Evidence that Vascular Endothelial Derived Endothelin‐1 Promotes Development of Tunicamycin‐Induced Endoplasmic Reticulum Stress in Renal Vessels

Abstract

Levels of the vasoconstrictor peptide endothelin-1 (ET-1) are elevated in cardiovascular disease. Endoplasmic reticulum (ER) stress is one of the known mechanisms for cellular apoptosis. Our group has recently implicated the ET-1 system in the activation of renal ER stress pathways, although it is unclear which cells are involved. To clarify the role of ET-1 in the development of renal vascular ER stress, we hypothesized that lack of ET-1 in endothelial cells attenuates tunicamycin (TM)-induced ER stress in renal vessels. Female mice lacking ET-1 in vascular endothelial cells (VEET KO) and the corresponding flox controls (n=5-9/group) received a single i.p. injection of either TM (1.5 mg/kg) or saline. 24 hours post-injection, renal vessels were isolated, ER stress genes determined by qRT-PCR, and renal apoptosis detected by TUNEL staining. TM significantly increased the expression of ER stress markers in renal vessels from flox mice (saline vs. TM, fold change/flox+saline, p<0.05; GRP94: 1.0±0.3 vs. 16.5±6.6, ATF-6: 1.0±0.5 vs. 6.8±3.5, and CHOP: 1.4±0.4 vs. 12.5±1.9). TM treatment led to increased outer medullary, non-vascular TUNEL staining in flox mice as well. TM failed to increase renal vascular ER stress markers or renal apoptosis in VEET KO mice. These results indicate that ET-1 is critical for the development of renal vascular ER stress and apoptosis in response to TM, and highlight the possibility of targeting the ET-1 system as a therapeutic approach against ER stress-induced renal vascular damage. Funded by NIH T32 DK007545 to CDM and P01 HL95499 to DMP and JSP.