Antisense oligonucleotides: the next frontier for treatment of neurological disorders

The infinite possibilities of RNA therapeutics

Although the study of ribonucleic acid (RNA) therapeutics started decades ago, for many years, this field of research was overshadowed by the growing interest in DNA-based therapies. Nowadays, the role of several types of RNA in cell regulation processes and the development of various diseases have been elucidated, and research in RNA therapeutics is back with force. This short literature review aims to present general aspects of many of the molecules currently used in RNA therapeutics, including in vitro transcribed mRNA (IVT mRNA), antisense oligonucleotides (ASOs), aptamers, small interfering RNAs (siRNAs), and microRNAs (miRNAs). In addition, we describe the state of the art of technologies applied for synthetic RNA manufacture and delivery. Likewise, we detail the RNA-based therapies approved by the FDA so far, as well as the ongoing clinical investigations. As a final point, we highlight the current and potential advantages of working on RNA-based therapeutics and how these could lead to a new era of accessible and personalized healthcare.

Hidden Treasures: Macrophage Long Non-Coding RNAs in Lung Cancer Progression

Ever since RNA sequencing of whole genomes and transcriptomes became available, numerous RNA transcripts without having the classic function of encoding proteins have been discovered. Long non-coding RNAs (lncRNAs) with a length greater than 200 nucleotides were considered as "junk" in the beginning, but it has increasingly become clear that lncRNAs have crucial roles in regulating a variety of cellular mechanisms and are often deregulated in several diseases, such as cancer. Lung cancer is the leading cause of cancer-related deaths and has a survival rate of less than 10%. Immune cells infiltrating the tumor microenvironment (TME) have been shown to have a great effect on tumor development with macrophages being the major cell type within the TME. Macrophages can inherit an inflammatory M1 or an anti-inflammatory M2 phenotype. Tumor-associated macrophages, which are predominantly polarized to M2, favor tumor growth, angiogenesis, and metastasis. In this review, we aimed to describe the complex roles and functions of lncRNAs in macrophages and their influence on lung cancer development and progression through the TME.

An RNA/DNA hybrid origami-based nanoplatform for efficient gene therapy

Nucleic acid nanostructures are promising biomaterials for the delivery of homologous gene therapy drugs. Herein, we report a facile strategy for the construction of target mRNA (scaffold) and antisense (staple strands) co-assembled RNA/DNA hybrid "origami" for efficient gene therapy. In our design, the mRNA was folded into a chemically well-defined nanostructure through RNA-DNA hybridization with high yield. After the incorporation of an active cell-targeting aptamer, the tailored RNA/DNA hybrid origami demonstrated efficient cellular uptake and controllable release of antisenses in response to intracellular RNase H digestion. The biocompatible RNA/DNA origami (RDO) elicited a noticeable inhibition of cell proliferation based on the silencing of the tumor-associated gene polo-like kinase 1 (PLK1). This RDO-based nanoplatform provides a novel strategy for the further development of gene therapy.

Antisense oligonucleotide treatment rescues UBE3A expression and multiple phenotypes of an Angelman syndrome mouse model

Angelman syndrome (AS) is a severe neurodevelopmental disorder for which only symptomatic treatment with limited benefits is available. AS is caused by mutations affecting the maternally inherited ubiquitin protein ligase E3A (UBE3A) gene. Previous studies showed that the silenced paternal Ube3a gene can be activated by targeting the antisense Ube3a-ATS transcript. We investigated antisense oligonucleotide-induced (ASO-induced) Ube3a-ATS degradation and its ability to induce UBE3A reinstatement and rescue of AS phenotypes in an established Ube3a mouse model. We found that a single intracerebroventricular injection of ASOs at postnatal day 1 (P1) or P21 in AS mice resulted in potent and specific UBE3A reinstatement in the brain, with levels up to 74% of WT levels in the cortex and a full rescue of sensitivity to audiogenic seizures. AS mice treated with ASO at P1 also showed rescue of established AS phenotypes, such as open field and forced swim test behaviors, and significant improvement on the reversed rotarod. Hippocampal plasticity of treated AS mice was comparable to WT but not significantly different from PBS-treated AS mice. No rescue was observed for the marble burying and nest building phenotypes. Our findings highlight the promise of ASO-mediated reactivation of UBE3A as a disease-modifying treatment for AS.

Novel Treatments and Clinical Research in Child Neurology

The molecular understanding of the pathogenic mechanisms responsible for neurologic diseases of children has led to a remarkable period of research that addresses the root causes of diseases. The promise of this research has been realized with cures and treatments that correct underlying deficiencies. The breakneck rate at which new research is being proposed promises to usher in a transformation of child neurology from a diagnostic and supportive field into an interventional one. Training child neurology residents in clinical research and therapeutic intervention is increasingly important to assure the ongoing ability to support research discoveries and treatment.

Integration of chemically modified nucleotides with DNA strand displacement reactions for applications in living systems

Watson-Crick base pairing rules provide a powerful approach for engineering DNA-based nanodevices with programmable and predictable behaviors. In particular, DNA strand displacement reactions have enabled the development of an impressive repertoire of molecular devices with complex functionalities. By relying on DNA to function, dynamic strand displacement devices represent powerful tools for the interrogation and manipulation of biological systems. Yet, implementation in living systems has been a slow process due to several persistent challenges, including nuclease degradation. To circumvent these issues, researchers are increasingly turning to chemically modified nucleotides as a means to increase device performance and reliability within harsh biological environments. In this review, we summarize recent progress toward the integration of chemically modified nucleotides with DNA strand displacement reactions, highlighting key successes in the development of robust systems and devices that operate in living cells and in vivo. We discuss the advantages and disadvantages of commonly employed modifications as they pertain to DNA strand displacement, as well as considerations that must be taken into account when applying modified oligonucleotide to living cells. Finally, we explore how chemically modified nucleotides fit into the broader goal of bringing dynamic DNA nanotechnology into the cell, and the challenges that remain. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing.

Role of mammalian long non-coding RNAs in normal and neuro oncological disorders

Long non-coding RNAs (lncRNAs) are expressed at lower levels than protein-coding genes but have a crucial role in gene regulation. LncRNA is distinct, they are being transcribed using RNA polymerase II, and their functionality depends on subcellular localization. Depending on their niche, they specifically interact with DNA, RNA, and proteins and modify chromatin function, regulate transcription at various stages, forms nuclear condensation bodies and nucleolar organization. lncRNAs may also change the stability and translation of cytoplasmic mRNAs and hamper signaling pathways. Thus, lncRNAs affect the physio-pathological states and lead to the development of various disorders, immune responses, and cancer. To date, ~40% of lncRNAs have been reported in the nervous system (NS) and are involved in the early development/differentiation of the NS to synaptogenesis. LncRNA expression patterns in the most common adult and pediatric tumor suggest them as potential biomarkers and provide a rationale for targeting them pharmaceutically. Here, we discuss the mechanisms of lncRNA synthesis, localization, and functions in transcriptional, post-transcriptional, and other forms of gene regulation, methods of lncRNA identification, and their potential therapeutic applications in neuro oncological disorders as explained by molecular mechanisms in other malignant disorders.

Simultaneous quantitation of inorganic ions in oligonucleotides using mixed-mode liquid chromatography coupled with a charged aerosol detector

The amounts of inorganic ions (e.g. sodium, potassium, magnesium, calcium, chloride, and phosphate) in intrathecally administered oligonucleotide drug products need to be controlled in order to meet the final target formulation composition. During process development, these ions are measured to ensure the solution composition does not change during purification or drug product compounding and to ensure the final drug product targets are achieved. A quantitative method for ion analysis in antisense oligonucleotide (ASO) drugs was developed by mixed-mode anion exchange/cation exchange-hydrophilic interaction liquid chromatography (AEX/CEX-HILIC) with a charged aerosol detector (CAD). This thirteen-minute method measures monovalent and multivalent cations and anions simultaneously. LC separation conditions, CAD parameters, and sample preparation were judiciously optimized to ensure that the method is specific, accurate, precise, linear, robust, and rugged. With this LC-CAD approach, ion analysis for oligonucleotide drugs can be performed in most analytical labs to support drug development.

Approaches for corneal endothelium regenerative medicine

The state of the art therapy for treating corneal endothelial disease is transplantation. Advances in the reproducibility and accessibility of surgical techniques are increasing the number of corneal transplants, thereby causing a global deficit of donor corneas and leaving 12.7 million patients with addressable visual impairment. Approaches to regenerate the corneal endothelium offer a solution to the current tissue scarcity and a treatment to those in need. Methods for generating corneal endothelial cells into numbers that could address the current tissue shortage and the possible strategies used to deliver them have now become a therapeutic reality with clinical trials taking place in Japan, Singapore and Mexico. Nevertheless, there is still a long way before such therapies are approved by regulatory bodies and become clinical practice. Moreover, acellular corneal endothelial graft equivalents and certain drugs could provide a treatment option for specific disease conditions without the need of donor tissue or cells. Finally, with the emergence of gene modulation therapies to treat corneal endothelial disease, it would be possible to treat presymptomatic patients or those presenting early symptoms, drastically reducing the need for donor tissue. It is necessary to understand the most recent developments in this rapidly evolving field to know which conditions could be treated with which approach. This article provides an overview of the current and developing regenerative medicine therapies to treat corneal endothelial disease and provides the necessary guidance and understanding towards the treatment of corneal endothelial disease.

Electrophysiological Biomarkers in Genetic Epilepsies

Precision treatments for epilepsy targeting the underlying genetic diagnoses are becoming a reality. Historically, the goal of epilepsy treatments was to reduce seizure frequency. In the era of precision medicine, however, outcomes such as prevention of epilepsy progression or even improvements in cognitive functions are both aspirational targets for any intervention. Developing methods, both in clinical trial design and in novel endpoints, will be necessary for measuring, not only seizures, but also the other neurodevelopmental outcomes that are predicted to be targeted by precision treatments. Biomarkers that quantitatively measure disease progression or network level changes are needed to allow for unbiased measurements of the effects of any gene-level treatments. Here, we discuss some of the promising electrophysiological biomarkers that may be of use in clinical trials of precision therapies, as well as the difficulties in implementing them.

UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome

Half a century ago, Harry Angelman reported three patients with overlapping clinical features, now well known as Angelman syndrome. Angelman syndrome is caused by mutations affecting the maternally inherited UBE3A gene, which encodes an E3-ubiquitin ligase that is critical for typical postnatal brain development. Emerging evidence indicates that UBE3A plays a particularly important role in the nucleus. However, the critical substrates that are controlled by UBE3A remain elusive, which hinders the search for effective treatments. Moreover, given the multitude of signalling mechanisms that are derailed, it is unlikely that targeting a single pathway is going to be very effective. Therefore, expectations are very high for approaches that aim to restore UBE3A protein levels. A particular promising strategy is an antisense oligonucleotide approach, which activates the silenced paternal UBE3A gene. When successful, such treatments potentially offer a disease-modifying therapy for Angelman syndrome and several other neurodevelopmental disorders. What this paper adds Loss of UBE3A affects multiple signalling pathways in the brain. Emerging evidence suggests that UBE3A plays a critical role in the cell nucleus. Trials using antisense oligonucleotides to restore UBE3A levels are continuing.

Local application of Usag-1 siRNA can promote tooth regeneration in Runx2-deficient mice

Runt-related transcription factor 2 (Runx2)-deficient mice can be used to model congenital tooth agenesis in humans. Conversely, uterine sensitization-associated gene-1 (Usag-1)-deficient mice exhibit supernumerary tooth formation. Arrested tooth formation can be restored by crossing both knockout-mouse strains; however, it remains unclear whether topical inhibition of Usag-1 expression can enable the recovery of tooth formation in Runx2-deficient mice. Here, we tested whether inhibiting the topical expression of Usag-1 can reverse arrested tooth formation after Runx2 abrogation. The results showed that local application of Usag-1 Stealth small interfering RNA (siRNA) promoted tooth development following Runx2 siRNA-induced agenesis. Additionally, renal capsule transplantation of siRNA-loaded cationized, gelatin-treated mouse mandibles confirmed that cationized gelatin can serve as an effective drug-delivery system. We then performed renal capsule transplantation of wild-type and Runx2-knockout (KO) mouse mandibles, treated with Usag-1 siRNA, revealing that hindered tooth formation was rescued by Usag-1 knockdown. Furthermore, topically applied Usag-1 siRNA partially rescued arrested tooth development in Runx2-KO mice, demonstrating its potential for regenerating teeth in Runx2-deficient mice. Our findings have implications for developing topical treatments for congenital tooth agenesis.

Therapies in preclinical and clinical development for Angelman syndrome

Introduction: Angelman syndrome is a rare genetic neurodevelopmental disorder, caused by deficiency or abnormal function of the maternal ubiquitin protein-ligase E3A, known as UBE3A, in the central nervous system. There is no disease-modifying treatment available, but the therapeutic pipeline of Angelman syndrome includes at least 15 different approaches at preclinical or clinical development. In the coming years, several clinical trials will be enrolling patients, which prompted this comprehensive review.Areas covered: We summarize and critically review the different therapeutic approaches. Some approaches attempt to restore the missing or nonfunctional UBE3A protein in the neurons via gene replacement or enzyme replacement therapies. Other therapies aim to induce expression of the normal paternal copy of the UBE3A gene by targeting a long non-coding RNA, the UBE3A-ATS, which interferes with its own expression. Another therapeutic category includes compounds that target molecular pathways and effector proteins known to be involved in Angelman syndrome pathophysiology.Expert opinion: We believe that by 2022-2023, more than five disease-modifying treatments will be simultaneously at clinical testing. However, the are several challenges with regards to safety and efficacy, which need to be addressed. Additionally, there is still a significant unmet need for clinical trial readiness.

Long non-coding RNA: An underlying bridge linking neuroinflammation and central nervous system diseases

Central nervous system (CNS) diseases are responsible for a large proportion of morbidity and mortality worldwide. CNS diseases caused by intrinsic and extrinsic stimuli stimulate the resident immune cells including microglia and astrocyte, resulting in neuroinflammation that exacerbates the progression of diseases. Recent evidence reveals the aberrant expression patterns of long non-coding RNAs (lncRNAs) in the damaged tissues following CNS diseases. It was also proposed that lncRNAs possessed immune-modulatory activities by directly or indirectly affecting various effector proteins including transcriptional factor, acetylase, protein kinase, phosphatase, etc. In addition, lncRNAs can form a sophisticated network by interacting with other molecules to regulate the expression or activation of downstream immune response pathways. However, the major roles of lncRNAs in CNS pathophysiologies are still elusive, especially in neuroinflammation. Herein, we tend to review some potential roles of lncRNAs in modulating neuroinflammation based on current evidence in various CNS diseases, in order to provide novel explanations for the initiation and progression of CNS diseases and help to establish therapeutic strategies targeting neuroinflammation.

Future Perspectives of Therapeutic, Diagnostic and Prognostic Aptamers in Eye Pathological Angiogenesis

Aptamers are single-stranded DNA or RNA oligonucleotides that are currently used in clinical trials due to their selectivity and specificity to bind small molecules such as proteins, peptides, viral particles, vitamins, metal ions and even whole cells. Aptamers are highly specific to their targets, they are smaller than antibodies and fragment antibodies, they can be easily conjugated to multiple surfaces and ions and controllable post-production modifications can be performed. Aptamers have been therapeutically used for age-related macular degeneration, cancer, thrombosis and inflammatory diseases. The aim of this review is to highlight the therapeutic, diagnostic and prognostic possibilities associated with aptamers, focusing on eye pathological angiogenesis.

Advances of Antisense Oligonucleotide Technology in the Treatment of Hereditary Neurodegenerative Diseases

Antisense nucleic acids are single-stranded oligonucleotides that have been specially chemically modified, which can bind to RNA expressed by target genes through base complementary pairing and affect protein synthesis at the level of posttranscriptional processing or protein translation. In recent years, the application of antisense nucleic acid technology in the treatment of neuromuscular diseases has made remarkable progress. In 2016, the US FDA approved two antisense nucleic acid drugs for the treatment of Duchenne muscular dystrophy (DMD) and spinal muscular atrophy (SMA), and the development to treat other neurodegenerative diseases has also entered the clinical stage. Therefore, ASO represents a treatment with great potential. The article will summarize ASO therapies in terms of mechanism of action, chemical modification, and administration methods and analyze their role in several common neurodegenerative diseases, such as SMA, DMD, and amyotrophic lateral sclerosis (ALS). This article systematically summarizes the great potential of antisense nucleic acid technology in the treatment of hereditary neurodegenerative diseases.

SD-91 as A Potent and Selective STAT3 Degrader Capable of Achieving Complete and Long-Lasting Tumor Regression

Signal transducer and activator of transcription 3 (STAT3) is an attractive cancer therapeutic target. We report herein our extensive in vitro and in vivo evaluations of SD-91, the product of the hydrolysis of our previously reported STAT3 degrader SD-36. SD-91 binds to STAT3 protein with a high affinity and displays >300-fold selectivity over other STAT family protein members. SD-91 potently and effectively induces degradation of STAT3 protein and displays a high selectivity over other STAT members and >7000 non-STAT proteins in cells. A single administration of SD-91 selectively depletes STAT3 protein in tumor tissues with a persistent effect. SD-91 achieves complete and long-lasting tumor regression in the MOLM-16 xenograft model in mice even with weekly administration. Hence, SD-91 is a potent, highly selective, and efficacious STAT3 degrader for extensive evaluations for the treatment of human cancers and other diseases for which STAT3 plays a key role.

Long Noncoding RNAs: Novel Important Players in Adipocyte Lipid Metabolism and Derivative Diseases

Obesity, a global public health issue, is characterized by excessive adiposity and is strongly related to some chronic diseases including cardiovascular diseases and diabetes. Extra energy intake-induced adipogenesis involves various transcription factors and long noncoding RNAs (lncRNAs) that control lipogenic mRNA expression. Currently, lncRNAs draw much attention for their contribution to adipogenesis and adipose tissue function. Increasing evidence also manifests the pivotal role of lncRNAs in modulating white, brown, and beige adipose tissue development and affecting the progression of the diseases induced by adipose dysfunction. The aim of this review is to summarize the roles of lncRNAs in adipose tissue development and obesity-caused diseases to provide novel drug targets for the treatment of obesity and metabolic diseases.

Adiponectin Paradox as a Therapeutic Target in Alzheimer's Disease

Despite the apparent neurotoxicity of amyloid-β (Aβ), recent clinical trials of Aβ immunotherapy have not shown any clinical benefit in Alzheimer’s disease (AD). Given this, clarification of the next generation therapeutic strategy in AD is warranted. Hypothetically, adiponectin might be involved in promoting amyloidogenic evolvability in reproduction, which may result in the adiponectin paradox through antagonistic pleiotropy mechanism in aging, leading to AD. Accordingly, preventing the adiponectin paradox by suppressing adiponectin signaling might prove therapeutic in AD.

Therapeutic effects, immunogenicity and cytotoxicity of a cell penetrating peptide-peptide nucleic acid conjugate against cagA of Helicobacter pylori in cell culture and animal model

BACKGROUND AND OBJECTIVES

Helicobacter pylori causes several gastrointestinal diseases, including asymptomatic gastritis, chronic peptic ulcer, duodenal ulcer, lymphoma of the mucosa-associated lymphoid tissue (MALT), and gastric adenocarcinoma. In recent years, failure to eradicate H. pylori infections has become an alarming problem for physicians. It is now clear that the current treatment strategies may become ineffective, necessitating the development of innovative antimicrobial compounds as alternative treatments.

MATERIALS AND METHODS

In this experimental study, a cell-penetrating peptide-conjugated peptide nucleic acid (CPP-PNA) was used to target the cagA expression. cagA expression was evaluated using RT-qPCR assay after treatment by the CPPPNA in cell culture and animal model. Additionally, immunogenicity and toxicity of the CPP-PNA were assessed in both cell culture and animal models.

RESULTS

Our analysis showed that cagA mRNA levels reduced in H. pylori-infected HT29 cells after treatment with CPPPNA in a dose-dependent manner. Also, cagA expression in bacterial RNA extracted from stomach tissue of mice treated with PNA was reduced compared to that of untreated mice. The expression of inflammatory cytokines also decreased in cells and tissue of H. pylori-infected mice after PNA treatment. The tested CPP-PNA showed no significant adverse effects on cell proliferation of cultured cells and no detectable toxicity and immunogenicity were observed in mice.

CONCLUSION

These results suggest the effectiveness of CPP-PNA in targeting CagA for various research and therapeutic purposes, offering a potential antisense therapy against H. pylori infections.

Fluorescent base analogues in gapmers enable stealth labeling of antisense oligonucleotide therapeutics

To expand the antisense oligonucleotide (ASO) fluorescence labeling toolbox beyond covalent conjugation of external dyes (e.g. ATTO-, Alexa Fluor-, or cyanine dyes), we herein explore fluorescent base analogues (FBAs) as a novel approach to endow fluorescent properties to ASOs. Both cytosine and adenine analogues (tC, tC^O, 2CNqA, and pA) were incorporated into a 16mer ASO sequence with a 3-10-3 cEt-DNA-cEt (cEt = constrained ethyl) gapmer design. In addition to a comprehensive photophysical characterization, we assess the label-induced effects on the gapmers' RNA affinities, RNA-hybridized secondary structures, and knockdown efficiencies. Importantly, we find practically no perturbing effects for gapmers with single FBA incorporations in the biologically critical gap region and, except for pA, the FBAs do not affect the knockdown efficiencies. Incorporating two cytosine FBAs in the gap is equally well tolerated, while two adenine analogues give rise to slightly reduced knockdown efficiencies and what could be perturbed secondary structures. We furthermore show that the FBAs can be used to visualize gapmers inside live cells using fluorescence microscopy and flow cytometry, enabling comparative assessment of their uptake. This altogether shows that FBAs are functional ASO probes that provide a minimally perturbing in-sequence labeling option for this highly relevant drug modality.

Harnessing the physicochemical properties of DNA as a multifunctional biomaterial for biomedical and other applications

The biological purpose of DNA is to store, replicate, and convey genetic information in cells. Progress in molecular genetics have led to its widespread applications in gene editing, gene therapy, and forensic science. However, in addition to its role as a genetic material, DNA has also emerged as a nongenetic, generic material for diverse biomedical applications. DNA is essentially a natural biopolymer that can be precisely programed by simple chemical modifications to construct materials with desired mechanical, biological, and structural properties. This review critically deciphers the chemical tools and strategies that are currently being employed to harness the nongenetic functions of DNA. Here, the primary product of interest has been crosslinked, hydrated polymers, or hydrogels. State-of-the-art applications of macroscopic, DNA-based hydrogels in the fields of environment, electrochemistry, biologics delivery, and regenerative therapy have been extensively reviewed. Additionally, the review encompasses the status of DNA as a clinically and commercially viable material and provides insight into future possibilities.

siRNA: Mechanism of action, challenges, and therapeutic approaches

Owing to specific and compelling gene silencing, RNA interference (RNAi) is expected to become an essential approach in treating a variety of infectious, hemato-oncological, cardiovascular, and neurodegenerative conditions. The mechanism of action of small interfering RNA (siRNA) is based on post-transcriptional gene silencing. siRNA molecules are usually specific and efficient in the knockdown of disease-related genes. However, they are characterized by low cellular uptake and are susceptible to nuclease-mediated degradation. Therefore, siRNAs require a carrier for their protection and efficient delivery into target cells. The current review highlights the siRNA-based mechanism of action, challanges, and recent advances in clinical applications.

Short DNA/RNA heteroduplex oligonucleotide interacting proteins are key regulators of target gene silencing

Antisense oligonucleotide (ASO)-based therapy is one of the next-generation therapy, especially targeting neurological disorders. Many cases of ASO-dependent gene expression suppression have been reported. Recently, we developed a tocopherol conjugated DNA/RNA heteroduplex oligonucleotide (Toc-HDO) as a new type of drug. Toc-HDO is more potent, stable, and efficiently taken up by the target tissues compared to the parental ASO. However, the detailed mechanisms of Toc-HDO, including its binding proteins, are unknown. Here, we developed native gel shift assays with fluorescence-labeled nucleic acids samples extracted from mice livers. These assays revealed two Toc-HDO binding proteins, annexin A5 (ANXA5) and carbonic anhydrase 8 (CA8). Later, we identified two more proteins, apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) and flap structure-specific endonuclease 1 (FEN1) by data mining. shRNA knockdown studies demonstrated that all four proteins regulated Toc-HDO activity in Hepa1-6, mouse hepatocellular cells. In vitro binding assays and fluorescence polarization assays with purified recombinant proteins characterized the identified proteins and pull-down assays with cell lysates demonstrated the protein binding to the Toc-HDO and ASO in a biological environment. Taken together, our findings provide a brand new molecular biological insight as well as future directions for HDO-based disease therapy.

Gys1 antisense therapy rescues neuropathological bases of murine Lafora disease

Lafora disease is a fatal progressive myoclonus epilepsy. At root, it is due to constant acquisition of branches that are too long in a subgroup of glycogen molecules, leading them to precipitate and accumulate into Lafora bodies, which drive a neuroinflammatory response and neurodegeneration. As a potential therapy, we aimed to downregulate glycogen synthase, the enzyme responsible for glycogen branch elongation, in the disease's mouse models. We synthesized an antisense oligonucleotide (Gys1-ASO) that targets the mRNA of the brain-expressed glycogen synthase 1 gene (Gys1). We administered Gys1-ASO by intracerebroventricular injection and analyzed the pathological hallmarks of Lafora disease, namely glycogen accumulation, Lafora body formation, and neuroinflammation. Gys1-ASO prevented Lafora body formation in young mice that had not yet formed them. In older mice that already exhibited Lafora bodies, Gys1-ASO inhibited further accumulation, markedly preventing large Lafora bodies characteristic of advanced disease. Inhibition of Lafora body formation was associated with prevention of astrogliosis and strong trends towards correction of dysregulated expression of disease immune and neuroinflammatory markers. Lafora disease manifests gradually in previously healthy teenagers. Our work provides proof of principle that an antisense oligonucleotide targeting the GYS1 mRNA could prevent, and halt progression of, this catastrophic epilepsy.

Therapeutic Development for CGG Repeat Expansion-Associated Neurodegeneration

Non-coding repeat expansions, such as CGG, GGC, CUG, CCUG, and GGGGCC, have been shown to be involved in many human diseases, particularly neurological disorders. Of the diverse pathogenic mechanisms proposed in these neurodegenerative diseases, dysregulated RNA metabolism has emerged as an important contributor. Expanded repeat RNAs that form particular structures aggregate to form RNA foci, sequestering various RNA binding proteins and consequently altering RNA splicing, transport, and other downstream biological processes. One of these repeat expansion-associated diseases, fragile X-associated tremor/ataxia syndrome (FXTAS), is caused by a CGG repeat expansion in the 5'UTR region of the fragile X mental retardation 1 (FMR1) gene. Moreover, recent studies have revealed abnormal GGC repeat expansion within the 5'UTR region of the NOTCH2NLC gene in both essential tremor (ET) and neuronal intranuclear inclusion disease (NIID). These CGG repeat expansion-associated diseases share genetic, pathological, and clinical features. Identification of the similarities at the molecular level could lead to a better understanding of the disease mechanisms as well as developing novel therapeutic strategies. Here, we highlight our current understanding of the molecular pathogenesis of CGG repeat expansion-associated diseases and discuss potential therapeutic interventions for these neurological disorders.

Targeting Poison Exons to Treat Developmental and Epileptic Encephalopathy

Developmental and epileptic encephalopathies (DEEs) describe a subset of neurodevelopmental disorders categorized by refractory epilepsy that is often associated with intellectual disability and autism spectrum disorder. The majority of DEEs are now known to have a genetic basis with de novo coding variants accounting for the majority of cases. More recently, a small number of individuals have been identified with intronic SCN1A variants that result in alternative splicing events that lead to ectopic inclusion of poison exons (PEs). PEs are short highly conserved exons that contain a premature truncation codon, and when spliced into the transcript, lead to premature truncation and subsequent degradation by nonsense-mediated decay. The reason for the inclusion/exclusion of these PEs is not entirely clear, but research suggests an autoregulatory role in gene expression and protein abundance. This is seen in proteins such as RNA-binding proteins and serine/arginine-rich proteins. Recent studies have focused on targeting these PEs as a method for therapeutic intervention. Targeting PEs using antisense oligonucleotides (ASOs) has shown to be effective in modulating alternative splicing events by decreasing the amount of transcripts harboring PEs, thus increasing the abundance of full-length transcripts and thereby the amount of protein in haploinsufficient genes implicated in DEE. In the age of personalized medicine, cellular and animal models of the genetic epilepsies have become essential in developing and testing novel precision therapeutics, including PE-targeting ASOs in a subset of DEEs.

Hereditary transthyretin amyloidosis: current treatment

PURPOSE OF REVIEW

Hereditary transthyretin amyloidosis (ATTRv) is a rare autosomal dominant, life-threatening disease. Until recently only early stages of ATTRv-PN (polyneuropathy) had access to disease-modifying therapy (DMT), whereas there was no specific treatment for ATTRv-CM (cardiomyopathy). This review updates our knowledge about results of three phase 3 clinical trials, expert's consensus for early diagnosis and emerging biomarkers.

RECENT FINDINGS

Two phase 3 studies using RNAi and antisense oligonucleotides (ASO) were successful. Primary endpoints were progression of neuropathic score mNIS +7 and quality of Life (QOL) in a population of ATTRv-PN at different levels of severity. They knock downed circulating amyloidogenic mutant and wild-type TTR. Safety concerned ASO with a risk of thrombocytopenia. RNAi showed possible reversibility of the disease. Phase 3 ATTRACT trial-tested tafamidis versus placebo in patients with ATTRv-CM and ATTRwt-CM and showed a significant reduction of all-cause mortality and rates of cardiovascular-related hospitalizations. All three drugs obtained marketing authorization by European Medicines Agency (EMA) and Food and drug administration (FDA). Early diagnosis criteria for ATTRv-PN and ATTRv-CM are available. Ongoing clinical trials for ATTRv are presented. New biomarkers are plasma neurofilament light chain, intraepidermal nerve fiber density.

SUMMARY

The majority of patients with ATTRv may have now access to a DMT. Criteria for early diagnosis are available.

CRISPR/dCas9 as a Therapeutic Approach for Neurodevelopmental Disorders: Innovations and Limitations Compared to Traditional Strategies

Brain development is a complex process that requires a series of precise and coordinated events to take place. When alterations in some of those events occur, neurodevelopmental disorders (NDDs) may appear, with their characteristic symptoms, including cognitive, social motor deficits, and epilepsy. While pharmacologic treatments have been the only therapeutic options for many years, more recently the research is turning to the direct removal of the underlying genetic cause of each specific NDD. This is possible thanks to the increased knowledge of genetic basis of those diseases and the enormous advances in genome-editing tools. Together with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-based strategies, there is a great development also of nuclease defective Cas9 (dCas9) tools that, with an extreme flexibility, allow the recruitment of specific protein functions to the desired genomic sites. In this work, we review dCas9-based tools and discuss all the published applications in the setting of therapeutic approaches for NDDs at the preclinical level. In particular, dCas9-based therapeutic strategies for Dravet syndrome, transcallosal dysconnectivity caused by mutations in C11orf46 gene, and Fragile X syndrome are presented and discussed. A direct comparison with other possible therapeutic strategies, such as classic gene replacement or CRISPR/Cas9-based strategies, is provided. We also highlight not only those aspects that constitute a clear advantage compared to previous strategies but also the main technical hurdles related to their applications that need to be overcome.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Silencing acpP gene via antisense oligonucleotide-niosome complex in clinical Pseudomonas aeruginosa isolates

Pseudomonas aeruginosa, an opportunistic Gram-negative pathogen, is one of the major causes of nosocomial infections. In addition to its physiological adaptation capacity, it can develop resistance to disinfectants and antibiotics through various mechanisms. Recently, new eradication methods are gaining attention. Therefore, in this study, an LNA-2'-O-methyl hybrid antisense oligonucleotide targeting the acyl carrier protein P (acpP) gene was introduced into P. aeruginosa isolates. The design was determined through sequence analysis and prediction of the secondary structure of mRNA by software. Niosomes were used for enhancing cellular uptake. The control of the binding and transfection ability of the sequence was determined fluorometrically by labeling with 6-Fam. The effects were determined with broth microdilution method and qPCR studies. Eight different formulations were prepared. Among these, one formulation has shown to have ASO complexation ability whose composition was 312 μl Span 80 + 69.5 mg Cholesterol+ 36.4 mg CTAB+1 ml Chloroform and 5 ml dH₂O. Thus this formulation was determined as the delivery system for the next stages. Significant gene inhibition was detected at the six isolates. Results of this study suggested that niosomes can be used as a delivery system for cellular uptake of ASO and could eliminate bacterial growth.

Exploring the Alternative Splicing of Long Noncoding RNAs

Like protein-coding genes, long noncoding RNA (lncRNA) genes are composed of introns and exons. After their transcription, lncRNAs are subject to constitutive and/or alternative splicing. Here, we describe the current knowledge on lncRNA splice variants and their functional implications in cell biology.

Allele-Specific RNA Knockdown with a Biologically Stable and Catalytically Efficient XNAzyme

Therapeutic targeting of allele-specific single nucleotide mutations in RNA is a major challenge in biology and medicine. Herein, we describe the utility of the XNAzyme X10-23 to knock down allele-specific mRNA sequences in cells. We demonstrate the value of this approach by targeting the "undruggable" mutation G12V in oncogenic KRAS. Our results demonstrate how catalytic XNAs could be employed to suppress the expression of mRNAs carrying disease-causing mutations that are difficult to target at the protein level with small molecule therapeutics.

In Vivo Administration of Therapeutic Antisense Oligonucleotides

With the rapid revolution in RNA/DNA sequencing technologies, it is evident that mammalian genomes express tens of thousands of long noncoding RNAs (lncRNAs). Since a large majority of lncRNAs have been functionally implicated in cancer development and progression, there is an increasing appreciation for the use of antisense oligonucleotide (ASO)-based therapies targeting lncRNAs in several cancers. Despite their great potential in therapeutic applications, their use is still limited due to cellular toxicity and shortcomings in achieving required stability in biological fluids and tissue uptake. To overcome these limitations, major changes in ASO chemistry have been introduced to generate second and third generation ASOs, including locked nucleic acids (LNA) technology. Here we describe two different LNA-ASO delivery approaches, a peritumoral administration and a systemic delivery in xenograft models of lung adenocarcinoma, that significantly reduced tumor growth without inducing toxicity.

Noncoding RNAs in Glioblastoma: Emerging Biological Concepts and Potential Therapeutic Implications

Simple Summary

Since the completion of the Human Genome Project, noncoding RNAs (ncRNAs) have emerged as an important class of genetic regulators. Several classes of ncRNAs, which include microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and piwi-interacting RNAs (piRNAs), have been shown to play important roles in controlling developmental and disease processes. In this article, we discuss the potential roles of ncRNAs in regulating glioblastoma (GBM) formation and progression as well as potential strategies to exploit the diagnostic and therapeutic potential of ncRNAs in GBM.

Abstract

Noncoding RNAs (ncRNAs) have emerged as a novel class of genomic regulators, ushering in a new era in molecular biology. With the advent of advanced genetic sequencing technology, several different classes of ncRNAs have been uncovered, including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and piwi-interacting RNAs (piRNAs), which have been linked to many important developmental and disease processes and are being pursued as clinical and therapeutic targets. Molecular phenotyping studies of glioblastoma (GBM), the most common and lethal cancer of the adult brain, revealed that several ncRNAs are frequently dysregulated in its pathogenesis. Additionally, ncRNAs regulate many important aspects of glioma biology including tumour cell proliferation, migration, invasion, apoptosis, angiogenesis, and self-renewal. Here, we present an overview of the biogenesis of the different classes of ncRNAs, discuss their biological roles, as well as their relevance to gliomagenesis. We conclude by discussing potential approaches to therapeutically target the ncRNAs in clinic.

The duality of PRDM proteins: epigenetic and structural perspectives

PRDF1 and RIZ1 homology domain containing (PRDMs) are a subfamily of Krüppel-like zinc finger proteins controlling key processes in metazoan development and in cancer. PRDMs exhibit unique dualities: (a) PR domain/ZNF arrays-their structure combines a SET-like domain known as a PR domain, typically found in methyltransferases, with a variable array of C2H2 zinc fingers (ZNF) characteristic of DNA-binding transcription factors; (b) transcriptional activators/repressors-their physiological function is context- and cell-dependent; mechanistically, some PRDMs have a PKMT activity and directly catalyze histone lysine methylation, while others are rather pseudomethyltransferases and act by recruiting transcriptional cofactors; (c) oncogenes/tumor suppressors-their pathological function depends on the specific PRDM isoform expressed during tumorigenesis. This duality is well known as the 'Yin and Yang' of PRDMs and involves a complex regulation of alternative splicing or alternative promoter usage, to generate full-length or PR-deficient isoforms with opposing functions in cancer. In conclusion, once their dualities are fully appreciated, PRDMs represent a promising class of targets in oncology by virtue of their widespread upregulation across multiple tumor types and their somatic dispensability, conferring a broad therapeutic window and limited toxic side effects. The recent discovery of a first-in-class compound able to inhibit PRDM9 activity has paved the way for the identification of further small molecular inhibitors able to counteract PRDM oncogenic activity.

Recent advances in the diagnosis and management of amyloid cardiomyopathy

Amyloidosis is a disorder characterized by misfolded precursor proteins that form depositions of fibrillar aggregates with an abnormal cross-beta-sheet conformation, known as amyloid, in the extracellular space of several tissues. Although there are more than 30 known amyloidogenic proteins, both hereditary and non-hereditary, cardiac amyloidosis (CA) typically arises from either misfolded transthyretin (ATTR amyloidosis) or immunoglobulin light-chain aggregation (AL amyloidosis). Its prevalence is more common than previously thought, especially among patients with heart failure and preserved ejection fraction (HFpEF) and aortic stenosis. If there is a clinical suspicion of CA, focused echocardiography, laboratory screening for the presence of a monoclonal protein (serum and urinary electrophoresis with immunofixation and serum free light-chain ratio), and cardiac scintigraphy with 99mtechnetium-labeled bone-tracers are sensitive and specific initial diagnostic tests. In some cases, more advanced/invasive techniques are necessary and, in the last several years, treatment options for both AL CA and ATTR CA have rapidly expanded. It is important to note that the aims of therapy are different. Systemic AL amyloidosis requires treatment targeted against the abnormal plasma cell clone, whereas therapy for ATTR CA must be targeted to the production and stabilization of the TTR molecule. It is likely that a multistep treatment approach will be optimal for both AL CA and ATTR CA. Additionally, treatment of CA includes the management of restrictive cardiomyopathy with preserved or reduced ejection fraction in addition to treating the amyloid deposition. Future studies are necessary to define optimal management strategies for AL CA and ATTR CA and confirm cardiac response to therapy.

Advances in the Design of (Nano)Formulations for Delivery of Antisense Oligonucleotides and Small Interfering RNA: Focus on the Central Nervous System

RNA-based therapeutics have emerged as one of the most powerful therapeutic options used for the modulation of gene/protein expression and gene editing with the potential to treat neurodegenerative diseases. However, the delivery of nucleic acids to the central nervous system (CNS), in particular by the systemic route, remains a major hurdle. This review will focus on the strategies for systemic delivery of therapeutic nucleic acids designed to overcome these barriers. Pathways and mechanisms of transport across the blood–brain barrier which could be exploited for delivery are described, focusing in particular on smaller nucleic acids including antisense oligonucleotides (ASOs) and small interfering RNA (siRNA). Approaches used to enhance delivery including chemical modifications, nanocarrier systems, and target selection (cell-specific delivery) are critically analyzed. Learnings achieved from a comparison of the successes and failures reported for CNS delivery of ASOs versus siRNA will help identify opportunities for a wider range of nucleic acids and accelerate the clinical translation of these innovative therapies.

Development of Antisense Oligonucleotide Gapmers for the Treatment of Huntington's Disease

The field of neuromuscular and neurodegenerative diseases has been revolutionized by the advent of genetics and molecular biology to evaluate the pathogenicity, thereby providing considerable insight to develop suitable therapies. With the successful translation of antisense oligonucleotides (AOs) from in vitro into animal models and clinical practice, modifications are being continuously made to the AOs to improve the pharmacokinetics and pharmacodynamics. In order to activate RNase H-mediated cleavage of the target mRNA, as well as to increase the binding affinity and specificity, gapmer AOs are designed to have a phosphorothioate (PS) backbone flanked with the modified AOs on both sides. Antisense-mediated knockdown of mutated huntingtin is a promising therapeutic approach for Huntington's disease (HD), a devastating disorder affecting the motor and cognitive abilities. This chapter focuses on the modified gapmer AOs for the treatment of HD.

Development of Antisense Oligonucleotide Gapmers for the Treatment of Dyslipidemia and Lipodystrophy

Although technological advances in molecular genetics over the last few decades have greatly expedited the identification of mutations in many genetic diseases, the translation of the genetic mechanisms into a clinical setting has been quite challenging, with a minimum number of effective treatments available. The advancements in antisense therapy have revolutionized the field of neuromuscular disorders as well as lipid-mediated diseases. With the approval of splice-switching antisense oligonucleotide (AO) therapy for nusinersen and eteplirsen for the treatment of spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD), several modified AOs are now being evaluated in clinical trials for the treatment of a number of disorders. In order to activate RNase H-mediated cleavage of the target mRNA, as well as to increase the binding affinity and specificity, gapmer AOs are designed that have a PS backbone flanked with the modified AOs on both sides. Mipomersen (trade name Kynamro), a 2'-O-methoxyethyl (MOE) gapmer, was approved by the Food and Drug Administration (FDA) for the treatment of homozygous familial hypercholesterolemia (HoFH) in 2013. Volanesorsen, another 20-mer MOE gapmer has shown to be successful in lowering the levels of triglycerides (TGs) in several lipid disorders and has received conditional approval in the European Union for the treatment of Familial chylomicronemia syndrome (FCS) in May 2019 following successful results from phase II/III clinical trials. This chapter focuses on the clinical applications of gapmer AOs for genetic dyslipidemia and lipodystrophy.

Development and Clinical Applications of Antisense Oligonucleotide Gapmers

DNA-like molecules called antisense oligonucleotides have opened new treatment possibilities for genetic diseases by offering a method of regulating gene expression. Antisense oligonucleotides are often used to suppress the expression of mutated genes which may interfere with essential downstream pathways. Since antisense oligonucleotides have been introduced for clinical use, different chemistries have been developed to further improve efficacy, potency, and safety. One such chemistry is a chimeric structure of a central block of deoxyribonucleotides flanked by sequences of modified nucleotides. Referred to as a gapmer, this chemistry produced promising results in the treatment of genetic diseases. Mipomersen and inotersen are examples of recent FDA-approved antisense oligonucleotide gapmers used for the treatment of familial hypercholesterolemia and hereditary transthyretin amyloidosis, respectively. In addition, volanesorsen was conditionally approved in the EU for the treatment of adult patients with familial chylomicronemia syndrome (FCS) in 2019. Many others are being tested in clinical trials or under preclinical development. This chapter will cover the development of mipomersen and inotersen in clinical trials, along with advancement in gapmer treatments for cancer, triglyceride-elevating genetic diseases, Huntington's disease, myotonic dystrophy, and prion diseases.

Impurity profiling of siRNA by two-dimensional liquid chromatography-mass spectrometry with quinine carbamate anion-exchanger and ion-pair reversed-phase chromatography

A short RNA with the sequence of the antisense strand of Patisiran has been selected as test material for the investigation of its common impurities using three different two-dimensional liquid chromatography (2D-LC) platforms. On the one hand, a quinine (QN) carbamate-based weak anion-exchange (AX) stationary phase (QN-AX) and a classical C18 reversed phase (RP) stationary phase in ion-pair (IP) mode with tripropylammonium acetate, respectively, have been used in the first dimension (¹D) to provide the selectivity for impurities formed during the synthesis of the RNA. In the next step, certain peaks of interest from ¹D have been transferred by multiple-heart-cutting (MHC) into a ²D in which an ESI-MS-compatible non-ionpairing RP method has been used for desalting via a diverter valve to remove non-volatile phosphate buffer components and ion-pair agents, respectively. Thus, a sensitive electrospray-ionization quadrupole time of flight mass spectrometry (ESI-TOF-MS) analysis of resolved impurity peaks of the siRNA has become possible under MS-friendly conditions. With both 2D-LC setups, peak purity of the ON has been evaluated by selective comprehensive (high resolution) sampling of the main peak. In a third MHC 2D-LC approach, the QN-AX LC mode was online coupled with the IP-RPLC in the ²D using UV detection. It allows the separation of additional impurities which coeluted in the first dimension. The potential of these methods for comprehensive impurity profiling of ON therapeutics is illustrated and discussed.

CaMKIIδ Splice Variants in the Healthy and Diseased Heart

RNA splicing has been recognized in recent years as a pivotal player in heart development and disease. The Ca²⁺/calmodulin dependent protein kinase II delta (CaMKIIδ) is a multifunctional Ser/Thr kinase family and generates at least 11 different splice variants through alternative splicing. This enzyme, which belongs to the CaMKII family, is the predominant family member in the heart and functions as a messenger toward adaptive or detrimental signaling in cardiomyocytes. Classically, the nuclear CaMKIIδB and cytoplasmic CaMKIIδC splice variants are described as mediators of arrhythmias, contractile function, Ca²⁺ handling, and gene transcription. Recent findings also put CaMKIIδA and CaMKIIδ9 as cardinal players in the global CaMKII response in the heart. In this review, we discuss and summarize the new insights into CaMKIIδ splice variants and their (proposed) functions, as well as CaMKII-engineered mouse phenotypes and cardiac dysfunction related to CaMKIIδ missplicing. We also discuss RNA splicing factors affecting CaMKII splicing. Finally, we discuss the translational perspective derived from these insights and future directions on CaMKIIδ splicing research in the healthy and diseased heart.

Local Protein Translation and RNA Processing of Synaptic Proteins in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a heritable neurodevelopmental condition associated with impairments in social interaction, communication and repetitive behaviors. While the underlying disease mechanisms remain to be fully elucidated, dysfunction of neuronal plasticity and local translation control have emerged as key points of interest. Translation of mRNAs for critical synaptic proteins are negatively regulated by Fragile X mental retardation protein (FMRP), which is lost in the most common single-gene disorder associated with ASD. Numerous studies have shown that mRNA transport, RNA metabolism, and translation of synaptic proteins are important for neuronal health, synaptic plasticity, and learning and memory. Accordingly, dysfunction of these mechanisms may contribute to the abnormal brain function observed in individuals with autism spectrum disorder (ASD). In this review, we summarize recent studies about local translation and mRNA processing of synaptic proteins and discuss how perturbations of these processes may be related to the pathophysiology of ASD.

Structure and luminescence of DNA-templated silver clusters

DNA serves as a versatile template for few-atom silver clusters and their organized self-assembly. These clusters possess unique structural and photophysical properties that are programmed into the DNA template sequence, resulting in a rich palette of fluorophores which hold promise as chemical and biomolecular sensors, biolabels, and nanophotonic elements. Here, we review recent advances in the fundamental understanding of DNA-templated silver clusters (Ag N -DNAs), including the role played by the silver-mediated DNA complexes which are synthetic precursors to Ag N -DNAs, structure-property relations of Ag N -DNAs, and the excited state dynamics leading to fluorescence in these clusters. We also summarize the current understanding of how DNA sequence selects the properties of Ag N -DNAs and how sequence can be harnessed for informed design and for ordered multi-cluster assembly. To catalyze future research, we end with a discussion of several opportunities and challenges, both fundamental and applied, for the Ag N -DNA research community. A comprehensive fundamental understanding of this class of metal cluster fluorophores can provide the basis for rational design and for advancement of their applications in fluorescence-based sensing, biosciences, nanophotonics, and catalysis.

Hypoxia-induced alternative splicing in human diseases: the pledge, the turn, and the prestige

Maintenance of oxygen homeostasis is an indispensable criterion for the existence of multicellular life-forms. Disruption of this homeostasis due to inadequate oxygenation of the respiring tissues leads to pathological hypoxia, which acts as a significant stressor in several pathophysiological conditions including cancer, cardiovascular defects, bacterial infections, and neurological disorders. Consequently, the hypoxic tissues develop necessary adaptations both at the tissue and cellular level. The cellular adaptations involve a dramatic alteration in gene expression, post-transcriptional and post-translational modification of gene products, bioenergetics, and metabolism. Among the key responses to oxygen-deprivation is the skewing of cellular alternative splicing program. Herein, we discuss the current concepts of oxygen tension-dependent alternative splicing relevant to various pathophysiological conditions. Following a brief description of cellular response to hypoxia and the pre-mRNA splicing mechanism, we outline the impressive number of hypoxia-elicited alternative splicing events associated with maladies like cancer, cardiovascular diseases, and neurological disorders. Furthermore, we discuss how manipulation of hypoxia-induced alternative splicing may pose promising strategies for novel translational diagnosis and therapeutic interventions.