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ObjectiveTo observe the effects of five Huoxue Huayu prescriptions on blood lipid metabolism， liver tissue and adenosine triphosphate binding cassette transporter A1 （ABCA1） and peroxisome proliferator-activated receptor γ（PPARγ） expression in New Zealand rabbits with blood stasis syndrome， and to compare their differences in order to provide laboratory evidence for clinical selection of prescriptions and drugs. MethodSeventy New Zealand rabbits were randomly divided into normal group （n=10） and model group （n=60）. The blood stasis syndrome was modeled by the method of starvation+high-fat feed+adrenaline. After the models were successfully established， they were randomly divided into Xuefu Zhuyutang（3.55 g·kg-1·d-1） group， Danshenyin（1.962 g·kg-1·d-1） group， Shixiaosan（0.56 g·kg-1·d-1） group， Huoluo Xiaolingdan（2.80 g·kg-1·d-1） group， and Taohong Siwutang（2.66 g·kg-1·d-1） group， and were given corresponding compound prescriptions by gavage. The normal group and model group were given the same dose of distilled water. After the treatment of 30 consecutive days， blood was taken from the abdominal aorta to detect the content of total cholesterol （TC）， triglycerides （TG）， high-density lipoprotein cholesterol （HDL-C）， low-density lipoprotein cholesterol（LDL-C） and apolipoprotein A1 （ApoA1）. Hematoxylin-eosin（HE） staining was used to observe the changes in liver tissue. Real-time polymerase chain reaction （Real-time PCR） and Western blot were used to detect the mRNA and protein expression of ABCA1 and PPARγ in liver tissue， respectively. ResultCompared with the conditions in the normal group， increased mRNA and protein levels of HDL-C， LDL-C， TG， TC， and PPARγ （P<0.01）， decreased ApoA1 level （P<0.05） and decreased mRNA and protein levels of ABCA1 （P<0.01） were found in the model group. Compared with the conditions in the model group， the HDL-C level in the five Huoxue Huayu prescriptions was lowered （P<0.05）， and lowered TG level in Xuefu Zhuyutang group and Shixiaosan group （P<0.05）， decreased LDL-C and TC levels in Shixiaosan group （P<0.05）， and increased ApoA1 level in the Huoluo Xiaolingdan group （P<0.01） and Taohong Siwutang group （P<0.05） were observed. Furthermore， the mRNA and protein levels of ABCA1 in Xuefu Zhuyutang group， Shixiaosan group， Huoluo Xiaolingdan group and Taohong Siwutang group were elevated （P<0.05， P<0.01）， and the elevated levels were higher than that of Danshenyin group （P<0.05）. The mRNA level of PPARγ in the five Huoxue Huayu prescriptions was reduced （P<0.01）， and its protein level was also decreased in Xuefu Zhuyutang group， Shixiaosan group， Huoluo Xiaolingdan group and Taohong Siwutang group （P<0.01）. ConclusionThe five Huoxue Huayu prescriptions had a certain therapeutic effect on dyslipidemia，which might be achieved by up-regulating the expression of ApoA1 and ABCA1 to promote the production of HDL-C and strengthen the excretion of dysfunctional HDL-C. And Xuefu Zhuyutang had the optimal effect in lowering lipid.
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OBJECTIVE: To investigate the effect of liver X receptor(LXR)-adenosine triphosphate-binding cassette transporter A1(ABCA1) signaling pathway on the free silica(SiO_2)-induced foaming of macrophages. METHODS: Human histiocytic lymphoma U937 cells were induced to differentiate into macrophages by phorbol myristate acetate. The macrophages at logarithmic growth phase were randomly divided into 4 groups: the cells in the control group received no treatment, the cells in the SiO_2 stimulation group were stimulated with SiO_2 suspension at a dose of 50 mg/L, and the cells in the oxidized low-density lipoprotein(ox-LDL) group were treated with ox-LDL at the dosed 50 mg/L, the cells in the combination group were simultaneously stimulated with SiO_2 suspension and ox-LDL at a dose of 50 mg/L. Cells were collected after 48 hours of culture. Macrophage foaming was observed by oil red O staining. The levels of total cholesterol(TC), free cholesterol(FC), cholesteryl ester(CE) and CE specific gravity(CE%) in macrophages were detected using a microplate reader. The expression of LXR and ABCA1 was detected using Western blotting. RESULTS: The results of the oil red O staining showed that all the macrophages in the SiO_2 stimulation group, ox-LDL group and the combination group had foaming changes. The degree of foaming in the macrophages in the combination group was higher than that in the other two groups. The levels of TC, FC, CE and CE% in macrophages increased(P<0.05), and the protein relative expression of LXR and ABCA1 decreased(P<0.05), in SiO_2 stimulation group, ox-LDL group and combination group compared with the control group. The macrophages in the combination group were transformed into foam cells. The levels of TC, FC, CE and CE% in macrophages of the combination group increased(P<0.05), and the protein relative expression of LXR and ABCA1 decreased(P<0.05), compared with the SiO_2 stimulation group and the ox-LDL group. CONCLUSION:sFree SiO_2 can induce foaming of macrophages, and ox-LDL in combination with SiO_2 has a synergistic effect on the formation of foaming of macrophages.The process of macrophage foaming may be achieved by inhibiting the LXR-ABCA1 signaling pathway.
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Objective: To investigate the underlying mechanisms and intracellular signaling of up-regulating adenosine triphosphate binding cassette transporter A1 (ABCA1) by interleukin-17A (IL-17) in macrophages. Methods: Mouse RAW264.7 cells were treated with 20ng/mL of IL-17A. The protein expressions of ABCA1 and p-p38MAPK were detected using Western blot. The ubiquitination level of ABCA1 was detected using Co-immunoprecipitation. Results: IL-17A increased the expression of ABCA1 at the protein level, but not at the mRNA level. IL-17A reduced the degradation of ABCA1 protein. IL-17A attenuated binding of ABCA1 to ubiquitin. SB203580, p38MAPK inhibitor, reversed the decrease of ubiquitination and increased expression of ABCA1 protein induced by IL-17A in macrophages. Conclusion: IL-17A increases the expression of ABCA1 protein by inhibiting its degradation through p38MAPK pathway in macrophages.
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AIM:To examine the effects of hypoxia on sodium-hydrogen exchange 1 (NHE1) expression, in-tracellular Ca2+concentration ( [ Ca2+] i ) and calpain activity, and to explore the effect of amiloride on adenosine triphos-phate-binding cassette transporter A1 (ABCA1) degradation and its calpain-related mechanism.METHODS:RAW264.7 cells were exposed to hypoxia for 0 h, 12 h, 24 h and 48 h.The cell viability was measured by MTT assay and the expres-sion of NHE1 at mRNA and protein levels was detected by real-time PCR and Western blot.[ Ca2+] i was analyzed by flow cytometry.Calpain activity was assessed by the method of Suc-LLVY-aminoluciferin.Furthermore, the protein levels of ABCA1 in the RAW264.7 cells exposed to hypoxia for 24 h were determined after 6 h or 12 h treatment with NHE1 inhibi-tor amiloride in the presence of cycloheximide.ABCA1 protein levels and calpain activity were detected after 12 h incuba-tion with calpain inhibitor ALLN or intracellular calcium-chelating agent BAPTA.RESULTS: Hypoxia inhibited the cell viability in a time-dependent manner.Hypoxia up-regulated the mRNA and protein expression of NHE1, and increased [ Ca2+] i and calpain activity.Hypoxia increased the degradation of ABCA1 and amiloride slowed down the ABCA1 degra-dation.ALLN or BAPTA increased ABCA1 protein level and decreased calpain activity.CONCLUSION:NHE1 inhibitor amiloride attenuates the calpain-mediated degradation of ABCA1, indicating that hypoxia-induced NHE1 might, at least in part, participate in the ABCA1 degradation.
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microRNAs (miRNAs or miRs) are small non-coding RNAs that are involved in post-transcriptional regulation of their target genes in a sequence-specific manner. Emerging evidence demonstrates that miRNAs are critical regulators of lipid synthesis, fatty acid oxidation and lipoprotein formation and secretion. Dysregulation of miRNAs disrupts gene regulatory network, leading to metabolic syndrome and its related diseases. In this review, we introduced epigenetic and transcriptional regulation of miRNAs expression. We emphasized on several representative miRNAs that are functionally involved into lipid metabolism, including miR-33/33(⁎), miR122, miR27a/b, miR378/378(⁎), miR-34a and miR-21. Understanding the function of miRNAs in lipid homeostasis may provide potential therapeutic strategies for fatty liver disease.