Vascular smooth muscle cell contractile protein expression is increased through protein kinase G-dependent and -independent pathways by glucose-6-phosphate dehydrogenase inhibition and deficiency

Abstract

Homeostatic control of vascular smooth muscle cell (VSMC) differentiation is critical for contractile activity and regulation of blood flow. Recently, we reported that precontracted blood vessels are relaxed and the phenotype of VSMC is regulated from a synthetic to contractile state by glucose-6-phosphate dehydrogenase (G6PD) inhibition. In the current study, we investigated whether the increase in the expression of VSMC contractile proteins by inhibition and knockdown of G6PD is mediated through a protein kinase G (PKG)-dependent pathway and whether it regulates blood pressure. We found that the expression of VSMC-restricted contractile proteins, myocardin (MYOCD), and miR-1 and miR-143 are increased by G6PD inhibition or knockdown. Importantly, RNA-sequence analysis of aortic tissue from G6PD-deficient mice revealed uniform increases in VSMC-restricted genes, particularly those regulated by the MYOCD-serum response factor (SRF) switch. Conversely, expression of Krüppel-like factor 4 (KLF4) is decreased by G6PD inhibition. Interestingly, the G6PD inhibition-induced expression of miR-1 and contractile proteins was blocked by Rp-β-phenyl-1,N-etheno-8-bromo-guanosine-3',5'-cyclic monophosphorothioate, a PKG inhibitor. On the other hand, MYOCD and miR-143 levels are increased by G6PD inhibition through a PKG-independent manner. Furthermore, blood pressure was lower in the G6PD-deficient compared with wild-type mice. Therefore, our results suggest that the expression of VSMC contractile proteins induced by G6PD inhibition occurs via PKG1α-dependent and -independent pathways.

Signaling and metabolic properties of fast and slow smooth muscle types from mice

“…However, it has been shown that G6PDH is upregulated in isolated smooth muscle cells during mechanical/oxidative stress and that downregulation of the enzyme leads to increased oxidative stress [ 30 ]. In intact smooth muscle tissues, the activity of G6PDH is negatively correlated with the expression of contractile proteins [ 10 ], and a generally lower expression of G6PDH in the bladder might be important for maintaining a contractile phenotype. At the same time, oxidative stress of bladder smooth muscle has been proposed to be a pathological mechanism in bladder disorders [ 31 ], and a lower expression of G6PDH might be involved in these processes.…”

Metabolism of vascular smooth muscle cells in vascular diseases

“…PPP, catalyzed by HK and consuming glucose-6-phosphate as a primary substrate, is the main source of nicotinamide adenine dinucleotide phosphate reduced (NADPH), which can be used either to transform the oxidized form of glutathione (GSSG) to its reduced form (GSH) or as a substrate to fuel NADPH oxidase (NOX) (184,188). In animal models, glucose-6-phosphate dehydrogenase (G6PDH), the rate-limiting enzyme of the PPP, is involved in the regulation of coronary artery contraction and relaxation (11,45,84). Enhanced activity of G6PDH could reduce murine VSMC apoptosis and enhance VSMC viability via GSH homeostasis (62).…”

Role of Uremic Toxins in Early Vascular Ageing and Calcification

“…In physiological conditions, VSMCs maintain a certain degree of differentiation plasticity and have a contractile phenotype that confers the contraction and relaxation properties of the blood vessels and maintain vessel wall integrity and structural characteristics. However, under mechanical trauma or certain chemical stimuli, and among those several uremic toxins, VSMCs can switch to a synthetic phenotype that mediates vascular repair and remodeling processes associated with medial hypertrophy and atherosclerosis [ 25 , 26 ].…”