title: Transgene expression in the Nop-tTA driver line is not inherently restricted to the entorhinal cortex.
abstract: The entorhinal cortex (EC) plays a central role in episodic memory and is among the earliest sites of neurodegeneration and neurofibrillary tangle formation in Alzheimer's disease. Given its importance in memory and dementia, the ability to selectively modulate gene expression or neuronal function in the EC is of widespread interest. To this end, several recent studies have taken advantage of a transgenic line in which the tetracycline transactivator (tTA) was placed under control of the neuropsin (Nop) promoter to limit transgene expression within the medial EC and pre-/parasubiculum. Although the utility of this driver is contingent on its spatial specificity, no detailed neuroanatomical analysis of its expression has yet been conducted. We therefore undertook a systematic analysis of Nop-tTA expression using a lacZ reporter and have made the complete set of histological sections available through the Rodent Brain Workbench tTA atlas, www.rbwb.org . Our findings confirm that the highest density of tTA expression is found in the EC and pre-/parasubiculum, but also reveal considerable expression in several other cortical areas. Promiscuous transgene expression may account for the appearance of pathological protein aggregates outside of the EC in mouse models of Alzheimer's disease using this driver, as we find considerable overlap between sites of delayed amyloid deposition and regions with sparse β-galactosidase reporter labeling. While different tet-responsive lines can display individual expression characteristics, our results suggest caution when designing experiments that depend on precise localization of gene products controlled by the Nop-tTA or other spatially restrictive transgenic drivers.
authors: Departments of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, BCM295, One Baylor Plaza, Houston, TX, 77030, USA.
authors: Michael J
authors: MJ
authors: Yetman
authors: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors: Sveinung
authors: S
authors: Lillehaug
authors: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors: Jan G
authors: JG
authors: Bjaalie
authors: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
authors: Trygve B
authors: TB
authors: Leergaard
authors: Departments of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, BCM295, One Baylor Plaza, Houston, TX, 77030, USA. jankowsk@bcm.edu.|Departments of Neurology and Neurosurgery, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA. jankowsk@bcm.edu.
authors: Joanna L
authors: JL
authors: Jankowsky
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism; D018728:Entorhinal Cortex / Q000378:metabolism*; D005697:Galactosides / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D007150:Immunohistochemistry; D007211:Indoles / Q000378:metabolism; D007610:Kallikreins / Q000378:metabolism*; D007763:Lac Operon; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D013752:Tetracycline / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D016564:Amyloid beta-Protein Precursor; D005697:Galactosides; D007211:Indoles; D015534:Trans-Activators; D007610:Kallikreins; C114664:Prss19 protein, mouse; D013752:Tetracycline; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside
keywords: Ectopic expression; Rodent brain atlas; Tet-lacZ reporter; Tet-off transgenic; Tetracycline transactivator