Alu-elements

Term used in genetics. Alu elements are a family of short, repetitive DNA sequences that occur in the genomes of many eukaryotes, especially in the human genome. They belong to the class of transposable elements or jumping genes and are a form of non-coding DNA. Alu elements are about 300 base pairs long and were named after the restriction enzyme AluI, which can cut them at specific sites. Alu elements are very common and make up about 10% of the human genome. There are several hundred thousand copies of these elements in human DNA.

Transposability: Alu elements can move within the genome. They have the ability to replicate and integrate into other genome units through a mechanism called retrotransposition. This process occurs via an RNA intermediate.

The function of Alu elements are not yet fully understood, but there are some postulated and known roles and effects:

• Genomic variation: Alu elements can contribute to genetic diversity by generating mutations and structural variations in the genome. Their integration into genes may influence the expression of genes or lead to functional changes.
• Regulation of gene expression: Some studies suggest that Alu elements can act as regulatory elements by influencing the transcription of neighboring genes. They can act as binding sites for transcription factors or as enhancers.
• Evolutionary role: Alu elements may have contributed to the evolution of new genes by bringing exons (coding sequences) and introns (non-coding sequences) into new combinations or by generating new protein variants through exon splicing.
• Genomic instability: The mobility of Alu elements may also have genotoxic effects by causing chromosomal breaks or other genomic instabilities, which in some cases have been linked to diseases such as cancer.

1. Ule J (2013) Alu elements: at the crossroads between disease and evolution. Biochem Soc Trans 41:1532-1535.