RSUME INHIBITS TYPE 2 VHL MUTANTS FUNCTION LEADING TO TUMORAL ANGIOGENESIS BY INHIBITING THE ASSEMBLY OF THE VHL FUNCTIONAL COMPLEX

TEDESCO, LUCAS; ELGUERO, BELÉN; TEDESCO, LUCAS; ELGUERO, BELÉN; PACIN, DAVID GONILSKI; FUERTES, MARIANA; PACIN, DAVID GONILSKI; FUERTES, MARIANA; SENIN, SERGIO; ARZT, EDUARDO; SENIN, SERGIO; ARZT, EDUARDO

Buenos Aires

Congreso; LXIII Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica; 2018

Sociedad Argentina de Investigación Clínica

von Hippel-Lindau (VHL) disease is associated with the development of high vascularized tumors due to Hypoxia Inducible Factors (HIF) deregulation caused by mutations in VHL gene. VHL is the substrate recognition component of the E3 ligase complex, composed of Cullin2, Elongin B, Elongin C, and pVHL, that participates in the oxygen-sensing system that drives HIF degradation. Certain mutations retain a partial function on HIF downregulation implying additional mechanisms involved in VHL mutants loss of function. We have already demonstrated that RSUME interacts with VHL, and inhibits its function, leading to HIF-alpha stabilization. Even more, we also found the same action of RSUME on representative Type 2 mutants (VHLY112H; VHLR167Q; VHLL188V) and we found this mechanism was independent of VHL sumoylation status. The aim of this work is to reveal the molecular mechanism behind RSUME potentiation of Type 2 VHL phenotype and its functional impact.COS-7 cells were cotransfected with Flag-VHLY112H-GFP or Flag-VHLR167Q-GFP or Flag-VHLL188V-GFP, the ECV complex components (Cullin2, Elongin B, Elongin C) and/or V5-RSUME. By VHL immunoprecipitation we observed that RSUME interaction with VHL type 2 mutants impairs the ECV complex assembly, which inhibits its function.In RCC-786-O clones expressing VHL, VHLK171R, VHLL188V or VHLL188V/K171R, co-expression of shRNA against RSUME resulted in a decrease of VEGF mRNA. EA.hy926 endothelial cells cultured in conditioned media of these clones, in which RSUME expression was silenced, decrease the capillary-like structures formation. Mice injected with these stable clones presented new vessels around the injection area, but those clones in which RSUME expression was knocked-down showed a decreased in vessel density. This confirms that in absence of RSUME, VHL Type 2 mutant become more potent and might limit early tumoral angiogenesis.RSUME is critical in VHL mutants deregulation that leads to VHL disease onset.