Effects of Shenling Baizhu powder on endoplasmic reticulum stress related signaling pathway in liver tissues of nonalcoholic fatty liver disease rats

Background:According to our previous studies,Shenling Baizhu powder has an excellent preventive and therapeutic effect on nonalcoholic fatty liver disease,but the prevention mechanism is still not clear.In this study,we intended to explore the effects of Shenling Baizhu powder on the endoplasmic reticulum stress related signaling pathway in nonalcoholic fatty liver disease rats’liver tissues.Methods:After 16 weeks,the levels of serum total cholesterol,triglyceride,high-density lipoprotein cholesterol,low-density lipoprotein cholesterol,alanine transaminase and aspartate transaminase were evaluated by an automatic biochemical analyzer,and the levels of serum free fatty acid and hepatic total cholesterol and triglyceride were evaluated by commercial kits.Then,histological changes of the liver were observed by hematoxylin and eosin and oil red-O staining.Protein expression related to the liver unfolded protein response signalling pathway was assessed using Western blot analysis.Results:The results showed that Shenling Baizhu powder supplementation reduced serum total cholesterol,triglyceride,free fatty acid,alanine transaminase,and aspartate transaminase(P<0.05 or P<0.01),as well as the levels of hepatic total cholesterol and triglyceride(P<0.01).Pathological examination showed that Shenling Baizhu powder improved hepatic steatosis and lipid accumulation.The results of biochemical parameters and histological changes indicated that Shenling Baizhu powder administration exerted protective effects against nonalcoholic fatty liver disease.In addition,Shenling Baizhu powder decreased the protein expression levels of binding immunoglobulin protein,activating transcription factor 6,phosphorylation of eukaryotic initiation factor 2 alpha,protein kinase RNA-like endoplasmic reticulum kinase and X-box binding protein 1s in the liver(P<0.05 or P<0.01).Conclusion:Shenling Baizhu powder can ameliorate high-fat diet-induced liver lipid metabolism disorder in nonalcoholic fatty liver disease rats.The mechanisms may be related to the inhibition of the expression of proteins related to unfolded protein response signaling pathways in endoplasmic reticulum stress.

Endoplasmic Reticulum Stress Induces the Early Appearance of Pro-apoptotic and Anti-apoptotic Proteins in Neurons of Five Familial Alzheimer＇s Disease Mice

Background： Amyloid β （Aβ） deposits and the endoplasmic reticulum stress （ERS） are both well established in the development and progression of Alzheimer＇s disease （AD）. However, the mechanism and role of Aβ-induced ERS in AD-associated pathological progression remain to be elucidated. Methods： The five familial AD （5×FAD） mice and wild-type （WT） mice aged 2, 7, and 12 months were used in the present study. Monis water maze test was used to evaluate their cognitive performance, lmmunofluorescence and Western blot analyses were used to examine the dynamic changes of pro-apoptotic （CCAAT/enhancer-binding protein homologous protein [CHOP] and cleaved caspase-12） and anti-apoptotic factors （chaperone glucose-regulated protein [GRP] 78 and endoplasmic reticulum-associated protein degradation-associated ubiquitin ligase synovial apoptosis inhibitor 1 [SYVN 1]） in the ERS-associated unfolded protein response （UPR） pathway. Results： Compared with age-matched WT mice, 5 xFAD mice showed higher cleaved caspase-3, lower neuron-positive staining at the age of 12 months, but earlier cognitive deficit at the age of 7 months （all P 〈 0.05）. Interestingly, for 2-month-old 5×FAD mice, the related proteins involved in the ERS-associated UPR pathway, including CHOP, cleaved caspase-12, GRP 78, and SYVN 1, were significantly increased when compared with those in age-matched WT mice （all P 〈 0.05）. Moreover, ERS occurred mainly in neurons, not in astrocytes. Conclusions： These findings suggest that compared with those of age-matched WT mice, ERS-associated pro-apoptotic and anti-apoptotic proteins are upregulated in 2-month-old 5×FAD mice, consistent with intracellular Aβ aggregation in neurons.

Common variants in PERK, JNK, BIP and XBP1 genes are associated with the risk of prediabetes or diabetes-related phenotypes in a Chinese population

Background Prediabetes is an early stage of β-cell dysfunction presenting as insulin resistance.Evidences suggest that endoplasmic reticulum （ER） stress is involved in the pathogenesis of type 2 diabetes mellitus and prediabetes.In a Chinese population with prediabetes,we investigated single nucleotide polymorphisms （SNPs） in the genes of PERK,JNK,XBP1,BIP and CHOP which encode molecular proteins involved in ER stress pathways.Methods Nine SNPs at the PERK,JNK,XBP1,BIP and CHOP loci were genotyped by mass spectrometry in 1 448 unrelated individuals.By using a 75 g oral glucose tolerance test （OGTT）,828 subjects were diagnosed as prediabetes and 620 subjects aged 55 years and over as normal controls based on WHO diagnostic criteria （1999） for diabetes mellitus.Results The allele C of SNP rs867529 at PERK locus was a risk factor for prediabetes,with the carriers of C allele genotype at a higher risk of prediabetes compared to non-carriers （OR=1.279,95％ CI：1.013-1.614,P=0.039,after adjustment for age,sex and body mass index （BMI）.The SNPs rs6750998 at PERK locus was associated with homeostasis model assessments of insulin resistance （HOMA-IR） （P=0.019）,and rs17037621 with BMI （P=0.044）.The allele G of SNP rs10986663 in BIP gene was associated with a decreased risk of prediabetes （OR=0.699,95％ CI：0.539-0.907,P=0.007）.The SNP rs2076431 in JNK gene was associated with fasting plasma glucose levels （P=0.006） and waist-hip ratios （P=0.019）.The SNP rs2239815 in XBP1 gene was associated with 2-hour plasma glucose levels after 75 g oral glucose load （P=0.048） in the observed population.Conclusion Common variants at PERK and BIP loci contributed to the risk of prediabetes,and the genetic variations in JNK and XBP1 genes are associated with diabetes-related clinical parameters in this Chinese population.