Smek1 deficiency exacerbates experimental autoimmune encephalomyelitis by activating proinflammatory microglia and suppressing the IDO1-AhR pathway.

BACKGROUND: Experimental autoimmune encephalomyelitis (EAE) is an animal disease model of multiple sclerosis (MS) that involves the immune system and central nervous system (CNS). However, it is unclear how genetic predispositions promote neuroinflammation in MS and EAE. Here, we investigated how partial loss-of-function of suppressor of MEK1 (SMEK1), a regulatory subunit of protein phosphatase 4, facilitates the onset of MS and EAE. METHODS: C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG35-55) to establish the EAE model. Clinical signs were recorded and pathogenesis was investigated after immunization. CNS tissues were analyzed by immunostaining, quantitative polymerase chain reaction (qPCR), western blot analysis, and enzyme-linked immunosorbent assay (ELISA). Single-cell analysis was carried out in the cortices and hippocampus. Splenic and lymph node cells were evaluated with flow cytometry, qPCR, and western blot analysis. RESULTS: Here, we showed that partial Smek1 deficiency caused more severe symptoms in the EAE model than in controls by activating myeloid cells and that Smek1 was required for maintaining immunosuppressive function by modulating the indoleamine 2,3-dioxygenase (IDO1)-aryl hydrocarbon receptor (AhR) pathway. Single-cell sequencing and an in vitro study showed that Smek1-deficient microglia and macrophages were preactivated at steady state. After MOG35-55 immunization, microglia and macrophages underwent hyperactivation and produced increased IL-1ß in Smek1-/+ mice at the peak stage. Moreover, dysfunction of the IDO1-AhR pathway resulted from the reduction of interferon γ (IFN-γ), enhanced antigen presentation ability, and inhibition of anti-inflammatory processes in Smek1-/+ EAE mice. CONCLUSIONS: The present study suggests a protective role of Smek1 in autoimmune demyelination pathogenesis via immune suppression and inflammation regulation in both the immune system and the central nervous system. Our findings provide an instructive basis for the roles of Smek1 in EAE and broaden the understanding of the genetic factors involved in the pathogenesis of autoimmune demyelination.

[Association of two SNPs in 3'UTR of ETS1 gene with systemic lupus erythematosus in a northern Chinese Han population].

OBJECTIVE: To assess the association between 2 single nucleotide polymorphisms (SNPs) of ETS1 gene and susceptibility to systemic lupus erythematosus (SLE) in a northern Chinese Han population. METHODS: Two SNPs within the ETS1 gene mapped to 11q23 were selected based on HapMap data. Genotyping was conducted with Taqman method in 231 patients with SLE and 474 healthy controls from Qilu Hospital, Shandong and analyzed with PLINK1.07 software. Haplotypes were analyzed with SHEsis software. RESULTS: A statistically significant difference was detected in the distribution of rs1128334 and rs4937333 genotypes between the two groups (all P< 0.01). For rs1128334, the frequency of the minor allele was 0.291 and 0.428 in controls and cases, respectively. For rs4937333, the minor allele frequency was 0.381 and 0.476 in controls and cases respectively. An A-C haplotype was found to be strongly associated with increased risk for SLE, while another haplotype G-C may reduce this risk. CONCLUSION: Our study has suggested that rs1128334 and rs4937333 are strongly associated with the risk for SLE in northern Chinese Han population.

[Analysis on genetic polymorphism of 5 STR loci selected from X chromosome].

OBJECTIVE: To select short tandem repeats(STR) from X chromosome. METHODS: STR is a universal genetic marker that has changeable polymorphism and stable heredity in human genome. It is a specific DNA segment composed of 2-6 base pairs as its core sequence. It is an ideal DNA marker used in linkage analysis and gene mapping. In this study, 8 short tandem repeats were selected from two genomic clones on X chromosome by using BCM Search Launcher. Primers amplifying the STR loci were designed by using Primer 3.0 according to the unique sequence flanking the STRs. Polymorphisms of the short tandem repeats in Chinese population were evaluated by PCR amplification and PAGE. RESULTS: Five of these STRs were polymorphic. Chi-square test indicated that the distribution of genotypes agreed with Hardy-Weinberg equilibrium (P>0.05). CONCLUSION: Five polymorphic short tandem repeats have been identified on chromosome X and will be useful for linkage analysis and gene mapping.

[Fine mapping of Smith-Fineman-Myers syndrome and exclusion of GPC3, GPCR2 MST4 and GLUD2 as candidate genes].

OBJECTIVE: Smith-Fineman-Myers syndrome (SFMS) is an X-linked mental retardation syndrome. The authors had ascertained a large Chinese family with SFMS from Shandong and had mapped the disease locus to an interval of 19.8 Mb on Xq25 flanked by markers DXS8064 and DXS8050. Further investigation suggested that SFMS exhibited locus heterogeneity. In this study for facilitating the identification of the gene responsible for SFMS, the additional markers were analyzed to narrow down the candidate region, and four candidate genes (GPC3, MST4,GPCR2 and GLUD2) were chosen and screened for disease-causing mutation. METHODS: PCR and denaturing polyacrylamide gel electrophoresis were used to genotype 13 new polymorphic markers distributed within the candidate region. Mutation detection was accomplished by sequencing the exons and intron-exon junctions of the candidate genes. RESULTS: By analyzing 13 additional polymorphic markers, SFMS candidate region can be reduced to an interval of 10.18 Mb bounded by XSTR3 and XSTR4, and no disease-causing mutation was identified in the coding regions of four candidate genes. CONCLUSION: GPCR2 GPC3, MST4 and GLUD2 were excluded as pathogenic genes for SFMS. The refined SFMS locus will assist in the identification and characterization of other candidate genes for SFMS.

[Application of homozygosity mapping to the fine mapping of the osteoporosis-pseudoglioma syndrome locus].

OBJECTIVE: To evaluate the role of homozygosity mapping in the fine mapping of the genes responsible for the rare autosomal recessive diseases. METHODS: Polymerase chain reaction-single sequence length polymorphism was used to genotype the family members from 8 families with osteoporosis-pseudoglioma syndrome(OPS) for 14 polymorphic loci within candidate region. The OPS candidate region was narrowed by searching for homozygous region in affected. RESULTS: The OPS candidate region was narrowed to a 1 cM interval between D11S1296 and D11S4136. CONCLUSION: Homozygosity mapping is a powerful method for mapping and narrowing the candidate region of the genes responsible for the rare autosomal recessive diseases.

[Polymorphic loci and polymorphism analysis of short tandem repeats within XNP gene].

To select polymorphic short tandem repeat markers within X-linked nuclear protein (XNP) gene, genomic clones which contain XNP gene were recognized by homologous analysis with XNP cDNA. By comparing the cDNA with genomic DNA, non-exonic sequences were identified, and short tandem repeats were selected from non-exonic sequences by using BCM search Launcher. Polymorphisms of the short tandem repeats in Chinese population were evaluated by PCR amplification and PAGE. Five short tandem repeats were identified from XNP gene, two of which were polymorphic. Four and 11 alleles were observed in Chinese population for XNPSTR1 and XNPSTR4, respectively. Heterozygosities were 47% for XNPSTR1 and 70% for XNPSTR4. XNPSTR1 and XNPSTR4 localized within 3' end and intron 10, respectively. Two polymorphic short tandem repeats have been identified within XNP gene and will be useful for linkage analysis and gene diagnosis of XNP gene.