Pre–B-Cell Colony–Enhancing Factor Regulates NAD ⁺ -Dependent Protein Deacetylase Activity and Promotes Vascular Smooth Muscle Cell Maturation

Abstract

Abstract-Conversion of vascular smooth muscle cells (SMCs) from a proliferative state to a nonproliferative, contractile state confers vasomotor function to developing and remodeling blood vessels. Using a maturation-competent human SMC line, we determined that this shift in phenotype was accompanied by upregulation of pre-B-cell colony-enhancing factor (PBEF), a protein proposed to be a cytokine. Knockdown of endogenous PBEF increased SMC apoptosis and reduced the capacity of synthetic SMCs to mature to a contractile state. In keeping with these findings, human SMCs transduced with the PBEF gene had enhanced survival, an elongated bipolar morphology, and increased levels of h-caldesmon, smoothelin-A, smoothelin-B, and metavinculin. Notwithstanding some prior reports, PBEF did not have attributes of a cytokine but instead imparted the cell with increased nicotinamide phosphoribosyltransferase activity. Intracellular nicotinamide adenine dinucleotide (NAD ϩ ) content was increased in PBEF-overexpressing SMCs and decreased in PBEF-knockdown SMCs. Furthermore, NAD ϩ -dependent protein deacetylase activity was found to be essential for SMC maturation and was increased by PBEF. Xenotransplantation of human SMCs into immunodeficient mice revealed an increased capacity for PBEF-overexpressing SMCs to mature and intimately invest nascent endothelial channels. This microvessel chimerism and maturation process was perturbed when SMC PBEF expression was lowered. These findings identify PBEF as a regulator of NAD ϩ -dependent reactions in SMCs, reactions that promote, among other potential processes, the acquisition of a mature SMC phenotype. Key Words: vascular smooth muscle Ⅲ pre-B-cell colony-enhancing factor Ⅲ maturation Ⅲ nicotinamide phosphoribosyltransferase Ⅲ deacetylation C onversion of smooth muscle cells (SMCs) from a proliferative, noncontractile state to a nonproliferative, contractile state is essential for conferring vasomotor function to developing arteries. 1,2 This shift toward a more mature SMC phenotype is also important for terminating SMC-mediated remodeling of diseased arteries. 2 Recently, we cloned adult vascular SMC lines that, in contrast to other human SMC preparations, could reversibly convert between a spread, proliferative, and synthetic state when cultured in the presence of serum to a highly elongated, nonproliferative state when serum was withdrawn. 3,4 In the latter state, the cells displayed decreased apoptosis, increased contractile protein expression, and the ability to contract in response to vasoactive agonists. This system, therefore, provided us with an opportunity to seek out factors that enabled a proliferative adult SMC to efficiently shift to a more quiescent state specialized to contract. Accordingly, we undertook differential display polymerase chain reaction (PCR) and high-density microarray analyses to identify genes that were differentially expressed as these human SMCs executed this key shift in phenotype.These surveys consistently identified pre-B cell colonyenhancing ...

Pre–B cell colony‐enhancing factor/visfatin, a new marker of inflammation in rheumatoid arthritis with proinflammatory and matrix‐degrading activities

“…PBEF mimics insulin signaling by binding to the insulin receptor with an affinity similar to that of insulin but does not share the binding site with insulin on the insulin receptor. In contrast, previous studies have shown intracellular expression of PBEF and have demonstrated that PBEF is a nicotinamide phosphoribosyltransferase (7,8). Overexpression of PBEF in human vascular SMCs induced enhanced survival by its regulatory effect on NADdependent deacetylase activity.…”

“…Later, it became evident that PBEF is a multifunctional protein, having nicotinamide phosphoribosyltransferase, adipokine, and cytokine activities. In smooth muscle cells (SMCs), intracellularly located PBEF regulates NADϩ-dependent reactions and promotes the acquisition of a mature SMC phenotype (7,8). Fukuhara et al reported the expression of PBEF in visceral fat adipocytes and noted that its insulin-like effect is dependent on binding to the insulin receptor (9).…”

Visfatin activates eNOS via Akt and MAP kinases and improves endothelial cell function and angiogenesis in vitro and in vivo: translational implications for atherosclerosis

“…Indeed, visfatin has been described to extend the life span of smooth muscle cells, via augmenting SIRT1-mediated p53 degradation (24,25). Furthermore, visfatin, in a NAD-dependent fashion, promotes the acquisition of a mature smooth Fig.…”

“…Recent data have suggested that visfatin may also function analogous to a visceral fat adipocytokine and may alter insulin and glucose signaling, although this remains controversial (5). Evidence is accumulating to suggest that visfatin may serve as a cellular survival factor and may exert beneficial effects on both endothelial (8) and vascular smooth muscle cells (25). Indeed, in vascular smooth muscle cells, visfatin functions as a longevity protein, in part via optimizing Sirt1-mediated p53 degradation, whereas, in endothelial cells, visfatin may stimulate angiogenesis and augment endothelial survival (24).…”

Sirtuins and inflammation: Friends or foes?

“…[55]. A similar direct relationship between Nampt, intracellular NAD levels and SIRT1 activity has been recently confirmed in several cell types including skeletal myoblasts [56], vascular smooth muscle cells [7], [57], and chondrocytes [58]. Of interest, the nuclear form of Nicotinamide…”