Poldip2 knockdown inhibits vascular smooth muscle proliferation and neointima formation by regulating the expression of PCNA and p21

Abstract

Polymerase delta interacting protein 2 (Poldip2) is a multi-functional protein with numerous roles in the vasculature, including the regulation of cell apoptosis and migration as well as extracellular matrix deposition; however, its role in VSMC proliferation and neointimal formation is unknown. In this study, we investigated the role of Poldip2 in intraluminal wire-injury induced neointima formation and proliferation of vascular smooth muscle cells in vitro and in vivo. Poldip2 expression was observed in the intima and media of human atherosclerotic arteries, where it colocalized with proliferating cell nuclear antigen (PCNA). Wire injury of femoral arteries of Poldip2 +/+ mice induced robust neointimal formation after two weeks, which was impaired in Poldip2 +/− mice. PCNA expression was significantly reduced and expression of the cell cycle inhibitor p21 was significantly increased in wire-injured arteries of Poldip2 +/− animals compared to wild type controls. No difference was observed in apoptosis. Down-regulation of Poldip2 in rat aortic smooth muscle cells significantly reduced serum-induced proliferation and PCNA expression, but upregulated p21 expression. Downregulation of p21 using siRNA reversed the inhibition of proliferation induced by knock down of Poldip2. These results indicate that Poldip2 plays a critical role in the proliferation of VSMCs.

Disease-relevant single cell photonic signatures identify S100β stem cells and their myogenic progeny in vascular lesions

“…While heterozygous Poldip2 deletion has no obvious phenotype, mice are protected against neointimal formation following injury 116 underlying the importance of metabolism in disease progression. Therefore, it is possible that the changes in the photonic emissions from ligated cells may also involve alterations in the metabolic state of these cells, in particular, if these cells are de-differentiated SMCs and/or stem cell derived myogenic progeny.…”

“…Poldip2 deficiency reduces the activity of the Krebs cycle and inhibits rates of oxidative metabolism while increasing rates of glycolytic activity in many different cell types, including vascular SMCs [67]. While heterozygous Poldip2 deletion has no obvious phenotype, it is notable that mice are protected against neointimal formation following injury [72] underlying the importance of metabolism in disease progression. Therefore, it is possible that the changes in the photonic profile from ligated cells may also involve alterations in the metabolic state of these cells, in particular, if these cells are mVSc cell-derived myogenic progeny.…”

The pathophysiological basis of vascular disease

“…Of note, ROS play a clear role in the regulation of VSMC phenotypic switching, which was comprehensively reviewed by Durgin et al in "Redox control of vascular smooth muscle cell function and plasticity", in which the authors discuss the current understanding of the role of vascular Noxes in VSMC differentiation state [38]. In a study by Datla et al, they investigated the role of Poldip2, a multi-function protein with numerous roles in the vasculature, in the neo-intimal formation process [39]. They first establish in stage II human atherosclerotic plaques that Polidp2 is highly expressed in the endothelium and in the underlying VSMCs, where Poldip2 co-localized with proliferating cell nuclear antigen (PCNA) [39].…”

“…In a study by Datla et al, they investigated the role of Poldip2, a multi-function protein with numerous roles in the vasculature, in the neo-intimal formation process [39]. They first establish in stage II human atherosclerotic plaques that Polidp2 is highly expressed in the endothelium and in the underlying VSMCs, where Poldip2 co-localized with proliferating cell nuclear antigen (PCNA) [39]. Furthermore, they clearly show in a femoral-artery wire injury model that the lack of Poldip2 (heterozygous mice) decreases neointimal formation and ROS production in vivo and VSMC proliferation in vitro and in vivo, potentially via increased expression of the cell cycle inhibitor p21 [39].…”

“…They first establish in stage II human atherosclerotic plaques that Polidp2 is highly expressed in the endothelium and in the underlying VSMCs, where Poldip2 co-localized with proliferating cell nuclear antigen (PCNA) [39]. Furthermore, they clearly show in a femoral-artery wire injury model that the lack of Poldip2 (heterozygous mice) decreases neointimal formation and ROS production in vivo and VSMC proliferation in vitro and in vivo, potentially via increased expression of the cell cycle inhibitor p21 [39]. One proposed mechanism by Datla et al is the regulation of hydrogen peroxide production from Nox4 by Poldip2, since it was previously shown that Poldip2 increases Nox4 activity and ROS generation [40] and VSMC migration [41].…”