complex nature of lymphatic vessel abnormalities and disease remain poorly understood. Thus, our long-term goal is to understand the molecular and cellular mechanisms responsible for the formation and function of the lymphatic vascular system. FoxC1 and FoxC2 are closely related members of the Fox (Forkhead box) transcription factor family, and our group has previously shown that murine Foxc1 and Foxc2 have numerous essential roles in cardiovascular development. Mutations in human FOXC2 are responsible for the autosomal dominant syndrome Lymphedema-distichiasis, which is characterized by the obstruction of lymphatic drainage in the limbs, venous valve failure, and the growth of an extra set of eyelashes. Recent studies have shown that Foxc2 is also essential for lymphatic valve formation, but the role of FoxC1 in the lymphatic system has yet to be defined. Thus, we have recently generated mice that carry lymphatic endothelial cell (LEC)-specific mutations for Foxc1, Foxc2, or both, which will enable us to determine the precise functions of Foxc1 and Foxc2 in the cellular processes that lead to the development of lymphatic vessels. Our initial studies indicate that the loss of Foxc1 and Foxc2, alone or in combination, leads to lymphatic hyperplasia and is accompanied by declines in the expression of RasGAP genes and by the hyperactivation of ERK. Furthermore, our new genome-wide RNA-seq analysis indicates that Notch signaling genes such as Notch1 and Dll4 are significantly downregulated in LECs that have been isolated from conditional compound LEC-Foxc1;LEC-Foxc2 mutants. Thus, the objective of this application is to study the role of the transcription factors Foxc1 and Foxc2 in lymphatic vessel development. Our central hypothesis is that Foxc1 and Foxc2 are essential for lymphatic cell fate determination, lymphangiogenesis, and lymphatic valve development, and we will test our central hypothesis and accomplish the objective of this application by pursuing the following three Specific Aims: 1) To determine whether Foxc1 and Foxc2 participate in lymphatic cell fate determination by interacting with the Notch signaling pathway. 2) To define the mechanisms by which Foxc1 and Foxc2 regulate the Ras/ERK pathway during lymphangiogenesis. 3) To elucidate the cooperative and distinct functions of Foxc1 and Foxc2 in lymphatic valve development. In summary, the outcome of our project is an extensive characterization of the critical roles that Foxc1 and Foxc2 play in lymphatic vessel development. We expect our findings to have an important positive impact on patient care, because completion of the proposed studies will likely lead to the development and refinement of novel strategies for preventing and treating lymphatic disorders, such as lymphedema.

Public Health Relevance

The proposed research is relevant to public health because congenital malformations of the lymphatic system are associated with an increased risk of lymphatic disorders such as lymphedema, but their causes and underlying developmental mechanisms are poorly understood. The results of the proposed studies will significantly contribute to a better understanding of the molecular and cellular mechanisms underlying the formation and function of the lymphatic vessel system and will gain insight into the etiology of lymphatic disease. Thus, the proposal is relevant to the part of NIH's mission that could leads to the development of new therapeutic strategies for patient care.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL126920-01
Application #
8867008
Study Section
Special Emphasis Panel (ZRG1-DKUS-E (57))
Program Officer
Tolunay, Eser
Project Start
2015-09-01
Project End
2019-06-30
Budget Start
2015-09-01
Budget End
2016-06-30
Support Year
1
Fiscal Year
2015
Total Cost
$386,250
Indirect Cost
$136,250
Name
Northwestern University at Chicago
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
005436803
City
Chicago
State
IL
Country
United States
Zip Code
60611
Kume, Tsutomu; Shackour, Tarek (2018) Meta-analysis of the likelihood of FOXC1 expression in early- and late-stage tumors. Oncotarget 9:36625-36630
Kume, Tsutomu; Shackour, Tarek (2018) Meta-analysis of the likelihood of FOXC2 expression in early- and late-stage tumors. Oncotarget 9:33396-33402
Inman, Kimberly E; Caiaffa, Carlo Donato; Melton, Kristin R et al. (2018) Foxc2 is required for proper cardiac neural crest cell migration, outflow tract septation, and ventricle expansion. Dev Dyn 247:1286-1296
Cui, Chang-Yi; Ishii, Ryuga; Campbell, Dean P et al. (2017) Foxc1 Ablated Mice Are Anhidrotic and Recapitulate Features of Human Miliaria Sweat Retention Disorder. J Invest Dermatol 137:38-45
Fatima, Anees; Wang, Ying; Uchida, Yutaka et al. (2016) Foxc1 and Foxc2 deletion causes abnormal lymphangiogenesis and correlates with ERK hyperactivation. J Clin Invest 126:2437-51
Lambers, Erin; Arnone, Baron; Fatima, Anees et al. (2016) Foxc1 Regulates Early Cardiomyogenesis and Functional Properties of Embryonic Stem Cell Derived Cardiomyocytes. Stem Cells 34:1487-500
Lambers, Erin; Kume, Tsutomu (2016) Navigating the labyrinth of cardiac regeneration. Dev Dyn 245:751-61