Story Of Lymphatic System Expands To İnclude Chapter On Valve Formation

A century after the valves that link the lymphatic and blood systems were first described, St. Jude Children's Research Hospital scientists have detailed how those valves form and identified a gene that is critical to the process. The gene is Prox1. Earlier work led by Guillermo Oliver, Ph.D., a member of the St. Jude Department of Genetics, showed Prox1 was essential for formation and maintenance of the entire lymphatic vasculature. The lymphatic vasculature is the network of vessels and ducts that help maintain the body's fluid balance and serves as a highway along which everything from cancer cells to disease-fighting immune components moves.

Oliver is senior author of the new study, which appeared in the October 15 edition of the scientific journal Genes & Development.

The new research suggests that Prox1 is also essential for proper formation of the one-way valves that control movement of fluid and nutrients from the lymphatic system into the blood stream. Researchers found evidence that the Prox1 protein also has a role in formation of the venous valves.

"Understanding how valves form is crucial to efforts to develop treatments for valve defects that affect both children and adults," said the paper's first author, R. Sathish Srinivasan, Ph.D., a research associate in the St. Jude Department of Genetics. Those defects are linked to a variety of problems including lymphedema and deep vein thrombosis, which are blood clots that form deep in veins and have the potential for causing life-threatening complications. Lymphedema is the painful and sometimes disfiguring swelling that can occur when lymph flow is disrupted.

For more than a decade, the lymphatic system has been a focus of Oliver's laboratory. The laboratory's contributions through the years include evidence that leaky lymphatic vessels might contribute to obesity. Oliver and his colleagues also demonstrated how the lymphatic system forms from Prox1-producing cells destined to become lymphatic endothelial cells (LECs) when they leave the developing veins and migrate throughout the body.