RESUMO
Current literature indicates that abrogation of the IGF-I response pathway affects longevity in Caenorhabditis elegans, and that the down-regulation of IGF-I gene expression is associated with an extension of the life span in mice. In this paper we tested the hypothesis that polymorphic variants of IGF-I response pathway genes, namely IGF-IR (IGF-I receptor; G/A, codon 1013), PI3KCB (phosphoinositol 3-kinase; T/C, -359 bp; A/G, -303 bp), IRS-1 (insulin receptor substrate-1; G/A, codon 972), and FOXO1A (T/C, +97347 bp), play a role in systemic IGF-I regulation and human longevity. The major finding of this investigation was that subjects carrying at least an A allele at IGF-IR have low levels of free plasma IGF-I and are more represented among long-lived people. Moreover, genotype combinations at IGF-IR and PI3KCB genes affect free IGF-I plasma levels and longevity. These findings represent the first indication that free IGF-I plasma levels and human longevity are coregulated by an overlapping set of genes, contributing to the hypothesis that the impact of the IGF-I/insulin pathway on longevity is a property that has been evolutionarily conserved throughout the animal kingdom.
Assuntos
Fator de Crescimento Insulin-Like I/metabolismo , Longevidade/genética , Fosfatidilinositol 3-Quinases/genética , Polimorfismo Genético , Receptor IGF Tipo 1/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/genética , Proteínas de Ligação a DNA/genética , Evolução Molecular , Feminino , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead , Frequência do Gene , Genótipo , Humanos , Insulina/metabolismo , Masculino , Pessoa de Meia-Idade , Fatores de Transcrição/genéticaRESUMO
The activity of tissue transglutaminase is present in many cells and tissues but almost absent in leucocytes and lymphocytes. The present work describes the distribution of 5-methylcytosine along the bisulphite-converted promoter of the human tissue transglutaminase gene as being in an essentially repressed state. In this promoter, the chain-specific sequencing revealed the location of three CpG-rich domains whose methylation responds to an 'all or nothing' signal. While the CpGs of domain 1, at the 5'-end, and 2, in the mid-promoter, were fully methylated, those of domain 3, at the 3'-end, were fully unmethylated. Before the 5'-UTR sequence, from site+1 to site+67, also unmethylated, there was thus a striking contrast in the post-synthetic modification between the sequence, from -1594 to -436, containing domains 1 and 2, and the sequence, from -435 to -1, containing domain 3 with the core promoter.
Assuntos
Ilhas de CpG/genética , Citosina/análogos & derivados , Metilação de DNA , Regiões Promotoras Genéticas/genética , Transglutaminases/genética , 5-Metilcitosina , Sequência de Bases , Sítios de Ligação/genética , Citosina/metabolismo , DNA/química , DNA/genética , DNA/metabolismo , Regulação Enzimológica da Expressão Gênica , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNARESUMO
The human forkhead box O1A (FOXO1A) gene belongs to the human forkhead gene family and acts downstream of the human insulin signalling pathway. In this study, polymorphisms of the Intron I of FOXO1A gene were studied in Italian healthy people and insulin resistant subjects. No significant association between the germ-line variability in the Intron I of FOXO1A and insulin resistance was observed. Interestingly, during the study, a new 39-bp sequence insertion polymorphism in Intron I of FOXO1A gene was described. The polymorphism was found to co-segregate in a co-dominant Mendelian fashion and to be present in an ethnically distinct population (Greeks). A BLAST search showed that the sequence shares 100% identity with a mtDNA (mitochondrial DNA) sequence coding for the ATP synthase 8 (ATPase8) and ATP synthase 6 (ATPase6) genes. Hence, FOXO1A Intron I is a polymorphic nuclear region involved in the exchange of DNA material between mitochondrial and genomic DNA, which is a well-established mechanism of evolutionary change in eukaryotes.
Assuntos
DNA Mitocondrial/genética , Proteínas de Ligação a DNA/genética , Íntrons/genética , Mutagênese Insercional , Polimorfismo de Nucleotídeo Único , Fatores de Transcrição/genética , Adenosina Trifosfatases/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Alelos , DNA/química , DNA/genética , Análise Mutacional de DNA , Feminino , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead , Frequência do Gene , Genótipo , Haplótipos , Humanos , Resistência à Insulina/genética , Itália , Desequilíbrio de Ligação , Masculino , Pessoa de Meia-Idade , Linhagem , Deleção de SequênciaRESUMO
In the present investigation we analysed Interleukin 6 (IL-6) in vitro production by Epstein-Barr virus (EBV)-immortalized B lymphocytes established from 43 subjects, 15 young people and 28 elderly people, including 18 centenarians, after 3, 6, 9, 24, 48 and 72 h of culture. The subjects were genotypized for the C to G transition at nucleotide -174 of IL-6 gene promoter (-174 C/G) and were classified as C allele carriers (C+) and non-carriers (C-). We found that: (i) the interindividual difference in in vitro IL-6 production was wider in elderly individuals in respect to young individuals, leading to different coefficient of variation in the two groups; (ii) the -174 C/G polymorphism had an age-related effect on IL-6 in vitro production. Only among C- people, cells from elderly subjects produced significant higher level of IL-6 than cells from young subjects. These data are consistent with our previous results regarding the IL-6 serum levels in a large group of people of different age, including centenarians. Thus, the EBV-immortalized B lymphocytes can be considered a useful in vitro model for studying the genetic control of IL-6 production and its changes with age.