Transgelin as a therapeutic target to prevent hypoxic pulmonary hypertension

Endothelial Overexpression of TGF-β-Induced Protein Impairs Venous Thrombus Resolution: Possible Role in CTEPH

Endothelial cells play a critical role during venous thrombus remodeling, and unresolved, fibrotic thrombi with irregular vessels obstruct the pulmonary artery in patients with chronic thromboembolic pulmonary hypertension (CTEPH). This study sought to identify endothelial mediators of impaired venous thrombus resolution and to determine their role in the pathogenesis of the vascular obstructions in patients with CTEPH. Endothelial cells outgrown from pulmonary endarterectomy specimens (PEA) were processed for mRNA profiling, and nCounter gene expression and immunohistochemistry analysis of PEA tissue microarrays and immunoassays of plasma were used to validate the expression in CTEPH. Lentiviral overexpression in human pulmonary artery endothelial cells (HPAECs) and exogenous administration of the recombinant protein into C57BL/6J mice after inferior Vena cava ligation were employed to assess their role for venous thrombus resolution. RT2 PCR profiler analysis demonstrated the significant overexpression of factors downstream of transforming growth factor beta (TGFβ), that is TGFβ-Induced Protein (TGFBI or BIGH3) and transgelin (TAGLN), or involved in TGFβ signaling, that is follistatin-like 3 (FSTL3) and stanniocalcin-2 (STC2). Gene expression and immunohistochemistry analysis of tissue microarrays localized potential disease candidates to vessel-rich regions. Lentiviral overexpression of TGFBI in HPAECs increased fibrotic remodeling of human blood clots in vitro, and exogenous administration of recombinant TGFBI in mice delayed venous thrombus resolution. Significantly elevated plasma TGFBI levels were observed in patients with CTEPH and decreased after PEA. Our findings suggest that overexpression of TGFBI in endothelial promotes venous thrombus non-resolution and fibrosis and is causally involved in the pathophysiology of CTEPH.

Transgelin exacerbates pulmonary artery smooth muscle cell dysfunction in shunt-related pulmonary arterial hypertension

AIMS

Orchestrating the transition from reversible medial hypertrophy to irreversible plexiform lesions is crucial for pulmonary arterial hypertension related to congenital heart disease (CHD-PAH). Transgelin is an actin-binding protein that modulates pulmonary arterial smooth muscle cell (PASMC) dysfunction. In this study, we aimed to probe the molecular mechanism and biological function of transgelin in the pathogenesis of CHD-PAH.

METHODS AND RESULTS

Transgelin expression was detected in lung tissues from both CHD-PAH patients and monocrotaline (MCT)-plus aortocaval (AV)-induced PAH rats by immunohistochemistry. In vitro, the effects of transgelin on the proliferation, migration, and apoptosis of human PASMCs (HPASMCs) were evaluated by the cell count and EdU assays, transwell migration assay, and TUNEL assay, respectively. And the effect of transgelin on the expression of HPASMC phenotype markers was assessed by the immunoblotting assay. (i) Compared with the normal control group (n = 12), transgelin expression was significantly overexpressed in the pulmonary arterioles of the reversible (n = 15) and irreversible CHD-PAH group (n = 4) (reversible group vs. control group: 18.2 ± 5.1 vs. 13.6 ± 2.6%, P < 0.05; irreversible group vs. control group: 29.9 ± 4.7 vs. 13.6 ± 2.6%, P < 0.001; irreversible group vs. reversible group: 29.9 ± 4.7 vs. 18.2 ± 5.1, P < 0.001). This result was further confirmed in MCT-AV-induced PAH rats. Besides, the transgelin expression level was positively correlated with the pathological grading of pulmonary arteries in CHD-PAH patients (r = 0.48, P = 0.03, n = 19). (ii) Compared with the normal control group (n = 12), TGF-β1 expression was notably overexpressed in the pulmonary arterioles of the reversible (n = 15) and irreversible CHD-PAH group (n = 4) (reversible group vs. control group: 14.8 ± 4.4 vs. 6.0 ± 2.5%, P < 0.001; irreversible group vs. control group: 20.1 ± 4.4 vs. 6.0 ± 2.5%, P < 0.001; irreversible group vs. reversible group: 20.1 ± 4.4 vs. 14.8 ± 4.4, P < 0.01). The progression-dependent correlation between TGF-β1 and transgelin was demonstrated in CHD-PAH patients (r = 0.48, P = 0.04, n = 19) and MCT-AV-induced PAH rats, which was further confirmed at sub-cellular levels. (iii) Knockdown of transgelin diminished proliferation, migration, apoptosis resistance, and phenotypic transformation of HPASMCs through repressing the TGF-β1 signalling pathway. On the contrary, transgelin overexpression resulted in the opposite effects.

CONCLUSIONS

These results indicate that transgelin may be an indicator of CHD-PAH development via boosting HPASMC dysfunction through positive regulation of the TGF-β1 signalling pathway, as well as a potential therapeutic target for the treatment of CHD-PAH.

RNA-sequencing of human aortic valves identifies that miR-629-3p and TAGLN miRNA-mRNA pair involving in calcified aortic valve disease

This study aimed to uncover the microRNA and messenger RNA (miRNA/mRNA) interactions in the pathophysiological process of calcified aortic valve disease (CAVD) of the human aortic valve. RNA sequencing of six selected samples (3 healthy control samples vs. 3 CAVD samples) was performed to obtain mRNA and miRNA sequences, and differential expression (DE) analysis of miRNA and mRNAs was performed. To build a CAVD-specific miRNA-mRNA interactome, the upregulated mRNAs and downregulated miRNAs were selected, followed by the establishment of inverse DE of mRNA-miRNA co-expression network based on Pearson's correlation coefficient using miRanda in the R language software. Subsequently, pathway enrichment analysis was performed to elucidate CAVD-related pathways that were likely mediated by miRNA regulatory mechanisms. In addition, miRNAs with an mRNA correlation greater than 0.9 in the co-expression network were selected for anti-calcification verification in a CAVD cellular model. We identified 216 mRNAs (99 downregulated and 117 upregulated) and 602 miRNAs (371 downregulated and 231 upregulated) that were differentially expressed between CAVD and healthy aortic valves. After applying Pearson's correlation toward miRNA-mRNA targets, a regulatory network of 67 miRNAs targeting 76 mRNAs was created. The subsequent pathway enrichment analysis of these targeted mRNAs elucidated that genes within the focal adhesion pathway are likely mediated by miRNA regulatory mechanisms. The selected hsa-miR-629-3p and TAGLN pair exhibited anti-calcification effects on osteogenic differentiation-induced human aortic valve interstitial cells (hVICs). On integrating the miRNA and mRNA sequencing data for healthy aortic valves and those with CAVD, the CAVD-associated miRNA-mRNA interactome and related pathways were elucidated. Additional cell function data demonstrated anti-calcification effects of the selected hsa-miR-629-3p targeting TAGLN, validating that it is a potential therapeutic target for inhibiting CAVD.

PKN2 deficiency leads both to prenatal congenital cardiomyopathy and defective angiotensin II stress responses

The protein kinase PKN2 is required for embryonic development and PKN2 knockout mice die as a result of failure in the expansion of mesoderm, cardiac development and neural tube closure. In the adult, cardiomyocyte PKN2 and PKN1 (in combination) are required for cardiac adaptation to pressure-overload. The specific role of PKN2 in contractile cardiomyocytes during development and its role in the adult heart remain to be fully established. We used mice with cardiomyocyte-directed knockout of PKN2 or global PKN2 haploinsufficiency to assess cardiac development and function using high resolution episcopic microscopy, MRI, micro-CT and echocardiography. Biochemical and histological changes were also assessed. Cardiomyocyte-directed PKN2 knockout embryos displayed striking abnormalities in the compact myocardium, with frequent myocardial clefts and diverticula, ventricular septal defects and abnormal heart shape. The sub-Mendelian homozygous knockout survivors developed cardiac failure. RNASeq data showed up-regulation of PKN2 in patients with dilated cardiomyopathy, suggesting an involvement in adult heart disease. Given the rarity of homozygous survivors with cardiomyocyte-specific deletion of PKN2, the requirement for PKN2 in adult mice was explored using the constitutive heterozygous PKN2 knockout. Cardiac hypertrophy resulting from hypertension induced by angiotensin II was reduced in these haploinsufficient PKN2 mice relative to wild-type littermates, with suppression of cardiomyocyte hypertrophy and cardiac fibrosis. It is concluded that cardiomyocyte PKN2 is essential for heart development and the formation of compact myocardium and is also required for cardiac hypertrophy in hypertension. Thus, PKN signalling may offer therapeutic options for managing congenital and adult heart diseases.

Construction and analysis of the abnormal lncRNA-miRNA-mRNA network in hypoxic pulmonary hypertension

The incidence of hypoxic pulmonary hypertension (HPH) is increasing. Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play an important role in HPH, but the functions and mechanism have yet to be fully elucidated. In the present study, we established a HPH rat model with 8 h of hypoxia exposure (10% O2) per day for 21 days. High-throughput sequencing identified 60 differentially expressed (DE) lncRNAs, 20 DE miRNAs and 695 DE mRNAs in rat lung tissue. qRT-PCR verified the accuracy of the results. The DE mRNAs were significantly enriched in immune response, inflammatory response, leukocyte migration, cell cycle, cellular response to interleukin-1, IL-17 signalling pathway, cytokine-cytokine receptor interaction and Toll-like receptor signalling pathway. According to the theory of competing endogenous RNA (ceRNA) networks, lncRNA-miRNA-mRNA network was constructed by Cytoscape software, 16 miRNAs and 144 mRNAs. The results suggested that seven DE lncRNAs (Ly6l, AABR07038849.2, AABR07069008.2, AABR07064873.1, AABR07001382.1, AABR07068161.1 and AABR07060341.2) may serve as molecular sponges of the corresponding miRNAs and play a major role in HPH.

Differential Expression of Drosophila Transgelins Throughout Development

Transgelins are a conserved family of actin-binding proteins involved in cytoskeletal remodeling, cell contractility, and cell shape. In both mammals and Drosophila, three genes encode transgelin proteins. Transgelins exhibit a broad and overlapping expression pattern, which has obscured the precise identification of their role in development. Here, we report the first systematic developmental analysis of all Drosophila transgelin proteins, namely, Mp20, CG5023, and Chd64 in the living organism. Drosophila transgelins display overall higher sequence identity with mammalian TAGLN-3 and TAGLN-2 than with TAGLN. Detailed examination in different developmental stages revealed that Mp20 and CG5023 are predominantly expressed in mesodermal tissues with the onset of myogenesis and accumulate in the cytoplasm of all somatic muscles and heart in the late embryo. Notably, at postembryonic developmental stages, Mp20 and CG5023 are detected in the gut’s circumferential muscles with distinct subcellular localization: Z-lines for Mp20 and sarcomere and nucleus for CG5023. Only CG5023 is strongly detected in the adult fly in the abdominal, leg, and synchronous thoracic muscles. Chd64 protein is primarily expressed in endodermal and ectodermal tissues and has a dual subcellular localization in the cytoplasm and the nucleus. During the larval–pupae transition, Chd64 is expressed in the brain, eye, legs, halteres, and wings. In contrast, in the adult fly, Chd64 is expressed in epithelia, including the alimentary tract and genitalia. Based on the non-overlapping tissue expression, we predict that Mp20 and CG5023 mostly cooperate to modulate muscle function, whereas Chd64 has distinct roles in epithelial, neuronal, and endodermal tissues.

Genetic Delivery and Gene Therapy in Pulmonary Hypertension

Pulmonary hypertension (PH) is a progressive complex fatal disease of multiple etiologies. Hyperproliferation and resistance to apoptosis of vascular cells of intimal, medial, and adventitial layers of pulmonary vessels trigger excessive pulmonary vascular remodeling and vasoconstriction in the course of pulmonary arterial hypertension (PAH), a subgroup of PH. Multiple gene mutation/s or dysregulated gene expression contribute to the pathogenesis of PAH by endorsing the proliferation and promoting the resistance to apoptosis of pulmonary vascular cells. Given the vital role of these cells in PAH progression, the development of safe and efficient-gene therapeutic approaches that lead to restoration or down-regulation of gene expression, generally involved in the etiology of the disease is the need of the hour. Currently, none of the FDA-approved drugs provides a cure against PH, hence innovative tools may offer a novel treatment paradigm for this progressive and lethal disorder by silencing pathological genes, expressing therapeutic proteins, or through gene-editing applications. Here, we review the effectiveness and limitations of the presently available gene therapy approaches for PH. We provide a brief survey of commonly existing and currently applicable gene transfer methods for pulmonary vascular cells in vitro and describe some more recent developments for gene delivery existing in the field of PH in vivo.

Resistin-like molecule β acts as a mitogenic factor in hypoxic pulmonary hypertension via the Ca2+-dependent PI3K/Akt/mTOR and PKC/MAPK signaling pathways

Background

Pulmonary arterial smooth muscle cell (PASMC) proliferation plays a crucial role in hypoxia-induced pulmonary hypertension (HPH). Previous studies have found that resistin-like molecule β (RELM-β) is upregulated de novo in response to hypoxia in cultured human PASMCs (hPASMCs). RELM-β has been reported to promote hPASMC proliferation and is involved in pulmonary vascular remodeling in patients with PAH. However, the expression pattern, effects, and mechanisms of action of RELM-β in HPH remain unclear.

Methods

We assessed the expression pattern, mitogenetic effect, and mechanism of action of RELM-β in a rat HPH model and in hPASMCs.

Results

Overexpression of RELM-β caused hemodynamic changes in a rat model of HPH similar to those induced by chronic hypoxia, including increased mean right ventricular systolic pressure (mRVSP), right ventricular hypertrophy index (RVHI) and thickening of small pulmonary arterioles. Knockdown of RELM-β partially blocked the increases in mRVSP, RVHI, and vascular remodeling induced by hypoxia. The phosphorylation levels of the PI3K, Akt, mTOR, PKC, and MAPK proteins were significantly up- or downregulated by RELM-β gene overexpression or silencing, respectively. Recombinant RELM-β protein increased the intracellular Ca²⁺ concentration in primary cultured hPASMCs and promoted hPASMC proliferation. The mitogenic effects of RELM-β on hPASMCs and the phosphorylation of PI3K, Akt, mTOR, PKC, and MAPK were suppressed by a Ca²⁺ inhibitor.

Conclusions

Our findings suggest that RELM-β acts as a cytokine-like growth factor in the development of HPH and that the effects of RELM-β are likely to be mediated by the Ca²⁺-dependent PI3K/Akt/mTOR and PKC/MAPK pathways.

Transcriptome-wide map of m6A circRNAs identified in a rat model of hypoxia mediated pulmonary hypertension

Background

Hypoxia mediated pulmonary hypertension (HPH) is a lethal disease and lacks effective therapy. CircRNAs play significant roles in physiological process. Recently, circRNAs are found to be m⁶A-modified. The abundance of circRNAs was influenced by m⁶A. Furthermore, the significance of m⁶A circRNAs has not been elucidated in HPH yet. Here we aim to investigate the transcriptome-wide map of m⁶A circRNAs in HPH.

Results

Differentially expressed m⁶A abundance was detected in lungs of HPH rats. M⁶A abundance in circRNAs was significantly reduced in hypoxia in vitro. M⁶A circRNAs were mainly from protein-coding genes spanned single exons in control and HPH groups. Moreover, m⁶A influenced the circRNA–miRNA–mRNA co-expression network in hypoxia. M⁶A circXpo6 and m⁶A circTmtc3 were firstly identified to be downregulated in HPH.

Conclusion

Our study firstly identified the transcriptome-wide map of m⁶A circRNAs in HPH.

M⁶A can influence circRNA–miRNA–mRNA network. Furthermore, we firstly identified two HPH-associated m⁶A circRNAs: circXpo6 and circTmtc3. However, the clinical significance of m⁶A circRNAs for HPH should be further validated.

MiRNA let-7b promotes the development of hypoxic pulmonary hypertension by targeting ACE2

Angiotensin-converting enzyme 2 (ACE2) protects against hypoxic pulmonary hypertension (HPH) by inhibiting the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs). Under hypoxia, the hypoxia-inducible factor 1α (HIF-1α) inhibits ACE2 indirectly; however, the underlying mechanism is unclear. In the present study, we found that exposure to chronic hypoxia stimulated microRNA (miRNA) let-7b expression in rat lung via a HIF-1α-dependent pathway. Let-7b downregulated ACE2 expression by directly targeting the coding sequence of ACE2. Our in vitro and in vivo results revealed that let-7b contributed to the pathogenesis of HPH by inducing PASMCs proliferation and migration. Let-7b knockout mitigated right ventricle hypertrophy and pulmonary vessel remodeling in HPH by restoring ACE2 expression. Overall, we demonstrated that HIF-1α inhibited ACE2 expression via the HIF-1α-let-7b-ACE2 axis, which contributed to the pathogenesis of HPH by stimulating PASMCs proliferation and migration. Since let-7b knockout alleviated the development of HPH, let-7b may serve as a potential clinical target for the treatment of HPH.

LncRNA H19 promotes the proliferation of pulmonary artery smooth muscle cells through AT1R via sponging let-7b in monocrotaline-induced pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is related to inflammation, and the lncRNA H19 is associated with inflammation. However, whether PDGF-BB-H19-let-7b-AT1R axis contributes to the pathogenesis of PAH has not been thoroughly elucidated to date. This study investigated the role of H19 in PAH and its related mechanism.

METHODS

In the present study, SD rats, C57/BL6 mice and H19-/- mice were injected with monocrotaline (MCT) to establish a PAH model. H19 was detected in the cytokine-stimulated pulmonary arterial smooth muscle cells (PASMCs), serum and lungs of rats/mice. H19 overexpression and knockdown experiments were also conducted. A dual luciferase reporter assay was used to explore whether let-7b is a sponge miRNA of H19, and AT1R is a novel target of let-7b. A CCK-8 assay and flow cytometry were used to analyse cell proliferation.

RESULTS

The results showed that H19 was highly expressed in the serum and lungs of MCT-induced rats/mice, and H19 was upregulated by PDGF-BB in vitro. H19 upregulated AT1R expression via sponging miRNA let-7b following PDGF-BB stimulation. AT1R is a novel target of let-7b. Moreover, the overexpression of H19 and AT1R could facilitate PASMCs proliferation in vitro. H19 knockout protected mice from pulmonary artery remodeling and PAH following MCT treatment.

CONCLUSION

Our study showed that H19 is highly expressed in MCT-induced rodent lungs and upregulated by PDGF-BB. The H19-let-7b-AT1R axis contributed to the pathogenesis of PAH by stimulating PASMCs proliferation. The H19 knockout had a protective role in the development of PAH. H19 may be a potential tar-get for the treatment of PAH.

Transgelin as a potential target in the reversibility of pulmonary arterial hypertension secondary to congenital heart disease

BACKGROUND

The reversibility of pulmonary arterial hypertension (PAH) in congenital heart disease (CHD) is of great importance for the operability of CHD. Proteomics analysis found that transgelin was significantly up-regulated in the lung tissue of CHD-PAH patients, especially in the irreversible group. However, how exactly it participated in CHD-PAH development is unknown.

METHODS

Immunohistochemical staining and Western blot were performed for further qualitative and quantitative analysis of transgelin in the lung tissues of CHD-PAH patients. The mechanism of transgelin in CHD-PAH development was explored in vitro. Primary human pulmonary arterial smooth muscle cells (hPASMCs) were cultured and infected with TAGLN siRNA or TAGLN lentiviral vector. Cell morphologic change (Coomassie Brilliant Blue staining), proliferation (cell count and EdU assay), apoptosis (terminal deoxyribonucleotidyl transferase mediated dUTP nick end labeling assay and Annexin-V flow cytometry) and migration (transwell) were evaluated following the cell treatment. The mRNA and protein expression levels were detected in real-time PCR and Western blot.

RESULTS

In line with the proteomic findings, transgelin was obviously expressed in PASMC of the middle pulmonary arterioles, especially in the irreversible PAH group. Also, transgelin expression showed positive relation with pathological grading. Experiment in vitro demonstrated that transgelin overexpression promoted PASMC proliferation and migration, strengthened cytoskeleton and was accompanied by increased expression of synthetic phenotype markers (osteopontin, proliferating cell nuclear antigen) and anti-apoptotic protein (bcl-2). On the other hand, suppression of transgelin expression activated PASMC apoptosis, reducing cell proliferation and migration.

CONCLUSIONS

Transgelin may be a potential target in the development of irreversible CHD-PAH through inducing PASMC phenotype change, proliferation, migration and reducing cell apoptosis.

New Methods for Disease Modeling Using Lentiviral Vectors

Lentiviral vectors (LVs) transduce quiescent cells and provide stable integration to maintain transgene expression. Several approaches have been adopted to optimize LV safety profiles. Similarly, LV targeting has been tailored through strategies including the modification of envelope components, the use of specific regulatory elements, and the selection of appropriate administration routes. Models of aortic disease based on a single injection of pleiotropic LVs have been developed that efficiently transduce the three aorta layers in wild type mice. This approach allows the dissection of pathways involved in aortic aneurysm formation and the identification of targets for gene therapy in aortic diseases. LVs provide a fast, efficient, and affordable alternative to genetically modified mice to study disease mechanisms and develop therapeutic tools.

Effect of progesterone on Smad signaling and TGF-β/Smad-regulated genes in lung epithelial cells

The effect of endogenous progesterone and/or exogenous pre- or postnatal progesterone application on lung function of preterm infants is poorly defined. While prenatal progesterone substitution may prevent preterm birth, in vitro and in vivo data suggest a benefit of postnatal progesterone replacement on the incidence and severity of bronchopulmonary dysplasia (BPD). However, the molecular mechanisms responsible for progesterone's effects are undefined. Numerous factors are involved in lung development, airway inflammation, and airway remodeling: the transforming growth factor beta (TGF-β)/mothers against decapentaplegic homolog (Smad) signaling pathway and TGF-β-regulated genes, such as connective tissue growth factor (CTGF), transgelin (TAGLN), and plasminogen activator inhibitor-1 (PAI-1). These processes contribute to the development of BPD. The aim of the present study was to clarify whether progesterone could affect TGF-β1-activated Smad signaling and CTGF/transgelin/PAI-1 expression in lung epithelial cells. The pharmacological effect of progesterone on Smad signaling was investigated using a TGF-β1-inducible luciferase reporter and western blotting analysis of phosphorylated Smad2/3 in A549 lung epithelial cells. The regulation of CTGF, transgelin, and PAI-1 expression by progesterone was studied using a promoter-based luciferase reporter, quantitative real-time PCR, and western blotting in the same cell line. While progesterone alone had no direct effect on Smad signaling in lung epithelial cells, it dose-dependently inhibited TGF-β1-induced Smad3 phosphorylation, as shown by luciferase assays and western blotting analysis. Progesterone also antagonized the TGF-β1/Smad-induced upregulation of CTGF, transgelin, and PAI-1 at the promoter, mRNA, and/or protein levels. The present study highlights possible new molecular mechanisms involving progesterone, including inhibition of TGF-β1-activated Smad signaling and TGF-β1-regulated genes involved in BPD pathogenesis, which are likely to attenuate the development of BPD by inhibiting TGF-β1-mediated airway remodeling. Understanding these mechanisms might help to explain the effects of pre- or postnatal application of progesterone on lung diseases of preterm infants.

Comparative iTRAQ analysis of protein abundance in the human sinoatrial node and working cardiomyocytes

Our objective was to assess the changes in protein abundance in the human sinoatrial node (SAN) compared with working cardiomyocytes to identify SAN-specific protein signatures. Four pairs of samples (the SAN and working cardiomyocytes) were obtained postmortem from four human donors with no evidence of cardiovascular disease. We performed protein identification and quantitation using two-dimensional chromatography-tandem mass spectrometry with isobaric peptide labeling (iTRAQ). We identified 451 different proteins expressed in both the SAN and working cardiomyocytes, 166 of which were differentially regulated (110 were upregulated in the SAN and 56 in the working cardiomyocytes). We identified sarcomere structural proteins in both tissues, although they were differently distributed among the tested samples. For example, myosin light chain 4, myosin regulatory light chain 2-atrial isoform, and tropomyosin alpha-3 chain levels were twofold higher in the SAN than in working cardiomyocytes, and myosin light chain 3 and myosin regulatory light chain 2-ventricular/cardiac muscle isoform levels were twofold higher in the ventricle tissue than in SAN. We identified many mitochondrial oxidative phosphorylation, β-oxidation, and tricarboxylic acid cycle proteins that were predominantly associated with working cardiomyocytes tissue. We detected upregulation of the fatty acid omega activation pathway proteins in the SAN samples. Some proteins specific for smooth muscle tissue were highly upregulated in the SAN (e.g. transgelin), which indicates that the SAN tissue might act as the bridge between the working myocardium and the smooth muscle. Our results show possible implementation of proteomic strategies to identify in-depth functional differences between various heart sub-structures.

Up-regulation of caveolin-1 by DJ-1 attenuates rat pulmonary arterial hypertension by inhibiting TGFβ/Smad signaling pathway

Pulmonary arterial hypertension (PAH), characterized by excessive proliferation and apoptosis resistance of pulmonary artery smooth muscle cells (PASMCs), is closely associated with the imbalance in vasoactive mediators and massive remodeling of pulmonary vasculature. DJ-1/park7, a multifunctional protein, plays a critical defense role in several cytobiological activity, such as transcriptional regulation, anti-oxidative stress and tumor formation. In this study, we investigated the effects of DJ-1 on hypoxia-induced PAH model rats and PASMCs, as well as its possible molecular mechanism. First, the low expressions of DJ-1 and caveolin-1 (Cav-1) were synchronously detected in lung tissue of PAH model rats and hypoxia-induced PASMCs by Western blot. Then, the DJ-1 wild type (WT) or Knock out (KO) rats were exposed to chronic hypoxia to mimic a hypoxic PAH condition. The protein level of Cav-1 was markedly decreased in the tissue of DJ-1 KO rats, and additionally lower in tissue of the hypoxia group than that in the normoxia group for DJ-1 WT and KO rats. In vivo, hemodynamic data showed that the pulmonary arterial pressure (mPAP), right ventricle systolic pressure (RVSP) and pulmonary arterial systolic pressure (PASP), as well as the weight of the right ventricle/left ventricle plus septum (RV/LV+S) ratio of PAH model rats were higher in the DJ-1 KO group than those in the DJ-1 WT group. Moreover, knockout of DJ-1 also results in the phenotype switch from contractile to synthetic PASMC, which is reflected by reduced calponin and SM22α expressions. In vitro, DJ-1 overexpression reversed hypoxia-induced elevation of PASMC cell proliferation, migration and Ca²⁺ concentration, which were not obviously observed in Cav-1 shRNA (sh-Cav-1) and DJ-1 co-transfected cells. Then the increased levels of calponin and SM22α were detected in the DJ-1 group; similarly those levels were not changed in the DJ-1+sh-Cav-1 group. Finally, the expression of TGFβ1, p-Smad2 and p-Smad3 were obviously decreased in the ad-DJ-1 group, however those were all elevated in the DJ-1 and sh-Cav-1 co-transfected groups. In conclusion, these results indicate that DJ-1 may alleviate hypoxia-induced PASMCs injury by Cav-1 through inhibiting the TGFβ/Smad signaling pathway.

Recent Progress in Research on the Pathogenesis of Pulmonary Thromboembolism: An Old Story with New Perspectives

Pulmonary thromboembolism (PTE) is part of a larger clinicopathological entity, venous thromboembolism. It is also a complex, multifactorial disorder divided into four major disease processes including venous thrombosis, thrombus in transit, acute pulmonary embolism, and pulmonary circulation reconstruction. Even when treated, some patients develop chronic thromboembolic pulmonary hypertension. PTE is also a common fatal type of pulmonary vascular disease worldwide, but earlier studies primarily focused on the pathological changes in the blood component of the disease. With contemporary advances in molecular and cellular biology, people are becoming increasingly aware of coagulation pathways, the function of vascular smooth muscle cells, microparticles, and the inflammatory pathways that play key roles in PTE. Combined hypoxia and immune research has revealed that PTE should be regarded as a class of complex diseases caused by multiple factors involving the vascular microenvironment and vascular cell dysfunction.

Involvement of CapG in proliferation and apoptosis of pulmonary arterial smooth muscle cells and in hypoxia-induced pulmonary hypertension rat model

PURPOSE

Actin-binding protein capping protein gelsolin-like (CapG) was preferentially expressed in human pulmonary arterial smooth muscle cells (PASMCs) under hypoxia, and reduced CapG expression was accompanied by impaired migration ability in vitro. We intended to investigate the effects of CapG on rat PASMCs and hypoxia-induced pulmonary hypertension (HPH) rat model.

MATERIALS AND METHODS

We investigated the effect of RNA interference-medicated down-regulation of CapG expression in rat PASMCs as well as in HPH rat model. The proliferation, apoptosis and cell cycle of PASMCs were evaluated. The HPH rat model was established by intratracheal instillation of lentiviral vector and subsequent hypoxia exposure for four weeks. Right ventricular systolic pressure, right ventricular hypertrophy and the percentage of medial wall thickness were measured to evaluate the development of HPH.

RESULTS

Knock-down CapG in PASMCs resulted in decreased proliferation, increased apoptosis and induced cell cycle inhibition. Down-regulation of CapG expression locally could attenuate pulmonary hypertension, pulmonary vascular remodeling and right ventricular hypertrophy in HPH rat model.

CONCLUSIONS

Our study indicated that CapG participated in the pathogenesis of pulmonary vascular remodeling in HPH rats, which was probably mediated by promoting the proliferation and inhibiting the apoptosis of PASMCs. We proposed CapG modulating protective effects of pulmonary hypertension.

Update on novel targets and potential treatment avenues in pulmonary hypertension

Pulmonary hypertension (PH) is a condition marked by a combination of constriction and remodeling within the pulmonary vasculature. It remains a disease without a cure, as current treatments were developed with a focus on vasodilatory properties but do not reverse the remodeling component. Numerous recent advances have been made in the understanding of cellular processes that drive pathologic remodeling in each layer of the vessel wall as well as the accompanying maladaptive changes in the right ventricle. In particular, the past few years have yielded much improved insight into the pathways that contribute to altered metabolism, mitochondrial function, and reactive oxygen species signaling and how these pathways promote the proproliferative, promigratory, and antiapoptotic phenotype of the vasculature during PH. Additionally, there have been significant advances in numerous other pathways linked to PH pathogenesis, such as sex hormones and perivascular inflammation. Novel insights into cellular pathology have suggested new avenues for the development of both biomarkers and therapies that will hopefully bring us closer to the elusive goal: a therapy leading to reversal of disease.

Suppression of the expression of hypoxia-inducible factor-1α by RNA interference alleviates hypoxia-induced pulmonary hypertension in adult rats

Hypoxia-inducible factor-1α (HIF-1α) has been implicated in the pathogenesis of hypoxic pulmonary hypertension (PH). However, the potential clinical value of HIF-1α as a therapeutic target in the treatment of PH has not yet been evaluated. In this study, an animal model of hypoxia-induced PH was established by exposing adult rats to 10% O₂ for 3 weeks, and the effects of the lentivirus-mediated delivery of HIF-1α short hairpin RNA (shRNA) by intratracheal instillation prior to exposure to hypoxia on the manifestations of hypoxia-induced PH were assessed. The successful delivery of HIF-1α shRNA into the pulmonary arteries effectively suppressed the hypoxia-induced upregulation of HIF-1α, accompanied by the prominent attenuation the symptoms associated with hypoxia-induced PH, including the elevation of pulmonary arterial pressure, hypertrophy and hyperplasia of pulmonary artery smooth muscle cells (PASMCs), as well as the muscularization of pulmonary arterioles. In addition, the knockdown of HIF-1α in cultured rat primary PASMCs significantly inhibited the hypoxia-induced acceleration of the cell cycle and the proliferation of the PASMCs, suggesting that HIF-1α may be a direct mediator of PASMC hyperplasia in hypoxia-induced PH. In conclusion, this study demonstrates the potent suppressive effects of HIF-1α shRNA on hypoxia-induced PH and PASMC hyperplasia, providing evidence for the potential application of HIF-1α shRNA in the treatment of hypoxic PH.

Proteomics of pulmonary hypertension: could personalized profiles lead to personalized medicine?

Pulmonary hypertension (PH) is a fatal syndrome that arises from a multifactorial and complex background, is characterized by increased pulmonary vascular resistance and right heart afterload, and often leads to cor pulmonale. Over the past decades, remarkable progress has been made in reducing patient symptoms and delaying the progression of the disease. Unfortunately, PH remains a disease with no cure. The substantial heterogeneity of PH continues to be a major limitation to the development of newer and more efficacious therapies. New advances in our understanding of the biological pathways leading to such a complex pathogenesis will require the identification of the important proteins and protein networks that differ between a healthy lung (or right ventricle) and a remodeled lung in an individual with PH. In this article, we present the case for the increased use of proteomics--the study of proteins and protein networks--as a discovery tool for key proteins and protein networks operational in the PH lung. We review recent applications of proteomics in PH, and summarize the biological pathways identified. Finally, we attempt to presage what the future will bring with regard to proteomics in PH and offer our perspectives on the prospects of developing personalized proteomics and custom-tailored therapies.

Expression of Cofilin-1 and Transgelin in Esophageal Squamous Cell Carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) has attracted much research attention around the world, and the number of ESCC cases has increased gradually in recent years. Identifying the specific biomarkers of ESCC is an effective approach for the early diagnosis of tumors.

MATERIAL AND METHODS

Immunohistochemical streptavidin-peroxidase method was used to determine the expressions of Cofilin-1 and transgelin in 68 patients with esophageal squamous cell carcinoma (ESCC) and 48 individuals with normal esophageal tissues. In addition to the relationships between the expression of Cofilin-1 and transgelin, the clinicopathologic features of ESCC were also discussed. The correlation between Cofilin-1 and transgelin protein expression in ESCC was analyzed.

RESULTS

(1) The positive expression rates of Cofilin-1 and transgelin were 60.3% (41/68) and 54.4% (37/68) in esophageal carcinoma tissue, respectively. The positive expression rates of Cofilin-1 and transgelin in normal esophageal tissue were 27.1% (13/48) and 29.1% (14/48), respectively. The differences were statistically significant (P<0.05). (2) The positive expression rate of Cofilin-1 did not differ significantly (P>0.05) with sex, age, ethnicity, tumor size, or infiltration depth; but did have a statistically significant (P<0.05) difference with various degrees of tumor differentiation, lymph node metastasis, and clinical stages. (3) The positive expression rate of transgelin did not differ significantly (P>0.05) with sex, age, ethnicity, tumor size, infiltration depth, and clinical stage, but did significantly (P<0.05) differ with degree of tumor differentiation and lymph node metastasis.

CONCLUSIONS

Cofilin-1 and transgelin may play roles in the carcinogenesis and development of esophageal squamous cell carcinoma. Cofilin-1 may be useful as an important biomarker for indicating the degree of malignancy of esophageal squamous cell carcinoma, and the detection of transgelin is valuable in early diagnosis of esophageal squamous cell carcinoma.

Endothelin-1 driven proliferation of pulmonary arterial smooth muscle cells is c-fos dependent. Int J Biochem Cell Biol. 2014;54:137-148. [PMID: 25016214 DOI: 10.1016/j.biocel.2014.06.020]

Pulmonary hypertension (PH) is characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation leading to vascular remodeling. Although, multiple factors have been associated with pathogenesis of PH the underlying mechanisms are not fully understood. Here, we hypothesize that already very short exposure to hypoxia may activate molecular cascades leading to vascular remodeling. Microarray studies from lung homogenates of mice exposed to only 3h of hypoxia revealed endothelin-1 (ET-1) and connective tissue growth factor (CTGF) as the most upregulated genes, and the mitogen-activated protein kinase (MAPK) pathway as the most differentially regulated pathway. Evaluation of these results in vitro showed that ET-1 but not CTGF stimulation of human PASMCs increased DNA synthesis and expression of proliferation markers such as Ki67 and cell cycle regulator, cyclin D1. Moreover, ET-1 treatment elevated extracellular signal-regulated kinase (Erk)-dependent c-fos expression and phosphorylation of c-fos and c-jun transcription factors. Silencing of c-fos with siRNA abrogated the ET-1-induced proliferation of PASMCs. Expression and immunohistochemical analyses revealed higher levels of total and phosphorylated c-fos and c-jun in the vessel wall of lung samples of human idiopathic pulmonary arterial hypertension patents, hypoxia-exposed mice and monocrotaline-treated rats as compared to control subjects. These findings shed the light on the involvement of c-fos/c-jun in the proliferative response of PASMCs to ET-1 indicating that already very short hypoxia exposure leads to the regulation of mediators involved in vascular remodeling underlying PH.

Caffeine and rolipram affect Smad signalling and TGF-β1 stimulated CTGF and transgelin expression in lung epithelial cells

Caffeine administration is an important part of the therapeutic treatment of bronchopulmonary dysplasia (BPD) in preterm infants. However, caffeine mediated effects on airway remodelling are still undefined. The TGF-β/Smad signalling pathway is one of the key pathways involved in airway remodelling. Connective tissue growth factor (CTGF), a downstream mediator of TGF-β, and transgelin, a binding and stabilising protein of the cytoskeleton, are both regulated by TGF-β1 and play an important role in airway remodelling. Both have also been implicated in the pathogenesis of BPD. The aim of the present study was to clarify whether caffeine, an unspecific phosphodiesterase (PDE) inhibitor, and rolipram, a prototypical PDE-4 selective inhibitor, were both able to affect TGF-β1-induced Smad signalling and CTGF/transgelin expression in lung epithelial cells. Furthermore, the effect of transgelin knock-down on Smad signalling was studied. The pharmacological effect of caffeine and rolipram on Smad signalling was investigated by means of a luciferase assay via transfection of a TGF-β1-inducible reporter plasmid in A549 cells. The regulation of CTGF and transgelin expression by caffeine and rolipram were studied by promoter analysis, real-time PCR and Western blot. Endogenous transgelin expression was down-regulated by lentiviral transduction mediating transgelin-specific shRNA expression. The addition of caffeine and rolipram inhibited TGF-β1 induced reporter gene activity in a concentration-related manner. They also antagonized the TGF-β1 induced up-regulation of CTGF and transgelin on the promoter-, the mRNA-, and the protein-level. Functional analysis showed that transgelin silencing reduced TGF-β1 induced Smad-signalling and CTGF induction in lung epithelial cells. The present study highlights possible new molecular mechanisms of caffeine and rolipram including an inhibition of Smad signalling and of TGF-β1 regulated genes involved in airway remodelling. An understanding of these mechanisms might help to explain the protective effects of caffeine in prevention of BPD and suggests rolipram to be a potent replacement for caffeine.