Molecular docking in Nεcarboxymethyl lysine targeting scavenger receptor CD36 / 中华老年心脑血管病杂志

Objective To study whether Nεcarboxymethyl lysine(CML)can form a good molecular docking with the scavenger receptor CD36and induce a stable interaction.Methods The interaction between CML and CD36was studied by co-immunoprecipitation.The binding mode and affinity of CD36to CML were tested using AutoDock 4.2,iBabel and XQuartz-2.7.7software respectively. Results Co-immunoprecipitation showed that anti-CD36antibody magnetic bead could precipitate CD36from the total protein in RAW264.7cells and anti-CML could detect CD36 binding CML.CD36had a good molecular docking with CML,CD36and CML interacted stably with each other.The affinity of CML to 4Q4Bprotein structure of CD4extracellular domain was -29.62kJ/mol.ARG82,ASN71and THR70were the products of amino acid receptor interaction. Further docking analysis showed that CML could form 3interacting hydrogen bonds with 4Q4B,and the docking prediction inhibition constant was 6.92with a root mean square deviation of 2.54.Conclusion A good molecular docking between CML and 4Q4Bprotein structure of CD36extracellular domain can induce a stable interaction between CML and CD36.Hydrogen bonding is the main interaction mode.

PCSK9 Induces CD36 Degradation and Affects Long-Chain Fatty Acid Uptake and Triglyceride Metabolism in Adipocytes and in Mouse Liver.

OBJECTIVE: Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes the degradation of the low-density lipoprotein receptor thereby elevating plasma low-density lipoprotein cholesterol levels and the risk of coronary heart disease. Thus, the use of PCSK9 inhibitors holds great promise to prevent heart disease. Previous work found that PCSK9 is involved in triglyceride metabolism, independently of its action on low-density lipoprotein receptor, and that other yet unidentified receptors could mediate this effect. Therefore, we assessed whether PCSK9 enhances the degradation of CD36, a major receptor involved in transport of long-chain fatty acids and triglyceride storage. APPROACH AND RESULTS: Overexpressed or recombinant PCSK9 induced CD36 degradation in cell lines and primary adipocytes and reduced the uptake of the palmitate analog Bodipy FL C16 and oxidized low-density lipoprotein in 3T3-L1 adipocytes and hepatic HepG2 cells, respectively. Surface plasmon resonance, coimmunoprecipitation, confocal immunofluorescence microscopy, and protein degradation pathway inhibitors revealed that PCSK9 directly interacts with CD36 and targets the receptor to lysosomes through a mechanism involving the proteasome. Importantly, the level of CD36 protein was increased by >3-fold upon small interfering RNA knockdown of endogenous PCSK9 in hepatic cells and similarly increased in the liver and visceral adipose tissue of Pcsk9(-/-) mice. In Pcsk9(-/-) mice, increased hepatic CD36 was correlated with an amplified uptake of fatty acid and accumulation of triglycerides and lipid droplets. CONCLUSIONS: Our results demonstrate an important role of PCSK9 in modulating the function of CD36 and triglyceride metabolism. PCSK9-mediated CD36 degradation may serve to limit fatty acid uptake and triglyceride accumulation in tissues, such as the liver.

Receptor-Mediated Mechanism Controlling Tissue Levels of Bioactive Lipid Oxidation Products.

RATIONALE: Oxidative stress is an important contributing factor in several human pathologies ranging from atherosclerosis to cancer progression; however, the mechanisms underlying tissue protection from oxidation products are poorly understood. Oxidation of membrane phospholipids, containing the polyunsaturated fatty acid docosahexaenoic acid, results in the accumulation of an end product, 2-(ω-carboxyethyl)pyrrole (CEP), which was shown to have proangiogenic and proinflammatory functions. Although CEP is continuously accumulated during chronic processes, such as tumor progression and atherosclerosis, its level during wound healing return to normal when the wound is healed, suggesting the existence of a specific clearance mechanism. OBJECTIVE: To identify the cellular and molecular mechanism for CEP clearance. METHODS AND RESULTS: Here, we show that macrophages are able to bind, scavenge, and metabolize carboxyethylpyrrole derivatives of proteins but not structurally similar ethylpyrrole derivatives, demonstrating the high specificity of the process. F4/80(hi) and M2-skewed macrophages are much more efficient at CEP binding and scavenging compared with F4/80(lo) and M1-skewed macrophages. Depletion of macrophages leads to increased CEP accumulation in vivo. CEP binding and clearance are dependent on 2 receptors expressed by macrophages, CD36 and toll-like receptor 2. Although knockout of each individual receptor results in diminished CEP clearance, the lack of both receptors almost completely abrogates macrophages' ability to scavenge CEP derivatives of proteins. CONCLUSIONS: Our study demonstrates the mechanisms of recognition, scavenging, and clearance of pathophysiologically active products of lipid oxidation in vivo, thereby contributing to tissue protection against products of oxidative stress.

Development of a duplex fluorescence RT-PCR assay for identifying SRBⅠgene knockout mice / 天津医药

Objective To develop a duplex fluorescence RT-PCR assay for detection of scavenger receptor class B, typeⅠ(SRBⅠ) knockout mice. Methods Primers and probes were designed according to knockout region of SRBⅠgene and related substituted sequence. DNA samples were extracted from tails of mice and performed amplification using real-time PCR. SRBⅠgenotypes of mice were analyzed according to amplification curves of FAM and CY5 channels. Finally, the sensitivity of the method was detected and the accuracy was verified by the direct sequencing. Results The homozygous SRBⅠwild genotype showed an amplification curve only in FAM channel. When the homozygous SRBⅠknockout genotype was present, the typical S amplification curve appeared only in the CY5 channel. Heterozygous genotype showed two typical S amplification curves in both FAM and CY5 channels, respectively. The results showed that the sensitivity reached 4×101 copies/μL, and there was complete concordance between this method and direct DNA sequencing. Conclusion The new method is simple, rapid and accurate, which is suitable for genotyping SRBⅠknockout mice.

CD36 expression in monocytes and ankylosing spondylitis / 中国组织工程研究

BACKGROUND:Ankylosing spondylitis is an autoimmune disease involved in chronic systemic inflammation. Tumor necrosis factor and interleukin-6 levels increased in patients with ankylosing spondylitis. Inflammatory factors such as tumor necrosis factor and interleukin-6 can suppress CD36 expression in monocytes. OBJECTIVE: To analyze the correlation between CD36 expression in monocytes and ankylosing spondylitis. METHODS:A total of 84 newly diagnosed ankylosing spondylitis patients and 111 healthy individuals were included in this study. CD36 expressions in monocytes in ankylosing spondylitis patients and healthy individuals were tested using flow cytometer; meanwhile, biochemistry, immunology, routine blood examination and related inflammatory markers were determined between the two groups. RESULTS AND CONCLUSION:Results of baseline data in both groups demonstrated that CD36 fluorescence intensity in monocytes was significantly lower in patients with ankylosing spondylitis compared with healthy controls (P < 0.01). CD36 fluorescence intensity in monocytes was negatively correlated with C-reactive protein, erythrocyte sedimentation, interleukin-6 and tumor necrosis factor. In addition, CD36 fluorescence intensity in monocytes was negatively correlated with BASDAI score. Logistic regression analysis showed that erythrocyte sedimentation, interleukin-6, tumor necrosis factor and CD36 fluorescence intensity in monocytes were associated with ankylosing spondylitis, and risk factors for ankylosing spondylitis (P < 0.05). These findings confirm that inflammatory cytokine in patients with ankylosing spondylitis weakened the expression of CD36 in monocytes. There was a remarkable association between low expression of CD36 expression in monocytes and ankylosing spondylitis. CD36 expression of monocytes clinicaly may be considered to be an effective indicator to evaluate inflammation and disease activity in patients with ankylosing spondylitis.

The effects and underlying mechanism of CD36 in high glucose-induced rat glomerular mesangial cells apoptosis / 中华肾脏病杂志

Objective To investigate the effects and underlying mechanism of the scavenger receptor CD36 in high glucose-induced rat glomerular mesangial cells apoptosis.Methods The mesangial cells of rats were divided into 4 groups:control group (5.6 mmol/L glucose),mannitol group (24.2 mmol/L mannitol+5.6 mmo]/L glucose),high glucose group (30 mmol/L glucose),CD36 monoantibody group (30 mmol/L glucose+CD36 mono-antibody).The intracellular ROS level was detected by confocal microscopy with fluorescent probe CM-H2DCFDA.MDA,GSH-PX,8-OHDGA in cell supernatant were detected.Apoptosis was determined by flow cytometry followed by Annexin V-FITC/PI double stains.The expression of CD36,Bax and Bcl-2 were detected by RT-PCR and Western blotting.Results The expression of CD36 was detected in glomerular mesangial cells.The highest level was found in high glucose group in 24 hours.There was no significant difference found between control group and mannitol group with respect to intracellular ROS generation,MDA,8-OHDG,GSH-PX level,apoptosis rate,expression of CD36,Bax and Bcl-2 (all P ＞ 0.05).There was no significant difference in the expression of CD36 between CD36 mono-antibody group and high glucose group (P ＞ 0.05).Compared to control group,the intracellular ROS generation,MDA and 8-OHDG levels,apoptosis rate,the expression of CD36 and Bax were significantly increased,the GSH-PX level and the expression of Bcl-2 were significantly lower in high glucose group (all P ＜ 0.05).Compared to the high glucose group,the intracellular ROS generation,MDA and 8-OHDG levels,apoptosis rate,the expression of Bax were suppressed but the GSH-PX level and the expression of Bcl-2 increased in CD36 mono-antibody group (all P ＜ 0.05).The intracellular ROS level was positively correlated with apoptosis rate,protein expression of CD36 and Bax gene,was negatively correlated with Bcl-2 protein expression.Conclusions CD36 was involved in the high glucose induced apoptosis of mesangial cells which was potentially mediated by an increased level of oxidative stress.

The Association of CD36 rs7755 and rs3211956 Single Nucleotide Polymorphism with Premature Coronary Heart Disease / 天津医药

Objective To investigate the risk factors of premature atherosclerotic three-vessel coronary artery dis?ease (CHD), and the association between single nucleotide polymorphism (SNP) of CD36 rs3211956, rs7755 and premature CHD. Methods Patient with premature three-vessel coronary artery disease (n=102) which were confirmed by consecutive coronary angiogram (lesion group) and patients (n=72) without CHD (control group) were enrolled in the study. Conventional CHD risk factors were compared between the two groups as well as SNPs of CD36 rs3211956 and rs7755 to disclose inde?pendent risk factor for CHD, which were measured by mass spectrometry. Results Among the conventional CHD risk fac?tors, male, HBP, high LDL-C, low HDL-C were independent risk factors of premature CHD. The GT genotype proportion of rs3211956 was significantly lower (χ2=8.042,P=0.005) in the lesion group than that in control group while the TT genotype proportion is significantly higher in lesion group compared with that in control group (χ2=6.191,P=0.014). Patients with the TT genotype have higher score of BMI than patients with GG or GT genotype (P=0.037). The G allele proportion of rs7755 in the lesion group was significantly higher than control group (χ2=3.636, P=0.047). Patients of the GG genotype have higher scores of BMI but lower level of HDL-C than those with AA or AG genotype (P<0.001). Logistic regression analysis re?vealed that after excluding a number of confounding factors, GG and TT genotype of rs3211956 and GG and GA genotype of rs7755 were respectively one of the independent risk factors for premature CHD. Conclusion The SNPs of CD36 rs7755 and rs3211956 may be the independent risk factors of premature coronary heart disease and might affect the the onset of CHD by affectting BMI and HDL-C.

Effects of High Density Lipoprotein on Expression of Alpha-Granulemembrane Protein (CD62P) and Lysosome Intact Membrane Protein (CD63) on Platelet / 天津医药

Objective To investigate the effects of high density lipoprotein (HDL) on thrombin-activated platelet al-pha-granulemembrane protein (CD62P) and lysosome intact membrane protein (CD63) expressions in vitro. Methods The equivalent volume of washed platelets prepared by hand was preincubated with HDL (1 g/L) in 37℃water for 15 minutes, which was then stimulated with different concentrations of thrombin (0.5 U/mL, 1 U/mL and 10 U/mL) for 10 minutes in wa-ter of 37℃. Meanwhile another three groups of washed platelets were incubated with thrombin (0.5 U/mL, 1 U/mL and 10 U/mL) for 10 minutes, respectively. The CD62P and CD63 from each sample were analyzed by flow cytometry (FCM). Results The CD62P positive rates of HDL-preincubated groups were significantly lower than those of different concentrations of thrombin groups (0.5 U/mL,1 U/mL and 10 U/mL) in the absence of HDL (11.55%± 1.34% vs 18.14%± 1.50%, 17.19%± 0.17% vs 26.24%± 0.77% and 19.79%± 0.32% vs 80.38%± 5.66%,P ＜ 0.01). Meanwhile, The CD63 positive rates of HDL-preincubated groups were also significantly lower than those of thrombin-treated (0.5 U/mL, 1 U/mL and 10 U/mL) groups without HDL, namely,2.92%±0.22%vs 8.09%±0.48%(P＜0.001), 4.20%±0.98%vs 14.15%±1.39%(P＜0.001) and 5.12%± 0.09% vs 24.48%± 1.71%(P ＜ 0.01). Conclusion HDL inhibits the expression of CD62P and CD63 on throm-bin-stimulated platelets in vitro.

CD36 signaling inhibits the translation of heat shock protein 70 induced by oxidized low density lipoprotein through activation of peroxisome proliferators-activated receptor gamma

Oxidized LDL (OxLDL), a causal factor in atherosclerosis, induces the expression of heat shock proteins (Hsp) in a variety of cells. In this study, we investigated the role of CD36, an OxLDL receptor, and peroxisome proliferator-activated receptor gamma (PPAR gamma) in OxLDL-induced Hsp70 expression. Overexpression of dominant-negative forms of CD36 or knockdown of CD36 by siRNA transfection increased OxLDL-induced Hsp70 protein expression in human monocytic U937 cells, suggesting that CD36 signaling inhibits Hsp70 expression. Similar results were obtained by the inhibition of PPAR gamma activity or knockdown of PPAR gamma expression. In contrast, overexpression of CD36, which is induced by treatment of MCF-7 cells with troglitazone, decreased Hsp70 protein expression induced by OxLDL. Interestingly, activation of PPAR gamma through a synthetic ligand, ciglitazone or troglitazone, decreased the expression levels of Hsp70 protein in OxLDL-treated U937 cells. However, major changes in Hsp70 mRNA levels were not observed. Cycloheximide studies demonstrate that troglitazone attenuates Hsp70 translation but not Hsp70 protein stability. PPAR gamma siRNA transfection reversed the inhibitory effects of troglitazone on Hsp70 translation. These results suggest that CD36 signaling may inhibit stress- induced gene expression by suppressing translation via activation of PPAR gamma in monocytes. These findings reveal a new molecular basis for the anti-inflammatory effects of PPAR gamma.

Influences of wild-type p53 gene overexpression on the differentiation, apoptosis and expression of scavenger receptor CD36 in U937 cells / 中国病理生理杂志

AIM: To study the effect of wild-type p53 gene on the differentiation, apoptosis and expression of scavenger receptor CD36 in U937 cells. METHODS: Recombinant adenovirus vector with wild-type p53 gene was constructed and used to transfect U937 cells. With the expression of wild-type p53 gene following adenoviral infection, transfected U937 cells were largely promoted to differentiate into macrophages. RESUITS: Trypanblue-staining test demonstrated that the percentage of positive cells increased from (14.2±5.5)% to (64.6±9.2)% and nitroblue tetrazolium (NBT) reduction test reached similar results (6.3±1.8)% vs (49.7±12.6)%. Furthermore, CD36 mRNA was up-regulated as confirmed by RT-PCR. The increased expression level of CD 36 was also detected by flow cytometry analysis. CONCLUSION: These results suggest that wild-type p53 gene can affect U937 cells differentiation and apoptosis, up-regulate expression of scavenger receptor CD36. It may have a potential significance on atherogenesis.

Inflammatory stress induces insulin resistance in CD36 knockout mice / 第三军医大学学报

Objective To explore whether the inflammatory stress can increase insulin resistance in the CD36 knockout (KO) mice.Methods After the mice were fed a standard chow for 14 weeks,oral glucose tolerance test,insulin release tests,lipids metabolism,SAA,IL-6,TNF-? and hepatic mRNA and proteins expression of mTOR,S6K,IRS-1,pIRS-1,2 were measured.Results Compared with the wide-type,the CD36 KO mice un-inflamed exhibited insulin resistance,and the insulin resistance index was increased[(3.01?1.24) vs (0.81?0.12),P

Effect of activated nuclear receptors PPAR?,LXR?,RXR? on ABC1 and CD36 mRNA expression in THP-1 cell / 中国病理生理杂志

AIM: To study the discrepancy and it's significance of ATP binding cassette transporter(ABC1) and CD36 mRNA expression while activate nuclear receptor RRAR?,LXR?,RXR? in THP-1 cells. METHODS: Cultured THP-1 cells were induced to become macrophage by PMA at concentration of 40 ?g/L for 48 hours. Troglitazone, 22(R)-hydrocholesterol and 9-cis-retinoid acid(9-CRA),activators for PPAR?,LXR? and RXR? respectively, were incubated with the macrophage for 24 hours. Total RNA of these cells were abstracted and reverse transcriptional polymerase chain reaction were performed to inspect the expression of ABC1 and CD36 mRNA in the cells. RESULTS: Expression of ABC1 mRNA increased in the presence of troglitazone, 22(R)-HC and 9-CRA. CD36 mRNA also increased while PPAR? activated. Activation of LXR? showed almost no effect on CD36 mRNA expression, and expression of CD36 mRNA was decreased by 9-CRA.CONCLUSION: The discrepancies existing in ABC1 and CD36 mRNA expression while activate nuclear receptors PPAR?,LXR?,RXR? in THP-1 cells implyed that LXR?,RXR? were better targets to deal with to improve cholesterol reverse transportation.

Correlation between local hormones and CD_(36) transcription level in women with polycystic ovary / 中华妇产科杂志

Objective To detect CD_(36) expressions in polycystic ovary (PCO), and to explore its correlation with local androgen and insulin at transcription level. Methods From August 2002 to February 2003, 12 patients with asymmetric PCO, 15 primary or secondary infertile patients without endocrine disorders and 8 polycystic ovary syndrome (PCOS) with bilateral PCO were recruited. Extraction of follicular fluid and detection of testosterone(T), dehydroepiandrosterone sulfate (DHEAS), insulin (INS) and androstenedione (A_2) were performed. Relative CD_(36) mRNA expression level of human ovarian inner thecal cells was analyzed by auto image analysis system (IAS) after RT-PCR. Results The level of CD_(36) mRNA expression in thecal cells was 0.24?0.07 in polycystic ovary of PCO group and 0.21?0.05 in bilateral ovaries of PCOS group, respectively, which were significantly lower than 0.83?0.13 in normal ovaries (P

Effects of extract of gingko biloba on the lipid metabolism and the function of macrophages from diabetic rats / 中国病理生理杂志

AIM: To study effect of extract of ginkgo biloba(EGb) on the lipid metabolism and the function of macrophages from diabetic rats.METHODS: Sprague-Dauley rats were divided into four groups: normal control group,high-fat group,diabetic group and EGb treatment group.At the end of experiment,the rats were sacrificed,the blood glucose,blood insulin and serum lipid were measured.The activity of superoxide dismutase(SOD),content of malondialdehyde(MDA),nitric oxide(NO) in alveolar macrophages(AM) and peritoneal macrophages(PM) were assayed.In addition,peroxisome proliferator activated receptor ?(PPAR?),CD36 mRNA expression in AM was measured by RT-PCR.RESULTS: The concentration of the blood glucose,blood insulin and total cholesterol(TC),total triglycerides(TG),low-density lipoprotein-cholesterol(LDL-C) in blood increased significantly in type 2 diabetic group.The supplement of EGb decreased blood glucose,blood insulin and TC,TG,LDL-C levels.The activity of SOD decreased,while the content of NO,MDA increased in the diabetic macrophages,the activity of SOD became increased,but the content of NO and MDA decreased in EGb-treated group.The mRNA expression level of CD36 and PPAR? in alveolar macrophages from diabetic group increased,while expression level of CD36 and PPAR? mRNA in EGb treated rats continued to rise.CONCLUSIONS: EGb corrected insulin resistance and ameliorated disturbance of lipid metabolism caused by type2 diabetes in rats.Adjustment of PPAR? and CD36 mRNA expression of as well as reduction of lipid peroxidation and NO level may be involved in this process.