Ubiquilin-1 overexpression increases the lifespan and delays accumulation of Huntingtin aggregates in the R6/2 mouse model of Huntington's disease.
Huntington's Disease (HD) is a neurodegenerative disorder that is caused by abnormal expansion of a polyglutamine tract in huntingtin (htt) protein. The expansion leads to increased htt aggregation and toxicity. Factors that aid in the clearance of mutant huntingtin proteins should relieve the toxicity. We previously demonstrated that overexpression of ubiqulin-1, which facilitates protein clearance through the proteasome and autophagy pathways, reduces huntingtin aggregates and toxicity in mammalian cell and invertebrate models of HD. Here we tested whether overexpression of ubiquilin-1 delays or prevents neurodegeneration in R6/2 mice, a well-established model of HD. We generated transgenic mice overexpressing human ubiquilin-1 driven by the neuron-specific Thy1.2 promoter. Immunoblotting and immunohistochemistry revealed robust and widespread overexpression of ubiquilin-1 in the brains of the transgenic mice. Similar analysis of R6/2 animals revealed that ubiquilin is localized in huntingtin aggregates and that ubiquilin levels decrease progressively to 30% during the end-stage of disease. We crossed our ubiquilin-1 transgenic line with R6/2 mice to assess whether restoration of ubiquilin levels would delay HD symptoms and pathology. In the double transgenic progeny, ubiquilin levels were fully restored, and this correlated with a 20% increase in lifespan and a reduction in htt inclusions in the hippocampus and cortex. Furthermore, immunoblots indicated that endoplasmic reticulum stress response that is elevated in the hippocampus of R6/2 animals was attenuated by ubiquilin-1 overexpression. However, ubiquilin-1 overexpression neither altered the load of htt aggregates in the striatum nor improved motor impairments in the mice.
Neuroscience Graduate Program, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America.
Nathaniel
N
Safren
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, United States of America.
Amina
A
El Ayadi
Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America.
Lydia
L
Chang
Neuroscience Graduate Program, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Department of Psychiatry, School of Medicine University of Maryland, Baltimore, Maryland, United States of America.
Chantelle E
CE
Terrillion
Neuroscience Graduate Program, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Department of Psychiatry, School of Medicine University of Maryland, Baltimore, Maryland, United States of America ; Department of Pharmacology, School of Medicine University of Maryland, Baltimore, Maryland, United States of America.
Todd D
TD
Gould
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas, United States of America.
Darren F
DF
Boehning
Neuroscience Graduate Program, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America ; Department of Anatomy and Neurobiology, School of Medicine, University of Maryland, Baltimore, Maryland, United States of America.
Mervyn J
MJ
Monteiro
D048868:Adaptor Proteins, Signal Transducing; D000704:Analysis of Variance; D000818:Animals; D000071183:Autophagy-Related Proteins; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D003433:Crosses, Genetic; D017931:DNA Primers / Q000235:genetics; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000188:drug therapy*; D015151:Immunoblotting; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D045442:Rotarod Performance Test
D048868:Adaptor Proteins, Signal Transducing; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; C107792:UBQLN1 protein, human