Noninvasive and Quantitative Monitoring of the Distributions and Kinetics of MicroRNA-Targeting Molecules in Vivo by Positron Emission Tomography

Tailed-Hoogsteen Triplex DNA Silver Nanoclusters Emit Red Fluorescence upon Target miRNA Sensing

MicroRNAs (miRNAs) are small RNA molecules, typically 21‒22 nucleotides in size, which play a crucial role in regulating gene expression in most eukaryotes. Their significance in various biological processes and disease pathogenesis has led to considerable interest in their potential as biomarkers for diagnosis and therapeutic applications. In this study, a novel method for sensing target miRNAs using Tailed-Hoogsteen triplex DNA-encapsulated Silver Nanoclusters (DNA/AgNCs) is introduced. Upon hybridization of a miRNA with the tail, the Tailed-Hoogsteen triplex DNA/AgNCs exhibit a pronounced red fluorescence, effectively turning on the signal. It is successfully demonstrated that this miRNA sensor not only recognized target miRNAs in total RNA extracted from cells but also visualized target miRNAs when introduced into live cells, highlighting the advantages of the turn-on mechanism. Furthermore, through gel-fluorescence assays and small-angle X-ray scattering (SAXS) analysis, the turn-on mechanism is elucidated, revealing that the Tailed-Hoogsteen triplex DNA/AgNCs undergo a structural transition from a monomer to a dimer upon sensing the target miRNA. Overall, the findings suggest that Tailed-Hoogsteen triplex DNA/AgNCs hold great promise as practical sensors for small RNAs in both in vitro and cell imaging applications.

Molecular Imaging Using Cardiac PET/CT: Opportunities to Harmonize Diagnosis and Therapy

PURPOSE OF REVIEW

Current therapeutic strategies to mitigate heart failure progression after myocardial infarction involve support of endogenous repair through molecular targets. The capacity for repair varies greatly between individuals. In this review, we will assess how cardiac PET/CT enables precise characterization of early pathogenetic processes which govern ventricle remodeling and progression to heart failure.

RECENT FINDINGS

Inflammation in the first days after myocardial infarction predicts subsequent functional decline and can influence therapy decisions. The expansion of anti-inflammatory approaches to improve outcomes after myocardial infarction may benefit from noninvasive characterization using imaging. Novel probes also allow visualization of fibroblast transdifferentiation and activation, as a precursor to ventricle remodeling. The expanding arsenal of molecular imaging agents in parallel with new treatment options provides opportunity to harmonize diagnostic imaging with precision therapy.

Controlled Monofunctionalization of Molecular Spherical Nucleic Acids on a Buckminster Fullerene Core

An azide-functionalized 12-armed Buckminster fullerene has been monosubstituted in organic media with a substoichiometric amount of cyclooctyne-modified oligonucleotides. Exposing the intermediate products then to the same reaction (i.e., strain-promoted alkyne–azide cycloaddition, SPAAC) with an excess of slightly different oligonucleotide constituents in an aqueous medium yields molecularly defined monofunctionalized spherical nucleic acids (SNAs). This procedure offers a controlled synthesis scheme in which one oligonucleotide arm can be functionalized with labels or other conjugate groups (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, DOTA, and Alexa-488 demonstrated), whereas the rest of the 11 arms can be left unmodified or modified by other conjugate groups in order to decorate the SNAs’ outer sphere. Extra attention has been paid to the homogeneity and authenticity of the C₆₀-azide scaffold used for the assembly of full-armed SNAs.

Bringing MicroRNAs to Light: Methods for MicroRNA Quantification and Visualization in Live Cells

MiRNAs are small non-coding RNAs that interact with their target mRNAs for posttranscriptional gene regulation. Finely controlled miRNA biogenesis, target recognition and degradation indicate that maintaining miRNA homeostasis is essential for regulating cell proliferation, growth, differentiation and apoptosis. Increasingly, miRNAs have been recognized as a potential biomarker for disease diagnosis. MiRNAs can be found in blood, plasma, and tissues, and miRNA expression and activity differ in developmental stages, tissues and in response to external stimuli. MiRNA transcripts are matured from pri-miRNA over pre-miRNA to mature miRNA, a process that includes multiple steps and enzymes. Many tools are available to identify and quantify specific miRNAs, ranging from measuring total miRNA, specific miRNA activity, miRNA arrays and miRNA localization. The various miRNA assays differ in accuracy, cost, efficiency and convenience of monitoring miRNA dynamics. To acknowledge the significance and increasing research interest in miRNAs, we summarize the traditional as well as novel methods of miRNA quantification with strengths and limitations of various techniques in biochemical and medical research.

Genetically Encoded Reporter Genes for MicroRNA Imaging in Living Cells and Animals

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression by base paring with the complementary sequences of the target mRNAs, and then exert their function through degrading mRNA or inhibiting protein translation. They play a significant role as a regulatory factor in biological processes of organism development, cell proliferation, differentiation, and cell death. Some of the traditional methods for studying miRNAs, such as northern blot, real-time PCR, or microarray, have been extensively used to investigate the biological properties and expression patterns of miRNAs. However, these methods often require considerable time, cell samples, and the design of effective primers or specific probes. Therefore, in order to gain a deeper understanding of the role of miRNAs in biological processes and accelerate the clinical application of miRNAs in the field of disease treatment, non-invasive, sensitive, and efficient imaging methods are needed to visualize the dynamic expression of miRNAs in living cells and animals. In this study, we reviewed the recent progress in the genetically encoded reporter genes for miRNA imaging.