Proteomic Analysis Implicates Translationally Controlled Tumor Protein as a Novel Mediator of Occlusive Vascular Remodeling in Pulmonary Arterial Hypertension

Abstract

Although the genetic basis of PAH is known in some cases, the underlying mechanisms that link loss-of-function mutations in BMPR2 with the development of PAH and its characteristic lung vascular lesions are still unclear. Clinical Perspective on p 2135EC injury and apoptosis are key triggers for the development of PAH. Treatment of rats with a vascular endothelial growth factor receptor antagonist, SU5416, together with a period of chronic hypoxia, 9,10 results in a model of severe, Background-Pulmonary arterial hypertension (PAH) is a lethal disease characterized by excessive proliferation of pulmonary vascular endothelial cells (ECs). Hereditary PAH (HPAH)is often caused by mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2). However, the mechanisms by which these mutations cause PAH remain unclear. Therefore, we screened for dysregulated proteins in blood-outgrowth ECs of HPAH patients with BMPR2 mutations compared with healthy control subjects. Methods and Results-A total of 416 proteins were detected with 2-dimensional PAGE in combination with liquid chromatography/tandem mass spectrometry analysis, of which 22 exhibited significantly altered abundance in bloodoutgrowth ECs from patients with HPAH. One of these proteins, translationally controlled tumor protein (TCTP), was selected for further study because of its well-established role in promoting tumor cell growth and survival. Immunostaining showed marked upregulation of TCTP in lungs from patients with HPAH and idiopathic PAH, associated with remodeled vessels of complex lesions. Increased TCTP expression was also evident in the SU5416 rat model of severe and irreversible PAH, associated with intimal lesions, colocalizing with proliferating ECs and the adventitia of remodeled vessels but not in the vascular media. Furthermore, silencing of TCTP expression increased apoptosis and abrogated the hyperproliferative phenotype of blood-outgrowth ECs from patients with HPAH, raising the possibility that TCTP may be a link in the emergence of apoptosis-resistant, hyperproliferative vascular cells after EC apoptosis. The critical role of EC apoptosis as a trigger in experimental models of PAH is also supported by the efficacy of EC growth and survival factors (eg, vascular endothelial growth factor and angiopoietin-1) in monocrotalineinduced PAH. 13,14 The possible relevance of this paradigm for human PAH is supported by the observation that silencing of BMPR2 15 or overexpression of mutant BMPR2 in human ECs 16 increases apoptosis. Conclusion-ProteomicThe lack of availability of lung tissue from early-stage disease represents a significant limitation for unraveling the initiating mechanisms of human PAH. The selection pressures exerted on resident lung ECs make it is difficult to separate the direct effects of BMPR2 mutations on EC biology from reactive changes in response to the abnormal growth and survival influences of the lung PAH milieu. Recently, it has been recognized that cells with an endothelial phenotype nearly identical to that...

RNA Sequencing Analysis Detection of a Novel Pathway of Endothelial Dysfunction in Pulmonary Arterial Hypertension

“…PIR is an iron-binding protein driven by the antioxidant transcription factor NRF2 that could modulate the proinflammatory effects of nuclear factor-kB (41). Interestingly, none of these transcripts matched proteins identified in blood outgrowth ECs previously studied in patients with heritable PAH, perhaps related to differences in cell type and patient cohort (15).…”

“…Such unbiased approaches to gene expression analysis in PAH have been performed on peripheral blood mononuclear cells (12), whole lung tissue (13), and microdissected vessels (14). A recent study investigated proteomic changes in blood outgrowth ECs from four control subjects and four heritable patients with PAH (15) and another compared metabolomic and transcriptomic changes in PAECs engineered with a BMPR2 mutation (16), but no studies to date have specifically addressed changes in gene expression and the functional significance of those features in PAECs derived from patients with IPAH versus those from control lungs. This opportunity has been made possible through the Pulmonary Hypertension Breakthrough Initiative Network, which collects lung tissue from patients with IPAH and APAH and from unused donor control lungs (see the online supplement).…”

The Translational Controlled Tumour Protein TCTP: Biological Functions and Regulation

“…The hereditary form (HPAH) is often caused by mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2). Lavoie et al, through a proteomics screen, comparing HPAH patients with BMPR2 mutations with healthy control subjects, identified TCTP as one of 22 significantly altered proteins (Lavoie et al 2014). They reported that TCTP is markedly up-regulated in remodelled blood vessels of complex lesions in lungs from patients with PAH.…”

Fortilin: A Potential Target for the Prevention and Treatment of Human Diseases

“…Pulmonary arterial hypertension (PAH) is a lethal disease characterized by dysregulated growth and apoptosis resistance of pulmonary vascular ECs [97]. Hereditary PAH (HPAH) is often caused by loss-of-function mutations in the bone morphogenetic protein receptor type 2 gene (BMPR2), which is a gene that mediates survival signaling in ECs.…”