Mechanisms involved in ceramide-induced cell cycle arrest in human hepatocarcinoma cells

AIM： To investigate the effect of ceramide on the cell cycle in human hepatocarcinoma Bel7402 cells. Possible molecular mechanisms were explored. METHODS： [3- （4, 5）-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide （MTT） assay, plasmid transfection, reporter assay, FACS and Western blotting analyses were employed to investigate the effect and the related molecular mechanisms of C2-ceramide on the cell cycle of Bel7402 cells. RESULTS： C2-ceramide was found to inhibit the growth of Bel7402 cells by indudng cell cycle arrest. During the process, the expression of p21 protein increased, while that of cyclinD1, phospho-ERKl/2 and c-myc decreased. Furthermore, the level of CDK7 was downregulated, while the transcriptional activity of PPARy was upregulated. Addition of GW9662, which is a PPARy specific antagonist, could reserve the modulation action on CDK7. CONCLUSION： Our results support the hypothesis that cell cycle arrest induced by C2-ceramide may be mediated via accumulation of p21 and reduction of cyclinD1 and CDK7, at least partly, through PPARy activation. The ERK signaling pathway was involved in this process.

Is KPNB3 Locus Associated With Schizophrenia?

Objective To reconfirm the association of KPNB3 with schizophrenia in Chinese population. Methods Two single nucleotide polymorphisms （SNPs）, rs2588014 and rs626716 trios consisting of fathers, mothers, and affected offsprings at the KPNB3 locus, were genotyped in 304 Chinese Han family with schizophrenia. These 2 SNPs were detected by PCR-based restriction fragment length polymorphism （RFLP） analysis. The Hardy-Weinberg equilibrium for genotypic distributions was estimated by the goodness-of-fit test. The UNPHASED program was used to perform transmission disequilibrium test （TDT）, haplotype analysis, and pair-wise measure of linkage disequilibrium （LD） between these 2 SNPs. Results The genotypic distributions of both rs2588014 and rs626716 were in the Hardy-Weinberg equilibrium （P〉0.05）. The TDT revealed allelic association with rs626716 （χ^2 =9.31, P=0.0023） but not with rs2588014 （χ^2 =3.44, P=0.064）. The global P-value was 0.0099 for 100 permutations. The haplotype analysis also showed a disease association （χ^2 =25.97, df=3, P=0.0000097）. Conclusion The present study provides further evidence in support of the KPNB3 association with schizophrenia in Chinese population.

Genetic association between the polymorphism of cytosolicPLA2 gene family and schizophrenia

Abnormal phospholipid metabolism in the brain plays an important role in neuropsychiatric diseases.Phospholipase A2(PLA2)is a crucial element for normal neuro-physiological function.This study aims to investi-gate the genetic association between the polymorphism of cytosolic phospholipase A2(cPLA2)family genes and schizophrenia among Han Chinese in the northern part of China.The polymerase chain reaction-based ligase detec-tion reaction(PCR-LDR)was applied to detect the genotype ten single nucleotide polymorphisms(SNPs)of cPLA2 family genes among 201 pedigrees consisting of fathers,mothers and affected offsprings with schizophre-nia.The pedigrees were collected from 2000 to 2006.Haplotype relative risk(HRR)test,transmission disequili-brium test(TDT),haplotype transmission analysis and multiple locus analysis were conducted to analyze the genotyping data.The genotypic frequency of cPLA2 gene did not deviate from Hardy-Weinberg equilibrium either in case or control group.HRR and TDT showed that the ten SNPs were not associated with schizophrenia(P>0.05).Analysis for haplotype transmission showed that no haplotype system was associated with schizophrenia(P>0.05).The conditioning on allele(COA)and conditioning on gene(COG)tests showed disease associations with the haplotype of rs2162886-rs1668589,rs891014-rs1668589 and rs2307279-rs7542180(χ2=6.913,P=0.032;χ2=8.393,P=0.015;χ2=8.447,P=0.038).Our data suggest that many loci in the cPLA2 family genes may be associated with schizophrenia.