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Abstract
Research on the involvement of retroelements in developmental processes has been gaining momentum recently; however, most of the studies published so far have been focused on embryonic development. This commentary presents two recent papers, which document significant changes in transcriptional activity of retroelements in two different model systems, salamander limb regeneration and regeneration of radial organs in the sea cucumber Holothuria glaberrima. We hypothesize that transcriptional activity of the retrotransposons can be specifically controlled by the host and may play some hitherto unrecognized role in regeneration.
Figure 1. (A) The model organism, Holothuria glaberrima Selenka, 1867 (Echinodermata: Holothuroidea). (B) Injury paradigm. One of the five radial organ complexes (including the radial nerve, coelomic canal and muscle) was cut at about the mid-body level. For clarity, the diagram shows only the nervous system. The injured radial nerve is shaded in red.
Figure 2. Reverse transcription polymerase chain reaction (RT-PCR) showing temporal expression of Gypsy-1_Hg and Gypsy-2_Hg at different time points of visceral regeneration (Day 3−Day 28) and in the normal (Norm) digestive tube of the sea cucumber H. glaberrima. RT-PCR was performed as described in reference 15. Primer sequences for Gypsy-1_Hg and Gypsy-2_Hg were from reference 10. NADH dehydrogenasesubunit 5 was used as an internal control. The gel also includes a no-template control (“-” control) to test for contamination. Whereas Gypsy-1_Hg is not transcriptionally active in the normal gut but overexpressed in regeneration (in particular, at the early time points), Gypsy-2_Hg does not show any significant differences in expression level between the normal and regenerating digestive tube. This contrasts with expression of these genes in the radial organ complex regeneration in the same species (Fig. 3B in Mashanov et al.10), where both retroelements are barely detectable under the normal conditions, but show dramatic upregulation during regeneration.
Djebali,
Landscape of transcription in human cells.
2012, Pubmed
Djebali,
Landscape of transcription in human cells.
2012,
Pubmed
Faulkner,
Altruistic functions for selfish DNA.
2009,
Pubmed
Feschotte,
Transposable elements and the evolution of regulatory networks.
2008,
Pubmed
García-Arrarás,
Echinoderms: potential model systems for studies on muscle regeneration.
2010,
Pubmed
,
Echinobase
Macfarlan,
Embryonic stem cell potency fluctuates with endogenous retrovirus activity.
2012,
Pubmed
Mashanov,
Regeneration of the radial nerve cord in a holothurian: a promising new model system for studying post-traumatic recovery in the adult nervous system.
2008,
Pubmed
,
Echinobase
Mashanov,
Gut regeneration in holothurians: a snapshot of recent developments.
2011,
Pubmed
,
Echinobase
Mashanov,
Expression of Wnt9, TCTP, and Bmp1/Tll in sea cucumber visceral regeneration.
2012,
Pubmed
,
Echinobase
Mashanov,
Posttraumatic regeneration involves differential expression of long terminal repeat (LTR) retrotransposons.
2012,
Pubmed
,
Echinobase
Monaghan,
Microarray and cDNA sequence analysis of transcription during nerve-dependent limb regeneration.
2009,
Pubmed
Muotri,
Somatic mosaicism in neuronal precursor cells mediated by L1 retrotransposition.
2005,
Pubmed
Muotri,
The necessary junk: new functions for transposable elements.
2007,
Pubmed
Thurman,
The accessible chromatin landscape of the human genome.
2012,
Pubmed
Wilkins,
The enemy within: an epigenetic role of retrotransposons in cancer initiation.
2010,
Pubmed
Zhu,
Retrotransposon long interspersed nucleotide element-1 (LINE-1) is activated during salamander limb regeneration.
2012,
Pubmed
