| Non-Scientific
Abstract The ends of eukaryotic chromosomes have repeating segments of DNA called telomeres that prevent the chromosomes from shortening during
DNA replication.Most organisms extend telomeres with the telomerase protein. In fruit flies (Drosophila melanogaster) the telomere length
is maintained by two DNA elements called HeT-A and TART.These elements are a kind of retrotransposon that are similar to retroviruses (such
as HIV) because both make DNA from an RNA template. In Drosophila,HeT-A and TART localize specifically to the telomeres.One of the proteins
thought to be involved in this specific localization is a DnaJ chaperone. Chaperones are proteins that help other proteins to fold and interact
in large complexes.The DnaJ chaperone was tagged with a fluorescent protein so that its localization could be tracked with microscopy.This
study shows DnaJ localization throughout the Drosophila cell.HeT-A and TART were also fluorescently tagged.RNA interference, a technique
used to inhibit specific protein expression, was used to knock down the expression of the DnaJ chaperone. In cells with inhibited DnaJ chaperone
expression, the localization of HeT-A and TART were not affected, indicating that the chaperone protein is not directly involved in the
nuclear localization of the two retrotransposable elements,HeT-A and TART.
Abstract The non-LTR retrotransposons HeT-A and TART maintain Drosophila melanogaster telomeres by repeated transpositions onto the ends of
chromosomes. Unlike other retrotransposons, HeT-A localizes specifically to telomeres and does not encode its own reverse transriptase. A
putative DnaJ chaperone protein, CG8863, was shown to interact with the HeT-A protein in a yeast two-hybrid screen. To explore this predicted
interaction and its possible role in HeT-A localization or function, RNA interference was used to knock down the CG8863 protein in
Drosophila cells transiently transfected with a HeT-A:GFP fusion.A CG8863-GFP fusion was constructed and transfected into Drosophila cells
to analyze intracellular targeting of the putative chaperone. The results suggest that CG8863 is not directly involved in the nuclear localization
of the HeT-A protein and that it localizes throughout the cell and is not restricted to a single subcellular compartment. |
