Linkage Disequilibrium between LDLR rs688 and AvaII Genes and its Significant Association with Ischemic Stroke.

BACKGROUND: To analyze the polymorphism distribution of low density lipoprotein receptor rs688, AvaII, NcoI gene in ischemic stroke, and explore the linkage disequilibrium among them. The correlation between the linkage disequilibrium and ischemic stroke was further analyzed. METHODS: The levels of serum lipid (triglyceride, cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein A1, apolipoprotein B) and rs688, AvaII, NcoI polymorphism of low density lipoprotein receptor gene were tested in patients with ischemic stroke (n = 140), healthy control (n = 129) and patients with other cerebrovascular diseases (n = 122). Chi-square test was used to compare the gene frequency and allele frequency of each group. Both the linkage disequilibrium of the three genes and the alleles correlated with ischemic stroke were analyzed. The correlation of linkage disequilibrium gene and ischemic stroke was analyzed with logistic binary regression. RESULTS: In the ischemic stroke group, significant difference was observed in frequencies and allelic frequencies of low density lipoprotein receptor (LDLR) rs688 and AvaII. No difference of NcoI was found. Linkage disequilibrium was found for rs688 and AvaII (D' = 0.927, R2 = 0.509). Allelic genes correlate with ischemic stroke included T of rs688 (X2 = 46.105, p < 0.001) and C of AvaII (X2 = 20.436, p < 0.001). CONCLUSIONS: Linkage disequilibrium existed between LDLR rs688 and AvaII genes. With the wild type gene (WT) (rs688/AvaII: CC/TT) as reference, rs688/AvaII: CT/TC, CT/CC and TT/CC increased the risk of ischemic stroke, which might be a genetic marker used for the screen of high-risk population contributing to the prevention of the disease.

Elevated sdLDL level and LDLR rs688 C>T mutation are independent risk factors for ischemic stroke.

PURPOSE: To investigate the level of sdLDL and the frequency of LDLR rs688 polymorphisms, as well as the correspondence between them, and to analyze the risk factors for stroke. METHODS: Between March 2019 and November 2019, 232 patients diagnosed with stroke and 96 health volunteers were enrolled in Quanzhou First Hospital. Subjects were divided into control group, ischemic stroke group (n=120) and hemorrhagic stroke group (n=112). The level of sdLDL and the genotypes and allele frequencies of LDLR rs688 were compared between groups, the correspondence was analyzed with Spearman method. Risk factors were analyzed with Binary logistic regression. RESULTS: The level of sdLDL was highest in ischemic group, followed by hemorrhagic stroke group and lowest control group. The differences of genotypes and allele frequencies of LDLR rs688 were significant in ischemic stroke group (p=0.0000 and 0.0000 respectively), while were not significant in hemorrhagic group (p=0.184 and .0137). There was no obvious correlation between the level of sdLDL and LDLR rs688 genotype by Spearman analysis (p=0.116). CONCLUSION: Elevated sdLDL level and the C>T mutation of LDLR rs688 are independent risk factors for ischemic stroke, while they are not correlative to hemorrhagic stroke. The surveillance and regulatory of sdLDL level, the detection of LDLR rs688 gene polymorphisms may contribute to the prevention of ischemic stroke.

Downregulation of SUMO2 inhibits hepatocellular carcinoma cell proliferation, migration and invasion.

This study aimed to evaluate the prognostic value and biological function of small ubiquitin-like modifier 2 (SUMO2) in hepatocellular carcinoma (HCC). SUMO2 expression in HCC tissues was markedly higher than that in normal liver tissues, and patients with high SUMO2 expression had significantly shorter median overall survival than those with low SUMO2 expression. Furthermore, SUMO2 expression was closely correlated with lymph node metastasis and vascular invasion and was a predictor of poor prognosis. The knockdown of SUMO2 in two HCC cell lines (SMMC-7721 and Bel-7404) dramatically suppressed their proliferation, migration and invasion. Western blot analysis showed that the downregulation of SUMO2 significantly reduced the expression of Ki-67, matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) in SMMC-7721 and Bel-7404 cells. Similarly, quantitative reverse transcription-PCR revealed consistently decreased expression of MMP-9 and VEGF. Our data suggest that SUMO2 promotes proliferation, migration and invasion of HCC cells via mechanisms involving MMP-9 and VEGF. Therefore, SUMO2 may be a prognostic factor and a promising therapeutic target for patients with HCC.

Inhibitory effect of PXR on ammonia-induced hepatocyte autophagy via P53.

Pregnane X Receptor (PXR), a nuclear receptor transcription factor, participates in a wide range of physiological activities, but the regulation of ammonia-induced hepatocyte autophagy by PXR is not yet clear. In this study, the levels of down-regulated LC3B-II and up-regulated SQSTM1 were found in ammonia-induced PXR-overexpressing (PXR+) liver cells, but the opposite appeared in PXR-knockdown (PXR-) liver cells. Rifampicin, a PXR-activating agent, elicits a similar effect as PXR+ cells. The mechanism analysis reveals that the levels of the energy-sensitive molecule AMPKß1 and phosphorylated AMPKß1 (p-AMPKß1) in PXR- cells are higher than those in control cells, whereas the levels of this molecule in PXR+ cells are lower than those in control cells. Two active sites that bind to P53 exist in -253 to -19 at the promoter region of AMPKß1, and their mutation can reduce the transactivating effect of AMPKß1 that P53 relies on. A protein interaction also exists between PXR and P53. These findings indicate that PXR is a factor interfering the formation of ammonia-induced hepatocyte autophagy, and its inhibitory effect is achieved when P53 downregulates the expression and activity of AMPKß1. This conclusion provides an appropriate clinical explanation for hepatotoxicity caused by the inhibitory effect of PXR-activating agent on hepatocyte autophagy.

Optimizing combination of liver-enriched transcription factors and nuclear receptors simultaneously favors ammonia and drug metabolism in liver cells.

The HepG2 cell line is widely used in studying liver diseases because of its immortalization, but its clinical application is limited by its low expression of the urea synthesis key enzymes and cytochromes P450 (CYPs). On the basis of our previous work, we investigated the transcriptional regulation of arginase 1 (Arg1) and ornithine transcarbamylase (OTC) in HepG2 cells. We also screened for the optimal combination of liver enrichment transcription factors (LETFs) and xenobiotic nuclear receptors that can promote the expression of key urea synthases and five major CYPs in HepG2 cells. Thus, recombinant HepG2 cells were established. Results showed that C/EBPß, not C/EBPα, could upregulate expression of Arg1 and PGC1α and HNF4α cooperatively regulate the expression of OTC. The two optimal combinations C/EBPß+HNF4α+HNF6+PXR and C/EBPß+HNF4α+HNF6+CAR were selected. Compared with the control cells, the recombinant HepG2 cells modified by the two optimal combinations exhibited enhanced ammonia metabolism and CYP enzyme activity. Moreover, the HepG2/(C/EBPß+HNF4α+HNF6+PXR) cells more strongly reduced ammonia than any other combination tested in this study. The present work indicated that optimizing the combination of transcription factors will simultaneously promote hepatocyte ammonia metabolism and drug metabolism. The recombinant HepG2 liver cell line constructed by the optimal combination provided an improved alternative means for bioartificial liver applications and drug toxicity testing.