BACKGROUND: The structural and functional impairment of endothelium cells were mainly presented by lowered endothelium activity, reduced nitrogen monoxide production, as well as increased endothelium vasoconstrictor peptide (EVCP).OBJECTIVE: To study the protective role of astragalus polysaccharide on atherosclerosis induced by eudothelium cell injury, which was compared with that of Captopril.DESIGN: Randomly controlled observation.SETTING: Department of Physiology, Hubei College of Traditional Chinese Medicine; Department of Pathophysiology, Medical College of Wuhan University;Department of Surgery,Hetang Hospital of Guangdong Province;Department of Endocrinopathic Sciences,Renmin Hospital,Wuhan University.MATERIALS: The study was carried out at the Organic Function Laboratory of Hubei College of Traditional Chinese Medicine and the Pathophysiological Department of Wuhan Medical University from July 2001 to December 2002. Forty healthy male rabbits provided by the experimental animal center of Wuhan medical university, weighed of 2.4-3.0 kg, were randomly divided into blank group,model control group,astragalus polysaccharide group and captopril group with 10 rabbits in each group.Astragalus polysaccharide was extracted from Shanxi produced astragalus root and made into injection powder that should be freshly composed with physical saline before usage.METHODS: Rabbits in blank group were raised with granular feed, while rabbits in other three groups were given hyperlipid feed (80％ basal feed mixed with 15％ yolk powder, 0.5％ cholesterin and 5％ lard), in addition with venous injection of bovine serum by 1 mL/kg once, atherosclerosis induced endothelium injury model was established on rabbit by hyperlipid feed combined with immune injury. Rabbits in astragalus polysaccharide group received intraperitoneal injection of polysaccharide of 500 mg/kg once a day; which replaced by 5 mg/kg captopril in captopril group that equals to 5 times clinical dosage; While rabbits in blank group and model control group were given the same volume physical saline of 4 mL/kg for totally 50 days. Blood were collected from SVC 24 after the last medication and then rabbits were put to death, the morphological changes of abdominal aorta were observed under optical microscope, meanwhile the changes of serum total cholesterol, triglycerides, nitrogen monoxide, EVCP, superoxide dismutase, malonaldehyde and total antioxidation activity were examined.MAIN OUTCOME MEASURES: ① Morphological changesof abdominal aorta. ② Changes of serum parameters.RESULTS: All 40 rabbits complete the experiment without loss. ① In contrast with model control group group, the total serum total cholesterol and triglycerides in astragalus polysaccharide group and captopril group obviously decreased [(9.33±1.13), (6.60±0.61), (7.09±0.74) mmol/L, P ＜ 0.05;(3.05±0.44), (1.26±0.16), (2.17±0.46) mmol/L, P ＜ 0.01, P＜ 0.05],malonaldehyde and EVCP markedly decreased [(9.98 ± 1.11 ), (7.10 ±0.68),(9.46±1.27) μmol/L, P ＜ 0.01; (741.90±34.98), (632.62±26.95),(600.74±32.59) ng/L, P ＜ 0.01]. ② Comparing to model control group group,the serum nitrogen monoxide and superoxide dismutase were obviously increased in astragalus polysaccharide group and captopril group ·[(11.04±1.68),(19.96±6.05), (18.35±3.52) μmol/L, P ＜ 0.01, P ＜ 0.05; (159.32±5.26),(207.54±16.98), (197.59±28.41) NU/mL, P ＜ 0.0l, P ＜ 0.05], the total antioxidation activity also increased [(23.8±3.5), (34.7±5.6), (30.7±6.8)％,P ＜ 0.01, P ＜ 0.05]. ③ Either the decrement of serum triglycerides, total cholesterol and malonaldehyde or the increment of nitrogen monoxide, superoxide dismutase and total antioxidation activity in astragalus polysaccharide group was greater than captopril group (P ＜ 0.01). ④ Morphological changes of abdominal aorta: The aorta intima was smooth and endothelium cells were continuous with small intervals between cells in blank control group,endothelium cells presented normal configuration without edema;while intima in model control group became thick and upheaved, part of endothelinm cells detached with widened intervals. The media became thickened with leiomyocyte displaying hyperplasic and infiltering into endothelium, foaming cells could also be observed; the aorta intima was smooth and endothelium was closely connected in astragalus polysaccharide group, the hyperplasia of leiomyocyte was not active and foaming cells seldom observed; while in captopril group, the aorta intima was smooth without obvious detachment of endothelium cells and infiltration of leiomyocyte, leiomyocytes were normal and ranked orderly.CONCLUSION:Astragalus polysaccharide could markedly eliminate serum triglycerides, total cholesterol, malonaldehyde and EVCP, thereby alleviate vascular impairment induced by EVCP, meanwhile markedly increased serum nitrogen monoxide, superoxide dismutase and total antioxidation activity, the intima surface of abdominal aorta could be smooth due to the administration of AP, endothelium configuration would be basically complete, implying that it has better antioxidation property and protective role for endothelium cells.

Mitophagy is an essential intracellular process that eliminates dysfunctional mitochondria and maintains cellular homeostasis. Mitophagy is regulated by the post-translational modification of mitophagy receptors. Fun14 domain-containing protein 1 (FUNDC1) was reported to be a new receptor for hypoxia-induced mitophagy in mammalian cells and interact with microtubule-associated protein light chain 3 beta (LC3B) through its LC3 interaction region (LIR). Moreover, the phosphorylation modification of FUNDC1 affects its binding affinity for LC3B and regulates selective mitophagy. However, the structural basis of this regulation mechanism remains unclear. Here, we present the crystal structure of LC3B in complex with a FUNDC1 LIR peptide phosphorylated at Ser17 (pS), demonstrating the key residues of LC3B for the specific recognition of the phosphorylated or dephosphorylated FUNDC1. Intriguingly, the side chain of LC3B Lys49 shifts remarkably and forms a hydrogen bond and electrostatic interaction with the phosphate group of FUNDC1 pS. Alternatively, phosphorylated Tyr18 (pY) and Ser13 (pS) in FUNDC1 significantly obstruct their interaction with the hydrophobic pocket and Arg10 of LC3B, respectively. Structural observations are further validated by mutation and isothermal titration calorimetry (ITC) assays. Therefore, our structural and biochemical results reveal a working model for the specific recognition of FUNDC1 by LC3B and imply that the reversible phosphorylation modification of mitophagy receptors may be a switch for selective mitophagy.
Crystallography, X-Ray ; Membrane Proteins ; chemistry ; metabolism ; Microtubule-Associated Proteins ; chemistry ; metabolism ; Mitochondrial Degradation ; Mitochondrial Proteins ; chemistry ; metabolism ; Peptides ; chemistry ; metabolism ; Phosphorylation ; Protein Structure, Quaternary