Dysfunction of Cullin 3 RING E3 ubiquitin ligase causes vasoconstriction and increased sodium reabsorption in diabetes.

Impaired endothelium-mediated vasodilation and/or increased sensitivity to vasoconstrictors lead to vascular smooth muscle cell (VSMC) dysfunction in individuals with diabetes. Diabetic nephropathy is associated with a considerably higher risk of cardiovascular disease and death than their nondiabetic counterparts. We studied the activity of Cullin 3 RING ubiquitin ligase (CRL3) and its substrates in mice using an intraperitoneal injection of streptozotocin (STZ) and db/db mice. The levels of CRL3 adaptors, including Kelch-like 2/3 (KLHL2/3) and Rho-related BTB domain-containing protein 1, were significantly decreased in the aortic tissues and heart of the STZ group, whereas the levels of Cullin 3 (CUL3) and its neddylated derivatives were substantially increased. Decreased KLHL3 expression and significantly increased expression of NEDD8 conjugates were observed in the kidneys of db/db mice. The neddylation inhibitor MLN4924 decreased the degradation of KLHL2/KLHL3 under high-glucose conditions with/without insulin, and transfection with KLHL2 promoted the degradation of its substrates with-no-lysine (WNK) kinases. Increased abundance of WNK3, RhoA/ROCK activity and phosphodiesterase 5 enhanced the sensibility to vasoconstrictors and impaired vasodilation. Moreover, WNK3 localized in VSMCs undergoing cell division, and high-glucose medium increased WNK3 signaling in VSMCs undergoing mitosis, which might explain the increased thickness of aortic tissues in subjects with diabetes. Increases in WNK4 abundance resulted in increased sodium reabsorption in the distal renal tubules. Thus, KLHL2/RhoBTB1/KLHL3 inactivation in the aortic tissues and kidney is a result of excessive activation of neddylation in hyperglycemia and hyperinsulinemia, which affects vascular tone and sodium reabsorption.