Circular RNAs and tuberculosis infection

The role of circular RNA in immune response to tuberculosis and its potential as a biomarker and therapeutic target

Circular RNA (circRNA) is a new type of non-coding RNA that has gained significant attention in recent years, especially in tuberculosis research. Tuberculosis poses a major global public health threat. Its complex pathological mechanisms and worsening drug resistance urgently necessitate new research breakthroughs. The role of circRNA in mycobacterium tuberculosis infection is being gradually revealed, highlighting its importance in regulating gene expression, immune response, and inflammation. Additionally, researchers are interested in circRNA because of its potential for early tuberculosis diagnosis and its role as a biomarker. This article systematically analyzes existing literature to provide new insights into early tuberculosis diagnosis and personalized treatment. We also emphasize the need for future research to enhance the application of circRNA in tuberculosis prevention and control.

Circular RNA ZNF277 Sponges miR-378d to Inhibit the Intracellular Survival of Mycobacterium tuberculosis by Upregulating Rab10

Circular RNAs (circRNAs) are covalently closed non-coding RNAs formed by back-splicing, lacking a 5' cap and poly-A tail. They could act as important regulatory factors in the host's anti-tuberculosis immune process, but only a few have been identified, and their molecular mechanisms remain largely unclear. Here, we identified a novel circRNA, circ-ZNF277, which responds to Mycobacterium tuberculosis (Mtb) infection in THP-1 cells. Circ-ZNF277 binds microRNA-378d (miR-378d) in vivo. The expression level of circ-ZNF277 affects the clearance of the intracellular Mtb in THP-1 cells. Mechanistically, more circ-ZNF277 molecules could absorb more miR-378d, thereby competitively activating the NF-κB signaling pathway, promoting the release of pro-inflammatory cytokines including interleukins IL-1β and IL-6, and tumor necrosis factor-α (TNF-α), and inhibiting the survival of intracellular Mtb. Expressing miR-378d or si-Rab10 targeting the transcription of Rab10 could antagonize the effects of overexpression of circ-ZNF277, resulting in the reduced intracellular survival of Mtb. In summary, circ-ZNF277 inhibits the intracellular survival of Mtb via the miR-378d/Rab10 axis. This finding represents a novel mechanism of circular RNA in regulating host immune responses during Mtb infection.

Exosomal non-coding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is a type of gastrointestinal cancer with high morbidity and mortality rates, and is often accompanied by distant metastases. Metastasis is a major cause of shortened survival time and poor treatment outcomes for patients with CRC. However, the molecular mechanisms underlying the metastasis of CRC remain unclear. Exosomes are a class of small extracellular vesicles that originate from almost all human cells and can transmit biological information (e.g., nucleic acids, lipids, proteins, and metabolites) from secretory cells to target recipient cells. Recent studies have revealed that non-coding RNAs (ncRNAs) can be released by exosomes into the tumour microenvironment or specific tissues, and play a pivotal role in tumorigenesis by regulating a series of key molecules or signalling pathways, particularly those involved in tumour metastasis. Exosomal ncRNAs have potential as novel therapeutic targets for CRC metastasis, and can also be used as liquid biopsy biomarkers because of their specificity and sensitivity. Therefore, further investigations into the biological function and clinical value of exosomal ncRNAs will be of great value for the prevention, early diagnosis, and treatment of CRC metastasis.

Identification of Differential Circular RNA Expression Profiles and Functional Networks in Human Macrophages Induced by Virulent and Avirulent Mycobacterium tuberculosis Strains

Circular RNAs (circRNAs) are noncoding RNAs with diverse functions. However, most Mycobacterium tuberculosis (M.tb)-related circRNAs remain undiscovered. In this study, we infected THP-1 cells with virulent and avirulent M.tb strains and then sequenced the cellular circRNAs. Bioinformatic analysis predicted 58,009 circRNAs in all the cells. In total, 2035 differentially expressed circRNAs were identified between the M.tb-infected and uninfected THP-1 cells and 1258 circRNAs were identified in the virulent and avirulent M.tb strains. Further, the top 10 circRNAs were confirmed by Sanger sequencing, among which four circRNAs, namely circSOD2, circCHSY1, circTNFRSF21, and circDHTKD1, which were highly differentially expressed in infected cells compared with those in uninfected cells, were further confirmed by ring formation, specific primers, and RNase R digestion. Next, circRNA-miRNA-mRNA subnetworks were constructed, such as circDHTKD1/miR-660-3p/IL-12B axis. Some of the individual downstream genes, such as miR-660-3p and IL-12B, were previously reported to be associated with cellular defense against pathological processes induced by M.tb infection. Because macrophages are important immune cells and the major host cells of M.tb, these findings provide novel ideas for exploring the M.tb pathogenesis and host defense by focusing on the regulation of circRNAs during M.tb infection.

A review on circular RNAs and bacterial infections

Bacterial infections and related diseases have been a major burden on social public health and economic stability around the world. However, the effective diagnostic methods and therapeutic approaches to treat bacterial infections are still limited. As a group of non-coding RNA, circular RNAs (circRNAs) that were expressed specifically in host cells and played a key regulatory role have the potential to be of diagnostic and therapeutic value. In this review, we systematically summarize the role of circRNAs in common bacterial infections and their potential roles as diagnostic markers and therapeutic targets.

Analysis of the noncoding RNA regulatory networks of H37Rv- and H37Rv△1759c-infected macrophages

Noncoding RNAs regulate the process of Mycobacterium tuberculosis (M. tb) infecting the host, but there is no simultaneous transcriptional information of long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) and the global regulatory networks of non-coding RNA. Rv1759c, a virulence factor, is a member of protein family containing the proline-glutamic acid (PE) in M. tb, which can increase M. tb survival. To reveal the noncoding RNA regulatory networks and the effect of Rv1759c on non-coding RNA expression during M. tb infection, we collected samples of H37Rv- and H37Rv△1759c-infected macrophages and explored the full transcriptome expression profile. We found 356 mRNAs, 433 lncRNAs, 168 circRNAs, and 12 miRNAs differentially expressed during H37Rv infection, 356 mRNAs, 433 lncRNAs, 168 circRNAs, and 12 miRNAs differentially expressed during H37Rv△1759c infection. We constructed lncRNA/circRNA-miRNA-mRNA regulatory networks during H37Rv and H37Rv△1759c infection. We demonstrated the role of one of the hubs of the networks, hsa-miR-181b-3p, for H37Rv survival in macrophages. We discovered that the expression changes of 68 mRNAs, 92 lncRNAs, 26 circRNAs, and 3 miRNAs were only related to the deletion of Rv1759c by comparing the transcription profiles of H37Rv and H37Rv△1759c. Here, our study comprehensively characterizes the transcriptional profiles in THP1-derived-macrophages infected with H37Rv and H37Rv△1759c, which provides support and new directions for in-depth exploration of noncoding RNA and PE/PPE family functions during the infection process.