PGC-1β Mediates the Atheroprotective Roles of β-Aminoisobutyric Acid (BAIBA) in Vascular Endothelial Cells

Physical exercise exerts antiatherosclerotic effects through several mechanisms. One anti-inflammatory effect of exercise is directly exerted on vascular endothelial cells by β-aminoisobutyric acid (BAIBA), which is released from the skeletal muscles during physical activity. The increased expression of estrogen-related receptor α (ERRα) and peroxisome proliferator-activated receptor-gamma co-activator (PGC)-1β also plays a role in these mechanisms. However, the underlying mechanisms remain unknown, and we aimed to explore the effects of PGC-1β on the endothelial function.

We generated human umbilical vein endothelial cells (HUVECs) with PGC-1β knockdown using siRNA or by inducing the overexpression of PGC-1β using an adenovirus. We then examined the expression of inflammation-related genes induced by tumor necrosis factor α (TNFα) using qRT-PCR and the expression of endothelial nitric oxide synthase (eNOS) and its activation-related proteins using a western blot analysis.

BAIBA treatment suppressed the TNFα-induced expression of inflammation-related molecules in HUVECs. However, these protective effects were diminished following PGC-1β knockdown, which correlated with decreased levels of IκBα protein. Additionally, in PGC-1β knockdown-HUVECs, the total and phosphorylated levels of eNOS decreased along with the levels of active AMP-activated protein kinase (AMPK) and protein kinase B (Akt). Conversely, the overexpression of PGC-1β in HUVECs resulted in the opposite effect.

These results suggest that BAIBA exerts various protective effects on vascular endothelial cells through the PGC-1β-NFκB and PGC-1β-AMPK-Akt-eNOS axes.