Worm Breeder's Gazette 15(4): 19 (October 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.

Phenotypical and biochemical analysis of C. elegans carrying the human Huntington disease gene.

J.C. Dorsman1, M.A. Smoor1, H.G.A.M. van Luenen2, M. Bout1, J.T. den Dunnen1, R.H.A. Plasterk2, G.J.B. van Ommen1

1 Department of Human Genetics, Sylvius Laboratory, Leiden University Medical Center, Leiden, The Netherlands
2 The Netherlands Cancer Institute, Division of Molecular Biology, Amsterdam.

Huntington's disease (HD) is a neurodegenerative CAG (gln) repeat
expansion disorder with a mid-life onset. Animal models may assist in
the understanding of the molecular pathology of HD and other
neurodegenerative diseases caused by similar repeat expansions. In mice
an expanded CAG repeat in exon 1 of the HD gene is sufficient to cause a
progressive neurological phenotype. Thus far no HD homolog has been
identified in C. elegans.

We have generated transgenic nematodes carrying exon 1 or exon 1 to 7 of
the human HD gene, with 17, 73 or 140 CAG repeats. The transgenes are
present either as an extrachromosomal array or integrated into the
genome. Expression of the transgenes is driven by the HSP promoter which
is regulated by heatshock. The 17, 73 and the 140 CAG repeats are stable
upon transmission to offspring in C. elegans whereas they are unstable
in mammals. After heat shock induction HD expression of the transgenes
can be detected. Expression of the 140 HD transgene could only be
detected with a monoclonal antibody which specifically recognises
expanded glutamine repeats and with a polyclonal antibody. The protein
encompassing the expanded glutamine repeat is more stable in time than
the protein containing the normal repeat. An extensive survey of
transgenic worms containing the transgenes revealed that a single heat
shock of either eggs or L1 larvae has no significant effect on
viability. Analysis of the nematodes after recurrent heat shocks under
different environmental conditions is ongoing, including studies in
which specific neurons are stained with fluorescent dyes such as DiO.
Preliminary results indicate that in one line expressing exon 1 with an
expanded repeat dye-filling of the phasmid neurons is affected.
Interestingly, we have also identified an endogenous C. elegans protein
which reacts with the monoclonal antibody against expanded glutamine
repeats. A further characterisation of this protein, which might carry
an expanded glutamine repeat, is underway.