ISSN 10227954, Russian Journal of Genetics, 2011, Vol. 47, No. 6, pp. 682–690. © Pleiades Publishing, Inc., 2011.
Published in Russian in Genetika, 2011, Vol. 47, No. 6, pp. 774–782.
Nonlong terminal repeats (nonLTR) retrotrans
posons also called LINE (for Long Interspersed Nuclear
Element) belong to the mobile genetic elements that are
transposed into the host genome by reverse transcription
of RNA intermediate. A copy number of the defined
nonLTR retrotransposons may vary from several copies
per genome, as it has been shown for some elements in
, till 300000 and more copies
of the nonLTR element L1, which make up to 20% of
the whole human genome .
Although most of the nonLTR retrotransposons
seem to be functionally defective , the human genome
contains about 100 retrotranspositionactive L1 elements
, while the number of active L1 elements in mouse
genome reaches 3000 copies . Retroposition experi
ments carried out with human and murine L1 elements
have demonstrated that these elements are active in germ
cells during early embryogenesis [6, 7]. To date, L1 ret
rotransposition has been detected in germ cells [8–10],
transformed or immortalized cells [11–13], and, most
recently, in rodent somatic cells . The cell division was
proposed to be required for L1 retrotransposition .
Recently, Muotri with colleagues have shown that
human L1 element is active in both somatic brain tissues
of the transgenic mice and in adult rat neural progenitor
cells (NPCs), and in the last case de novo retrotransposi
tion events affected cell differentiation fate. Thus non
The article is published in the original.
Recipient of a DAAD fellowship.
LTR element L1 seems to be involved in the generation of
brain function diversity .
Based on their structure, all nonLTR retrotrans
posons can be crudely classified into two groups. The
elements of the first group possess a single open read
ing frame (ORF), which encodes for the reverse tran
scriptase (RT) and restrictionenzymelike endonu
clease (RELendo) activities. Elements from the sec
ond group are characterized by the presence of two
ORFs, ORF1 and ORF2, encoding for a gaglike, pro
tein as well as for a reverse transcriptase and an apu
rinic/apyrimidinic (AP) endonuclease, respectively
[15, 16]. For several elements, ORF2 has been shown
to contain ribonuclease H domain .
The current retrotransposition model named target
primed reverse transcription (TPRT) is based on the
data obtained from the
which has single ORF [17–20]. The homodimer of
ORFencoded protein asymmetrically bound to target
DNA affects integration of the element through a series
of ordered catalytic steps . R2Bm retrotransposition
is proposed to proceed via the following steps: (i) the
endonuclease of the upstream monomer cleaves the
first (bottom) DNA strand, (ii) the reverse transcriptase
of the upstream monomer uses the free 3' OH from the
newly created nick to initiate targetprimed reverse
transcription (TPRT) using the R2 RNA as the tem
plate, (iii) the downstream monomer cleaves the second
(top) DNA strand, and (iv) the second DNA strand is
A Retroposition Assay for the NLR1Cth from Midge
Genome in the Chinese Hamster Ovary Cells
, E. Papusheva
, E. Ponimaskin
, and A. Blinov
Institute of Cytology and Genetics, Novosibirsk, 630090 Russia
Cellular Neurophysiology, Medical School Hannover, Hannover D0625, Germany
Center for Molecular Physiology of the Brain (CMPB), Göttingen D37073, Germany
Received December 12, 2010
—NonLong Terminal Repeats (nonLTR or LINE) retrotransposons belong to the class of mobile
genetic elements that are transposed into the host genome by reverse transcription of the RNA intermediate.
Most of nonLTR retrotransposons contain two open reading frames (ORFs). The ORF1 codes for a gaglike
protein, while the ORF2 codes for a reverse transcriptase (RT). We cloned two constructs based on Jockey
like nonLTR retrotransposon from genome
(NLR1Cth). The retroposition assay per
formed in Chinese hamster ovary (CHO) cells demonstrated genome integrations of both constructs. The
finding that the insect mobile element NLR1Cth is functional in mammalian cells demonstrates that this ele
ment possess universal enzymatic machinery allowing for active propagation in the genome of distant taxa.
This suggests that the NLR1Cth transposon system may represent a useful tool for genetic analysis and
manipulation in vertebrate cells.