Phosphorylation of Akt at Thr308 regulates p-eNOS Ser1177 during physiological conditions.

Endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) plays a crucial role in maintaining vascular homeostasis. As a hallmark of eNOS activation, phosphorylation of eNOS at Ser1177 induced by activated protein kinase B (PKB/Akt) is pivotal for NO production. The complete activation of Akt requires its phosphorylation of both Thr308 and Ser473. However, which site plays the main role in regulating phosphorylation of eNOS Ser1177 is still controversial. The purpose of the present study is to explore the specific regulatory mechanism of phosphorylated Akt in eNOS activation. Inhibition of Akt Thr308 phosphorylation by a specific inhibitor or by siRNA in vitro led to a decrease in eNOS phosphorylation at Ser1177 and to lower NO concentration in the cell culture medium of HUVECs. However, inhibiting p-Akt Ser473 had no effect on eNOS phosphorylation at Ser1177. Next, we administered mice with inhibitors to downregulate p-Akt Ser473 or Thr308 activity. Along with the inhibition of p-Akt Thr308, vascular p-eNOS Ser1177 protein was simultaneously downregulated in parallel with a decrease in plasma NO concentration. Additionally, we cultured HUVECs at various temperature conditions (37, 22, and 4 °C). The results showed that p-Akt Ser473 was gradually decreased in line with the reduction in temperature, accompanied by increased levels of p-Akt Thr308 and p-eNOS Ser1177. Taken together, our study indicates that the phosphorylation of Akt at Thr308, but not at Ser473, plays a more significant role in regulating p-eNOS Ser1177 levels under physiological conditions.

Long-term outcomes of individualized treatment strategy in treatment of type I Budd-Chiari syndrome in 456 patients.

AIM: To evaluate individualized treatment strategy (ITS) and long-term outcomes of endovascular treatment of Budd-Chiari syndrome (BCS) with obstructed inferior vena cava (IVC) based on different degrees of hepatic vein (HV) involvement. METHODS: From January 2006 to June 2017, 456 consecutive patients with BCS with obstructed IVC underwent endovascular treatment with ITS. All patients received IVC recanalization. Then, 426 patients with at least one patent HV received no additional treatment. Twenty-fivepatients with membranous or segmental occlusion of HVs underwent HV recanalization and for the remaining five patients with diffuse HVs occlusion, a transjugular intrahepatic portosystemic shunt (TIPS) was performed. RESULTS: The endovascular treatment was technically successful in 455 of the 456 patients (99.8%). The complication rate was 5.0% (23/456), with major complications in 13 patients (2.8%) and minor complications in 10 patients (2.2%). Median follow-up time was 60.5 months (range, 4-120 months). The cumulative 1-, 2-, 5- and 10-year primary vessel patency rates were 93.6%, 89.9%, 80.5% and 74.3% respectively and the cumulative 1-, 2-, 5-, 10- year secondary patency rates were 99.8%, 99.8%, 98.2% and 97.2% respectively. The cumulative 1-, 2-, 5- and 10-year survival rates were 98.4%, 95.8%, 91.2% and 76.5% respectively. Illness duration and decreased serum albumin were independent predictors of survival. CONCLUSION: The ITS for Asian BCS with obstructed IVC and varying degrees of HV involvement appears to be effective and with good long-term outcomes.