Endothelial Twist1-PDGFB signaling mediates hypoxia-induced proliferation and migration of αSMA-positive cells

Abstract

Remodeling of distal pulmonary arterioles (pAs) associated with marked accumulation of pulmonary artery smooth muscle cells (pASMcs) represents one of the major pathologic features of pulmonary hypertension (PH). We have reported that the transcription factor Twist1 mediates hypoxia-induced PH. However, the mechanism by which endothelial Twist1 stimulates SMC accumulation to distal PAs in PH remains unclear. Here, we have demonstrated that Twist1 overexpression increases the expression of platelet-derived growth factor (PDGFB) in human pulmonary arterial endothelial (HPAE) cells. Hypoxia upregulates the levels of Twist1 and PDGFB in HPAE cells. When we implant hydrogel supplemented with endothelial cells (ECs) on the mouse lung, these ECs form vascular lumen structures and hypoxia upregulates PDGFB expression and stimulates accumulation of αSMA-positive cells in the gel, while knockdown of endothelial Twist1 suppresses the effects. The levels of Twist1 and PDGFB are higher in pAe cells isolated from idiopathic pulmonary arterial hypertension (ipAH) patients compared to those from healthy controls. IPAH patient-derived PAE cells stimulate accumulation of αSMA-positive cells in the implanted gel, while Twist1 knockdown in PAE cells inhibits the effects. Endothelial Twist1-PDGFB signaling plays a key role in αSMA-positive cell proliferation and migration in PH. Pulmonary hypertension (PH) is a multifactorial life-threatening cardiopulmonary disorder 1,2. It is characterized by a sustained increase in pulmonary arterial (PA) pressure, leading to right-sided heart failure 1,2. The current therapeutic options only partially improve symptoms and survival 1,3. Uncontrolled pulmonary artery smooth muscle cell (PASMC) proliferation and accumulation of PASMCs to normally non-muscularized distal PAs are the major histological characteristics of PH 2,4. Thus, we need to understand the mechanism of abnormal SMC proliferation, migration, and their accumulation to distal PAs. In addition to lining vascular structures, endothelial cells (ECs) regulate various physiological functions by secreting angiocrine factors 5. Deregulation of this paracrine mechanism leads to the development of diseases 5. In PH pathology, abnormal ECs release factors that stimulate SMC proliferation (e.g., FGF-2 6 , serotonin 7) or fail to produce factors that physiologically suppress SMC proliferation (e.g., apelin 8), indicating that aberrant pulmonary arterial EC signaling plays key roles in abnormal SMC accumulation to distal PAs 2. The transcription factor Twist1 controls physiological and pathological angiogenesis in various organs including the lungs 9-14. The levels of Twist1 are upregulated in the lungs of patients with pulmonary arterial hypertension (PAH; WHO group1 PH) 15,16 and mice with type II bone morphogenetic protein receptor (Bmpr2) gene mutation 15 , a gene mutated in familial and idiopathic PAH 17. Twist1 expression also increases in the patients with chronic lung diseases associated with PH such as pulmonary fibrosis 18,19. We have d...

Twist1 signaling in age-dependent decline in angiogenesis and lung regeneration

“…We found that upregulation of Twist1 mediates age-dependent decline in angiogenesis through PGC1α and VEGFR2 expression. Twist1 controls multiple angiogenic pathways (e.g., angiopoietins (Angs)-Tie2 [ 18 , 25 ], VEGF-VEGFR2 [ 24 ], PDGF [ 28 ]). For example, we have reported that Twist1 controls Tie2 expression by binding to its promoter region, E-box [ 18 , 25 ].…”

“…Mouse lung ECs were isolated from C57BL6 mice (2M and 24M old) using anti-CD31 conjugated magnetic beads and cultured as reported [ 27 , 28 , 50 ]. De-identified discarded human adipose tissues were collected from Medical College of Wisconsin (MCW) Tissue Bank.…”

“…A transcription factor, Twist1, contributes to the age- and angiogenesis-related diseases, including pulmonary fibrosis [ 17 , 18 ], diabetes [ 19 ], chronic obstructive pulmonary disease (COPD) [ 20 ], cancer [ 21 ], and atherosclerosis [ 22 , 23 ]. Twist1 regulates vascular development [ 24 ] and function [ 25 ] through multiple angiogenic signaling (e.g., Tie2, platelet-derived growth factor (PDGF), VEGFR2, transforming growth factor beta receptor (TGFβR)) [ 18 , 24 – 28 ]. Inhibition of Twist1 activity increases the expression of PGC1α that stimulates mitochondrial biogenesis [ 29 – 32 ] and angiogenesis [ 29 , 33 – 35 ] in fat cells [ 36 ].…”

mTOR Signaling in Pulmonary Vascular Disease: Pathogenic Role and Therapeutic Target

“…Furthermore, the new elegant study by Mammoto et al provided strong evidence that EndMT in PAEC and PDGF-mediated excessive PASMC proliferation could be interdependent in PH [ 175 ]. The authors found that TWIST1 overexpression increased PDGF-B protein in human PAEC.…”

Genetic Delivery and Gene Therapy in Pulmonary Hypertension

“…Twist1 implication in PH is also related to its contribution to EndoMT and is upregulated in patients with PAH [ 132 , 184 ]. Lentiviral knockdown of Twist1 using shRNA reduced the hypoxia-induced EndoMT as well as the accumulation of αSMA-positive cells in the fibrin gel implanted on the live mice [ 185 ].…”