Geranylgeranyl Transferase-I Knockout Inhibits Oxidative Injury of Vascular Smooth Muscle Cells and Attenuates Diabetes-Accelerated Atherosclerosis

Abstract

The proliferation of vascular smooth muscle cells (VSMCs) induced by oxidative injury is one of the main features in diabetes-accelerated atherosclerosis. Geranylgeranyl transferase-I (GGTase-I) is an essential enzyme mediating posttranslational modification, especially the geranylgeranylation of small GTPase, Rac1. Our previous studies found that GGTase-I played an important role in diabetes-accelerated atherosclerosis. However, its exact role is largely unclear. In this study, mouse conditional knockout of VSMC GGTase-I (Pggt1bΔ/Δ mice) was generated using the CRISPR/Cas9 system. The mouse model of diabetes-accelerated atherosclerosis was induced by streptozotocin injections and an atherogenic diet. We found that GGTase-I knockout attenuated diabetes-accelerated atherosclerosis in vivo and suppressed high-glucose-induced VSMC proliferation in vitro. Moreover, after a 16-week duration of diabetes, Pggt1bΔ/Δ mice exhibited lower α-smooth muscle actin (α-SMA) and nitrotyrosine level, Rac1 activity, p47phox and NOXO1 expression, and phospho-ERK1/2 and phosphor-JNK content than wild-type mice. Meanwhile, the same changes were found in Pggt1bΔ/Δ VSMCs cultured with high glucose (22.2 mM) in vitro. In conclusion, GGTase-I knockout efficiently blocked diabetes-accelerated atherosclerosis, and this protective effect must be related to the inhibition of VSMC proliferation. The potential mechanisms probably involved interfering Rac1 geranylgeranylation, inhibiting the assembly of NADPH oxidase cytosolic regulatory subunits, reducing oxidative injury, and decreasing ERK1/2 and JNK phosphorylation.

Role of glycolysis in diabetic atherosclerosis

“…Enhanced glycolysis in VSMCs is important for platelet-derived growth factor-induced VSMC proliferation and migration, which is an important contributor to AS[ 70 , 71 ]. In the context of diabetes, VSMC proliferation secondary to oxidative injury is a primary process that accelerates AS progression[ 72 ]. Intracellular transportation of low-density lipoprotein (LDL), followed by subintimal oxidation, results in the formation of oxidized LDL (ox-LDL)[ 73 ].…”

Targeting Small GTPases and Their Prenylation in Diabetes Mellitus

“…Although GGTase-I is an attractive target for cancer-related studies, its inhibitors are rarely used in diabetes research. GGTase-I might be overexpressed under high glucose concentrations ( Table 3 ), while its knock-down blocked diabetes-accelerated atherosclerosis, 251 which might be related to interfering with Rac1 geranylgeranylation, finally inhibiting ROS production, and ERK1/2 and JNK signaling.…”

Harnessing the Potential of CRISPR/Cas in Atherosclerosis: Disease Modeling and Therapeutic Applications

“…Down-regulation of other gene targets such as ANGPTL8, FMO3, and STXBP5 were also modeled in mice and displayed impaired lipogenesis with reduced body weight and plasma triglyceride levels [130], reduced thrombosis potential and atherosclerosis [131], and lowered plasma von Willebrand factor (VWF) levels with reduced thrombosis [132]. Besides, conditional Geranylgeranyl transferase-I (GGTase-I) knockout mice was generated to study the GGTase-I enzyme, which is involved in the mediation of post-translational modification (e.g., geranylgeranylation) of small GTPase, Rac1 [133]. GGTase-I produced from the expression of protein geranylgeranyltransferase type I subunit beta (PGGT1B) gene is associated to diabetes-accelerated atherosclerosis, and removal of PGGT1B gene in mice shown attenuated phenotype of diabetes-accelerated atherosclerosis with possible involvement of several mechanisms that inhibit VSMC proliferation [133].…”

“…Besides, conditional Geranylgeranyl transferase-I (GGTase-I) knockout mice was generated to study the GGTase-I enzyme, which is involved in the mediation of post-translational modification (e.g., geranylgeranylation) of small GTPase, Rac1 [133]. GGTase-I produced from the expression of protein geranylgeranyltransferase type I subunit beta (PGGT1B) gene is associated to diabetes-accelerated atherosclerosis, and removal of PGGT1B gene in mice shown attenuated phenotype of diabetes-accelerated atherosclerosis with possible involvement of several mechanisms that inhibit VSMC proliferation [133].…”