miR-322-5p targets IGF-1 and is suppressed in the heart of rats with pulmonary hypertension

Sarcopenia and cachexia: molecular mechanisms and therapeutic interventions

Sarcopenia is defined as a muscle-wasting syndrome that occurs with accelerated aging, while cachexia is a severe wasting syndrome associated with conditions such as cancer and immunodeficiency disorders, which cannot be fully addressed through conventional nutritional supplementation. Sarcopenia can be considered a component of cachexia, with the bidirectional interplay between adipose tissue and skeletal muscle potentially serving as a molecular mechanism for both conditions. However, the underlying mechanisms differ. Recognizing the interplay and distinctions between these disorders is essential for advancing both basic and translational research in this area, enhancing diagnostic accuracy and ultimately achieving effective therapeutic solutions for affected patients. This review discusses the muscle microenvironment's changes contributing to these conditions, recent therapeutic approaches like lifestyle modifications, small molecules, and nutritional interventions, and emerging strategies such as gene editing, stem cell therapy, and gut microbiome modulation. We also address the challenges and opportunities of multimodal interventions, aiming to provide insights into the pathogenesis and molecular mechanisms of sarcopenia and cachexia, ultimately aiding in innovative strategy development and improved treatments.

MicroRNAs as commonly expressed biomarkers for sarcopenia and frailty: A systematic review

BACKGROUND

Coexistent sarcopenia and frailty is more strongly associated with adverse health outcomes than each condition alone. As the importance of coexistent sarcopenia and frailty increases, exploring their underlying mechanisms is warranted. Recently, noncoding ribonucleic acids (RNAs) have been suggested as potential biomarkers of sarcopenia and frailty. This systematic review aimed to summarize noncoding RNAs commonly expressed in sarcopenia and frailty, and to search the predicted target genes and biological pathways of them.

METHODS

We systematically searched the literatures on PubMed, Embase, Cochrane Library, Web of Science, and Scopus for literature published till November 15, 2023. A total of 7,202 literatures were initially retrieved. After de-duplication, 34 studies (26 sarcopenia-related and 8 frailty-related) were full-text reviewed, and 15 studies (11 sarcopenia-related and 4 frailty-related) were finally included.

RESULTS

miR-29a-3p, miR-29b-3p, and miR-328 were identified as commonly expressed in same direction in sarcopenia and frailty. These microRNAs (miRNAs), identified in the literature search using PubMed, modulate transforming growth factor-β signaling via extracellular matrix components and calcineurin/nuclear factor of activated T cells 3 signaling via sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2a, which are involved in regulating skeletal muscle fibrosis and the growth of slow-twitch muscle fibers, respectively. miR-155-5p, miR-486, and miR-23a-3p were also commonly expressed in two conditions, although in different or conflicting directions.

CONCLUSION

In this systematic review, we highlight the potential of shared miRNAs that exhibit consistent expression patterns as biomarkers for the early diagnosis and progression assessment of both sarcopenia and frailty.

Identification and experimental verification of senescence-related gene signatures and molecular subtypes in idiopathic pulmonary arterial hypertension

Evidences illustrate that cell senescence contributes to the development of pulmonary arterial hypertension. However, the molecular mechanisms remain unclear. Since there may be different senescence subtypes between PAH patients, consistent senescence-related genes (SRGs) were utilized for consistent clustering by unsupervised clustering methods. Senescence is inextricably linked to the immune system, and the immune cells in each cluster were estimated by ssGSEA. To further screen out more important SRGs, machine learning algorithms were used for identification and their diagnostic value was assessed by ROC curves. The expression of hub genes were verified in vivo and in vitro. Transcriptome analysis was used to assess the effects of silence of hub gene on different pathways. Three senescence molecular subtypes were identified by consensus clustering. Compared with cluster A and B, most immune cells and checkpoint genes were higher in cluster C. Thus, we identified senescence cluster C as the immune subtype. The ROC curves of IGF1, HOXB7, and YWHAZ were remarkable in both datasets. The expression of these genes was increased in vitro. Western blot and immunohistochemical analyses revealed that YWHAZ expression was also increased. Our transcriptome analysis showed autophagy-related genes were significantly elevated after silence of YWHAZ. Our research provided several prospective SRGs and molecular subtypes. Silence of YWHAZ may contribute to the clearance of senescent endothelial cells by activating autophagy.

Identifying Key Biomarkers in Pediatric Pulmonary Hypertension: An Investigative Approach

This study assesses the utility of early biomarkers-5-hydroxyindoleacetic acid (5-HIAA) and insulin-like growth factor 1 (IGF-1)-for diagnosing and monitoring pulmonary hypertension (PH) in children with congenital heart defects (CHD). Due to the risks associated with invasive diagnostics, such as right heart catheterization, non-invasive biomarkers provide a safer alternative for early PH detection. This cohort-based study utilized blood and urine samples to measure 5-HIAA and IGF-1 levels via enzyme immunoassays. Our findings revealed significant changes in 5-HIAA concentrations across various biological matrices, supporting its potential as a diagnostic tool. Specifically, altered levels in urine and plasma reflect its role in serotonin metabolism and vascular remodeling in PH. IGF-1 levels were notably reduced in plasma, suggesting its involvement in PH pathophysiology. ROC analysis confirmed the diagnostic efficacy of these biomarkers, particularly 5-HIAA's high specificity and sensitivity. In conclusion, 5-HIAA and IGF-1 levels correlate well with PH, underscoring their diagnostic value for early PH detection in children with CHD.

The diverging roles of insulin-like growth factor binding proteins in pulmonary arterial hypertension

Pulmonary hypertension (PH) is a progressive, severe and to date not curable disease of the pulmonary vasculature. Alterations of the insulin-like growth factor 1 (IGF-1) system are known to play a role in vascular pathologies and IGF-binding proteins (IGFBPs) are important regulators of the bioavailability and function of IGFs. In this study, we show that circulating plasma levels of IGFBP-1, IGFBP-2 and IGFBP-3 are increased in idiopathic pulmonary arterial hypertension (IPAH) patients compared to healthy individuals. These binding proteins inhibit the IGF-1 induced IGF-1 receptor (IGF1R) phosphorylation and exhibit diverging effects on the IGF-1 induced signaling pathways in human pulmonary arterial cells (i.e. healthy as well as IPAH-hPASMCs, and healthy hPAECs). Furthermore, IGFBPs are differentially expressed in an experimental mouse model of PH. In hypoxic mouse lungs, IGFBP-1 mRNA expression is decreased whereas the mRNA for IGFBP-2 is increased. In contrast to IGFBP-1, IGFBP-2 shows vaso-constrictive properties in the murine pulmonary vasculature. Our analyses show that IGFBP-1 and IGFBP-2 exhibit diverging effects on IGF-1 signaling and display a unique IGF1R-independent kinase activation pattern in human pulmonary arterial smooth muscle cells (hPASMCs), which represent a major contributor of PAH pathobiology. Furthermore, we could show that IGFBP-2, in contrast to IGFBP-1, induces epidermal growth factor receptor (EGFR) signaling, Stat-3 activation and expression of Stat-3 target genes. Based on our results, we conclude that the IGFBP family, especially IGFBP-1, IGFBP-2 and IGFBP-3, are deregulated in PAH, that they affect IGF signaling and thereby regulate the cellular phenotype in PH.

MicroRNA-322-5p protects against myocardial infarction through targeting BTG2

BACKGROUND

Numerous studies have explored the therapeutic potential of microRNA (miR) in myocardial infarction (MI) treatment. This study focuses on the role of miR-322-5p in MI, particularly in its regulatory interaction with B-cell translocation gene 2 (BTG2).

MATERIALS AND METHODS

Expression levels of miR-322-5p and BTG2 were assessed in a rat MI model. Adenovirus altering miR-322-5p or BTG2 expression were administered to MI rats. Evaluation included cardiac function, inflammation, myocardial injury, pathological changes, apoptosis, and NF-κB pathway-related genes in MI rats post-targeted treatment. The miR-322-5p and BTG2 targeting relationship was investigated.

RESULTS

MI rats exhibited low miR-322-5p and high BTG2 expression in the myocardial tissues. Restoration of miR-322-5p enhanced cardiac function, alleviated inflammation and myocardial injury, mitigated pathological changes and apoptosis, and deactivated the NF-κB pathway in MI rats. BTG2 expression was negatively-regulated by miR-322-5p. Overexpressed BTG2 counteracted miR-322-5p-induced cardioprotection on MI rats.

CONCLUSION

This study provides evidence that miR-322-5p protects against MI by suppressing BTG2 expression.

MicroRNAs and their regulators: Potential therapeutic targets in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex and progressive disease characterized by pulmonary arterial remodeling. Despite that current combination therapy has shown improvement in morbidity and mortality, a better deciphering of the underlying pathological mechanisms and novel therapeutic targets is urgently needed to combat PAH. MicroRNA, the critical element in post-transcription mechanisms, mediates cellular functions mainly by tuning downstream target gene expression. Meanwhile, upstream regulators can regulate miRNAs in synthesis, transcription, and function. In vivo and in vitro studies have suggested that miRNAs and their regulators are involved in PAH. However, the miRNA-related regulatory mechanisms governing pulmonary vascular remodeling and right ventricular dysfunction remain elusive. Hence, this review summarized the controversial roles of miRNAs in PAH pathogenesis, focused on different miRNA-upstream regulators, including transcription factors, regulatory networks, and environmental stimuli, and finally proposed the prospects and challenges for the therapeutic application of miRNAs and their regulators in PAH treatment.

MircoRNA-322-5p promotes lipopolysaccharide-induced acute kidney injury mouse models and mouse primary proximal renal tubular epithelial cell injury by regulating T-box transcription factor 21/mitogen-activated protein kinase/extracellular signal-related kinase axis

INTRODUCTION AND OBJECTIVES

Acute kidney injury (AKI) is a common devastating complication characterized by an abrupt loss of renal function. It is of great significance to explore promising biomarkers for AKI treatment.

MATERIALS AND METHODS

Here, we established LPS (lipopolysaccharide)-induced AKI mice models and LPS-induced AKI mouse renal tubular epithelial cell model. The severity of AKI was determined by the levels of BUN (blood urea nitrogen) and SCr (serum creatinine), the observation of pathological section as well as the renal tubular injury score. The apoptosis was determined by the measurement of Caspase-3 and Caspase-9 activities, and cell apoptosis assays. qRT-PCR (quantitative real-time PCR) and western blot revealed that miR-322-5p (microRNA-322-5p) was up-regulated in LPS -induced AKI models while Tbx21 (T-box transcription factor 21) was down-regulated in LPS-induced AKI models. Dual-luciferase reporter and RNA pulldown assays detected the interaction of Tbx21 with miR-322-5p.

RESULTS

We found that miR-322-5p was overtly over-expressed in the in vitro LPS-induced AKI model and promoted the apoptosis of AKI mouse renal tubular epithelial cells via inhibiting Tbx21, which suppressed the mitochondrial fission and cell apoptosis through MAPK/ERK (mitogen-activated protein kinase/extracellular signal-related kinase) pathway.

CONCLUSIONS

We demonstrated that miR-322-5p promotes LPS-induced mouse AKI by regulating Tbx21/MAPK/ERK axis, which might provide new sights for AKI research.

6-Gingerol via overexpression of miR-322-5p impede lipopolysaccharide-caused inflammatory response in RAW264.7 cells

Acute lung injury (ALI) and sepsis are complicated syndromes that are often left untreated in critically ill patients. 6-Gingerol is a phenolic phytochemical compound that is found in fresh ginger, has pharmacological effects against inflammation. This study explored the roles of 6-gingerol in a mouse model of acute lung injury caused by lipopolysaccharide (LPS) and RAW-264.7 cells inflammation. The LPS-induced animal model underwent histopathological examinations, and RAW-264.7 cells viability was determined by Cell counting Kit-8 (CCk-8) assay. Additionally, qRT-PCR, Immunofluorescence, Western blot, and ELISA were used in vivo and in vitro to identify inflammatory factors and proteins associated with NF-κB and MAPK signaling pathways. In a histological examination 6-gingerol exhibited protective effects. Moreover, 6-gingerol elevated cell viability and downregulated inflammatory factors Interlukin-1β (IL-1β), Interlukin-6 (IL-6) and Tumor necrosis factor-α (TNF-α) in LPS-treated RAW-264.7 cells. Furthermore, 6-gingerol decreased phosphorylation of P65, P38 and the level of JNK in NF-κB and MAPK pathways. Importantly, 6-gingerol increased transcript abundance of miR-322-5p which suppressed by LPS and miR-322-5p downregulation negated the protective functions of 6-gingerol. The protective activity of 6-gingerol was mediated by miR-322-5p up-regulation.

Right Ventricle and Epigenetics: A Systematic Review

There is an increasing recognition of the crucial role of the right ventricle (RV) in determining the functional status and prognosis in multiple conditions. In the past decade, the epigenetic regulation (DNA methylation, histone modification, and non-coding RNAs) of gene expression has been raised as a critical determinant of RV development, RV physiological function, and RV pathological dysfunction. We thus aimed to perform an up-to-date review of the literature, gathering knowledge on the epigenetic modifications associated with RV function/dysfunction. Therefore, we conducted a systematic review of studies assessing the contribution of epigenetic modifications to RV development and/or the progression of RV dysfunction regardless of the causal pathology. English literature published on PubMed, between the inception of the study and 1 January 2023, was evaluated. Two authors independently evaluated whether studies met eligibility criteria before study results were extracted. Amongst the 817 studies screened, 109 studies were included in this review, including 69 that used human samples (e.g., RV myocardium, blood). While 37 proposed an epigenetic-based therapeutic intervention to improve RV function, none involved a clinical trial and 70 are descriptive. Surprisingly, we observed a substantial discrepancy between studies investigating the expression (up or down) and/or the contribution of the same epigenetic modifications on RV function or development. This exhaustive review of the literature summarizes the relevant epigenetic studies focusing on RV in human or preclinical setting.

Low-affinity insulin-like growth factor binding protein 7 and its association with pulmonary arterial hypertension severity and survival

Insulin-like growth factor (IGF) binding proteins (IGFBPs) are a family of growth factor modifiers, some of which are known to be independently associated with pulmonary arterial hypertension (PAH) survival. IGF factor binding protein 7 (IGFBP7) is a unique low-affinity IGFBP that, independent of IGF, stimulates prostacyclin production. This study proposed to establish associations between IGFBP7 and PAH severity and survival, using enrollment and longitudinal samples. Serum IGFBP7 levels were significantly elevated in patients with PAH compared to controls. After adjusting for age and sex, logarithmic increases in IGFBP7 were associated with a 20 m shorter six-minute walk distance (6MWD; p < 0.001), a 2-3 mmHg higher mean right atrial pressure (p < 0.001 and 0.02), and a higher likelihood of a greater REVEAL 2.0 risk category placement (p < 0.001). Kaplan-Meier analysis demonstrated significantly decreased survival with IGFBP7 above the median and Cox multivariable analysis adjusted for age and sex, demonstrated higher serum IGFBP7 was an independent predictor of survival. Though the exact mechanism is still unknown, given IGFBP7's role as a prostacyclin stimulant, it has potential use as a therapeutic target for disease modulation.

Current Therapy and Liver Transplantation for Portopulmonary Hypertension in Japan

Portopulmonary hypertension (PoPH) and hepatopulmonary syndrome are severe pulmonary complications associated with liver cirrhosis (LC) and portal hypertension. Three key pathways, involving endothelin, nitric oxide, and prostacyclin, have been identified in the development and progression of pulmonary arterial hypertension (PAH). To obtain a good effect with PAH-specific drugs in PoPH patients, it is important to diagnose PoPH at an early stage and promptly initiate therapy. The majority of therapeutic drugs are contraindicated for Child-Pugh grade C LC, and their effects decrease in the severe PAH stage. Among many LC patients, the measurement of serum brain natriuretic peptide levels might be useful for detecting PoPH. Previously, liver transplantation (LT) for PoPH was contraindicated; however, the indications for LT are changing and now take into account how well the PoPH is controlled by therapeutic drugs. In Japan, new registration criteria for deceased-donor LT have been established for PoPH patients. PoPH patients with a mean pulmonary arterial pressure <35 mmHg and pulmonary vascular resistance <400 dyn/s/cm−5 are indicated for LT, regardless of whether they are using therapeutic drugs. Combined with PAH-specific drugs, LT may lead to excellent long-term outcomes in PoPH patients. We aimed to review current therapies for PoPH, including LT.

Upregulated miR-322-5p regulates cell cycle and promotes cell proliferation and apoptosis by directly targeting Wee1 in mice liver injury

Liver injury from any number of causes (e.g. chemical material, drugs and diet, viral infection) is a global health problem, and its mechanism is not clearly understood. MicroRNAs (miRNAs) expression profiling is gaining popularity because miRNAs, as key regulators in gene expression networks, can influence many biological processes and have also shown promise as biomarkers for disease. Previous studies reported the regulation effects of miRNAs in liver injury, whereas function and molecular mechanisms of miR-322-5p were still unclear. Therefore, our study focused on the biological role of miR-322-5p in carbon tetrachloride (CCl4)-induced liver injury proliferation, apoptosis, and cell cycle. A mouse model of CCl4-induced liver injury was established, and the transcriptomes and miRNAs transcriptomes of 2d and 5d liver tissues after injury were sequenced. The expression of miR-322-5p and the cell cycle genes were detected in liver tissues and Hepa1-6 cell line by miRNA RT-PCR, qRT-PCR. The effects of miR-322-5p on liver cell proliferation, cell cycle and apoptosis were evaluated using MTS assays and flow cytometry analysis. The relationship between miR-322-5p and Wee1 was predicted and confirmed by bioinformatics analysis and a dual luciferase reporter assay. Functional experiments, including an MTS assay and flow cytometric analysis, were performed to study the effects of Wee1. MiR-322-5p was upregulated in injury liver tissues, and downregulated miR-322-5p was proved to inhibit proliferation, apoptosis and arrest cell cycle at G2/M in vitro. The dual-luciferase reporter assay results indicated that miR-322-5p has a binding site at position 285 in the Wee1 3´UTR. The effects of miR-322-5p in proliferation and cell cycle regulation can be abolished by Wee1 through rescue experiments. By directly targeting Wee1 influenced the expression of several cell cycle factors, including Cyclin dependent kinase 1 (Cdk1), cyclin B1 (Ccnb1) and Cell division cyclin 25C (Cdc25C). MiR-322-5p may function as a suppressive factor by negatively controlling Wee1, thus, highlighting the potential role of miR-322-5p as a therapeutic target for liver injury.Abbreviations: ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; GSH: Glutathione, γ-glutamyl cysteinel + glycine; CCl4: Carbon tetrachloride; HE: Haematoxylin and eosin; KEGG: Kyoto Encyclopedia of Genes and Genomes.

MiR-322-5p Alleviates Cell Injury and Impairment of Cognitive Function in Vascular Dementia by Targeting TSPAN5

PURPOSE

As the population ages, the incidence of clinical dementia has been rising around the world. It has been reported that microRNAs act as key diagnostic biomarkers and targets for various neurological conditions, including dementia. MiR-322-5p has been revealed to play an important role in multiple diseases. In this study, we aimed to investigate the role and regulatory mechanism of miR-322-5p in vascular dementia.

MATERIALS AND METHODS

In this study, neonatal rat neurons (NRNs) were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to induce cell injury. The animals were subjected to permanent bilateral occlusion of the carotid arteries (2-vessel occlusion, 2VO) to induce the model of chronic brain hypoperfusion.

RESULTS

MiR-322-5p expression was significantly downregulated in the neurons exposed to OGD/R and the hippocampi of 2VO rats. Overexpression of miR-322-5p ameliorated cell apoptosis and the inflammatory response in vitro. In a mechanistic study, miR-322-5p was confirmed to directly target and negatively regulate tetraspanin 5 (TSPAN5) in cultured NRNs. Moreover, overexpression of TSPAN5 could counteract the effects of miR-322-5p overexpression on cell apoptosis and the inflammatory response in OGD/R-treated neurons. More importantly, miR-322-5p improved cognitive ability and inhibited inflammatory production in 2VO rats.

CONCLUSION

Overall, the results suggest that miR-322-5p alleviates vascular dementia development by targeting TSPAN5. This discovery may provide a potential therapeutic target for dementia.

MicroRNAs in obesity, sarcopenia, and commonalities for sarcopenic obesity: a systematic review

Sarcopenic obesity is a distinct condition of sarcopenia in the context of obesity, with the cumulative health risks of both phenotypes. Differential expression of microRNAs (miRNAs) has been reported separately in people with obesity and sarcopenia and may play a role in the pathogenesis of sarcopenic obesity. However, this has not been explored to date. This study aimed to identify differentially expressed miRNAs reported in serum, plasma, and skeletal muscle of people with obesity and sarcopenia and whether there are any commonalities between these conditions. We performed a systematic review on Embase and MEDLINE (PROSPERO, CRD42020224486) for differentially expressed miRNAs (fold change >1.5 or P-value <0.05) in (i) sarcopenia or frailty and (ii) obesity or metabolic syndrome. The functions and targets of miRNAs commonly changed in both conditions, in the same direction, were searched using PubMed. Following deduplication, 247 obesity and 42 sarcopenia studies were identified for full-text screening. Screening identified 36 obesity and 6 sarcopenia studies for final inclusion. A total of 351 miRNAs were identified in obesity and 157 in sarcopenia. Fifty-five miRNAs were identified in both obesity and sarcopenia-by sample type, 48 were found in plasma and one each in serum and skeletal muscle. Twenty-four miRNAs were identified from 10 of the included studies as commonly changed in the same direction (22 in plasma and one each in serum and skeletal muscle) in obesity and sarcopenia. The majority of miRNA-validated targets identified in the literature search were members of the phosphoinositide 3-kinase/protein kinase B and transforming growth factor-β signalling pathways. The most common targets identified were insulin-like growth factor 1 (miR-424-5p, miR-483-3p, and miR-18b-5p) and members of the SMAD family (miR-483-3p, miR-92a-3p, and miR-424-5p). The majority of commonly changed miRNAs were involved in protein homeostasis, mitochondrial dynamics, determination of muscle fibre type, insulin resistance, and adipogenesis. Twenty-four miRNAs were identified as commonly dysregulated in obesity and sarcopenia with functions and targets implicated in the pathogenesis of sarcopenic obesity. Given the adverse health outcomes associated with sarcopenic obesity, understanding the pathogenesis underlying this phenotype has the potential to lead to effective screening, monitoring, or treatment strategies. Further research is now required to confirm whether these miRNAs are differentially expressed in older adults with sarcopenic obesity.

[Roles of growth factors on vascular remodeling in pulmonary hypertension]

Pulmonary hypertension (PH) is defined as mean pulmonary arterial pressure at rest ≥25 mmHg. Pulmonary arterial hypertension (PAH) is classified as group 1 of PH and is a progressive and fatal disease of the pulmonary artery. The pathogenesis is sustained pulmonary vasoconstriction and pulmonary vascular remodeling, which cause progressive elevations in pulmonary vascular resistance and pulmonary arterial pressure. Elevated pulmonary arterial pressure leads to right heart failure and finally death. The pulmonary vascular remodeling is triggered by an increase in cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt). [Ca²⁺]_cyt is regulated by the stimulation of vasoconstrictors and growth factors though their receptors and ion channels on the plasma membrane. It has been reported that the epidermal growth factor (EGF), fibroblast growth factor (FGF), insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) are involved in the development of PAH. Upon binding of these growth factors with their specific receptor tyrosine kinases, their receptors activate cytosolic Ca²⁺ signaling and signal transduction cascades to induce cell proliferation, differentiation, and migration. Expressions of some growth factors and their receptors upregulate in PAH patients, which contributes to the formation of vascular remodeling and plexiform lesions in PAH. We have recently found that enhanced Ca²⁺-sensing receptor (CaSR) function is involved the development of PAH and CaSR expression is upregulated by PDGF in pulmonary arterial smooth muscle cells (PASMCs) from idiopathic PAH patients. This review will be discussed the physiological and pathological roles of growth factors in PAH.

Modulation of Small RNA Signatures in Schwann-Cell-Derived Extracellular Vesicles by the p75 Neurotrophin Receptor and Sortilin

Schwann cells (SCs) are the main glial cells of the peripheral nervous system (PNS) and are known to be involved in various pathophysiological processes, such as diabetic neuropathy and nerve regeneration, through neurotrophin signaling. Such glial trophic support to axons, as well as neuronal survival/death signaling, has previously been linked to the p75 neurotrophin receptor (p75NTR) and its co-receptor Sortilin. Recently, SC-derived extracellular vesicles (EVs) were shown to be important for axon growth and nerve regeneration, but cargo of these glial cell-derived EVs has not yet been well-characterized. In this study, we aimed to characterize signatures of small RNAs in EVs derived from wild-type (WT) SCs and define differentially expressed small RNAs in EVs derived from SCs with genetic deletions of p75NTR (Ngfr-/-) or Sortilin (Sort1-/-). Using RNA sequencing, we identified a total of 366 miRNAs in EVs derived from WT SCs of which the most highly expressed are linked to the regulation of axonogenesis, axon guidance and axon extension, suggesting an involvement of SC EVs in axonal homeostasis. Signaling of SC EVs to non-neuronal cells was also suggested by the presence of several miRNAs important for regulation of the endothelial cell apoptotic process. Ablated p75NTR or sortilin expression in SCs translated into a set of differentially regulated tRNAs and miRNAs, with impact in autophagy and several cellular signaling pathways such as the phosphatidylinositol signaling system. With this work, we identified the global expression profile of small RNAs present in SC-derived EVs and provided evidence for a regulatory function of these vesicles on the homeostasis of other cell types of the PNS. Differentially identified miRNAs can pave the way to a better understanding of p75NTR and sortilin roles regarding PNS homeostasis and disease.

Growth factors in pulmonary arterial hypertension: Focus on preserving right ventricular function

Pulmonary arterial hypertension (PAH) is a rare and progressive disease, characterized by increased vascular resistance leading to right ventricle (RV) failure. The extent of right ventricular dysfunction crucially influences disease prognosis; however, currently no therapies have specific cardioprotective effects. Besides discussing the pathophysiology of right ventricular adaptation in PAH, this review focuses on the roles of growth factors (GFs) in disease pathomechanism. We also summarize the involvement of GFs in the preservation of cardiomyocyte function, to evaluate their potential as cardioprotective biomarkers and novel therapeutic targets in PAH.

Pulmonary artery banding is a relevant model to study the right ventricular remodeling and dysfunction that occurs in pulmonary arterial hypertension

Right ventricular (RV) dysfunction determines mortality in patients with pulmonary arterial hypertension (PAH) and RV pressure loading. Experimental models commonly use Sugen hypoxia (SuHx)-induced PAH, monocrotaline (MCT)-induced PAH, or pulmonary artery banding (PAB). Because PAH models cannot interrogate RV effects or therapies independent of pulmonary vascular effects, we aimed to compare RV function and fibrosis in experimental PAB vs. PAH. Thirty rats were randomized to either sham controls, PAB, SuHx-, or MCT-induced PAH. RV pressures and function were assessed by high-fidelity pressure-tipped catheters and by echocardiography. RV myocyte hypertrophy, fibrosis, and capillary density were quantified from hematoxylin-eosin, picrosirius red-stained, and CD31-immunostained RV sections, respectively. RV pressures and the RV-to-left ventricular pressure ratio were significantly increased in all three groups to a similar degree (PAB 65 ± 17 mmHg, SuHx 72 ± 16 mmHg, and MCT 70 ± 12 mmHg) vs. controls (23 ± 2 mmHg, all P < 0.01). RV dilatation, hypertrophy, and fibrosis were similarly increased, and capillary density decreased, in the three models (RV fibrosis; PAB 13.3 ± 3.6%, SuHx 9.8 ± 3.0% and MCT 10.9 ± 2.4% vs control 5.5 ± 1.1%, all P < 0.05). RV function was similarly decreased in all models vs. controls. We observed comparable RV dilatation, hypertrophy, systolic and diastolic dysfunction, fibrosis, and capillary rarefaction in rat models of PAB, SuHx-, and MCT-induced PAH. These results suggest that PAB, when sufficiently severe, induces features of maladaptive RV remodeling and can be used to investigate RV pathophysiology and therapy effects independent of pulmonary vascular resistance.NEW & NOTEWORTHY Although animal models of pulmonary arterial hypertension and pressure loading are important to study right ventricular (RV) pathophysiology, pulmonary arterial hypertension models cannot interrogate RV responses independent of pulmonary vascular effects. Comparing three commonly used rat models under similar elevated RV pressure, we found that all models resulted in comparable maladaptive RV remodeling and dysfunction. Thus, these findings suggest that the pulmonary artery banding model can be used to investigate mechanisms of RV dysfunction in RV pressure overload and the effect of potential therapies.

Plasma insulin-like growth factor binding protein 1 in pulmonary arterial hypertension

BACKGROUND

Beside the pulmonary vasoconstriction observed in pulmonary arterial hypertension (PAH), severe proliferative and antiapoptotic cellular phenotypes result in vascular remodelling. Many recent findings indicate similarities between PAH and tumour pathology. For instance, insulin-like growth factor (IGF)-1 signalling, which is known to promote tumour development, is implicated in PAH. Higher circulating IGF binding protein (IGFBP)-1 levels are associated with worse survival in PAH. The present study aimed to investigate the relationship between plasma levels of various tumour-related biomarkers and PAH. Methods: IGFBP-1, -2 and -7, along with other tumour-related biomarkers, were measured in plasma from 48 treatment-naïve PAH patients and 16 healthy controls, using proximity extension assays. Among the PAH patients, 33 were also studied at an early treatment follow-up. Results: Plasma IGFBP-1 (p < .003), IGFBP-2 (p < .001), IGFBP-7 (p < .008), vimentin (p < .001), carbonic anhydrase 9 (p < .001), S100A11 (p < .001), human epididymis protein 4 (p < .001) and folate receptor-α (p < .004) were elevated in PAH, compared to controls. IGFBP-1 exhibited the most interesting correlations to clinical parameters and was selected for further analyses. IGFBP-1 correlated specifically to N-terminal prohormone of brain natriuretic peptide (NT-proBNP) (r = 0.44, p < .002), mean right atrial pressure (r = 0.41, p < .004), venous oxygen saturation (r = -0.43, p < .003), cardiac index (r = -0.32, p < .03) and 6-minute walking distance (r = -0.29, p < .05). Plasma IGFBP-1 also correlated to risk scores based on the European Society of Cardiology/European Respiratory Society (ESC/ERS) PAH guidelines (r = 0.43, p < .003) and the REVEAL model (r = 0.46, p < .001). PAH patients with supra-median baseline IGFBP-1 levels showed a trend for worse overall survival than those with infra-median levels (p = .087). IGFBP-1 was unaltered between baseline and an early treatment follow-up. However, IGFBP-1 changes, between baseline and follow-up, correlated to changes in NT-proBNP (r = 0.48, p < .006). Conclusion: Plasma IGFBP-1 levels at PAH diagnosis show moderate association to NT-proBNP and hemodynamics as well as with ESC/ERS and REVEAL risk scores.

SP1-induced SNHG14 aggravates hypertrophic response in in vitro model of cardiac hypertrophy via up-regulation of PCDH17

Cardiac hypertrophy (CH) is a common cardiac disease and is closely associated with heart failure. Protocadherin 17 (PCDH17) was reported to aggravate myocardial infarction. Present study was designed to illustrate the impact of PCDH17 and the mechanism of PCDH17 expression regulation in CH. CH model in vivo and in vitro was established by transverse aortic constriction (TAC) and Ang‐II treatment. Hypertrophy was evaluated in PMC and H9c2 cells by examining cell surface area and hypertrophic markers. Results demonstrated that PCDH17 was up‐regulated in CH in vivo and in vitro. PCDH17 knock‐down alleviated hypertrophic response in Ang‐II‐induced cardiomyocytes. By means of ENCORI database and a series of mechanism assays, miR‐322‐5p and miR‐384‐5p were identified to interact with and inhibit PCDH17. Next, lncRNA SNHG14 (small nucleolar RNA host gene 14) was validated to sponge both miR‐322‐5p and miR‐384‐5p to elevate PCDH17 level. The subsequent rescue assays revealed that miR‐322‐5p and miR‐384‐5p restored SNHG14 depletion‐mediated suppression on hypertrophy in Ang‐II‐induced cardiomyocytes. Besides, Sp1 transcription factor (SP1) was verified as the transcription factor activating both SNHG14 and PCDH17. Both SNHG14 and PCDH17 reversed SP1 knock‐down‐mediated repression on hypertrophy in Ang‐II‐induced cardiomyocytes. Together, present study first uncovered ceRNA network of SNHG14/miR‐322‐5p/miR‐384‐5p/PCDH17 in Ang‐II‐induced cardiomyocytes.

Identification of microRNAs in skeletal muscle associated with lung cancer cachexia

BACKGROUND

Cachexia, highly prevalent in patients with non-small cell lung cancer (NSCLC), impairs quality of life and is associated with reduced tolerance and responsiveness to cancer therapy and decreased survival. MicroRNAs (miRNAs) are small non-coding RNAs that play a central role in post-transcriptional gene regulation. Changes in intramuscular levels of miRNAs have been implicated in muscle wasting conditions. Here, we aimed to identify miRNAs that are differentially expressed in skeletal muscle of cachectic lung cancer patients to increase our understanding of cachexia and to allow us to probe their potential as therapeutic targets.

METHODS

A total of 754 unique miRNAs were profiled and analysed in vastus lateralis muscle biopsies of newly diagnosed treatment-naïve NSCLC patients with cachexia (n = 8) and age-matched and sex-matched healthy controls (n = 8). miRNA expression analysis was performed using a TaqMan MicroRNA Array. In silico network analysis was performed on all significant differentially expressed miRNAs. Differential expression of the top-ranked miRNAs was confirmed using reverse transcription-quantitative real-time PCR in an extended group (n = 48) consisting of NSCLC patients with (n = 15) and without cachexia (n = 11) and healthy controls (n = 22). Finally, these miRNAs were subjected to univariate and multivariate Cox proportional hazard analysis using overall survival and treatment-induced toxicity data obtained during the follow-up of this group of patients.

RESULTS

We identified 28 significant differentially expressed miRNAs, of which five miRNAs were up-regulated and 23 were down-regulated. In silico miRNA-target prediction analysis showed 158 functional gene targets, and pathway analysis identified 22 pathways related to the degenerative or regenerative processes of muscle tissue. Subsequently, the expression of six top-ranked miRNAs was measured in muscle biopsies of the entire patient group. Five miRNAs were detectable with reverse transcription-quantitative real-time PCR analysis, and their altered expression (expressed as fold change, FC) was confirmed in muscle of cachectic NSCLC patients compared with healthy control subjects: miR-424-5p (FC = 4.5), miR-424-3p (FC = 12), miR-450a-5p (FC = 8.6), miR-144-5p (FC = 0.59), and miR-451a (FC = 0.57). In non-cachectic NSCLC patients, only miR-424-3p was significantly increased (FC = 5.6) compared with control. Although the statistical support was not sufficient to imply these miRNAs as individual predictors of overall survival or treatment-induced toxicity, when combined in multivariate analysis, miR-450-5p and miR-451a resulted in a significant stratification between short-term and long-term survival.

CONCLUSIONS

We identified differentially expressed miRNAs putatively involved in lung cancer cachexia. These findings call for further studies to investigate the causality of these miRNAs in muscle atrophy and the mechanisms underlying their differential expression in lung cancer cachexia.

miR-1-5p targets TGF-βR1 and is suppressed in the hypertrophying hearts of rats with pulmonary arterial hypertension

The microRNA miR-1 is an important regulator of muscle phenotype including cardiac muscle. Down-regulation of miR-1 has been shown to occur in left ventricular hypertrophy but its contribution to right ventricular hypertrophy in pulmonary arterial hypertension are not known. Previous studies have suggested that miR-1 may suppress transforming growth factor-beta (TGF-β) signalling, an important pro-hypertrophic pathway but only indirect mechanisms of regulation have been identified. We identified the TGF-β type 1 receptor (TGF-βR1) as a putative miR-1 target. We therefore hypothesized that miR-1 and TGF-βR1 expression would be inversely correlated in hypertrophying right ventricle of rats with pulmonary arterial hypertension and that miR-1 would inhibit TGF-β signalling by targeting TGF-βR1 expression. Quantification of miR-1 and TGF-βR1 in rats treated with monocrotaline to induce pulmonary arterial hypertension showed appropriate changes in miR-1 and TGF-βR1 expression in the hypertrophying right ventricle. A miR-1-mimic reduced enhanced green fluorescent protein expression from a reporter vector containing the TGF-βR1 3’- untranslated region and knocked down endogenous TGF-βR1. Lastly, miR-1 reduced TGF-β activation of a (mothers against decapentaplegic homolog) SMAD2/3-dependent reporter. Taken together, these data suggest that miR-1 targets TGF-βR1 and reduces TGF-β signalling, so a reduction in miR-1 expression may increase TGF-β signalling and contribute to cardiac hypertrophy.

Fetal malnutrition-induced catch up failure is caused by elevated levels of miR-322 in rats

If sufficient nutrition is not obtained during pregnancy, the fetus changes its endocrine system and metabolism to protect the brain, resulting in a loss of body size. The detailed mechanisms that determine the success or failure of growth catch-up are still unknown. Therefore, we investigated the mechanism by which catch-up growth failure occurs. The body weights of rat pups at birth from dams whose calorie intake during pregnancy was reduced by 40% were significantly lower than those of controls, and some offspring failed to catch up. Short-body-length and low-bodyweight rats showed blood IGF-1 levels and mRNA expression levels of IGF-1 and growth hormone receptor (GHR) in the liver that were lower than those in controls. The next generation offspring from low-bodyweight non-catch-up (LBW-NCG) rats had high expression of miR-322 and low expression of GHR and IGF-1. The expression of miR-322 showed a significant negative correlation with GHR expression and body length, and overexpression of miR-322 suppressed GHR expression. We found that insufficient intake of calories during pregnancy causes catch-up growth failure due to increased expression of miR-322 and decreased expression of GHR in the livers of offspring, and this effect is inherited by the next generation.

Co-expression analysis reveals dysregulated miRNAs and miRNA-mRNA interactions in the development of contrast-induced acute kidney injury

The pathogenesis of contrast-induced acute kidney injury (CI-AKI) is incompletely understood. MicroRNAs (miRNAs) are important mediators that normally function via post-transcriptional degradation of target mRNAs. Emerging evidence indicates the appearance of differentially expressed (DE) miRNAs in CI-AKI following the injection of intravenous contrast medium. However, there are differences in the pathological mechanism and incidence of CI-AKI between intravenous and intra-arterial contrast administration. The present study aimed to investigate the critical roles of dysregulated miRNAs and their associated mRNAs in kidney injury following intra-arterial contrast medium exposure. Based on a reliable CI-AKI rat model, we conducted genome-wide miRNA and mRNA expression profiling analysis using deep sequencing. In the study, 36 DE mature miRNAs were identified (fold change > 1.5 and p value < 0.05) in the kidneys of CI-AKI rats (n = 3) compared with that in the controls (n = 3), consisting of 23 up-regulated and 13 down-regulated DE miRNAs. Bioinformatic analysis revealed that wingnut (Wnt), transforming growth factor beta (TGF-β), and 5'-AMP-activated protein kinase (AMPK) signaling pathways were most likely to be modulated by these dysregulated miRNAs. Around 453 dysregulated genes (fold change > 2.0 and p value < 0.05) were identified. Integrated analysis revealed 2037 putative miRNA-mRNA pairs with negative correlations. Among them, 6 DE miRNAs and 13 genes were selected for further quantitative real-time reverse transcription polymerase chain reaction validation (n = 6 for each group), and a good correspondence between the two techniques was observed. In conclusion, the present study provided evidence of miRNA-mRNA interactions in the development of kidney injury following an intra-arterial contrast injection. These findings provide insights into the underlying mechanisms of CI-AKI.

Quadriceps miR-542-3p and -5p are elevated in COPD and reduce function by inhibiting ribosomal and protein synthesis

Reduced physical performance reduces quality of life in patients with chronic obstructive pulmonary disease (COPD). Impaired physical performance is, in part, a consequence of reduced muscle mass and function, which is accompanied by mitochondrial dysfunction. We recently showed that miR-542-3p and miR-542-5p were elevated in a small cohort of COPD patients and more markedly in critical care patients. In mice, these microRNAs (miRNAs) promoted mitochondrial dysfunction suggesting that they would affect physical performance in patients with COPD, but we did not explore the association of these miRNAs with disease severity or physical performance further. We therefore quantified miR-542-3p/5p and mitochondrial rRNA expression in RNA extracted from quadriceps muscle of patients with COPD and determined their association with physical performance. As miR-542-3p inhibits ribosomal protein synthesis its ability to inhibit protein synthesis was also determined in vitro. Both miR-542-3p expression and -5p expression were elevated in patients with COPD (5-fold P < 0.001) and the degree of elevation associated with impaired lung function (transfer capacity of the lung for CO in % and forced expiratory volume in 1 s in %) and physical performance (6-min walk distance in %). In COPD patients, the ratio of 12S rRNA to 16S rRNA was suppressed suggesting mitochondrial ribosomal stress and mitochondrial dysfunction and miR-542-3p/5p expression was inversely associated with mitochondrial gene expression and positively associated with p53 activity. miR-542-3p suppressed RPS23 expression and maximal protein synthesis in vitro. Our data show that miR-542-3p and -5p expression is elevated in COPD patients and may suppress physical performance at least in part by inhibiting mitochondrial and cytoplasmic ribosome synthesis and suppressing protein synthesis. NEW & NOTEWORTHY miR-542-3p and -5p are elevated in the quadriceps muscle of patients with chronic obstructive pulmonary disease (COPD) in proportion to the severity of their lung disease. These microRNAs inhibit mitochondrial and cytoplasmic protein synthesis suggesting that they contribute to impaired exercise performance in COPD.

Muscle wasting in the presence of disease, why is it so variable?

Skeletal muscle wasting is a common clinical feature of many chronic diseases and also occurs in response to single acute events. The accompanying loss of strength can lead to significant disability, increased care needs and have profound negative effects on quality of life. As muscle is the most abundant source of amino acids in the body, it appears to function as a buffer for fuel and substrates that can be used to repair damage elsewhere and to feed the immune system. In essence, the fundamentals of muscle wasting are simple: less muscle is made than is broken down. However, although well-described mechanisms modulate muscle protein turnover, significant individual differences in the amount of muscle lost in the presence of a given severity of disease complicate the understanding of underlying mechanisms and suggest that individuals have different sensitivities to signals for muscle loss. Furthermore, the rate at which muscle protein is turned over under normal conditions means that clinically significant muscle loss can occur with changes in the rate of protein synthesis and/or breakdown that are too small to be measurable. Consequently, the changes in expression of factors regulating muscle turnover required to cause a decline in muscle mass are small and, except in cases of rapid wasting, there is no consistent pattern of change in the expression of factors that regulate muscle mass. MicroRNAs are fine tuners of cell phenotype and are therefore ideally suited to cause the subtle changes in proteome required to tilt the balance between synthesis and degradation in a way that causes clinically significant wasting. Herein we present a model in which muscle loss as a consequence of disease in non-muscle tissue is modulated by a set of microRNAs, the muscle expression of which is associated with severity of disease in the non-muscle tissue. These microRNAs alter fundamental biological processes including the synthesis of ribosomes and mitochondria leading to reduced protein synthesis and increased protein breakdown, thereby freeing amino acids from the muscle. We argue that the variability in muscle loss observed in the human population arises from at least two sources. The first is from pre-existing or disease-induced variation in the expression of microRNAs controlling the sensitivity of muscle to the atrophic signal and the second is from the expression of microRNAs from imprinted loci (i.e. only expressed from the maternally or paternally inherited allele) and may control the rate of myonuclear recruitment. In the absence of disease, these factors do not correlate with muscle mass, since there is no challenge to the established balance. However, in the presence of such a challenge, these microRNAs determine the rate of decline for a given disease severity. Together these mechanisms provide novel insight into the loss of muscle mass and its variation in the human population. The involvement of imprinted loci also suggests that genes that regulate early development also contribute to the ability of individuals to resist muscle loss in response to disease.

miR-429 and miR-424-5p inhibit cell proliferation and Ca2+ influx by downregulating CaSR in pulmonary artery smooth muscle cells

Cytosolic free Ca²⁺ concentration is a key factor in pulmonary vasoconstriction and vascular remodeling of pulmonary artery smooth muscle cells (PASMCs). These processes contribute to pulmonary arterial hypertension and are influenced by expression of calcium-sensing receptor (CaSR). Although regulation of CaSR expression is precisely controlled, the contribution of microRNAs (miR) is incompletely understood. Here, we demonstrate that miR-429, miR-424-5p, miR-200b-3p, and miR-200c-3p regulate CaSR by targeting specific 3'-untranslated region, suggesting that these miRNAs function as CaSR inhibitors in PASMCs. Moreover, miR-429 and miR-424-5p inhibit proliferation of PASMCs by downregulating CaSR, resulting in reduced Ca²⁺ influx under both normoxia and hypoxia. These findings indicate miR-429 and miR-424-5p target CaSR and may function as Ca²⁺ influx suppressors in pulmonary arterial hypertension-associated diseases.

Regulation of muscle atrophy by microRNAs: 'AtromiRs' as potential target in cachexia

PURPOSE OF REVIEW

To provide an overview and describe the mode of action of miRNAs recently implicated in muscle atrophy, and discuss the challenges to explore their potential as putative therapeutic targets in cachexia.

RECENT FINDINGS

Recent work showed differentially expressed miRNAs in skeletal muscle of patients with cachexia-associated diseases. Studies using experimental models revealed miRNA regulation of the anabolic IGF-1 and catabolic TGF- β/myostatin pathways, and downstream protein synthesis and proteolysis signaling in control of muscle mass.

SUMMARY

Cachexia is a complex metabolic condition associated with progressive body weight loss, wasting of skeletal muscle mass and decrease in muscle strength. MiRNAs play a central role in post-transcriptional gene regulation by targeting mRNAs, thereby coordinating and fine-tuning many cellular processes. MiRNA expression profiling studies of muscle biopsies have revealed differentially expressed miRNAs in patients with low muscle mass or cachexia. Evaluation in experimental models has revealed muscle atrophy, inhibition of protein synthesis and activation of proteolysis in response to modulation of specific miRNAs, termed 'atromiRs' in this review. These exciting findings call for further studies aimed at exploring the conservation of differentially expressed miRNAs across diseases accompanied by cachexia, identification of miRNA clusters and targets involved in muscle atrophy, and probing whether these miRNAs might be potential therapeutic targets for cachexia.