Role of miRNAs in hypoxia-related disorders

MiR-18a affects hypoxia induced glucose metabolism transition in HT22 hippocampal neuronal cell line through the Hif1a gene

Hypoxia can cause a variety of diseases, including ischemic stroke and neurodegenerative diseases. Within a certain range of partial pressure of oxygen, cells can respond to changes in oxygen. Changes in oxygen concentration beyond a threshold will cause damage or even necrosis of tissues and organs, especially for the central nervous system. Therefore, it is very important to find appropriate measures to alleviate damage. MiRNAs can participate in the regulation of hypoxic responses in various types of cells. MiRNAs are involved in regulating hypoxic responses in many types of tissues by activating the hypoxia-inducible factor (HIF) to affect angiogenesis, glycolysis and other biological processes. By analyzing differentially expressed miRNAs in hypoxia and hypoxia-related studies, as well as the HT22 neuronal cell line under hypoxic stress, we found that the expression of miR-18a was changed in these models. MiR-18a could regulate glucose metabolism in HT22 cells under hypoxic stress by directly regulating the 3'UTR of the Hif1a gene. As a small molecule, miRNAs are easy to be designed into small nucleic acid drugs, so this study can provide a theoretical basis for the research and treatment of nervous system diseases caused by hypoxia.

miRNA-encapsulated abiotic materials and biovectors for cutaneous and oral wound healing: Biogenesis, mechanisms, and delivery nanocarriers

MicroRNAs (miRNAs) as therapeutic agents have attracted increasing interest in the past decade owing to their significant effectiveness in treating a wide array of ailments. These polymerases II-derived noncoding RNAs act through post-transcriptional controlling of different proteins and their allied pathways. Like other areas of medicine, researchers have utilized miRNAs for managing acute and chronic wounds. The increase in the number of patients suffering from either under-healing or over-healing wound demonstrates the limited efficacy of the current wound healing strategies and dictates the demands for simpler approaches with greater efficacy. Various miRNA can be designed to induce pathway beneficial for wound healing. However, the proper design of miRNA and its delivery system for wound healing applications are still challenging due to their limited stability and intracellular delivery. Therefore, new miRNAs are required to be identified and their delivery strategy needs to be optimized. In this review, we discuss the diverse roles of miRNAs in various stages of wound healing and provide an insight on the most recent findings in the nanotechnology and biomaterials field, which might offer opportunities for the development of new strategies for this chronic condition. We also highlight the advances in biomaterials and delivery systems, emphasizing their challenges and resolutions for miRNA-based wound healing. We further review various biovectors (e.g., adenovirus and lentivirus) and abiotic materials such as organic and inorganic nanomaterials, along with dendrimers and scaffolds, as the delivery systems for miRNA-based wound healing. Finally, challenges and opportunities for translation of miRNA-based strategies into clinical applications are discussed.

The role of hypoxia-associated miRNAs in acquired sensorineural hearing loss

Introduction: Sensorineural hearing loss (SNHL) is a prevalent sensory deficit presenting commonly as age-related hearing loss. Other forms of SNHL include noise-induced and sudden SNHL. Recent evidence has pointed to oxidative stress as a common pathogenic pathway in most subtypes of acquired SNHL. MicroRNAs (miRNAs) are small non-coding RNA sequences that suppress target mRNA expression and affect downstream processes. Many studies have shown that miRNAs are integral biomolecules in hypoxia-adaptive responses. They also promote apoptosis in response to oxidative stress resulting in SNHL. Our hypothesis is that miRNAs are involved in the pathophysiological responses to hypoxia and oxidative stress that result in SNHL. This study reviews the evidence for hypoxia-adaptive miRNAs (hypoxamiRs) in different types of acquired SNHL and focuses on miRNAs involved in hypoxia driven SNHL.

Methods: Electronic bibliographic databases PubMed, Ovid MEDLINE, Ovid EMBASE, and Web of Science Core Collection were searched independently by two investigators for articles published in English from the inception of individual databases to the end of July 2020. The text word or medical subject heading searches of all fields, titles, abstracts, or subject headings depending on the database were undertaken with combinations of the words “microRNAs”, “hypoxia”, “hypoxamiRs”, “oxidative stress”, “ischemia” and “hearing loss”. The reference lists of studies meeting the inclusion criteria were searched to identify additional relevant studies. The inclusion criteria included relevant clinical studies with human subjects, animals, and in vitro experiments. The risk of bias was assessed using the Cochrane risk of bias assessment tool for human studies and the Systematic Review Center for Laboratory animal Experimentation (SYRCLE) a risk of bias assessment tool for animal model and in vitro studies.

Results: A total of 15 primary articles were selected for full text screening after excluding duplicates, reviews, retracted articles, and articles not published in English. All nine articles meeting the study inclusion criteria were from animal or in vitro model studies and were assessed to be at low risk of bias. miRNAs miR-34a and miR-29b were reported to be involved in SNHL in inner ear cell models exposed to oxidative stress. Signaling pathways Sirtuin 1/peroxisome proliferator-activated receptor gamma coactivator-1-alpha (SIRT1/PGC-1α), SIRT1/p53, and SIRT1/hypoxia-inducible factor 1-alpha (HIF-1α) were identified as underlying pathways involved in acquired SNHL.

Conclusion: There is evidence that miR-34a and -29b are involved in hypoxia-driven and other causes of oxidative stress-related acquired SNHL. Further studies are required to determine if these findings are clinically applicable.

Effect of ghrelin on hypoxia-related cardiac angiogenesis: involvement of miR-210 signalling pathway

OBJECTIVE

Hypoxia is the main stimulus for angiogenesis. Hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and miR-210 are involved in the hypoxia-induced angiogenesis. This study examined the effects of hypoxia and/or ghrelin on miR-210, HIF-1α, and VEGF levels in the heart of rats.

METHODS

Wistar rats were randomly divided into 4 groups (n = 6): control; ghrelin, received daily intraperitoneal injections of ghrelin; hypoxia, was exposed to hypoxic condition; hypoxia + ghrelin, was exposed to hypoxic condition and received intraperitoneal injections of ghrelin, for 2 weeks. Myocardial angiogenesis, the expression level of miR-210, and protein levels of HIF-1α and VEGF were assayed in the heart samples.

RESULTS

Hypoxia increased myocardial angiogenesis and cardiac levels of miR-210, HIF-1α, and VEGF. However, ghrelin inhibited these hypoxia-induced changes. Interestingly, ghrelin had no significant effect on miR-210, HIF-1α, and VEGF levels in normoxic condition.

CONCLUSION

Ghrelin may be useful as an anti-angiogenic factor.

Elevation of Circulating miR-210 Participates in the Occurrence and Development of Type 2 Diabetes Mellitus and Its Complications

OBJECTIVE

Circulating miRNAs are acclaimed biomarkers to predict the occurrence and progression of type 2 diabetes mellitus (T2DM). This study is aimed at analyzing the correlation of circulating miR-210 level and obesity-associated T2DM and then investigating the underlying mechanism of circulating miR-210 in T2DM.

METHODS

Totally, 137 serum samples from patients with T2DM were collected; meanwhile, the demographic, general, and clinical hematological characteristics, disease history, and dietary patterns were recorded. The miR-210 level in exosomes from serum was detected by qRT-PCR. Then, the correlations of BMI or miR-210 level with patients' clinical characteristics were analyzed. Furthermore, the miR-210 level was detected in T2DM related various cells under high glucose condition. Meanwhile, the expression of carbohydrate responsive element binding protein (ChREBP) and hypoxia-inducible factor 1α (HIF-1α) was measured by western blotting.

RESULTS

The miR-210 level in exosomes from serum was obviously elevated in the BMI > 24 group compared with the BMI ≤ 24 group. Higher BMI was correlated with abnormal lipid metabolism and impaired liver function as well as higher miR-210 level. Notably, higher miR-210 level was also correlated with abnormal lipid metabolism, disease history, and dietary patterns. In addition, compared with normal cells, high glucose increased the miR-210 level in exosomes from cell culture supernatants as well as cells in HUVEC, VSMC, RAW 264.7, 3 T3-L1, SMC, and Beta-TC-6 cells, while it reduced the expression of ChREBP and HIF-1α.

CONCLUSIONS

Circulating miR-210 level was closely correlated with obesity-associated T2DM. Furthermore, higher miR-210 level might be implicated in the occurrence and development of T2DM and its complications.

Association Between miR-143/145 rs4705343 Polymorphism and Risk of Congenital Heart Disease in a Chinese Tibetan Population

Objective: Congenital heart disease (CHD) is the most common birth defect worldwide and is caused by both genetic and environmental factors. The microRNA (miR)-143/145 cluster is involved in various biological processes related to cardiovascular development. The functional single nucleotide polymorphism (SNP) rs4705343 of miR-143/145 may influence the expression of these miRNAs. In this study, we aimed to estimate the association between miR-143/145 rs4705343 and the risk of CHD in a Chinese Tibetan population. Methods: Matrix-assisted laser desorption ionization time-of-flight mass spectrometry assays were performed to genotype the miRNA-143/145 rs4705343 SNP in 510 CHD Tibetan patients and 681 unrelated Tibetan healthy controls. The associations between the SNP frequencies and the CHD risk were analyzed by χ² test/Fisher's test and assessed by odds ratios (ORs) and 95% confidence intervals (95% CIs). Results: We successfully genotyped 1165 subjects with a SNP call rate of 97.8%. Under the allelic model we found that rs4705343 was not associated with the risk of CHD (p = 0.082), but under the recessive model the CC genotype at this locus was associated with a significantly increased risk of CHD compared with the other genotypes (CC vs TT+TC: OR = 1.60, 95% CI = 1.08-2.37, p = 0.017). Conclusion: The present study suggests that the rs4705343 CC genotype of miR-143/145 is associated with CHD risk in a Chinese Tibetan population.

MicroRNAs in the Tumor Microenvironment

The tumor microenvironment (TME) is decisive for the eradication or survival of any tumor mass. Moreover, it plays a pivotal role for metastasis and for providing the metastatic niche. The TME offers special physiological conditions and is composed of, for example, surrounding blood vessels, the extracellular matrix (ECM), diverse signaling molecules, exosomes and several cell types including, but not being limited to, infiltrated immune cells, cancer-associated endothelial cells (CAEs), and cancer-associated fibroblasts (CAFs). These cells can additionally and significantly contribute to tumor and metastasis progression, especially also by acting via their own deregulated micro (mi) RNA expression or activity. Thus, miRNAs are essential players in the crosstalk between cancer cells and the TME. MiRNAs are small non-coding (nc) RNAs that typically inhibit translation and stability of messenger (m) RNAs, thus being able to regulate several cell functions including proliferation, migration, differentiation, survival, invasion, and several steps of the metastatic cascade. The dynamic interplay between miRNAs in different cell types or organelles such as exosomes, ECM macromolecules, and the TME plays critical roles in many aspects of cancer development. This chapter aims to give an overview on the multiple contributions of miRNAs as players within the TME, to summarize the role of miRNAs in the crosstalk between different cell populations found within the TME, and to illustrate how they act on tumorigenesis and the behavior of cells in the TME context. Lastly, the potential clinical utility of miRNAs for cancer therapy is discussed.

HAHmiR.DB: a server platform for high-altitude human miRNA-gene coregulatory networks and associated regulatory circuits

Around 140 million people live in high-altitude (HA) conditions! and even a larger number visit such places for tourism, adventure-seeking or sports training. Rapid ascent to HA can cause severe damage to the body organs and may lead to many fatal disorders. During induction to HA, human body undergoes various physiological, biochemical, hematological and molecular changes to adapt to the extreme environmental conditions. Several literature references hint that gene-expression-regulation and regulatory molecules like miRNAs and transcription factors (TFs) control adaptive responses during HA stress. These biomolecules are known to interact in a complex combinatorial manner to fine-tune the gene expression and help in controlling the molecular responses during this stress and ultimately help in acclimatization. High-Altitude Human miRNA Database (HAHmiR.DB) is a unique, comprehensive and curated collection of miRNAs that have been experimentally validated to be associated with HA stress, their level of expression in different altitudes, fold change, experiment duration, biomarker association, disease and drug association, tissue-specific expression level, Gene Ontology (GO) and Kyoto Encyclopaedia of Gene and Genomes (KEGG) pathway associations. As a server platform, it also uniquely constructs and analyses interactive miRNA-TF-gene coregulatory networks and extracts regulatory circuits/feed-forward loops (FFLs). These regulatory circuits help to offer mechanistic insights into complex regulatory mechanisms during HA stress. The server can also build these regulatory networks between two and more miRNAs of the database and also identify the regulatory circuits from this network. Hence, HAHmiR.DB is the first-of-its-kind database in HA research, which is a reliable platform to explore, compare, analyse and retrieve miRNAs associated with HA stress, their coregulatory networks and FFL regulatory-circuits. HAHmiR.DB is freely accessible at http://www.hahmirdb.in.

nSARS-Cov-2, pulmonary edema and thrombosis: possible molecular insights using miRNA-gene circuits in regulatory networks

Background

Given the worldwide spread of the novel Severe Acute Respiratory Syndrome Coronavirus 2 (nSARS-CoV-2) infection pandemic situation, research to repurpose drugs, identify novel drug targets, vaccine candidates have created a new race to curb the disease. While the molecular signature of nSARS-CoV-2 is still under investigation, growing literature shows similarity among nSARS-CoV-2, pulmonary edema, and thromboembolic disorders due to common symptomatic features. A network medicine approach is used to to explore the molecular complexity of the disease and to uncover common molecular trajectories of edema and thrombosis with nSARS-CoV-2.

Results and conclusion

A comprehensive nSARS-CoV-2 responsive miRNA: Transcription Factor (TF): gene co-regulatory network was built using host-responsive miRNAs and it’s associated tripartite, Feed-Forward Loops (FFLs) regulatory circuits were identified. These regulatory circuits regulate signaling pathways like virus endocytosis, viral replication, inflammatory response, pulmonary vascularization, cell cycle control, virus spike protein stabilization, antigen presentation, etc. A unique miRNA-gene regulatory circuit containing a consortium of four hub FFL motifs is proposed to regulate the virus-endocytosis and antigen-presentation signaling pathways. These regulatory circuits also suggest potential correlations/similarity in the molecular mechanisms during nSARS-CoV-2 infection, pulmonary diseases and thromboembolic disorders and thus could pave way for repurposing of drugs. Some important miRNAs and genes have also been proposed as potential candidate markers. A detailed molecular snapshot of TGF signaling as the common pathway, that could play an important role in controlling common pathophysiologies among diseases, is also put forth.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s41544-020-00057-y.

Stabilization of HIF-1α in Human Retinal Endothelial Cells Modulates Expression of miRNAs and Proangiogenic Growth Factors

Retinal hypoxia is one of the causative factors of diabetic retinopathy and is also one of the triggers of VEGF release. We hypothesized that specific dysregulated miRNAs in diabetic retinopathy could be linked to hypoxia-induced damage in human retinal endothelial cells (HRECs). We investigated in HRECs the effects of chemical (CoCl₂) hypoxia on the expression of HIF-1α, VEGF, PlGF, and of a focused set of miRNAs. We found that miR-20a-5p, miR-20b-5p, miR-27a-3p, miR-27b-3p, miR-206-3p, miR-381-3p correlated also with expression of TGFβ signaling pathway genes in HRECs, challenged with chemical hypoxic stimuli. In conclusion, our data suggest that retinal angiogenesis would be promoted, at least under HIF-1α activation, by upregulation of PlGF and other factors such as miRNAs, VEGFA, and TGFβ1.

miR-20a inhibits hypoxia-induced autophagy by targeting ATG5/FIP200 in colorectal cancer

Autophagy is a highly conserved lysosome-mediated protective cellular process in which cytosolic components, including damaged organelles and long-lived proteins, are cleared. Many studies have shown that autophagy was upregulated in hypoxic regions. However, the precise molecular mechanism of hypoxia-induced autophagy in colorectal cancer (CRC) is still elusive. In this study, we found that miR-20a was significantly downregulated under hypoxia in colon cancer cells, and overexpression of miR-20a alleviated hypoxia-induced autophagy. Moreover, miR-20a inhibits the hypoxia-induced autophagic flux by targeting multiple key regulators of autophagy, including ATG5 and FIP200. Furthermore, by dual-luciferase assay we demonstrated that miR-20a directly targeted the 3'-untranslated region of ATG5 and FIP200, regulating their messenger RNA and protein levels. In addition, reintroduction of exogenous ATG5 or FIP200 partially reversed miR-20a-mediated autophagy inhibition under hypoxia. A negative correlation between miR-20a and its target genes is observed in the hypoxic region of colon cancer tissues. Taken together, our findings suggest that hypoxia-mediated autophagy was regulated by miR-20a/ATG5/FI200 signaling pathway in CRC. miR-20a-mediated autophagy defect that might play an important role in hypoxia-induced autophagy during colorectal tumorigenesis.

Analysis of Hypoxiamir-Gene Regulatory Network Identifies Critical MiRNAs Influencing Cell-Cycle Regulation Under Hypoxic Conditions

BACKGROUND

Hypoxia is a pathophysiological condition which arises due to low oxygen concentration in conditions like cardiovascular diseases, inflammation, ascent to higher altitude, malignancies, deep sea diving, prenatal birth, etc. A number of microRNAs (miRNAs), Transcription Factors (TFs) and genes have been studied separately for their role in hypoxic adaptation and controlling cell-cycle progression and apoptosis during this stress.

OBJECTIVE

We hypothesize that miRNAs and TFs may act in conjunction to regulate a multitude of genes and play a crucial and combinatorial role during hypoxia-stress-responses and associated cellcycle control mechanisms.

METHOD

We collected a comprehensive and non-redundant list of human hypoxia-responsive miRNAs (also known as hypoxiamiRs). Their experimentally validated gene-targets were retrieved from various databases and a comprehensive hypoxiamiR-gene regulatory network was built.

RESULTS

Functional characterization and pathway enrichment of genes identified phospho-proteins as enriched nodes. The phospho-proteins which were localized both in the nucleus and cytoplasm and could potentially play important role as signaling molecules were selected; and further pathway enrichment revealed that most of them were involved in NFkB signaling. Topological analysis identified several critical hypoxiamiRs and network perturbations confirmed their importance in the network. Feed Forward Loops (FFLs) were identified in the subnetwork of enriched genes, miRNAs and TFs. Statistically significant FFLs consisted of four miRNAs (hsa-miR-182-5p, hsa- miR-146b-5p, hsa-miR-96, hsa-miR-20a) and three TFs (SMAD4, FOXO1, HIF1A) both regulating two genes (NFkB1A and CDKN1A).

CONCLUSION

Detailed BioCarta pathway analysis identified that these miRNAs and TFs together play a critical and combinatorial role in regulating cell-cycle under hypoxia, by controlling mechanisms that activate cell-cycle checkpoint protein, CDKN1A. These modules work synergistically to regulate cell-proliferation, cell-growth, cell-differentiation and apoptosis during hypoxia. A detailed mechanistic molecular model of how these co-regulatory FFLs may regulate the cell-cycle transitions during hypoxic stress conditions is also put forth. These biomolecules may play a crucial and deterministic role in deciding the fate of the cell under hypoxic-stress.