Investigating and exploiting the interaction of Multimerin-2 and its receptors CLEC14A and CD93

Multimerin-2 is an endothelial specific extracellular matrix protein, which has been found to play a role in angiogenesis and tumour progression. MMRN2 is a ligand for the C-type lectin domain family proteins CLEC14A, CD93 and CD248. CLEC14A and CD93 bind to MMRN2 in the same mapped region MMRN2495-674. CLEC14A is expressed in the vessel of a number of tumour types as tumour endothelial marker (TEM) and like CD93 is involved in angiogenesis. Single or double siRNA-mediated knockdown of CLEC14A, CD93 and MMRN2 confirmed an important role of CD93 in sprouting angiogenesis that is CLEC14A and MMRN2 independent. Furthermore, due to the high affinity of the binding of MMRN2495-674 to the TEM CLEC14A, it has been exploited to target tumour endothelium. The fragment has been employed in the generation of a Chimeric Antigen Receptor (CAR) and other applications. T cells transduced with this receptor were activated on stimulation with both purified antigens and antigens expressed on the cell surface. The activation of T cells was measured as levels of IFNγ released in ELISA assays. Overall, this work sheds light on the interactions of MMRN2 and two of its receptors in in vitro models of angiogenesis.