Abstract
Although some preliminary work has revealed the potential transcriptional regulatory function of the introns in eukaryotes, additional evidences are needed to support this conjecture. In this study, we perform systemic analyses of the sequence characteristics of human introns. The results show that the first introns are generally longer and C, G and their dinucleotide compositions are over-represented relative to other introns, which are consistent with the previous findings. In addition, some new phenomena concerned with transcriptional regulation are found: i) the first introns are enriched in CpG islands; and ii) the percentages of the first introns containing TATA, CAAT and GC boxes are relatively higher than other position introns. The similar features of introns are observed in tissue-specific genes. The results further support that the first introns of human genes are likely to be involved in transcriptional regulation, and give an insight into the transcriptional regulatory regions of genes.
Highlights
Protein coding genes in eukaryotes contain multiple introns that are cut off in RNA splicing process [1]
The previous work have studied the length and nucleotide content of the introns and found that the first introns are generally longer than other introns and are enriched in C+G and CG dinucleotide compared to other introns [17,20,21], suggesting that the longer first introns may be favorable for the presence of regulatory elements [20,21]
We focus on investigating the intron features associated with transcriptional regulation in human genes
Summary
Protein coding genes in eukaryotes contain multiple introns that are cut off in RNA splicing process [1]. The introns have been considered as ‘‘junk DNA’’ for a long time. Some studies have suggested that the first introns may play a vital role in transcriptional regulation of genes [13,14,15,16]. The previous work have studied the length and nucleotide content of the introns and found that the first introns are generally longer than other introns and are enriched in C+G and CG dinucleotide compared to other introns [17,20,21], suggesting that the longer first introns may be favorable for the presence of regulatory elements [20,21]. It is necessary to study intron length and nucleotide content for evaluating the function of introns in transcription
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