Background: rTg4510 mice are transgenic mice expressing P301L mutant tau and have been
developed as an animal model of tauopathy including Alzheimer’s Disease (AD). Cornel Iridoid Glycoside
(CIG) is an active ingredient extracted from Cornus officinalis, a traditional Chinese herb. The purpose
of the present study was to investigate the effects of CIG on tau pathology and underlying mechanisms
using rTg4510 mice.
Methods: The cognitive functions were detected by Morris water maze and objective recognition tests.
Western blotting and immunofluorescence were conducted to measure the levels of phosphorylated tau
and related proteins. Serine/threonine phosphatase assay was applied to detect the activity of protein
phosphatase 2A (PP2A).
Results: Intragastric administration of CIG for 3 months improved learning and memory abilities, prevented
neuronal and synapse loss, halted brain atrophy, elevated levels of synaptic proteins, protected
cytoskeleton, reduced tau hyperphosphorylation and aggregation in the brain of rTg4510 mice. In the
mechanism studies, CIG increased the activity of PP2A, elevated the methylation of PP2A catalytic C
(PP2Ac) at leucine 309, decreased the phosphorylation of PP2Ac at tyrosine 307, and increased protein
expression of leucine carboxyl methyltransferase 1 (LCMT-1), protein tyrosine phosphatase 1B
(PTP1B), and protein phosphatase 2A phosphatase activator (PTPA) in the brain of rTg4510 mice.
Conclusion: CIG might have the potential to treat tauopathy such as AD via activating PP2A.