Fig. 2.

Relations between genes responsible for circadian rhythm and neurodegeneration are numerous. Deleting the BMAL1 center clock’s gene in the cortex and hippocampus leads to oxidative stress including severe reactive astrocytosis, neuronal oxidative damage, the degeneration of synaptic terminals, and neurodegeneration. In turn, neurodegenerative protein Aβ triggers deterioration of BMAL1 and CBP center clock proteins which then change the expression of BMAL1 and PER2 center clock’s genes resulting in a disturbed circadian rhythm. BMAL1 and CLOCK proteins also activate PSEN-2 gene expression which codes presenilin-2 protein. This protein cleaves APP and, as a result, diminishes the amount of Aβ [11, 22, 39, 40]