Background-Deficiencies of iron-sulfur (Fe-S) clusters, metal complexes that control redox state and mitochondrial metabolism, have been linked to pulmonary hypertension (PH), a deadly vascular disease with poorly defined molecular origins. The BolA Family Member 3 (BOLA3) regulates Fe-S biogenesis, and mutations in BOLA3 result in multiple mitochondrial dysfunction syndrome, a fatal disorder associated with PH. The mechanistic role of BOLA3 in PH remains undefined. Methods-In vitro assessment of BOLA3 regulation and gain and loss of function assays were performed in human pulmonary artery endothelial cells (PAECs) using siRNA and lentiviral vectors expressing the mitochondrial isoform of BOLA3. Polymeric nanoparticle 7C1 was utilized for lung endothelial-specific delivery of BOLA3 siRNA oligonucleotides in mice. Overexpression of pulmonary vascular BOLA3 was performed by orotracheal transgene delivery of adenoassociated virus in mouse models of PH. Results-In cultured hypoxic PAECs as well as lung from human Group 1 and 3 PH patients as well as multiple rodent models of PH, endothelial BOLA3 expression was down-regulated, which involved HIF-2α-dependent transcriptional repression via HDAC-mediated histone deacetylation. In vitro gain and loss of function studies demonstrated that BOLA3 regulated Fe-S integrity, thus modulating lipoate-containing 2-oxoacid dehydrogenases with consequent control over glycolysis and mitochondrial respiration. In contexts of siRNA knockdown and naturally occurring human genetic mutation, cellular BOLA3 deficiency down-regulated the glycine cleavage system protein H (GCSH), thus bolstering intracellular glycine content. In the setting of these alterations of oxidative metabolism and glycine levels, BOLA3 deficiency increased endothelial proliferation, survival, and vasoconstriction, while decreasing angiogenic potential. In vivo, pharmacologic knockdown of endothelial BOLA3 and targeted overexpression of BOLA3 in mice demonstrated that BOLA3 deficiency promotes histologic and hemodynamic manifestations of PH. Notably, the therapeutic effects of BOLA3 expression were reversed by exogenous glycine supplementation. Conclusions-BOLA3 acts as a crucial lynchpin connecting Fe-S-dependent oxidative respiration and glycine homeostasis with endothelial metabolic reprogramming critical to PH pathogenesis. These results provide a molecular explanation for the clinical associations linking PH with hyperglycinemic syndromes and mitochondrial disorders. These findings also identify novel metabolic targets, including those involved in epigenetics, iron-sulfur biogenesis, and glycine biology, for diagnostic and therapeutic development. Yu et al.

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Circulating microRNAs (c-miRNAs), plasma-based noncoding RNAs that control posttranscriptional gene expression, mediate processes that underlie phenotypical plasticity to exercise. The relationship and biological relevance between c-miRNA expression and variable dose exercise exposure remains uncertain. We hypothesized that certain c-miRNAs respond to changes in exercise intensity and/or duration in a dose-dependent fashion. Muscle release of such c-miRNAs may then deplete intracellular stores, thus facilitating gene reprogramming and exercise adaptation. To address these hypotheses, healthy men participated in variable intensity ( n = 12, 30 × 1 min at 6, 7, and 8 miles/h, order randomized) and variable duration ( n = 14, 7 × 1 mile/h for 30, 60, and 90 min, order randomized) treadmill-running protocols. Muscle-enriched c-miRNAs (i.e., miRNA-1 and miRNA-133a) and others with known relevance to exercise were measured before and after exercise. c-miRNA responses followed three profiles: 1) nonresponsive (miRNA-21 and miRNA-210), 2) responsive to exercise at some threshold but without dose dependence (miRNA-24 and miRNA-146a), and 3) responsive to exercise with dose dependence to increasing intensity (miRNA-1) or duration (miRNA-133a and miRNA-222). We also studied aerobic exercise-trained mice, comparing control, low-intensity (0.5 km/h), or high-intensity (1 km/h) treadmill-running protocols over 4 wk. In high- but not low-intensity-trained mice, we found increased plasma c-miR-133a along with decreased intracellular miRNA-133a and increased serum response factor, a known miR-133a target gene, in muscle. Characterization of c-miRNAs that are dose responsive to exercise in humans and mice supports the notion that they directly mediate physiological adaptation to exercise, potentially through depletion of intracellular stores of muscle-specific miRNAs. NEW & NOTEWORTHY In this study of humans and mice, we define circulating microRNAs in plasma that are dose responsive to exercise. Our data support the notion that these microRNAs mediate physiological adaptation to exercise potentially through depletion of intracellular stores of muscle-specific microRNAs and releasing their inhibitory effects on target gene expression.

A network dependency platform was generated to define a landscape of cancer drug mechanisms in pulmonary hypertension.

Background Pulmonary hypertension (PH) is a deadly disease characterized by vascular stiffness and altered cellular metabolism. Current treatments focus on vasodilation and not other root causes of pathogenesis. Previously, it was demonstrated that glutamine metabolism, as catalyzed by GLS1 (glutaminase 1) activity, is mechanoactivated by matrix stiffening and the transcriptional coactivators YAP1 (yes‐associated protein 1) and transcriptional coactivator with PDZ‐binding motif (TAZ), resulting in pulmonary vascular proliferation and PH. Pharmacologic inhibition of YAP1 (by verteporfin) or glutaminase (by CB‐839) improved PH in vivo. However, systemic delivery of these agents, particularly YAP1 inhibitors, may have adverse chronic effects. Furthermore, simultaneous use of pharmacologic blockers may offer additive or synergistic benefits. Therefore, a strategy that delivers these drugs in combination to local lung tissue, thus avoiding systemic toxicity and driving more robust improvement, was investigated. Methods and Results We used poly(lactic‐co‐glycolic) acid polymer‐based microparticles for delivery of verteporfin and CB‐839 simultaneously to the lungs of rats suffering from monocrotaline‐induced PH. Microparticles released these drugs in a sustained fashion and delivered their payload in the lungs for 7 days. When given orotracheally to the rats weekly for 3 weeks, microparticles carrying this drug combination improved hemodynamic (right ventricular systolic pressure and right ventricle/left ventricle+septum mass ratio), histologic (vascular remodeling), and molecular markers (vascular proliferation and stiffening) of PH. Importantly, only the combination of drug delivery, but neither verteporfin nor CB‐839 alone, displayed significant improvement across all indexes of PH. Conclusions Simultaneous, lung‐specific, and controlled release of drugs targeting YAP1 and GLS1 improved PH in rats, addressing unmet needs for the treatment of this deadly disease.

Background The clinical value of programmed death-ligand 1 (PD-L1) expression in colorectal liver oligometastases (CLOs) remains undefined. This study aimed to detect PD-L1 in the microenvironment of CLOs and determine its association with patient prognosis. Methods We collected 126 liver-resection specimens from CLO patients who underwent curative liver resection between June 1999 and December 2016. Immunohistochemistry (IHC) was performed to assess PD-L1 expression in paraffin-embedded specimens. Overall survival (OS) and recurrence-free survival (RFS) were analysed using the Kaplan–Meier method and log-rank test. Results PD-L1 was mainly expressed in the stroma of liver oligometastases. Patients with high PD-L1 expression had a higher proportion of clinical-risk scores (CRSs) of 2–4 (67.7% vs 40.4%; P = 0.004). With a median 58-month follow-up, patients with high PD-L1 expression had a significantly lower 3-year OS rate (65.5% vs 92.7%; P = 0.001) and 3-year RFS rate (34.7% vs 83.8%; P < 0.001) than patients with low PD-L1 expression. Multivariate Cox analysis demonstrated that high PD-L1 expression (hazard ratio [HR] = 3.581; 95% confidence interval [CI] 2.301–9.972; P = 0.015), CRS 2–4 (HR = 6.960; 95% CI 1.135–42.689; P = 0.036) and increased preoperative CA19-9 (HR = 2.843; 95% CI 1.229–6.576; P = 0.015) were independent risk factors for OS. High PD-L1 expression (HR = 4.815; 95% CI 2.139–10.837; P < 0.001) and lymph-node metastasis (HR = 2.115; 95% CI 1.041–4.297; P = 0.038) were independent risk factors for RFS. Conclusion This study found that PD-L1 was commonly expressed in the tumour stroma of CLOs and high PD-L1 expression was associated with poor prognosis.

Deficiency of iron-sulfur (Fe-S) clusters promotes metabolic rewiring of the endothelium and the development of pulmonary hypertension (PH) in vivo. Joining a growing number of Fe-S biogenesis proteins critical to pulmonary endothelial function, recent data highlighted that frataxin (FXN) reduction drives Fe-S-dependent genotoxic stress and senescence across multiple types of pulmonary vascular disease. Trinucleotide repeat mutations in the FXN gene cause Friedreich ataxia, a disease characterized by cardiomyopathy and neurodegeneration. These tissue-specific phenotypes have historically been attributed to mitochondrial reprogramming and oxidative stress. Whether FXN coordinates both nuclear and mitochondrial processes in the endothelium is unknown. Here, we aim to identify the mitochondria-specific effects of FXN deficiency in the endothelium that predispose to pulmonary hypertension. Our data highlight an Fe-S-driven metabolic shift separate from previously described replication stress whereby FXN knockdown diminished mitochondrial respiration and increased glycolysis and oxidative species production. In turn, FXN-deficient endothelial cells exhibited a vasoconstrictive phenotype consistent with PH. These data were observed in both primary pulmonary endothelial cells after pharmacologic inhibition of FXN and inducible pluripotent stem cell-derived endothelial cells from patients with FXN mutations. Altogether, this study defines FXN as a shared upstream driver of pathologic aberrations in both metabolism and genomic stability. Moreover, our study highlights FXN-specific vasoconstriction, suggesting available and future therapies may be beneficial and targeted for PH subtypes with FXN deficiency.

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