MicroRNA-708 regulates CD38 expression through signaling pathways JNK MAP kinase and PTEN/AKT in human airway smooth muscle cells

Noncoding RNAs in asthmatic airway smooth muscle cells

Asthma is a complex and heterogeneous airway disease caused by genetic, environmental and epigenetic factors treated with hormones and biologics. Irreversible pathological changes to airway smooth muscle cells (ASMCs) such as hyperplasia and hypertrophy can occur in asthmatic patients. Determining the mechanisms responsible is vital for preventing such changes. In recent years, noncoding RNAs (ncRNAs), especially microRNAs, long noncoding RNAs and circular RNAs, have been found to be associated with abnormalities of the ASMCs. This review highlights recent ncRNA research into ASMC pathologies. We present a schematic that illustrates the role of ncRNAs in pathophysiological changes to ASMCs that may be useful in future research in diagnostic and treatment strategies for patients with asthma.

Comparative microRNA profiling of Trypanosoma cruzi infected human cells

Introduction

Trypanosoma cruzi, the causative agent of Chagas disease, can infect almost any nucleated cell in the mammalian host. Although previous studies have described the transcriptomic changes that occur in host cells during parasite infection, the understanding of the role of post-transcriptional regulation in this process is limited. MicroRNAs, a class of short non-coding RNAs, are key players in regulating gene expression at the post-transcriptional level, and their involvement in the host-T. cruzi interplay is a growing area of research. However, to our knowledge, there are no comparative studies on the microRNA changes that occur in different cell types in response to T. cruzi infection.

Methods and results

Here we investigated microRNA changes in epithelial cells, cardiomyocytes and macrophages infected with T. cruzi for 24 hours, using small RNA sequencing followed by careful bioinformatics analysis. We show that, although microRNAs are highly cell type-specific, a signature of three microRNAs -miR-146a, miR-708 and miR-1246, emerges as consistently responsive to T. cruzi infection across representative human cell types. T. cruzi lacks canonical microRNA-induced silencing mechanisms and we confirm that it does not produce any small RNA that mimics known host microRNAs. We found that macrophages show a broad response to parasite infection, while microRNA changes in epithelial and cardiomyocytes are modest. Complementary data indicated that cardiomyocyte response may be greater at early time points of infection.

Conclusions

Our findings emphasize the significance of considering microRNA changes at the cellular level and complement previous studies conducted at higher organizational levels, such as heart samples. While miR-146a has been previously implicated in T. cruzi infection, similarly to its involvement in many other immunological responses, miR-1246 and miR-708 are demonstrated here for the first time. Given their expression in multiple cell types, we anticipate our work as a starting point for future investigations into their role in the post-transcriptional regulation of T. cruzi infected cells and their potential as biomarkers for Chagas disease.

Neurodegeneration and inflammation crosstalk: Therapeutic targets and perspectives

Glia, which was formerly considered to exist just to connect neurons, now plays a key function in a wide range of physiological events, including formation of memory, learning, neuroplasticity, synaptic plasticity, energy consumption, and homeostasis of ions. Glial cells regulate the brain's immune responses and confers nutritional and structural aid to neurons, making them an important player in a broad range of neurological disorders. Alzheimer's, ALS, Parkinson's, frontotemporal dementia (FTD), and epilepsy are a few of the neurodegenerative diseases that have been linked to microglia and astroglia cells, in particular. Synapse growth is aided by glial cell activity, and this activity has an effect on neuronal signalling. Each glial malfunction in diverse neurodegenerative diseases is distinct, and we will discuss its significance in the progression of the illness, as well as its potential for future treatment.

Mechanistic Links Between Obesity and Airway Pathobiology Inform Therapies for Obesity-Related Asthma

Obesity-related asthma is associated with a high disease burden and a poor response to existent asthma therapies, suggesting that it is a distinct asthma phenotype. The proposed mechanisms that contribute to obesity-related asthma include the effects of the mechanical load of obesity, adipokine perturbations, and immune dysregulation. Each of these influences airway smooth muscle function. Mechanical fat load alters airway smooth muscle stretch affecting airway wall geometry, airway smooth muscle contractility, and agonist delivery; weight loss strategies, including medically induced weight loss, counter these effects. Among the metabolic disturbances, insulin resistance and free fatty acid receptor activation influence distinct signaling pathways in the airway smooth muscle downstream of both the M2 muscarinic receptor and the β2 adrenergic receptor, such as phospholipase C and the extracellular signal-regulated kinase signaling cascade. Medications that decrease insulin resistance and dyslipidemia are associated with a lower asthma disease burden. Leptin resistance is best understood to modulate muscarinic receptors via the neural pathways but there are no specific therapies for leptin resistance. From the immune perspective, monocytes and T helper cells are involved in systemic pro-inflammatory profiles driven by obesity, notably associated with elevated levels of interleukin-6. Clinical trials on tocilizumab, an anti-interleukin antibody, are ongoing for obesity-related asthma. This armamentarium of therapies is distinct from standard asthma medications, and once investigated for its efficacy and safety among children, will serve as a novel therapeutic intervention for pediatric obesity-related asthma. Irrespective of the directionality of the association between asthma and obesity, airway-specific mechanistic studies are needed to identify additional novel therapeutic targets for obesity-related asthma.

A lncRNA MALAT1 is a positive regulator of RhoA protein expression in bronchial smooth muscle cells

AIMS

Augmented smooth muscle contractility of the airways associated with an increased expression of RhoA, a monomeric GTPase responsible for Ca²⁺ sensitization of contraction, is one of the causes of airway hyperresponsiveness. However, the mechanism of the altered properties of airway smooth muscle cells, including the RhoA upregulation, is not fully understood. This study aims to define functional role of a long non-coding RNA MALAT1 in the RhoA expression and development of bronchial smooth muscle (BSM) hyper-contractility.

MAIN METHODS

Cultured human BSM cells were transfected with MALAT1 antisense oligonucleotide (AS), miR-133a-3p mimic, and/or inhibitor, and then stimulated with interleukin-13 (IL-13). In animal experiments, the ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction.

KEY FINDINGS

Treatment of the cells with IL-13 induced an increase in RhoA protein. Either MALAT1 AS or miR-133a-3p mimic transfection inhibited the IL-13-induced upregulation of RhoA. The inhibitory effect of MALAT1 AS was abolished by co-transfection with miR-133a-3p inhibitor. In BSMs of the murine asthma model, upregulations of Malat1 and RhoA protein were observed concomitantly with downregulation of miR-133a-3p.

SIGNIFICANCE

These findings suggest that MALAT1 positively regulates RhoA protein expression by inhibiting miR-133a-3p in BSM cells, and that its upregulation causes the RhoA upregulation, resulting in an augmented BSM contractility.

The Double Face of miR-708: A Pan-Cancer Player with Dissociative Identity Disorder

Over the last decades, accumulating evidence has shown tumor-dependent profiles of miR-708, being either up- or downregulated, and thus, acting as a "Janus" regulator of oncogenic pathways. Herein, its functional duality was assessed through a thorough review of the literature and further validation in silico using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. In the literature, miR-708 was found with an oncogenic role in eight tumor types, while a suppressor tumor role was described in seven cancers. This double profile was also found in TCGA and GEO databases, with some tumor types having a high expression of miR-708 and others with low expression compared with non-tumor counterparts. The investigation of validated targets using miRBase, miRTarBase, and miRecords platforms, identified a total of 572 genes that appeared enriched for PI3K-Akt signaling, followed by cell cycle control, p53, Apellin and Hippo signaling, endocrine resistance, focal adhesion, and cell senescence regulations, which are all recognized contributors of tumoral phenotypes. Among these targets, a set of 15 genes shared by at least two platforms was identified, most of which have important roles in cancer cells that influence either tumor suppression or progression. In a clinical scenario, miR-708 has shown to be a good diagnostic and prognosis marker. However, its multitarget nature and opposing roles in diverse human tumors, aligned with insufficient experimental data and the lack of proper delivery strategies, hamper its potential as a sequence-directed therapeutic.

The Interaction Network of MicroRNAs with Cytokines and Signaling Pathways in Allergic Asthma

Allergic asthma is a complicated disease that is affected by many factors. Numerous cytokines and signaling pathways are attributed to the cause of asthma symptoms. MicroRNAs (miRNAs) are a group of small non-coding single-stranded RNA molecules that are involved in gene silencing and posttranscriptional regulation of gene expression by targeting mRNAs. In pathological conditions, altered expression of microRNAs differentially regulates cytokines and signaling pathways and therefore, can be the underlying reason for the pathogenesis of allergic asthma. Indeed, microRNAs participate in airway inflammation via inducing airway structural cells and activating immune responses by targeting cytokines and signaling pathways. Thus, to make a complete understanding of allergic asthma, it is necessary to investigate the communication network of microRNAs with cytokines and signaling pathways which is contributed to the pathogenesis of allergic asthma. Here, we shed light on this aspect of asthma pathology by Summarizing our current knowledge of this topic.

Molecular and Immunomodulatory Actions of New Antiasthmatic Agents: Exploring the Diversity of Biologics in Th2 Endotype Asthma

Asthma is a major respiratory disorder characterised by chronic inflammation and airway remodelling. It affects about 1-8% of the global population and is responsible for over 461,000 deaths annually. Until recently, the pharmacotherapy of severe asthma involved high doses of inhaled corticosteroids in combination with β-agonist for prolonged action, including theophylline, leukotriene antagonist or anticholinergic yielding limited benefit. Although the use of newer agents to target Th2 asthma endotypes has improved therapeutic outcomes in severe asthmatic conditions, there seems to be a paucity of understanding the diverse mechanisms through which these classes of drugs act. This article delineates the molecular and immunomodulatory mechanisms of action of new antiasthmatic agents currently being trialled in preclinical and clinical studies to remit asthmatic conditions. The ultimate goal in developing antiasthmatic agents is based on two types of approaches: either anti-inflammatory or bronchodilators. Biologic and most small molecules have been shown to modulate specific asthma endotypes, targeting thymic stromal lymphopoietin, tryptase, spleen tyrosine kinase (Syk), Janus kinase, PD-L1/PD-L2, GATA-3, and CD38 for the treatment and management of Th2 endotype asthma.

Ruxolitinib Ameliorates Airway Hyperresponsiveness and Lung Inflammation in a Corticosteroid-Resistant Murine Model of Severe Asthma

Asthma prevalence has increased considerably over the decades and it is now considered as one of the most common chronic disorders in the world. While the current anti-asthmatic therapies are effective for most asthma patients, there are 5-10% subjects whose disease is not controlled by such agents and they account for about 50% of the asthma-associated healthcare costs. Such patients develop severe asthma (SA), a condition characterized by a dominant Th1/Th17 cytokine response that is accompanied by Type 2 (T2)-low endotype. As JAK (Janus Kinase) signaling is very important for the activation of several cytokine pathways, we examined whether inhibition of JAKs might lessen the clinical and laboratory manifestations of SA. To that end, we employed a recently described murine model that recapitulates the complex immune response identified in the airways of human SA patients. To induce SA, mice were sensitized with house dust mite extract (HDME) and cyclic (c)-di-GMP and then subsequently challenged with HDME and a lower dose of c-di-GMP. In this model, treatment with the JAK inhibitor, Ruxolitinib, significantly ameliorated all the features of SA, including airway hyperresponsiveness and lung inflammation as well as total IgE antibody titers. Thus, these studies highlight JAKs as critical targets for mitigating the hyper-inflammation that occurs in SA and provide the framework for their incorporation into future clinical trials for patients that have severe or difficult-to manage asthma.

Role of CD38 in Adipose Tissue: Tuning Coenzyme Availability?

Nicotinamide adenine dinucleotide (NAD⁺) is a fundamental molecule in the regulation of energy metabolism, representing both a coenzyme and a substrate for different NAD⁺ degrading enzymes. Among these enzymes, CD38 can be seen under two perspectives: as the enzyme synthesizing Ca²⁺-mobilizing second messenger, starting from NAD⁺, and as the major NAD⁺-consumer, to be inhibited to increase NAD⁺ levels. Indeed, the regulation of NAD⁺ availability is a key event during different processes. In this review, we examine the recent studies related to the modulation of CD38 expression and activity, and the consequent changes in NAD(P)(H), in adipose tissue, during inflammation and cold-induced thermogenesis.

CD38 and MGluR1 as possible signaling molecules involved in epileptogenesis: A potential role for NAD+ homeostasis

In spite of long-term intensive scientific research efforts, there are still many issues concerning the mechanisms of epileptogenesis and epilepsy to be resolved. Temporal lobe, in particular hippocampus, is vulnerable to epileptogenic process. Herein, electrical kindling model of temporal lobe were analyzed using proteomic approach. A dramatic decrease in nicotinamide adenine dinucleotide (NAD⁺) level was exhibited during the kindling procedure in hippocampus. After stage 3, high CD38 expression was detected by qPCR, nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) and western blot analysis. An increase in expression of CD38/NADase activity was observed during the kindling procedure in hippocampus that suggest it as one of the most important NAD⁺ degrading enzymes during epileptogenesis. Subsequently, gene expression of CD38 metabolite related proteins (Ryr2, FKBP-12.6, Chrm1, mGluR1 and Cnx43) were examined. Among them, changes in the expression level of mGluR1 was more than other genes, which was also confirmed by LC MS/MS and western blotting analysis. These findings provided valuable information about changes in the expression of CD38/cADPR signaling pathway and suggest its crucial role during epileptogenesis.

MicroRNAs as Potential Regulators of Immune Response Networks in Asthma and Chronic Obstructive Pulmonary Disease

Chronic respiratory diseases (CRDs) are an important factor of morbidity and mortality, accounting for approximately 6% of total deaths worldwide. The main CRDs are asthma and chronic obstructive pulmonary disease (COPD). These complex diseases have different triggers including allergens, pollutants, tobacco smoke, and other risk factors. It is important to highlight that although CRDs are incurable, various forms of treatment improve shortness of breath and quality of life. The search for tools that can ensure accurate diagnosis and treatment is crucial. MicroRNAs (miRNAs) are small non-coding RNAs and have been described as promising diagnostic and therapeutic biomarkers for CRDs. They are implicated in multiple processes of asthma and COPD, regulating pathways associated with inflammation, thereby showing that miRNAs are critical regulators of the immune response. Indeed, miRNAs have been found to be deregulated in several biofluids (sputum, bronchoalveolar lavage, and serum) and in both structural lung and immune cells of patients in comparison to healthy subjects, showing their potential role as biomarkers. Also, miRNAs play a part in the development or termination of histopathological changes and comorbidities, revealing the complexity of miRNA regulation and opening up new treatment possibilities. Finally, miRNAs have been proposed as prognostic tools in response to both conventional and biologic treatments for asthma or COPD, and miRNA-based treatment has emerged as a potential approach for clinical intervention in these respiratory diseases; however, this field is still in development. The present review applies a systems biology approach to the understanding of miRNA regulatory networks in asthma and COPD, summarizing their roles in pathophysiology, diagnosis, and treatment.

Novel Pathway of Adenosine Generation in the Lungs from NAD+: Relevance to Allergic Airway Disease

Adenosine and uric acid (UA) play a pivotal role in lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). In the present experiments, we measured adenosine synthesis from nicotinamide adenine dinucleotide (NAD⁺) in membranes prepared from wild type (WT) and CD38 knockout (CD38KO) mouse lungs, from cultured airway smooth muscle and epithelial cells, and in bronchoalveolar lavage fluid after airway challenge with epidemiologically relevant allergens. Adenosine was determined using an enzymatically coupled assay that produces ATP and is detected by luminescence. Uric acid was determined by ELISA. Exposure of cultured airway epithelial cells to Alternaria alternata extract caused significant nucleotide (NAD⁺ and ATP) release in the culture media. The addition of NAD⁺ to membranes prepared from WT mice resulted in faster generation of adenosine compared to membranes from CD38KO mice. Formation of adenosine from NAD⁺ affected UA and ATP concentrations, its main downstream molecules. Furthermore, NAD⁺ and adenosine concentrations in the bronchoalveolar lavage fluid decreased significantly following airway challenge with house-dust mite extract in WT but not in CD38KO mice. Thus, NAD⁺ is a significant source of adenosine and UA in the airways in mouse models of allergic airway disease, and the capacity for their generation from NAD⁺ is augmented by CD38, a major NADase with high affinity for NAD⁺. This novel non-canonical NAD⁺-adenosine-UA pathway that is triggered by allergens has not been previously described in the airways.

CD38 downregulation modulates NAD+ and NADP(H) levels in thermogenic adipose tissues

Different strategies to boost NAD⁺ levels are considered promising means to promote healthy aging and ameliorate dysfunctional metabolism. CD38 is a NAD⁺-dependent enzyme involved in the regulation of different cell functions. In the context of systemic energy metabolism, it has been demonstrated that brown adipocytes, the parenchymal cells of brown adipose tissue (BAT) as well as beige adipocytes that emerge in white adipose tissue (WAT) depots in response to catabolic conditions, are important to maintain metabolic homeostasis. In this study we aim to understand the functional relevance of CD38 for NAD⁺ and energy metabolism in BAT and WAT, also using a CD38^-/- mouse model. During cold exposure, an increase in NAD⁺ levels occurred in BAT of wild type mice, together with a marked downregulation of CD38, as detected at the mRNA and protein level. CD38 downregulation was observed also in WAT of cold-exposed mice, where it was accompanied by a strong increase in NADP(H) levels. Accordingly, NAD kinase and glucose-6-phosphate dehydrogenase activities were enhanced in WAT (but not in BAT). Increased NAD⁺ levels were observed in BAT/WAT from CD38^-/- compared with wild type mice, in line with CD38 being a major NAD⁺-consumer in AT. CD38^-/- mice kept at 6 °C had higher levels of Ucp1 and Pgc-1α in BAT and WAT, and increased levels of phosphorylated hormone-sensitive lipase in BAT, compared with wild type mice. These results demonstrate that CD38, by modulating cellular NAD(P)⁺ levels, is involved in the regulation of thermogenic responses in cold-activated BAT and WAT.

Differential expression profile of microRNA in yak skeletal muscle and adipose tissue during development

BACKGROUND

miRNAs play an important role in regulating normal animal development. Muscle tissue and fat metabolism are important for maintaining energy balance in animals. Yak has important agricultural and economic importance as it provides milk, meat, and hair. It is used for transportation as well. However, the miRNA expression profiles of their muscle and adipose tissue are currently unknown.

OBJECTIVE

To explore the regulatory roles of miRNAs in the skeletal muscle and adipose tissues of yak.

METHODS

A total of 12 small RNA libraries were constructed from the skeletal muscle and adipose samples from yak aged 0.5, 2.5, 4.5, and 7.5 years. High-throughput sequencing and bioinformatics analysis were used to determine the dynamic expression profile of miRNA, and a miRNA regulatory network related to muscle and adipose tissue development was established.

RESULTS

miR-1-3p and miR-143-3p showed the highest expression during yak skeletal muscle and fat development, respectively. The MAPK and Ras signaling pathways were the pivotal pathways. miR-181-5p, miR-542-3p, and miR-424-5p may have key roles in skeletal muscle development, and CREBRF, GRB10, CDK1, RFX3, and EPC2 were the core target genes. While miR-127-5p, miR-379-3p, and miR-494-3p may play important regulatory roles in adipose deposition, and ETV1, XPO7, and C5AR2 were the core target genes.

CONCLUSION

This study provides valuable resources for further study of the molecular mechanisms underlying yak skeletal muscle and adipose tissue development, and also a basis for studying the interactions between genes and miRNAs.

PTEN participates in airway remodeling of asthma by regulating CD38/Ca2+/CREB signaling

Both phosphatase and tensin homologue deleted on chromosome ten (PTEN) and cluster of differentiation 38 (CD38) have been suggested to be key regulators of the pathogenesis of asthma. However, the precise role and molecular mechanisms by which PTEN and CD38 are involved in airway remodeling throughout asthma pathogenesis remains poorly understood. This study aimed to elucidate the role of PTEN and CD38 in airway remodeling of asthma. Exposure to tumor necrosis factor-α (TNF-α) in airway smooth muscle (ASM) cells markedly decreased PTEN expression, and increased expression of CD38. Overexpression of PTEN suppressed the expression of CD38 and downregulated proliferation and migration induced by TNF-α stimulation, which was partially reversed by CD38 overexpression. PTEN/CD38 axis regulated Ca2+ levels and cyclic AMP response-element binding protein (CREB) phosphorylation in TNF-α-stimulated ASM cells. The in vitro knockdown of CD38 or overexpression of PTEN remarkably restricted airway remodeling and decreased Ca2+ concentrations and CREB phosphorylation in asthmatic mice. CD38 overexpression abolished the inhibitory effects of PTEN overexpression on airway remodeling. These findings demonstrate that PTEN inhibits airway remodeling of asthma through the downregulation of CD38-mediated Ca2+/CREB signaling, highlighting a key role of PTEN/CD38/Ca2+/CREB signaling in the molecular pathogenesis of asthma.

miR-708-5p targets oncogenic prostaglandin E2 production to suppress a pro-tumorigenic phenotype in lung cancer cells

Many cancers maintain an inflammatory microenvironment to promote their growth. Lung cancer is of particular importance, as it is the deadliest cancer worldwide. One inflammatory pathway commonly dysregulated in cancer is the metabolism of arachidonic acid (AA) by Cyclooxygenase-2 (COX-2) and microsomal Prostaglandin E Synthase 1 (mPGES-1) into Prostaglandin E2 (PGE2). While researchers have identified PGE2's pro-tumorigenic functions, the mechanisms governing overexpression of COX-2 and mPGES-1 are incompletely understood. MicroRNAs (miRNAs) are important post-transcriptional regulators commonly dysregulated in cancer. Interestingly, miR-708-5p (miR-708) is predicted to target both COX-2 and mPGES-1. In this study, we show that high miR-708 expression is associated with survival rates in lung squamous cell carcinoma patients. miR-708 also represses PGE2 production by suppressing both COX-2 and mPGES-1 expression in lung cancer cells. miR-708 regulation of COX-2 and mPGES-1 is mediated through targeting of their 3' untranslated regions (UTRs). Moreover, miR-708 decreases proliferation, survival, and migration of lung cancer cells, which can be partially attributed to miR-708's inhibition of PGE2 signaling. Lastly, we identify novel miR-708 predicted targets and possible regulators of miR-708 expression in lung cancer. Collectively, these data demonstrate that dysregulated miR-708 expression contributes to exacerbated PGE2 production, leading to an enhanced pro-tumorigenic phenotype in lung cancer cells.

MicroRNAs in chronic airway diseases: Clinical correlation and translational applications

MicroRNAs (miRNAs) are short single-stranded RNAs that have pivotal roles in disease pathophysiology through transcriptional and translational modulation of important genes. It has been implicated in the development of many diseases, such as stroke, cardiovascular conditions, cancers and inflammatory airway diseases. There is recent evidence that miRNAs play important roles in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD), and could help to distinguish between T2-low (non-eosinophilic, steroid-insensitive) versus T2-high (eosinophilic, steroid-sensitive) disease endotypes. As these are the two most prevalent chronic respiratory diseases globally, with rising disease burden, miRNA research might lead to the development of new diagnostic and therapeutic targets. Research involving miRNAs in airway disease is challenging because: (i) asthma and COPD are heterogeneous inflammatory airway diseases; there are overlapping but distinct inter- and intra-disease differences in the immunological pathophysiology, (ii) there exists more than 2000 known miRNAs and a single miRNA can regulate multiple targets, (iii) differential effects of miRNAs could be present in different cellular subtypes and tissues, and (iv) dysregulated miRNA expression might be a direct consequence of an indirect effect of airway disease onset or progression. As miRNAs are actively secreted in fluids and remain relatively stable, they have the potential for biomarker development and therapeutic targets. In this review, we summarize the preclinical data on potential miRNA biomarkers that mediate different pathophysiological mechanisms in airway disease. We discuss the framework for biomarker development using miRNA and highlight the need for careful patient characterization and endotyping in the screening and validation cohorts, profiling both airway and blood samples to determine the biological fluids of choice in different disease states or severity, and adopting an untargeted approach. Collaboration between the various stakeholders - pharmaceutical companies, laboratory professionals and clinician-scientists is crucial to reduce the difficulties and cost required to bring miRNA research into the translational stage for airway diseases.

Role of CD38/cADPR signaling in obstructive pulmonary diseases

The worldwide socioeconomical burden associated with chronic respiratory diseases is substantial. Enzymes involved in the metabolism of nicotinamide adenine dinucleotide (NAD) are increasingly being implicated in chronic airway diseases. One such enzyme, CD38, utilizes NAD to produce several metabolites, including cyclic ADP ribose (cADPR), which is involved in calcium signaling in airway smooth muscle (ASM). Upregulation of CD38 in ASM caused by exposure to cytokines or allergens leads to enhanced calcium mobilization by agonists and the development of airway hyperresponsiveness (AHR) to contractile agonists. Glucocorticoids and microRNAs can suppress CD38 expression in ASM, whereas cADPR antagonists such as 8Br-cADPR can directly antagonize intracellular calcium mobilization. Bronchodilators act via CD38-independent mechanisms. CD38-dependent mechanisms could be developed for chronic airway diseases therapy.

CD2 Regulates Pathogenesis of Asthma Induced by House Dust Mice Extract

Characteristic of allergic asthma, CD4+Th2 lymphocytes secrete Th2 cytokines, interleukin (IL)-4, IL-13, and IL-5 that mediate the inflammatory immune response. Surface expression of CD2 and its ligand, CD58, is increased on the monocytes and eosinophils of asthma patients, which correlate with elevated serum IgE levels, suggesting that CD2 may contribute to allergic airway inflammation. Using a murine model of asthma, we observed that house dust mice extract (HDME)-exposed Balb/c mice have increased airway hyperresponsiveness (AHR), lung inflammation, goblet cell hyperplasia, and elevated levels of Th2 cytokines in the lungs, as well as increased serum IgE levels as compared to the control mice. In contrast, with the exception of serum IgE levels, all the other parameters were significantly reduced in HDME-treated Cd2 ^-/- mice. Interestingly, Il13 but not Il4 or Il5 gene expression in the lungs was dramatically decreased in HDME-exposed Cd2 ^-/- mice. Of note, the gene expression of IL-13 downstream targets (Muc5b and Muc5ac) and high affinity IL-13Rα2 were upregulated in the lungs of HDME-exposed Balb/c mice but were significantly reduced in HDME-exposed Cd2 ^-/- mice. Consistently, gene expression of microRNAs regulating mucin production, inflammation, airway smooth muscle cell proliferation and IL-13 transcripts were increased in the lungs of HDME-exposed Cd2 ^-/- mice. Given the established role of IL-13 in promoting goblet cell hyperplasia, lung inflammation and AHR in allergic asthma, our studies reveal a unique role for CD2 in the regulation of Th2-associated allergic asthma.

CD38 in Neurodegeneration and Neuroinflammation

Neurodegenerative diseases are characterized by neuronal degeneration as well as neuroinflammation. While CD38 is strongly expressed in brain cells including neurons, astrocytes as well as microglial cells, the role played by CD38 in neurodegeneration and neuroinflammation remains elusive. Yet, CD38 expression increases as a consequence of aging which is otherwise the primary risk associated with neurodegenerative diseases, and several experimental data demonstrated that CD38 knockout mice are protected from neurodegenerative and neuroinflammatory insults. Moreover, nicotinamide adenine dinucleotide, whose levels are tightly controlled by CD38, is a recognized and potent neuroprotective agent, and NAD supplementation was found to be beneficial against neurodegenerative diseases. The aims of this review are to summarize the physiological role played by CD38 in the brain, present the arguments indicating the involvement of CD38 in neurodegeneration and neuroinflammation, and to discuss these observations in light of CD38 complex biology.

Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia

Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.

miR-29b Reverses T helper 1 cells/T helper 2 cells Imbalance and Alleviates Airway Eosinophils Recruitment in OVA-Induced Murine Asthma by Targeting Inducible Co-Stimulator

Asthma is a complex chronic disease and the pathogenesis is still not entirely clear. In this study, we aimed to clarify the role and mechanism of miR-29b in the development of asthma. We observed that miR-29b levels were decreased in the lung and spleen of OVA-induced asthmatic mice. Reverse transcription-quantitative polymerase chain reaction and flow cytometry demonstrated that the inducible co-stimulator (ICOS) expression at mRNA and protein levels was elevated in the lung of asthmatic mice, and miR-29b expression in the lung of asthmatic mice was negatively associated with ICOS mRNA levels by Pearson Correlation analysis. Additional, flow cytometry showed that the percentage of CD4+ICOS+ T cells in the lung and spleen was regulated by miR-29b, and dual luciferase reporter assay confirmed ICOS was a target gene of miR-29b. Furthermore, miR-29b overexpression in asthmatic mice was induced with miR-29b agomir by intranasal administration; miR-29b alleviated total inflammatory cell infiltration and CCL24 levels, decreased IL-5 levels in bronchoalveolar lavage fluid and serum, and upregulated IFN-γ expression in serum. This study demonstrates that miR-29b targets ICOS, thereby reverses the imbalance of T helper 1 cells (Th1)/Th2 responses and decreases eosinophils recruitment in the airway, which are key features of allergic airway inflammation. Therefore, miR-29b might be an attractive candidate target for asthma treatment.

miR-19 targets PTEN and mediates high mobility group protein B1(HMGB1)-induced proliferation and migration of human airway smooth muscle cells

Background

The abnormal proliferation and migration of airway smooth muscle (ASM) cells contributes to airway remodeling during asthma. MiR-19a has been demonstrated to promote cell proliferation and angiogenesis of several cancer types by regulating the PTEN/PI3K/AKT pathway. Our previous study has shown that High-mobility group box protein 1 (HMGB1) is involved in the pathogenesis of airway remodeling using a mouse model of chronic asthma. However, the effects of HMGB1 on proliferation and migration of ASM cells and its underlying mechanisms remain unknown.

Methods

Human ASM cells were obtained by primary explant techniques. MiR-19a expression was evaluated using qRT-PCR. Cell proliferation and migration were evaluated by the CCK-8 and the transwell migration assays, respectively. Transfection studies of ASM cells were performed to identify the underlying mechanisms.

Results

HMGB1 stimulated ASM cell proliferation and migration in a dose-dependent manner. The expression levels of miR-19a and the PTEN and AKT signaling proteins were also modulated by HMGB1. Functional studies indicated that overexpression of miR-19a enhanced the proliferation and migration of ASM cells, whereas inhibition of miR-19a decreased the proliferation and migration of ASM cells. Western blot analysis demonstrated that miR-19a negatively regulated PTEN expression and positively regulated p-AKT expression. MiR-19 only regulates the proliferation of HASM cells induced by HMGB1, but not PDGF, EGF, TGF-β1. Furthermore, we demonstrated that miR-19 contributed to the promoting effects of HMGB1 on ASM cells by targeting PTEN 3’-UTR.

Conclusion

Our results demonstrated that HMGB1 induced proliferation and migration of ASM cells via the miR-19a /PTEN/AKT axis and provided direct evidence on the role of HMGB1 in ASM cells proliferation in vitro. The present study further indicated that miR-19a may be explored as a potential novel therapeutic target to reverse proliferation and migration of ASM cells.

Role of microRNA in severe asthma

The various roles of microRNAs (miRNAs) in the epigenetic regulation of human disease are gaining importance as areas of research, and a better understanding of these roles may identify targets for development of novel therapies for severe asthma. MiRNAs, a class of small non-coding RNAs that serve as post-transcriptional gene repressors, are recognized as critical components in regulating tissue homeostasis. Alteration in miRNA expression disrupts homeostasis and is an underlying mechanism for development of chronic respiratory diseases, including asthma. Differential profiles of miRNA expression are involved in inflammation and remodeling pathogenicity via activating airway structural cells and immune cells and inducing cytokine releases. miRNA action leads to asthma progression from mild to severe stages. Here, current knowledge of the heterogeneous roles of miRNAs in severe asthma, including biological mechanisms underlying Th2 and macrophage polarization, type 2 innate lymphoid cell (ILC2) biology regulation, steroid-resistant asthma phenotype, airway smooth muscle (ASM) dysfunction, and impaired anti-viral innate immune, are reviewed.

Epigenetic Changes in Airway Smooth Muscle as a Driver of Airway Inflammation and Remodeling in Asthma

Epigenetic changes are heritable changes in gene expression, without changing the DNA sequence. Epigenetic processes provide a critical link between environmental insults to the airway and functional changes that determine how airway cells respond to future stimuli. There are three primary epigenetic processes: histone modifications, DNA modification, and noncoding RNAs. Airway smooth muscle has several important roles in the development and maintenance of the pathologic processes occurring in asthma, including inflammation, remodeling, and contraction/hyperresponsiveness. In this review, we describe the evidence for the role of epigenetic changes in driving these processes in airway smooth muscle cells in asthma, with a particular focus on histone modifications. We also discuss how existing therapies may target some of these changes and how epigenetic processes provide targets for the development of novel asthma therapeutics. Epigenetic marks may also provide a biomarker to assess phenotype and treatment responses.

Asthma MicroRNA Regulome Development Using Validated miRNA-Target Interaction Visualization

Asthma is a common multifactorial complex disease caused by an interaction of genetic and environmental factors. There are no robust biomarkers or molecular diagnostics for asthma or its detailed phenotypic stratification in the clinic. Regulatory and epigenomic factors are priority candidates for asthma biomarker discovery and translational research because this common disease emerges in association with host/environment interactions. In this context, epigenomic molecular events such as microRNA (miRNA) silencing affect asthma susceptibility and severity. We report here an analysis of the miRNAs in the literature, their targets associated with asthma, and present the findings organized as an miRNA-target network, an miRNA regulome of asthma. The miRNA-target interactions in asthma were extracted from the PubMed and the Web of Science databases, while the miRNA-target network was visualized with the Cytoscape tool. Genomic locations of miRNA and target genes were displayed using the Ensembl Whole Genome tool. We cataloged miRNAs associated with asthma and their experimentally validated targets, retrieving 48 miRNAs associated with asthma, and 54 experimentally validated miRNA targets. Four central molecules involved in 34.5% of all interactions were identified in the network. The miRNA-target pairs were constructed as an asthma-associated miRNA-target regulatory network. The network revealed subnetworks pointing toward potential asthma biomarker candidates. The asthma miRNA regulome reported here offers a strong foundation for future translational research and systems medicine applications for asthma diagnostic and therapeutic innovation. Developed protocol for constructing miRNA regulome could now be used for biomarker development in multifactorial diseases.

CD38/cADPR Signaling Pathway in Airway Disease: Regulatory Mechanisms

Asthma is an inflammatory disease in which proinflammatory cytokines have a role in inducing abnormalities of airway smooth muscle function and in the development of airway hyperresponsiveness. Inflammatory cytokines alter calcium (Ca²⁺) signaling and contractility of airway smooth muscle, which results in nonspecific airway hyperresponsiveness to agonists. In this context, Ca²⁺ regulatory mechanisms in airway smooth muscle and changes in these regulatory mechanisms encompass a major component of airway hyperresponsiveness. Although dynamic Ca²⁺ regulation is complex, phospholipase C/inositol tris-phosphate (PLC/IP3) and CD38-cyclic ADP-ribose (CD38/cADPR) are two major pathways mediating agonist-induced Ca²⁺ regulation in airway smooth muscle. Altered CD38 expression or enhanced cyclic ADP-ribosyl cyclase activity associated with CD38 contributes to human pathologies such as asthma, neoplasia, and neuroimmune diseases. This review is focused on investigations on the role of CD38-cyclic ADP-ribose signaling in airway smooth muscle in the context of transcriptional and posttranscriptional regulation of CD38 expression. The specific roles of transcription factors NF-kB and AP-1 in the transcriptional regulation of CD38 expression and of miRNAs miR-140-3p and miR-708 in the posttranscriptional regulation and the underlying mechanisms of such regulation are discussed.

Role and regulation of MKP-1 in airway inflammation

Mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) is a protein with anti-inflammatory properties and the archetypal member of the dual-specificity phosphatases (DUSPs) family that have emerged over the past decade as playing an instrumental role in the regulation of airway inflammation. Not only does MKP-1 serve a critical role as a negative feedback effector, controlling the extent and duration of pro-inflammatory MAPK signalling in airway cells, upregulation of this endogenous phosphatase has also emerged as being one of the key cellular mechanism responsible for the beneficial actions of clinically-used respiratory medicines, including β₂-agonists, phosphodiesterase inhibitors and corticosteroids. Herein, we review the role and regulation of MKP-1 in the context of airway inflammation. We initially outline the structure and biochemistry of MKP-1 and summarise the multi-layered molecular mechanisms responsible for MKP-1 production more generally. We then focus in on some of the key in vitro studies in cell types relevant to airway disease that explain how MKP-1 can be regulated in airway inflammation at the transcriptional, post-translation and post-translational level. And finally, we address some of the potential challenges with MKP-1 upregulation that need to be explored further to fully exploit the potential of MKP-1 to repress airway inflammation in chronic respiratory disease.

miR-708-5p: a microRNA with emerging roles in cancer

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression post-transcriptionally. They are crucial for normal development and maintaining homeostasis. Researchers have discovered that dysregulated miRNA expression contributes to many pathological conditions, including cancer. miRNAs can augment or suppress tumorigenesis based on their expression and transcribed targetome in various cell types. In recent years, researchers have begun to identify miRNAs commonly dysregulated in cancer. One recently identified miRNA, miR-708-5p, has been shown to have profound roles in promoting or suppressing oncogenesis in a myriad of solid and hematological tumors. This review highlights the diverse, sometimes controversial findings reported for miR-708-5p in cancer, and the importance of further exploring this exciting miRNA.

MicroRNA regulation of airway smooth muscle function

Airway smooth muscle (ASM) controls airway narrowing and plays a pivotal role in the pathogenesis of asthma. MicroRNAs are small yet powerful gene tuners that regulate diverse cellular processes. Recent studies have demonstrated the versatile role of microRNAs in regulating multiple ASM phenotypes that are critically involved in asthma pathogenesis. These ASM phenotypes include proliferation, cell size, chemokine secretion, and contractility. Here we review microRNA-mediated regulation of ASM functions and discuss the potential of microRNAs as a novel class of therapeutic targets to improve ASM function for asthma therapy.

Neonatal Heart-Enriched miR-708 Promotes Proliferation and Stress Resistance of Cardiomyocytes in Rodents

Adult heart has limited potential for regeneration after pathological injury due to the limited cell proliferation of cardiomyocytes and the quiescent status of progenitor cells. As such, induction of cell-cycle reentry of cardiomyocytes is one of the key strategies for regeneration of damaged heart. In this study, a subset of miRNAs including miR-708 were identified to be much more abundant in the embryonic and neonatal cardiomyocytes than that in adult rodents. Overexpression of miR-708 promoted cellular proliferation of H9C2 cells or primary cardiomyocytes from neonatal rats or mice in vitro. Lipid nanoparticle delivery of miR-708 promoted myocardial regeneration and heart function recovery in vivo. In addition, miR-708 protected cardiomyocytes against stress-induced apoptosis under hypoxia or isoproterenol treatments. miR-708 inhibited the expression of MAPK14, which has been demonstrated arresting the cell cycle in cardiomyocytes. The cell proliferation-promoting function of miR-708 was dependent at least partly on the expression of MAPK14. These findings strengthen the potential of applying miRNAs to reconstitute lost cardiomyocytes in injured hearts, and may provide a novel miRNA candidate for promoting heart regeneration.

CD38 in the pathogenesis of allergic airway disease: Potential therapeutic targets

CD38 is an ectoenzyme that catalyzes the conversion of β-nicotinamide adenine dinucleotide (β-NAD) to cyclic adenosine diphosphoribose (cADPR) and adenosine diphosphoribose (ADPR) and NADP to nicotinic acid adenine dinucleotide phosphate (NAADP) and adenosine diphosphoribose-2'-phosphate (ADPR-P). The metabolites of NAD and NADP have roles in calcium signaling in different cell types including airway smooth muscle (ASM) cells. In ASM cells, inflammatory cytokines augment CD38 expression and to a greater magnitude in cells from asthmatics, indicating a greater capacity for the generation of cADPR and ADPR in ASM from asthmatics. CD38 deficient mice develop attenuated airway responsiveness to inhaled methacholine following allergen sensitization and challenge compared to wild-type mice indicating its potential role in asthma. Regulation of CD38 expression in ASM cells is achieved by mitogen activated protein kinases, specific isoforms of PI3 kinases, the transcription factors NF-κB and AP-1, and post-transcriptionally by microRNAs. This review will focus on the role of CD38 in intracellular calcium regulation in ASM, contribution to airway inflammation and airway hyperresponsiveness in mouse models of allergic airway inflammation, the transcriptional and post-transcriptional mechanisms of regulation of expression, and outline approaches to inhibit its expression and activity.

Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease

Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.

microRNA and Allergy

Allergy is a common hypersensitivity disorder of the immune system, which, along with other factors, is also subjected to regulation by microRNAs. The most common allergic diseases are allergic rhinitis, asthma, atopic dermatitis, and food allergy, which all are multifactorial and very heterogeneous conditions, highlighting the need for more individualized treatment techniques. More particular key questions in relation to allergic diseases are how microRNAs influence the differentiation, polarization, plasticity and functions of T helper and other immune cells, as well as the development of immune tolerance. In addition, microRNAs can affect allergic inflammation and tissue remodeling through their functions in epithelial and other tissue cells. Among immune system-related microRNAs, miR-21, miR-146a, and miR-155 are the most intensively studied and have convincingly been demonstrated to regulate immune responses and tissue inflammation in allergic diseases. Further characterization of microRNA functions is important, as similar to other conditions, the modulation of microRNA expression could potentially be used for therapeutic purposes in allergic diseases in the future. In addition, miRNAs could be implemented as biomarkers for endotyping complex allergic conditions.

MicroRNAs associated with increased AKT gene number in human lung carcinoma

MicroRNA (miRNA) expression profiles were examined in 3 groups of lung carcinomas that had been stratified by increases in AKT1 or AKT2 gene number. Microarray analysis using 2000 probes revealed 87 miRNAs that were up-regulated and 32 down-regulated miRNAs in carcinomas harboring amplification or high-level polysomy of the AKT1 (AKT1+), as well as 123 up-regulated and 83 down-regulated miRNAs in those of the AKT2 genes (AKT2+), in comparison with carcinomas harboring disomy of both (AKTd/d). In total, 182 miRNAs were up-regulated in AKT1+ or AKT2+, compared with AKTd/d. Among these, 28 miRNAs were up-regulated in both the AKT1+ and AKT2+ groups, with a log2 ratio between 1.02 and 3.71 relative to AKTd/d group, including all miR-200 family members. Quantitative real-time polymerase chain reaction showed that carcinomas exhibiting lymph vessel invasion had significantly lower expression of miR-200a (P=.0230) and miR-200b (P=.0168), regardless of the status of the AKT genes. Moreover, a detailed statistical analysis revealed that, in adenocarcinoma and in the early stage of carcinomas (pathologic stage I/II), expression of miR-200a was higher in the AKT2+ group compared with the AKT1+ group, and these differences were statistically significant (P=.0334 and P=.0239, respectively). However, the expression of miR-200a was not significantly correlated with the expression of its target, the zinc finger E-box-binding homeobox 1 (ZEB1; P=.3801) or E-cadherin (P=.2840), a marker of the epithelial-mesenchymal transition. These results suggest that AKT2 can regulate miR-200a in a histology- or stage-specific manner and that this regulation is independent of subsequent involvement of miR-200a in epithelial-mesenchymal transition.

MicroRNA Mediated Chemokine Responses in Human Airway Smooth Muscle Cells

Airway smooth muscle (ASM) cells play a critical role in the pathophysiology of asthma due to their hypercontractility and their ability to proliferate and secrete inflammatory mediators. microRNAs (miRNAs) are gene regulators that control many signaling pathways and thus serve as potential therapeutic alternatives for many diseases. We have previously shown that miR-708 and miR-140-3p regulate the MAPK and PI3K signaling pathways in human ASM (HASM) cells following TNF-α exposure. In this study, we investigated the regulatory effect of these miRNAs on other asthma-related genes. Microarray analysis using the Illumina platform was performed with total RNA extracted from miR-708 (or control miR)-transfected HASM cells. Inhibition of candidate inflammation-associated gene expression was further validated by qPCR and ELISA. The most significant biologic functions for the differentially expressed gene set included decreased inflammatory response, cytokine expression and signaling. qPCR revealed inhibition of expression of CCL11, CXCL10, CCL2 and CXCL8, while the release of CCL11 was inhibited in miR-708-transfected cells. Transfection of cells with miR-140-3p resulted in inhibition of expression of CCL11, CXCL12, CXCL10, CCL5 and CXCL8 and of TNF-α-induced CXCL12 release. In addition, expression of RARRES2, CD44 and ADAM33, genes known to contribute to the pathophysiology of asthma, were found to be inhibited in miR-708-transfected cells. These results demonstrate that miR-708 and miR-140-3p exert distinct effects on inflammation-associated gene expression and biological function of ASM cells. Targeting these miRNA networks may provide a novel therapeutic mechanism to down-regulate airway inflammation and ASM proliferation in asthma.

MicroRNA Regulation of Airway Inflammation and Airway Smooth Muscle Function: Relevance to Asthma

Genetic and environmental factors contribute to the onset and severity of asthma. Molecular pathogenesis of asthma involves changes in gene expression by a variety of inflammatory mediators acting in autocrine and paracrine fashion on effector cells of the airways. Transcriptional regulation of gene expression in resident airway cells has been studied extensively. However, protein function in a target cell can be regulated at multiple levels starting from transcription followed by post-transcription, translation, and post-translation steps. In this context, small noncoding RNAs known as microRNAs (miRNAs) have evolved as one of the key regulators of gene expression post-transcriptionally. Most importantly, miRNA expression is dynamic in nature and can be regulated by a variety of external stimuli. Altered expression of individual or a group of miRNAs is thought to contribute to human diseases. Recent studies have implicated differential expression of miRNAs in the lungs during inflammation. Most importantly, advanced biochemical and molecular tools could be used to manipulate miRNA expression thereby effecting functional changes in target cells and organ systems. This review summarizes the current understanding of miRNA in the regulation of airway function in health and disease, and highlights the potential clinical utility of mRNAs as biomarkers of airway diseases and as potential therapeutic targets.

MiR-138 suppresses airway smooth muscle cell proliferation through the PI3K/AKT signaling pathway by targeting PDK1

BACKGROUND

Airway smooth muscle cells (ASMCs) play important physiological roles in the lung, and their abnormal proliferation directly contributes to airway remodeling during development of lung diseases such as asthma. MicroRNAs are small yet versatile gene tuners that regulate a variety of cellular processes, including cell growth and proliferation, but little is known about the precise role of microRNAs in the proliferation of ASMCs.

METHODS

In this study, human ASMCs from asthmatic and non-asthmatic donors were used. MicroRNA and mRNA expression were measured by quantitative real-time PCR. Dual-luciferase reporter assays were performed to determine whether microRNA-138 (miR-138) binds directly to 3-phosphoinositide-dependent protein kinase-1(PDK1) 3' untranslated region (3'-UTR) to alter gene expression.

RESULTS

The results showed that overexpression of miR-138 reduced proliferation of human ASMCs, whereas inhibition of miR-138 increased proliferation of ASMCs. MiR-138 directly suppressed PDK1 expression by targeting the 3'-UTR of the gene. MiR-138 controls ASMC proliferation through directly inhibiting the phosphoinositide 3-kinase (PI3K) pathway.

CONCLUSIONS

Our study indicated that miR-138 regulation of PI3K signaling in ASMCs by altering the expression of PDK1 can have a profound impact on cell proliferation.

MicroRNA Expression Profile of Neural Progenitor-Like Cells Derived from Rat Bone Marrow Mesenchymal Stem Cells under the Influence of IGF-1, bFGF and EGF

Insulin-like growth factor 1 (IGF-1) enhances cellular proliferation and reduces apoptosis during the early differentiation of bone marrow derived mesenchymal stem cells (BMSCs) into neural progenitor-like cells (NPCs) in the presence of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF). BMSCs were differentiated in three groups of growth factors: (A) EGF + bFGF, (B) EGF + bFGF + IGF-1, and (C) without growth factor. To unravel the molecular mechanisms of the NPCs derivation, microarray analysis using GeneChip^® miRNA arrays was performed. The profiles were compared among the groups. Annotated microRNA fingerprints (GSE60060) delineated 46 microRNAs temporally up-regulated or down-regulated compared to group C. The expressions of selected microRNAs were validated by real-time PCR. Among the 46 microRNAs, 30 were consistently expressed for minimum of two consecutive time intervals. In Group B, only miR-496 was up-regulated and 12 microRNAs, including the let-7 family, miR-1224, miR-125a-3p, miR-214, miR-22, miR-320, miR-708, and miR-93, were down-regulated. Bioinformatics analysis reveals that some of these microRNAs (miR-22, miR-214, miR-125a-3p, miR-320 and let-7 family) are associated with reduction of apoptosis. Here, we summarize the roles of key microRNAs associated with IGF-1 in the differentiation of BMSCs into NPCs. These findings may provide clues to further our understanding of the mechanisms and roles of microRNAs as key regulators of BMSC-derived NPC maintenance.

Regulation of NAD biosynthetic enzymes modulates NAD-sensing processes to shape mammalian cell physiology under varying biological cues

In addition to its role as a redox coenzyme, NAD is a substrate of various enzymes that split the molecule to either catalyze covalent modifications of target proteins or convert NAD into biologically active metabolites. The coenzyme bioavailability may be significantly affected by these reactions, with ensuing major impact on energy metabolism, cell survival, and aging. Moreover, through the activity of the NAD-dependent deacetylating sirtuins, NAD behaves as a beacon molecule that reports the cell metabolic state, and accordingly modulates transcriptional responses and metabolic adaptations. In this view, NAD biosynthesis emerges as a highly regulated process: it enables cells to preserve NAD homeostasis in response to significant NAD-consuming events and it can be modulated by various stimuli to induce, via NAD level changes, suitable NAD-mediated metabolic responses. Here we review the current knowledge on the regulation of mammalian NAD biosynthesis, with focus on the relevant rate-limiting enzymes. This article is part of a Special Issue entitled: Cofactor-dependent proteins: evolution, chemical diversity and bio-applications.

CD38 and airway hyper-responsiveness: studies on human airway smooth muscle cells and mouse models

Asthma is an inflammatory disease in which altered calcium regulation, contractility, and airway smooth muscle (ASM) proliferation contribute to airway hyper-responsiveness and airway wall remodeling. The enzymatic activity of CD38, a cell-surface protein expressed in human ASM cells, generates calcium mobilizing second messenger molecules such as cyclic ADP-ribose. CD38 expression in human ASM cells is augmented by cytokines (e.g., TNF-α) that requires the activation of MAP kinases and the transcription factors, NF-κB and AP-1, and is post-transcriptionally regulated by miR-140-3p and miR-708 by binding to 3' Untranslated Region of CD38 as well as by modulating the activation of signaling mechanisms involved in its regulation. Mice deficient in Cd38 exhibit reduced airway responsiveness to inhaled methacholine relative to the response in wild-type mice. Intranasal challenge of Cd38-deficient mice with TNF-α or IL-13, or the environmental fungus Alternaria alternata, causes significantly attenuated methacholine responsiveness compared with wild-type mice, with comparable airway inflammation. Reciprocal bone marrow transfer studies revealed partial restoration of airway hyper-responsiveness to inhaled methacholine in the Cd38-deficient mice. These studies provide evidence for CD38 involvement in the development of airway hyper-responsiveness; a hallmark feature of asthma. Future studies aimed at drug discovery and delivery targeting CD38 expression and (or) activity are warranted.