Effect of Orexin-A on Mitochondrial Biogenesis, Mitophagy and Structure in HEK293-APPSWE Cell Model of Alzheimer's Disease.

Mitochondrial dysfunction plays a key role in the pathogenesis and progression of Alzheimer's Disease. Our previous studies showed that over expression of AD-associated mutant APP led to abnormalities of mitochondrial biogenesis and mitophagy, leading to mitochondrial dysfunction. However the mechanism remains unclear. In this study, we investigated the effect of orexin-A on mitochondrial biogenesis, mitophagy and mitochondrial structure in over expression of AD-associated mutant APP cells. We used 20E2 cells as the AD cell model. 20E2 cells were treated with orexin-A (50, 100 nM). The effect of different concentrations of orexin-A on cell activity was detected by MTT. As compared with the non-treated 20E2 cells, orexin-A-treated 20E2 cells showed increased expression of APP, decreased cell viability and decreased adenosine triphosphate (ATP) level, decreased levels of regulatory proteins of mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator 1-alpha [PGC-1α], nuclear respiratory factor 1/2 [NRF1/2], mitochondrial transcription factor A [TFAM]), increased levels of regulatory proteins of mitophagy (Parkin, PTEN-induced putative kinase 1 [PINK1], microtubule-associated protein light chain 3 II/I [LC3-II/LC3-I]) and decreased p62 level, with damaged mitochondrial structure. Orexin-A may reduce mitochondrial biogenesis, enhance mitophagy and damage mitochondrial structure in AD.