ApoE4 genotype is the most prevalent and also clinically most important risk factor for late-onset Alzheimer’s disease (AD). Available evidence suggests that the root cause for this increased risk is a trafficking defect at the level of the early endosome. ApoE4 differs from the most common ApoE3 isoform by a single amino acid that increases its isoelectric point and promotes unfolding of ApoE4 upon endosomal vesicle acidification. We found that pharmacological and genetic inhibition of NHE6, the primary proton leak channel in the early endosome, in rodents completely reverses the ApoE4-induced recycling block of the ApoE receptor Apoer2/Lrp8 and the AMPA- and NMDA-type glutamate receptors that are regulated by, and co-endocytosed in a complex with, Apoer2. Moreover, NHE6 inhibition restores the Reelin-mediated modulation of excitatory synapses that is impaired by ApoE4. Our findings suggest a novel potential approach for the prevention of late-onset AD.

Ising et al. report expression of anti-tau scFvs in the brain of a mouse model of tauopathy by AAV-mediated gene transfer. Treated mice show markedly decreased tau hyperphosphorylation and detergent-soluble tau species. Therefore, the Fc domain is not required to mediate effects in tauopathy.

Our previous study has demonstrated that bicarbonate in the uterine fluid plays an indispensable role in sperm capacitation. However, the cellular mechanisms underlying the formation of bicarbonate-rich uterine fluid and the regulatory mechanism remained largely unknown. In this study, the expression profiles of bicarbonate transport/production proteins, the cystic fibrosis transmembrane conductance regulator (CFTR), SLC26A6, carbonic anhydrase 2 (CAR2, CA2) and CAR12 (CA12), throughout the estrous cycle, were examined in the mouse uterus by western blot. The results showed that the maximum expression levels of the proteins examined were observed at estrus. Luminal surface pH measurements showed that the resting uterine surface pH at estrus was significantly higher than that at diestrus, which could be reduced significantly by CFTR blocker, diphenylamine-2,2 0 -dicarboxylic acid, SLC26A6 inhibitor, 4 0 ,4 0 -diisothiocyanostilbene-2 0 ,2 0 -disulfonic acid, and CA inhibitor, acetazolamide. In ovariectomized mice and primary culture of endometrial epithelial cells, estrogen could upregulate CFTR, SLC26A6, CAR2, and CAR12 expression with a corresponding increase in the bicarbonate-dependent short-circuit current (I sc ) and endometrial surface pH. The present results have demonstrated dynamic changes in uterine bicarbonate secretion and expression of the proteins involved in bicarbonate secretion during the estrous cycle and suggested a novel role of estrogen in regulating uterine bicarbonate transport, which may be important for successful reproduction.Reproduction (2010) 140 903-910

BackgroundThe accumulation of pathological tau is the main component of neurofibrillary tangles and other tau aggregates in several neurodegenerative diseases, referred to as tauopathies. Recently, immunotherapeutic approaches targeting tau have been demonstrated to be beneficial in decreasing tauopathy in animal models. We previously found that passive immunotherapy with anti-tau antibody to human tau or expression of an anti-tau secreted single-chain variable fragment (scFv) in the central nervous system of a mouse model of tauopathy decreased but did not remove all tau-associated pathology. Although these and other studies demonstrate that conventional immunotherapeutic approaches targeting tau can influence tau pathogenesis, the majority of pathological tau remains in the cytosol of cells, not typically accessible to an extracellular antibody. Therefore, we reasoned targeting intracellular tau might be more efficacious in preventing or decreasing tauopathy.MethodsBy utilizing our anti-tau scFv, we generated anti-tau intrabodies for the expression in the cytosol of neurons. To enhance the degradation capacity of conventional intrabodies, we engineered chimeric anti-tau intrabodies fused to ubiquitin harboring distinct mutations that shuttle intracellular tau for either the proteasome or lysosomal mediated degradation. To evaluate the efficacy in delaying or eliminating tauopathy, we expressed our tau degrading intrabodies or controls in human tau transgenic mice by adeno-associated virus prior to overt tau pathology and after tau deposition.ResultsOur results demonstrate, the expression of chimeric anti-tau intrabodies significantly reduce tau protein levels in primary neuronal cultures expression human tau relative to a non-modified anti-tau intrabody. We found the expression of engineered tau-degrading intrabodies destined for proteasomal-mediated degradation are more effective in delaying or eliminating tauopathy than a conventional intrabody in aged human tau transgenic mice.ConclusionThis study, harnesses the strength of intrabodies that are amendable for targeting specific domains or modifications with the cell-intrinsic mechanisms that regulate protein degradation providing a new immunotherapeutic approach with potentially improved efficacy.