Involvement of PI3K/Akt/CREB and redox changes in mitochondrial defect of osteoblastic MC3T3-E1 cells

Antimycin A (AMA) is an inhibitor of mitochondrial electron transport via its binding to complex III. In the present study, the mechanisms involved in AMA-induced cell damage were investigated. Treatment of osteoblastic MC3T3-E1 cells with AMA decreased adenosine 3′,5′-cyclic monophosphate (cAMP) level, activities of phosphoinositide 3-kinase (PI3K) and Akt (protein kinase B), and phosphorylated CREB (cAMP-response element-binding protein). To examine whether AMA-induced cell damage involves altered metabolism of pyridine nucleotides, the levels of NAD+, NADH, NADP+, and NADPH were measured. Treatment with AMA significantly decreased the levels of NAD+ and NADPH. Moreover, the activities of aconitase and thioredoxin reductase were decreased by AMA treatment. These results suggest that PI3K/Akt/CREB pathway and pyridine nucleotide (NAD+ and NADPH) are related to mitochondria function of osteoblasts.

► Pretreatment with kaempferol prior to antimycin A exposure reduced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, and [Ca2+]i elevation.
► Kaempferol decreased the ROS production induced by antimycin A.
► Kaempferol induced the activation of PI3K, Akt, and CREB inhibited by antimycin A.