Research Paper Volume 3, Issue 3 pp 237—261

Ubiquitin over-expression phenotypes and ubiquitin gene molecular misreading during aging in Drosophila melanogaster

Nicholas Hoe1, , Chung M. Huang1, , Gary Landis1, , Marian Verhage2,3, , Daniel Ford1, , Junsheng Yang1, , Fred W. van Leeuwen3, , John Tower1, ,

  • 1 Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2910
  • 2 Netherlands Institute for Neuroscience, 1105 BA Amsterdam, The Netherlands
  • 3 Maastricht University, Department of Neuroscience, 6229ER Maastricht, The Netherlands

Received: February 18, 2011       Accepted: March 10, 2011       Published: March 12, 2011
How to Cite

Copyright: © 2011 Hoe et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Molecular Misreading (MM) is the inaccurate conversion of genomic information into aberrant proteins. For example, when RNA polymerase II transcribes a GAGAG motif it synthesizes at low frequency RNA with a two-base deletion. If the deletion occurs in a coding region, translation will result in production of misframed proteins. During mammalian aging, misframed versions of human amyloid precursor protein (hApp) and ubiquitin (hUbb) accumulate in the aggregates characteristic of neurodegenerative diseases, suggesting dysfunctional degradation or clearance. Here cDNA clones encoding wild-type hUbb and the frame-shifted version hUbb+1 were expressed in transgenic Drosophila using the doxycycline-regulated system. Misframed proteins were abundantly produced, both from the transgenes and from endogenous Drosophila ubiquitin-encoding genes, and their abundance increased during aging in whole-fly extracts. Over-expression of wild-type hUbb, but not hUbb+1, was toxic during fly development. In contrast, when over-expressed specifically in adult flies, hUbb+1 caused small decreases in life span, whereas hUbb was associated with small increases, preferentially in males. The data suggest that MM occurs in Drosophila and that the resultant misframed proteins accumulate with age. MM of the ubiquitin gene can produce alternative ubiquitin gene products with different and sometimes opposing phenotypic effects.


hUbb: human ubiquitin-B; hApp: human amyloid precursor protein; hsp: heat shock protein; MM: molecular misreading; Ub: ubiquitin.