Human Molecular Genetics Advance Access published online on October 18, 2007
Human Molecular Genetics, doi:10.1093/hmg/ddm305
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ubiquilin antagonizes presenilin and promotes neurodegeneration in Drosophila
1 Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA 2 Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA 3 Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA
* Corresponding Author: Ming Guo, MD, PhD Department of Neurology & Pharmacology, David Geffen School of Medicine, Los Angeles, CA 90095-1761, Phone: (310) 206-9406 Fax: (310) 206-9406 Email: mingfly{at}ucla.edu
Received August 24, 2007; Revised September 24, 2007; Accepted October 10, 2007
The majority of familial Alzheimer's disease (AD) cases are caused by mutations in presenilins, therefore, identifying regulators of presenilins is crucial for understanding AD pathogenesis. Ubiquilin 1 (UBQLN1) binds Presenilins in mammalian cells; however, the functional significance of this interaction in vivo remains unclear. Moreover, while genetic variants in UBQLN1 have recently been reported to associate with an increased risk for AD, whether these variants have altered function is unknown. Here, we show that Drosophila Ubiquilin(Ubqn) binds to Drosophila Presenilin (Psn), and that loss of ubqn function suppresses phenotypes that arise from loss of psn function in vivo. In addition, overexpression of ubqn in the eye results in adult-onset, age-dependent retinal degeneration, which is at least partially apoptotic in nature. The degeneration associated with ubqn overexpression can also be suppressed by psn overexpression and enhanced by expression of a dominant negative version of Psn. Remarkably, expression of the human AD-associated variant of UBQLN1 leads to more severe degeneration than does comparable expression of the human wildtype UBQLN1. Together, these data identify Ubqn as a regulator of Psn, support an important role for UBQLN1 in AD pathogenesis, and suggest the possibility that expression of a human AD-associated variant can cause neurodegeneration independent of amyloid production.
4 The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.
5 Current address: Gevo, Inc., Pasadena, CA 91106
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