Genetic variation in sialidase and linkage to N-acetylneuraminate catabolism in Mycoplasma synoviae

We explored the genetic basis for intraspecific variation in mycoplasmal sialidase activity that correlates with virulence, and its potentially advantageous linkage to nutrient catabolism. Polymorphism in N-acetylneuraminate scavenging and degradation genes (sialidase, N-acetylneuraminate lyase, N-acetylmannosamine kinase, N-acetylmannosamine-6-phosphate epimerase, N-acetylglucosamine-6-phosphate deacetylase, and glucosamine-6-phosphate deaminase) was evident among eight strains of the avian pathogen Mycoplasma synoviae. Most differences were single nucleotide polymorphisms, ranging from 0.34+/-0.04 substitutions per 100 bp for N-acetylmannosamine kinase to 0.65+/-0.03 for the single-copy sialidase gene nanI. Missense mutations were twice as common as silent mutations in nanI; 26% resulted in amino acids dissimilar to consensus; and there was a 12-base deletion near the nanI promoter in strain WVU1853(T), supporting a complex genetic basis for differences in sialidase activity. Two strains had identical frameshifts in the N-acetylneuraminate lyase gene nanA, resulting in nonsense mutations, and both had downstream deletions in nanA. Such genetic lesions uncouple extracellular liberation of sialic acid from generation of fructose-6-phosphate and pyruvate via intracellular N-acetylneuraminate degradation. Retention of nanI by such strains, but not others in the M. synoviae phylogenetic cluster, is evidence that sialidase has an important non-nutritional role in the ecology of M. synoviae and certain other mycoplasmas.     

Association of UCP1 genetic polymorphisms with blood pressure among Korean female subjects

Recent studies have provided some clues with regard to the relationship existing between uncoupling protein 1 (UCP1) and blood pressure in animal experiments. In an attempt to determine the genetic polymorphisms that are associated with blood pressure in humans, we have analyzed genetic polymorphisms in UCP1 gene. In this study, we assessed the association between UCP1 genotypes and systolic blood pressure (SBP) and diastolic blood pressure (DBP), in a population comprised of 832 Korean female subjects, using a general linear model, which was adjusted for age and body mass index (BMI). Among 4 genetic polymorphisms and the haplotypes constructed from them, haplotype3 of UCP1, UCP1-ht3[GAGA], evidenced significant associations with SBP (p=0.005) and DBP (p=0.013). However, this haplotype was not significantly associated with obesity phenotypes, including BMI or fat mass (p>0.05), thereby suggesting that its association with blood pressure was independent of obesity phenotypes.     

Vascular endothelial growth factor gene polymorphisms and recurrent pregnancy loss

PROBLEM: To be successful, pregnancy must induce its own blood supply through angiogenesis and vascular endothelial growth factor (VEGF) is the best characterized regulator of angiogenesis and one polymorphism of the VEGF gene, -1154, has been suggested to be associated with recurrent spontaneous abortion. The aim of this study was to confirm or refute the relationship of VEGF -1154 to recurrent pregnancy loss (RPL). METHOD OF STUDY: Buccal swabs were obtained from 152 women with history of two or more consecutive spontaneous abortions and 65 control women. DNA was extracted from the buccal swabs and analyzed for the presence of the VEGF -1154A/A gene. RESULTS: The frequency of homozygosity of the VEGF -1154A gene was significantly higher among women experiencing RPL compared with fertile control women (16% versus 6%, P < 0.05). CONCLUSION: Homozygosity of the VEGF -1154A gene may serve as a susceptibility factor affecting for RPL.     

A Functional Polymorphism in the CHRNA3 Gene and Risk of Chronic Obstructive Pulmonary Disease in a Korean Population

A genome-wide association study has identified the 15q25 region as being associated with the risk of chronic obstructive pulmonary disease (COPD) in Caucasians. This study intended as a confirmatory assessment of this association in a Korean population. The rs6495309C > T polymorphism in the promoter of nicotinic acetylcholine receptor alpha subunit 3 (CHRNA3) gene was investigated in a case-control study that consisted of 406 patients with COPD and 394 healthy control subjects. The rs6495309 CT or TT genotype was associated with a significantly decreased risk of COPD when compared to the rs6495309 CC genotype (adjusted odds ratio = 0.69, 95% confidence interval = 0.50-0.95, P = 0.023). The effect of the rs6495309C > T on the risk of COPD was more evident in moderate to very severe COPD than in mild COPD under a dominant model for the variant T allele (P = 0.024 for homogeneity). The CHRNA3 rs6495309C > T polymorphism on chromosome 15q25 is associated with the risk of COPD in a Korean population.     

Promoter polymorphisms of SERPINE1 are associated with the antidepressant response to depression in Alzheimer's disease

Depression is one of the most frequent neuropsychiatric symptoms in Alzheimer's disease (AD). As the main regulator of the tissue plasminogen activator/brain-derived neurotrophic factor axis, plasminogen activator inhibitor-1 (PAI-1) is involved in the pathogenesis of both AD and depression. This suggests a potential role of the PAI-1 gene SERPINE1 in the development of AD-related depression and its response to antidepressant treatment. The purpose of this study was to explore the association between the SERPINE1 promoter polymorphisms (rs1799889 and rs2227631) and the risk of depression in AD and to determine the relationship between these 2 polymorphisms and the response to paroxetine treatment in AD patients with depressive symptoms. A total of 423 AD patients, all of which were inpatients, including 161 patients with obvious depressive symptoms, were recruited into this study, and the MassARRAY system was used for genotyping. We failed to detect any significant associations of these 2 polymorphisms with AD-related depression in the Chinese population (p>0.05). However, for the depressive symptoms in AD, the frequency of the 5G allele of rs1799889 was significantly higher (p=0.009 after Bonferroni correction) in responders than in non-responders to an 8-week paroxetine treatment. Our preliminary results suggest that the SERPINE1 promoter polymorphisms may be associated with antidepressant treatment, but not with the increased susceptibility to the depressive symptoms in AD.     

Neuronal gap junctions play a role in the secondary neuronal death following controlled cortical impact

Autosomal dominant cerebellar ataxias (ADCAs), genetically classified into spinocerebellar ataxias (SCAs), are a highly heterogeneous group of neurodegenerative disorders. Recently, mutations in the fibroblast growth factor 14 gene (FGF14) have been reported to cause SCA27 subtype. To evaluate the frequency of FGF14 mutations in mainland of China, we performed molecular genetic analysis in 67 unrelated familial ataxia cases and 500 normal controls by denaturing high-performance liquid chromatography (DHPLC) and DNA direct sequencing. Interestingly, we found a pair of siblings carried the same heterozygous variation (c.-10delC) characterized by different clinical features, which is probably a novel insertion/deletion (I/D) polymorphism in the 5'UTR region of the exon 1b. It suggests that SCA27 is a rare subtype in China.     

Chemokines and chemokine receptors in susceptibility to HIV-1 infection and progression to AIDS

A multitude of host genetic factors plays a crucial role in susceptibility to HIV-1 infection and progression to AIDS, which is highly variable among individuals and populations. This review focuses on the chemokine-receptor and chemokine genes, which were extensively studied because of their role as HIV co-receptor or co-receptor competitor and influences the susceptibility to HIV-1 infection and progression to AIDS in HIV-1 infected individuals.