Meprin ß knockout reduces brain Aß levels and rescues learning and memory impairments in the APP/lon mouse model for Alzheimer's disease.

ß-Site amyloid precursor protein (APP) cleaving enzyme-1 (BACE1) is the major described ß-secretase to generate Aß peptides in Alzheimer's disease (AD). However, all therapeutic attempts to block BACE1 activity and to improve AD symptoms have so far failed. A potential candidate for alternative Aß peptides generation is the metalloproteinase meprin ß, which cleaves APP predominantly at alanine in p2 and in this study we can detect an increased meprin ß expression in AD brain. Here, we report the generation of the transgenic APP/lon mouse model of AD lacking the functional Mep1b gene (APP/lon × Mep1b-/-). We examined levels of canonical and truncated Aß species using urea-SDS-PAGE, ELISA and immunohistochemistry in brains of APP/lon mouse × Mep1b-/-. Additionally, we investigated the cognitive abilities of these mice during the Morris water maze task. Aß1-40 and 1-42 levels are reduced in APP/lon mice when meprin ß is absent. Immunohistochemical staining of mouse brain sections revealed that N-terminally truncated Aß2-x peptide deposition is decreased in APP/lon × Mep1b-/- mice. Importantly, loss of meprin ß improved cognitive abilities and rescued learning behavior impairments in APP/lon mice. These observations indicate an important role of meprin ß within the amyloidogenic pathway and Aß production in vivo.

Cysteine proteases as therapeutic targets: does selectivity matter? A systematic review of calpain and cathepsin inhibitors.

Cysteine proteases continue to provide validated targets for treatment of human diseases. In neurodegenerative disorders, multiple cysteine proteases provide targets for enzyme inhibitors, notably caspases, calpains, and cathepsins. The reactive, active-site cysteine provides specificity for many inhibitor designs over other families of proteases, such as aspartate and serine; however, a) inhibitor strategies often use covalent enzyme modification, and b) obtaining selectivity within families of cysteine proteases and their isozymes is problematic. This review provides a general update on strategies for cysteine protease inhibitor design and a focus on cathepsin B and calpain 1 as drug targets for neurodegenerative disorders; the latter focus providing an interesting query for the contemporary assumptions that irreversible, covalent protein modification and low selectivity are anathema to therapeutic safety and efficacy.

The improvement of spatial memory deficits in APP/V717I transgenic mice by chronic anti-stroke herb treatment.

In China, herbal medicine has an extensive history for the treatment of cerebrovascular diseases. Clinical studies have shown that stroke patients are more likely to experience significant memory decline in comparison to their healthy counterparts. Cognition is improved in stroke patients treated with herbal medicine active components, Geniposide (GP) and Geniposide Rg1 (GRg1) (together, called TLJN). However, the effect of TLJN in Alzheimer disease remains unknown. Therefore, we investigated the behavioral effect of TLJN in male and female APP/V717I transgenic (Tg) mice. We conducted two different treatment strategies: (1) pretreatment strategy: medically treated at the age of 3 months which lasted for 3 months; (2) early treatment strategy: medically treated at the age of 6 months which lasted for 4 months. In open field test, locomotor activity and anxiety-like behavior were not affected after TLJN administration in Tg mice. In Morris Water Maze test, spatial learning processes in both genders were improved by TLJN treatments. Furthermore, retrieval processes were significantly improved in the pretreatment strategy for only male mice, which also showed a trend for improved retrieval processes with early treatment. In the inhibitory avoidance test, TLJN enhanced learning processes. In addition, gender differences were found in Tg mice exposed to TLJN treatments. In Tg male mice, significant efficacy was seen at high and middle doses, and in Tg female mice, a low dose was more effective.