Structural characterisation of the distal 5′ flanking region of the human interleukin-10 gene

Abstract

Interleukin-10 (IL-10) is an important immunoregulatory cytokine. The recent characterisation of the proximal 5' flanking region of IL-10 led to the identification of the promoter region. Two polymorphic dinucleotide repeats and 10 single nucleotide polymorphisms (SNPs) have been identified and suggested to be useful genetic markers in several diseases. We have sequenced a further 5275 bp from -9296 to -4021 of the distal part of the 5' flanking region of the human IL-10 gene from the cosmid clone pWE15-4/11. Our sequence analysis reveals a high density of Alu-repeats within the IL-10 gene locus, including three novel, related structures which we term Alu-IL10 (A-C). Using three overlapping PCR products spanning 5110 bp of this distal part of the IL-10 gene the following single base pair substitutions were identified: at -8571 C/T, -8531 G/A, -6752 A/T, -6208 G/C, -5402 C/G. In addition a heterozygous three base pair deletion at -7400 was observed. The SNPs at -8571 C/T and -8531 G/A are contained within an Alu-repeat. These data should further the understanding of how the IL-10 gene is controlled in man and how its function may vary between individuals.

Association tests with systemic lupus erythematosus (SLE) of IL10 markers indicate a direct involvement of a CA repeat in the 5′ regulatory region

“…Direct sequencing of the heteroduplex samples and one homoduplex as a reference for each fragment led to the identification of 16 sequence variations (Table 1). Most of them had been previously, identified in other studies 14,[17][18][19][20][21] with the exception of four SNPs located at positions À1270, +3814, +4123 and +4230 (Table 1).…”

“…This distance does not exclude the IL10 gene since peaks of linkage in complex diseases only define a confidence interval for the location of a gene and, therefore, susceptibility genes may map near peaks of linkage rather than directly under them. 13 Different polymorphisms were identified both in the 5' flanking region [14][15][16][17][18][19][20] and, more recently, in the transcribed region 21 of the IL10 gene including two microsatellites at position À4000 (IL10 15 ) and À1100 (IL10 16 ). One of the two microsatellites, IL10.G, has been shown to be associated to SLE by three independent studies, including ours [22][23][24] although this was not supported by a fourth work.…”

Sp1 binds to the G allele of the−1087 polymorphism in the IL-10 promoter and promotes IL-10 mRNA transcription and protein production

“…19,20 Changes in the IL-10 gene expression were suggested to be mainly transcriptional and several factor-binding sites that might be involved in the regulation of IL-10 were identified in the IL-10 promoter. [21][22][23][24] The À1087 single nucleotide polymorphism (SNP) is located in one of these sites that was associated with differences in IL-10 gene expression [25][26][27] and the GG genotype of the À1087 SNP was found to be associated with high levels of IL-10 production. 26,27 Recently, we reported that the PU.1, Spi-B and Sp1transcription factors bound to the À1087 SNP in Bcells.…”

The Sp1 transcription factor binds to the G-allele of the –1087 IL-10 gene polymorphism and enhances transcriptional activation

“…[17][18][19] Several factor-binding sites that might be involved in the regulation of IL-10 were identified in the IL-10 promoter. [20][21][22] The IL-10 promoter contains several single nucleotide polymorphisms (SNPs) among which the -1087 G/A SNP (sometimes referred to as À1082 G/A) was associated with differences in IL-10 promoter activity and IL-10 production. [23][24][25][26][27][28][29] Results of studies on the influence of the -1087 SNP on the IL-10 production in different cell types, 23,[25][26][27][28][29] however, are conflicting.…”