Akt-Dependent Glycolysis-Driven Lipogenesis Supports Proliferation and Survival of Human Pulmonary Arterial Smooth Muscle Cells in Pulmonary Hypertension

Abstract

Hyper-proliferation of pulmonary arterial vascular smooth muscle cells (PAVSMC) is an important pathological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH). Lipogenesis is linked to numerous proliferative diseases, but its role in PAVSMC proliferation in PAH remains to be elucidated. We found that early-passage human PAH PAVSMC had significant up-regulation of key fatty acids synthesis enzymes ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FASN), and increased unstimulated proliferation compared to control human PAVSMC. Treatment with an allosteric ACC inhibitor 5-tetradecyloxy-2-furoic acid (TOFA) significantly decreased proliferation and induced apoptosis of human PAH PAVSMC. Intracellular lipid content and proliferation of PAH PAVSMC were not reduced by incubation in lipid-depleted media but suppressed by a non-metabolizable analog of glucose 2-Deoxy-D-glucose (2-DG) and partially restored by addition of pyruvate. Protein kinase Akt was upregulated in human PAH PAVSMC in a sirtuin 7 (SIRT7)- and c-Jun N-terminal kinase (JNK)-dependent manner. Pharmacological inhibition of Akt down-regulated ACLY and ACC, significantly reduced intracellular lipid content, inhibited proliferation and induced apoptosis of human PAH PAVSMC. Taken together, these data demonstrate that human PAH PAVSMC have up-regulated lipogenesis, which is supported in an Akt- and glycolysis-dependent manner and is required for increased proliferation and survival. Our data suggest that there is a mechanistic link between glycolysis, lipogenesis, and the proliferation of human PAH PAVSMC and call for further studies to determine the potential attractiveness of a SIRT7/JNK-Akt-lipogenesis axis as a target pathway to inhibit PAVSMC hyper-proliferation in PAH.

Endothelium-specific SIRT7 targeting ameliorates pulmonary hypertension through Krüpple-like factor 4 deacetylation

“… 3 HIF-1α and HIF-2α are differentially expressed in IPAH PASMCs and PAECs. 28 We found reduced SIRT7 expression in PAH PAECs might be due to hyperactivation of HIF-2α. The imbalance of TGF-β signalling caused by BMPR2 loss is involved in vascular remodelling during PH, and increased TGF-β level and Smad3 signalling activation were observed in both PH patients and rodent models.…”

“…>HIF-2α has been reported to be specifically induced by hypoxia in PAECs. 28 We found that overexpression of HIF-2α suppressed SIRT7 expression, while knockdown of HIF-2α abolished the suppression of SIRT7 by hypoxia (see Supplementary material online , Figure S3C – F ).…”

Identification of Zip8-correlated hub genes in pulmonary hypertension by informatic analysis

“…The importance of lipid mechanism in PH ( Siques et al, 2020 ; Xu, Janocha & Erzurum, 2021 ) has been demonstrated, and imbalanced fatty acid metabolism is reported in the heart and lungs of PAH patients ( Hernandez-Saavedra et al, 2020 ; Zhao et al, 2014b ; Zhuang et al, 2019 ). A higher rate of de novo fatty acid synthesis was found in PAH-HPASMC, and increased expression of FASN was observed in the lungs of MCT-treated rats ( Singh et al, 2016 ) and human PAH pulmonary arterial vascular smooth muscle cells (PAVSMC) ( Jiang et al, 2022 ). In addition, another fatty acid synthesis enzyme ACLY was also upregulated in PAVSMC ( Jiang et al, 2022 ).…”

“…A higher rate of de novo fatty acid synthesis was found in PAH-HPASMC, and increased expression of FASN was observed in the lungs of MCT-treated rats ( Singh et al, 2016 ) and human PAH pulmonary arterial vascular smooth muscle cells (PAVSMC) ( Jiang et al, 2022 ). In addition, another fatty acid synthesis enzyme ACLY was also upregulated in PAVSMC ( Jiang et al, 2022 ). Furthermore, another study reveals that inhibition of FASN is beneficial for endothelial function in PH ( Singh et al, 2017 ) and improves cardiac function associated with PH ( Singh et al, 2019 ).…”

Single Nucleotide Polymorphism rs9277336 Controls the Nuclear Alpha Actinin 4‐Human Leukocyte Antigen‐DPA1 Axis and Pulmonary Endothelial Pathophenotypes in Pulmonary Arterial Hypertension

“…Cell isolation, characterization, and maintenance were performed under Pulmonary Hypertension Breakthrough Initiative‐approved protocols, as described previously. 28 , 29 , 30 , 31 Cells were maintained in complete PromoCell Smooth Muscle Cell Growth Medium 2 with SupplementPack and Antibiotic‐Antimycotic. Before experiments, cells were incubated for 48 hours in basal media supplemented with 0.1% BSA (for immunoblot lysates) or with 0.2% FBS (for RNA isolation).…”