Cocoa extracts reduce oligomerization of amyloid-ß: implications for cognitive improvement in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder, characterized by pathological aggregates of amyloid peptide-ß (Aß) and tau protein. Currently available therapies mediate AD symptoms without modifying disease progression. Polyphenol-rich diets are reported to reduce the risk for AD. OBJECTIVE: In the present study, we investigated the AD disease-modifying effects of cocoa, a rich source of flavanols, which are a class of polyphenols. We hypothesized that cocoa extracts interfere with amyloid-ß oligomerization to prevent synaptic deficits. METHODS: We tested the effects of three different cocoa extracts, viz. Natural, Dutched, and Lavado extracts, on Aß42 and Aß40 oligomerization, using photo-induced cross-linking of unmodified proteins technique. To assess the effects of cocoa extracts on synaptic function, we measured long term potentiation in mouse brain hippocampal slices exposed to oligomeric Aß. RESULTS: Our results indicate that cocoa extracts are effective in preventing the oligomerization of Aß, with Lavado extract being most effective. Lavado extract, but not Dutched extract, was effective in restoring the long term potentiation response reduced by oligomeric Aß. CONCLUSION: Our findings indicate that cocoa extracts have multiple disease-modifying properties in AD and present a promising route of therapeutic and/or preventative initiatives.

Targeted deletion of the gene encoding the La autoantigen (Sjögren's syndrome antigen B) in B cells or the frontal brain causes extensive tissue loss.

La antigen (Sjögren's syndrome antigen B) is a phosphoprotein associated with nascent precursor tRNAs and other RNAs, and it is targeted by autoantibodies in patients with Sjögren's syndrome, systemic lupus erythematosus, and neonatal lupus. Increased levels of La are associated with leukemias and other cancers, and various viruses usurp La to promote their replication. Yeast cells (Saccharomyces cerevisiae and Schizosaccharomyces pombe) genetically depleted of La grow and proliferate, whereas deletion from mice causes early embryonic lethality, raising the question of whether La is required by mammalian cells generally or only to surpass a developmental stage. We developed a conditional La allele and used it in mice that express Cre recombinase in either B cell progenitors or the forebrain. B cell Mb1(Cre) La-deleted mice produce no B cells. Consistent with αCamKII Cre, which induces deletion in hippocampal CA1 cells in the third postnatal week and later throughout the neocortex, brains develop normally in La-deleted mice until ∼5 weeks and then lose a large amount of forebrain cells and mass, with evidence of altered pre-tRNA processing. The data indicate that La is required not only in proliferating cells but also in nondividing postmitotic cells. Thus, La is essential in different cell types and required for normal development of various tissue types.