Tyrosinase is a novel endogenous regulator of developmental and inflammatory lymphangiogenesis.

Lymphangiogenesis is critically involved in tissue fluid balance, graft rejection, and tumor metastasis. Endogenous regulation of lymphangiogenesis is poorly understood. Here we use the lymphatic vessel architecture at the limbal border of the normally avascular cornea, a quantitative trait under strong genetic influence, as a model system to identify new candidate genes regulating lymphangiogenesis. Comparing low-lymphangiogenic BALB/cN versus high-lymphangiogenic C57BL/6N mice, we performed quantitative trait loci analysis of five phenotypes in a large BALB/cN x C57BL/6N intercross (n=795) and identified three to eight genome-wide significant loci, the strongest on chromosome 7 containing Tyrosinase (Tyr). Tyrosinase-negative mice showed significantly increased limbal lymphvascularized areas, a higher number of lymphatic vessel endpoints, and branching points and increased inflammation-induced lymphangiogenesis. These findings confirm that tyrosinase is a novel lymphangiogenesis regulator in developmental and inflammatory lymphangiogenesis. Our findings link melanin synthesis with lymphangiogenesis and open new treatment options in lymphangiogenesis-related diseases.