Application of the cis-regulatory region of a heat-shock protein 70 gene to heat-inducible gene expression in the ascidian Ciona intestinalis.

Temporally controlled induction of gene expression is a useful technique for analyzing gene function. To make such a technique possible in Ciona intestinalis embryos, we employed the cis-regulatory region of the heat-shock protein 70 (HSP70) gene Ci-HSPA1/6/7-like for heat-inducible gene expression in C. intestinalis embryos. We showed that Ci-HSPA1/6/7-like becomes heat shock-inducible by the 32-cell stage during embryogenesis. The 5'-upstream region of Ci-HSPA1/6/7-like, which contains heat-shock elements indispensable for heat-inducible gene expression, induces the heat shock-dependent expression of a reporter gene in the whole embryo from the 32-cell to the middle gastrula stages and in progressively restricted areas of embryos in subsequent stages. We assessed the effects of heat-shock treatments in different conditions on the normality of embryos and induction of transgene expression. We evaluated the usefulness of this technique through overexpression experiments on the well-characterized, developmentally relevant gene, Ci-Bra, and showed that this technique is applicable for inferring the gene function in C. intestinalis.

Regulatory SNP in the RBP4 gene modified the expression in adipocytes and associated with BMI.

Retinol-binding protein 4 (RBP4) is a recently identified adipokine that was involved in insulin resistance. RBP4 is predominantly expressed from the liver in normal metabolic state to transport retinoids throughout the body, but the exact physiological function and the regulatory mechanisms of adipocyte-derived RBP4 have not been revealed. We conducted the genetic analysis about metabolic parameters in Japanese and Mongolian; the minor allele carriers of regulatory single-nucleotide polymorphism (SNP -803G>A) showed significantly higher BMI in Japanese men (P = 0.009) and women (P = 0.017), and in Mongolian women (P = 0.009). Relative quantification of RBP4 transcripts in -803GA heterozygotes showed that the minor allele-linked haplotype-derived mRNA was significantly more abundant than the transcript from major allele. RBP4 promoter assay in 3T3L1 adipocytes revealed that the minor allele increased the promoter activity double to triple and the administration of 9-cis-retinoic acid (RA) and 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP) enhanced the activity. Multiple alignment analysis of human, mouse, rat, and cattle RBP4 promoter suggested conserved seven transcription factor binding motifs. Electrophoretic mobility shift assay showed the -803G>A SNP modulate the affinity against unidentified DNA-binding factor, which was assumed to be a suppressive factor. These results collectively suggested that the minor allele of RBP4 regulatory SNP enhanced the expression in adipocytes, which may be associated with the adipogenesis.

Genetic heterogeneity in a susceptible region for essential hypertension among demographically different local populations in Japan.

OBJECTIVE: The aim of the study was to investigate genetic heterogeneity among local Japanese populations. METHODS: We performed a single nucleotide polymorphism (SNP) study of four demographically distinct local populations (population 1: a large city; population 2: isolated islands; populations 3 and 4: rural areas). Seventy SNPs in a region spanning 5 Mb of chromosome 17 known to be a candidate region for essential hypertension were genotyped and linkage disequilibrium analyses were performed. RESULTS: Statistical analyses of SNP allele frequencies and haplotype distribution showed significant divergence among the populations, mostly between population 2 and the other populations. Pairwise D' declined with increasing population size, and smaller populations retained a high linkage disequilibrium. CONCLUSION: Population 2 is likely to have a different ancestry from the majority of the Japanese population, whereas the heterogeneity among the other populations may result from differences in population size or geographic background.

Comparative study of polymorphisms on genes associated with lifestyle related diseases in Asian and Pacific populations.

An increase in prevalence of lifestyle related diseases becomes one of the main threats to human health in Asia-Pacific regions. Especially Pacific countries face the marked epidemic of obesity and related disorders. Understanding of the genetic basis for these diseases is awaited. We investigated frequencies of 106 single nucleotide polymorphisms (SNPs) in genes associated with lifestyle related diseases in 1,878 individuals from five Asia-Pacific countries including Japan, China, Mongolia, Thailand, and Palau. Population genetic analyses revealed that disease susceptible variants of SNPs in TRIB3, PTGS2, ADIPOR1, DGAT1, UCP2, FOXC2, and ESR1 were overrepresented in the Palau population in comparison with the Asian populations. These gene variants likely contribute to the high prevalence of obesity and related diseases in Pacific populations. The present results would be helpful in coping with the lifestyle related diseases and may provide a new insight into the human dispersal in Asia-Pacific regions.

Identification of a regulatory SNP in the retinol binding protein 4 gene associated with type 2 diabetes in Mongolia.

Increased levels of retinol binding protein 4 (RBP4) in serum is associated with insulin resistance. To examine this further, the genomic region of RBP4 was genetically surveyed in Mongolian people, who as a group are suffering from a recent rapid increase in diabetes. The RBP4 gene was screened by DHPLC system, and the PCR fragments which showed heteroduplex peaks in multiple samples were followed by direct sequencing to identify common polymorphisms in 48 Mongolian diabetic samples. Identified single nucleotide polymorphisms (SNPs) were genotyped in 511 control and 281 type 2 diabetes samples. The functions of SNPs in the regulatory region were assessed by reporter gene assay and electrophoretic mobility shift assay. Possible association between functional SNPs and serum RBP4 levels or metabolic parameters was statistically assessed. Nine SNPs were identified in the RBP4 gene. A case-control study revealed that the rare alleles of four SNPs were associated with increased risk of diabetes, even after Bonferroni correction (-803, G > A, P = 0.0054; +5169, C > T, P = 0.0025; +6969, G > C, P = 0.0015; +7542, T > del, P = 0.0015). The -803 G > A SNP influenced the transcription efficiency in a hepatocarcinoma cell line as well as the binding efficiency of hepatocyte nuclear factor 1 alpha to the motif. In addition, the -803 A allele was associated with increased serum RBP4 levels in diabetic patients. We have identified a functional SNP in the RBP4 gene associated with type 2 diabetes in Mongolian people.

An intronic variable number of tandem repeat polymorphisms of the cold-induced autoinflammatory syndrome 1 (CIAS1) gene modifies gene expression and is associated with essential hypertension.

Cold-induced autoinflammatory syndrome 1 (CIAS1) gene is a member of the NALP subfamily of the CATERPILLER protein family that is expressed predominantly in peripheral blood leukocytes, which is to regulate apoptosis or inflammation through the activation of NF-kappaB and caspase. Recent genetic analyses suggested an association between inflammation and oxidative stress-related genes in the development of hypertension. This is the first genetic study indicating an association between the CIAS1 gene and susceptibility to essential hypertension (EH). The frequency of subject with the homozygote of 12 repeat allele was significantly higher in patients with hypertension compared with control subjects (987 cases, 924 controls) (P=0.030; odds ratio=1.24) at a novel VNTR polymorphism of CIAS1 intron 4 loci. We also found that the mean of systolic blood pressure of homozygotes of 12 repeat allele was 6.4 mmHg higher than those of homozygotes of non-12 repeat allele in male random population (P=0.009). The frequency of six SNPs spanning of the CIAS1 gene was not significantly between patients and controls. The real-time PCR analysis showed that among healthy young adults, 12-12 subjects expressed CIAS1 mRNA in peripheral leukocytes significantly more abundantly than homozygote of non-12 repeat alleles subjects (P<0.05). Reporter gene assay of the CIAS1-VNTR in HL60 stimulated by lipopolysaccharides showed that the intronic sequence involving 12 repeat increased the expression of luciferase compared with 9, 7, and 6 repeats. Thus, we propose here the CIAS1 is associated with EH through the dominant expression of transcripts, which may depend on the CIAS1-VNTR genotype.

Analysis of ascidian Not genes highlights their evolutionarily conserved and derived features of structure and expression in development.

The ascidian larva is often regarded as an organism close to the ancestral form of chordates, while it is generally accepted that the Spemann's organizer is absent from ascidian embryos. Not is one of the genes expressed in the organizer to execute functions in vertebrate embryos. To address the extent of conservation of Not gene expression among ascidians and vertebrates, we examined the structure and developmental expression of Not of the two distantly related ascidian species, Halocynthia and Ciona. Putative ascidian Not proteins were noted by the absence of one of the two motifs conserved among Not proteins of sea urchin and vertebrates. Analysis by in situ hybridization revealed that Not gene expression of ascidians could be categorized into three types: expression likely to be conserved between ascidians and vertebrates, that probably unique to ascidians, and that specific to ascidian species. Expression of ascidian Not in the posterior end of the tail as well as the notochord and a small part of the anterior neural tube at the tailbud stage is reminiscent of the expression of the vertebrate counterparts in the tailbud, which is regarded as a continuation of the organizer and the pineal gland, respectively. The expression of Not in the epidermis precursors during cleavage stage may be unique to ascidians. In the light of the present findings, evolutionary aspects of Not genes are discussed.