Limits...
Alu elements as regulators of gene expression.

Häsler J, Strub K - Nucleic Acids Res. (2006)

Bottom Line: They have been shown to be involved in alternative splicing, RNA editing and translation regulation.These findings highlight how the genome adapted to these repetitive elements by assigning them important functions in regulation of gene expression.Alu elements should therefore be considered as a large reservoir of potential regulatory functions that have been actively participating in primate evolution.

View Article: PubMed Central - PubMed

Affiliation: Université de Genève, Katharina Strub, Département de Biologie Cellulaire, 30 quai Ernest Ansermet, 1211 GENEVE 4, Switzerland.

ABSTRACT
Alu elements are the most abundant repetitive elements in the human genome; they emerged 65 million years ago from a 5' to 3' fusion of the 7SL RNA gene and amplified throughout the human genome by retrotransposition to reach the present number of more than one million copies. Over the last years, several lines of evidence demonstrated that these elements modulate gene expression at the post-transcriptional level in at least three independent manners. They have been shown to be involved in alternative splicing, RNA editing and translation regulation. These findings highlight how the genome adapted to these repetitive elements by assigning them important functions in regulation of gene expression. Alu elements should therefore be considered as a large reservoir of potential regulatory functions that have been actively participating in primate evolution.

Show MeSH

Related in: MedlinePlus

Architecture of Alu elements. Alu elements are about 300 nt long; they have a dimeric structure composed of two related but not equivalent monomers (left and right arms). The right arm contains a 31 nt insertion as compared to the left arm. Left and right arms are separated by an A-rich region (Mid A-stretch) and followed by a short poly(A) tail (Terminal A-stretch). The left arm contains functional, but weak, A and B boxes of the RNA polymerase III internal promoter.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC1636486&req=5

fig1: Architecture of Alu elements. Alu elements are about 300 nt long; they have a dimeric structure composed of two related but not equivalent monomers (left and right arms). The right arm contains a 31 nt insertion as compared to the left arm. Left and right arms are separated by an A-rich region (Mid A-stretch) and followed by a short poly(A) tail (Terminal A-stretch). The left arm contains functional, but weak, A and B boxes of the RNA polymerase III internal promoter.

Mentions: The initial sequencing of the human genome revealed that 55% of its nucleotide sequence is composed of repetitive elements (1). Among different families of repetitive elements, Alu elements are the most abundant in the human genome. They are present in more than one million copies, which altogether represent 10% of the whole genome mass. Alu belong to the SINE family (Short Interspersed Nuclear Elements) of repetitive elements; they emerged 55 millions years ago with the radiation of primates by a fusion of the 5′ and 3′ ends of the 7SL RNA gene, which encodes the RNA moiety of the signal recognition particle (SRP). The first fossil Alu monomers (FAMs) arose from this fusion (2); they were ∼160 bp long and are poorly represented in the human genome (2). According to the current model, modern Alu elements emerged from a head to tail fusion of two distinct FAMs (3) that gave rise to a dimeric structure composed of two similar but distinct monomers (left and right arms) joined by an A-rich linker (Figure 1). Modern Alu elements are ∼300 bp in length and are classified into subfamilies according to their relative ages [for a review see Ref. (4)]. Dimeric Alu elements are unique to primates; they amplified throughout the primate genomes via RNA intermediates by a mechanism of retrotransposition that remains to be elucidated. Their amplification has been dependent on the transposition machinery of other retrotransposons, since they do not encode any protein. It has recently been shown that they could use LINE-1 (long interspersed nuclear elements) elements for this purpose (5).


Alu elements as regulators of gene expression.

Häsler J, Strub K - Nucleic Acids Res. (2006)

Architecture of Alu elements. Alu elements are about 300 nt long; they have a dimeric structure composed of two related but not equivalent monomers (left and right arms). The right arm contains a 31 nt insertion as compared to the left arm. Left and right arms are separated by an A-rich region (Mid A-stretch) and followed by a short poly(A) tail (Terminal A-stretch). The left arm contains functional, but weak, A and B boxes of the RNA polymerase III internal promoter.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1636486&req=5

fig1: Architecture of Alu elements. Alu elements are about 300 nt long; they have a dimeric structure composed of two related but not equivalent monomers (left and right arms). The right arm contains a 31 nt insertion as compared to the left arm. Left and right arms are separated by an A-rich region (Mid A-stretch) and followed by a short poly(A) tail (Terminal A-stretch). The left arm contains functional, but weak, A and B boxes of the RNA polymerase III internal promoter.
Mentions: The initial sequencing of the human genome revealed that 55% of its nucleotide sequence is composed of repetitive elements (1). Among different families of repetitive elements, Alu elements are the most abundant in the human genome. They are present in more than one million copies, which altogether represent 10% of the whole genome mass. Alu belong to the SINE family (Short Interspersed Nuclear Elements) of repetitive elements; they emerged 55 millions years ago with the radiation of primates by a fusion of the 5′ and 3′ ends of the 7SL RNA gene, which encodes the RNA moiety of the signal recognition particle (SRP). The first fossil Alu monomers (FAMs) arose from this fusion (2); they were ∼160 bp long and are poorly represented in the human genome (2). According to the current model, modern Alu elements emerged from a head to tail fusion of two distinct FAMs (3) that gave rise to a dimeric structure composed of two similar but distinct monomers (left and right arms) joined by an A-rich linker (Figure 1). Modern Alu elements are ∼300 bp in length and are classified into subfamilies according to their relative ages [for a review see Ref. (4)]. Dimeric Alu elements are unique to primates; they amplified throughout the primate genomes via RNA intermediates by a mechanism of retrotransposition that remains to be elucidated. Their amplification has been dependent on the transposition machinery of other retrotransposons, since they do not encode any protein. It has recently been shown that they could use LINE-1 (long interspersed nuclear elements) elements for this purpose (5).

Bottom Line: They have been shown to be involved in alternative splicing, RNA editing and translation regulation.These findings highlight how the genome adapted to these repetitive elements by assigning them important functions in regulation of gene expression.Alu elements should therefore be considered as a large reservoir of potential regulatory functions that have been actively participating in primate evolution.

View Article: PubMed Central - PubMed

Affiliation: Université de Genève, Katharina Strub, Département de Biologie Cellulaire, 30 quai Ernest Ansermet, 1211 GENEVE 4, Switzerland.

ABSTRACT
Alu elements are the most abundant repetitive elements in the human genome; they emerged 65 million years ago from a 5' to 3' fusion of the 7SL RNA gene and amplified throughout the human genome by retrotransposition to reach the present number of more than one million copies. Over the last years, several lines of evidence demonstrated that these elements modulate gene expression at the post-transcriptional level in at least three independent manners. They have been shown to be involved in alternative splicing, RNA editing and translation regulation. These findings highlight how the genome adapted to these repetitive elements by assigning them important functions in regulation of gene expression. Alu elements should therefore be considered as a large reservoir of potential regulatory functions that have been actively participating in primate evolution.

Show MeSH
Related in: MedlinePlus