Worm Breeder's Gazette 15(2): 31 (February 1, 1998)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Tc1 jumps in human cells.

Henri G.A.M. van Luenen1, Govert J. Schouten2, Dinko Valerio2, Ronald H.A. Plasterk1

1 The Netherlands Cancer Institute, Division of Molecular Biology, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
2 Introgen/Leiden University Medical Centre, Department of Molecular Biology, Wassenaarseweg 72, 2333 AL Leiden, The Netherlands

Tc1 and Tc1-related transposons are found in many species from different
phyla. The distribution of these elements suggests that horizontal
transmission between species has occurred. The limited requirements for
transposition of Tc1 and Tc1-like elements might explain this successful
spread during evolution. We have shown before that Tc1 only requires its
terminal inverted repeats and the transposase protein for transposition
(Vos et. al. (1996) Genes & Development 10:755-761); the element is not
dependent on host encoded factors like the P-element from Drosophila.

We have tested previously whether Tc3 (member of the Tc1 family) is
active in zebrafish (Raz et. al. (1997) Current Biology 8:82-88).
Co-injection of a GFP-marked Tc3 element and Tc3 transposase mRNA into
one cell stage zebrafish embryos resulted in integration of the
transposon. The transposon could be mobilized in the progeny of embryos
carrying the transposon when Tc3 transposase mRNA was again injected.

We now tested Tc1 for its ability to jump into human cells. We cloned a
neomycin expression cassette into Tc1 and this construct was
co-transfected together with a Tc1 transposase expression construct into
a human embryo retina cell line. After selection with G418 we obtained
50% more colonies when Tc1 transposase was co- transfected. A few
colonies were isolated and analysed for the presence of the transposon.
Using the transposon display technique (Van Luenen and Plasterk (1996)
WBG 14:20) we cloned transposon flanks and sequenced them. Some of the
Tc1 elements were still flanked by the vector sequence, these result
from transposase independent non-homologous recombination events.
However some of the transposon flanks were new: Tc1 had become fused to
a novel sequence, with the junction precisely at the TA dinucleotide at
the transposon terminus. These flanks represent genuine integrations of
Tc1 into the human genome.

These results further support the hypothesis that Tc1-like elements have
spread via horizontal transmission since they can jump in a variety of
hosts; Tc1 from the nematode even jumps in human cells. We will continue
to develop Tc1 and related elements into tools for transgenesis and
mutagenesis of different hosts.