RESUMO
Objective:To assess the renal-protective effect of Elabela (Ela) on diabetic kidney disease (DKD), and explore its potential mechanism.Methods:db/db mice were randomly divided into diabetic group and Ela intervention group, while db/m mice were taken as normal control group. The mice in the Ela intervention group were intraperitoneally injected with Ela-21 5 mg·kg -1·d -1 for 8 weeks. At the end of the experiment, urinary albumin/creatinine ratio (UACR) was measured. The renal pathological changes were observed by HE and PAS staining. The expression of aquaporin 2(AQP2) examined by immunohistochemistry. The level of collage Ⅳ(Col-Ⅳ) and AQP2 in renal tissue was analyzed by Western blot. The human renal tubular epithelial cells (HK-2) were incubated with high glucose medium and further interfered with apelin receptors (APJ)-siRNA. Western blot analysis was used to detect the effect of Ela intervention on Col-Ⅳ and AQP2 expression. Finally, to clarify the possible mechanism of Ela regulating AQP2, the interaction between Ela-induced APJ activation and arginine vasopressin (AVP)-evoked arginine vasopressin receptor 2 (AVPR2) activation was investigated by NanoBit ? technology. Results:(1) Without affecting blood glucose and body weight, Ela intervention significantly reduced the UACR in db/db mice, and attenuate pathological changes of the kidney, as well as expression of Col-Ⅳ and AQP2. (2) Ela treatment could remarkably inhibit the high glucose-induced the expression of Col-Ⅳ and AQP2, which was reversed by interfering with APJ. (3) AVP-induced downstream β-Arrestin-2 signaling transduction via AVPR2 was obviously antagonized by interaction of Ela and APJ, further suggesting that the inhibitory effect of Ela on AQP2 may be related to antagonizing AVP/AVPR2 signaling.Conclusion:Ela exerts renal protection by inhibiting the expression of AQP2 through APJ.
RESUMO
Objective:To investigate the protective effects of Elabela(ELA) on the renal injury of db/db mice and its possible mechanism.Methods:Sixteen eight-week-old male db/db mice were intraperitoneally injected with ELA(5 mg·kg -1·day -1) or equivalent normal saline( n=8) for 8 weeks. Eight age-matched male db/m mice received equivalent normal saline injection as normal control. At the end of the experiment, blood and urine samples were obtained for HbA 1C and urinary albumin/creatinine(ACR) measurements. Immunohistochemistry was used to observe the expression of ELA. Histopathological changes in kidney tissue were observed by HE staining and Masson staining. The levels of collagen type Ⅳ(Col-Ⅳ) and transforming growth factor-β1(TGF-β1) as well as Yes-associated protein(YAP) phosphorylation in kidney tissue were examined by western blot. Results:Immunohistochemistry results showed that ELA expression was decreased in the renal tissue of db/db mice as compared with that of db/m mice( P<0.05). After ELA treatment, ACR and blood pressure were markedly decreased in db/db mice( P<0.05), but without significant changes in the body weight and HbA 1C. Renal tubular epithelial cells edema, basement membrane thickening, and increased collagen fiber in db/db were improved by ELA administration. Compared with db/m mice, the levels of TGF-β1 and Col-Ⅳ expression, as well as YAP phosphorylation were significantly increased in renal tissue of db/db mice(0.98±0.08 vs 0.68±0.10, 1.10±0.14 vs 0.51±0.08, 3.38±0.72 vs 0.81±0.13, all P<0.05), which were down-regulated after ELA administration(0.80±0.06, 0.51±0.05, 2.21±0.22, all P<0.05). Conclusion:ELA may improve the renal injury of db/db mice by regulating the signaling pathway of YAP, thereby delaying the development of diabetic nephropathy.