Alzheimer's disease (AD) is characterized by a substantial degeneration of pyramidal neurons and the appearance of neuritic plaques and neurofibrillary tangles. Here we present a novel transgenic mouse model, APP(SL)PS1KI that closely mimics the development of AD-related neuropathological features including a significant hippocampal neuronal loss. This transgenic mouse model carries M233T/L235P knocked-in mutations in presenilin-1 and overexpresses mutated human beta-amyloid (Abeta) precursor protein. Abeta(x-42) is the major form of Abeta species present in this model with progressive development of a complex pattern of N-truncated variants and dimers, similar to those observed in AD brain. At 10 months of age, an extensive neuronal loss (>50%) is present in the CA1/2 hippocampal pyramidal cell layer that correlates with strong accumulation of intraneuronal Abeta and thioflavine-S-positive intracellular material but not with extracellular Abeta deposits. A strong reactive astrogliosis develops together with the neuronal loss. This loss is already detectable at 6 months of age and is PS1KI gene dosage-dependent. Thus, APP(SL)PS1KI mice further confirm the critical role of intraneuronal Abeta(42) in neuronal loss and provide an excellent tool to investigate therapeutic strategies designed to prevent AD neurodegeneration.
The majority of inherited retinal degenerations converge on the phenotype of photoreceptor cell death. Second-and third-order neurons are spared in these diseases, making it possible to restore retinal light responses using optogenetics. Viral expression of channelrhodopsin in the third-order neurons under ubiquitous promoters was previously shown to restore visual function, albeit at light intensities above illumination safety thresholds. Here, we report (to our knowledge, for the first time) activation of macaque retinas, up to 6 months post-injection, using channelrhodopsin-Ca 2+ -permeable channelrhodopsin (CatCh) at safe light intensities. High-level CatCh expression was achieved due to a new promoter based on the regulatory region of the gamma-synuclein gene (SNCG) allowing strong expression in ganglion cells across species. Our promoter, in combination with clinically proven adeno-associated virus 2 (AAV2), provides CatCh expression in peri-foveolar ganglion cells responding robustly to light under the illumination safety thresholds for the human eye. On the contrary, the threshold of activation and the proportion of unresponsive cells were much higher when a ubiquitous promoter (cytomegalovirus [CMV]) was used to express CatCh. The results of our study suggest that the inclusion of optimized promoters is key in the path to clinical translation of optogenetics.
A two-step gene replacement procedure was developed that generates infectious adenoviral genomes through homologous recombination in Escherichia coli. As a prerequisite, a human adenovirus serotype 5 (Ad5)-derived genome was first introduced as a PacI restriction fragment into an incP-derived replicon which, in contrast to ColE1-derivatives (e.g., pBR322 or pUC plasmids), is functional in a polA mutant of E. coli. Any modification can be introduced at will following two consecutive homologous recombinations between the incP͞Ad5 replicon and the ColE1 plasmid. The overall procedure requires only the in vitro engineering of the ColE1-derivative by f lanking the desired modification with small stretches of identical sequences. In the first step, a cointegrate between the tetracycline-resistant incP͞Ad5 replicon and the kanamycin-resistant ColE1-derivative is selected by growing the polA host in the presence of both antibiotics. Resolution of this cointegrate is further selected in sucrose growth conditions due to the loss of a conditional suicide marker (the sacB gene of Bacillus subtilis) present in the ColE1 plasmid, leading to unmodified and modified incP͞Ad5 replicons that can be differentiated upon restriction analysis. Consecutive rounds of this two-step cloning procedure allowed the introduction of multiple independent modifications within the virus genome, with no requirement for an intermediate virus. The potential of this procedure is demonstrated by the recovery of several E1E3E4-deleted adenoviruses following transfection of the corresponding E. coli-derived genomes in IGRP2 cells.
Background-Apolipoprotein (apo) A-I is the major component of HDL, and it displays antiatherogenic properties. Methods and Results-The human apoA-I gene has been transferred into different mouse models by use of a recombinant adenovirus under the control of an RSV-LTR promoter (AV RSV apoA-I). Administration of AV RSV apoA-I to C57BL/6 mice resulted in moderate expression of human apoA-I for 3 weeks, leading to a transient elevation (40% at day 11 after injection) of HDL cholesterol concentration. In contrast, administration of AV RSV apoA-I to human apoA-I-transgenic mice induced a large increase of human apoA-I and HDL cholesterol concentrations (300% and 360%, respectively, at day 14 after injection) for 10 weeks, indicating that an immune response to the transgene was one major hurdle for long-term duration of expression. Recombinant adenovirus expressing human apolipoprotein A-I (AV RSV apoA-I) was also injected into human apoA-I-transgenic/apoE-deficient mice, which are prone to develop atherosclerosis. Over a 6-week period, overexpression of human apoA-I inhibited fatty streak lesion formation by 56% in comparison with control. Conclusions-Somatic gene transfer of human apoA-I prevents the development of atherosclerosis in the mouse model.(Circulation. 1999;99:105-110.)
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