Gene Editing Research Articles

Exploiting the efficient Exo:Cas12i3-5M fusions for robust single and multiplex gene editing in rice.

The development of a single and multiplex gene editing system is highly desirable for either functional genomics or pyramiding beneficial alleles in crop improvement. CRISPR/Cas12i3, which belongs to the Class II Type V-I Cas system, has attracted extensive attention recently due to its smaller protein size and less restricted canonical "TTN" protospacer adjacent motif (PAM). However, due to its relatively lower editing efficiency, Cas12i3-mediated multiplex gene editing has not yet been documented in plants. Here, we fused four 5' exonucleases (Exo) including T5E, UL12, PapE, ME15 to the N terminal of an optimized Cas12i3 variant (Cas12i3-5M), respectively, and systematically evaluated the editing activities of these Exo:Cas12i3-5M fusions across six endogenous targets in rice stable lines. We demonstrated that the Exo:Cas12i3-5M fusions increased the gene editing efficiencies by up to 12.46-fold and 1.25-fold compared with Cas12i3 and Cas12i3-5M, respectively. Notably, the UL12:Cas12i3-5M fusion enabled robust single gene editing with editing efficiencies of up to 90.42%-98.61% across the six tested endogenous genes. We further demonstrated that, although all the Exo:Cas12i5-5M fusions were capable of multiplex gene editing, UL12:Cas12i3-5M exhibited a superior performance in the simultaneous editing of three, four, five or six genes with efficiencies of 82.76%, 61.36%, 52.94%, and 51.06% in rice stable lines, respectively. Together, we evaluated different Exo:Cas12i3-5M fusions systemically and established UL12:Cas12i3-5M as the more robust system for single and multiplex gene editing in rice. The development of an alternative robust single and multiplex gene editing system will enrich plant genome editing toolkits and facilitate pyramiding of agronomically important traits for crop improvement.

Interplay between the cyclophilin homology domain of RANBP2 and MX2 regulates HIV-1 capsid dependencies on nucleoporins.

Human immunodeficiency virus 1 (HIV-1) entry into the nucleus is an essential step in viral replication that involves complex interactions between the viral capsid (CA) and multiple cellular proteins, including nucleoporins (Nups) such as RANBP2. Nups also mediate the function of the antiviral protein myxovirus resistance 2 (MX2); however, determining the precise role of Nups in HIV infection has proved challenging due to the complex nature of the nuclear pore complex (NPC) and significant pleiotropic effects elicited by Nup depletion. We have used precise gene editing to assess the role of the cyclophilin domain of RANBP2 in HIV-1 infection and MX2 activity. We find that this domain affects viral infection, nucleoporin requirements, MX2 sensitivity, and integration targeting in a CA-specific manner, providing detailed insights into how RANBP2 contributes to HIV-1 infection.

Acid sphingomyelinase downregulation alleviates diabetic myocardial fibrosis in mice.

Increased activity of acid sphingomyelinase (ASMase) has been linked to diabetes and organ fibrosis. Nevertheless, the precise influence of ASMase on diabetic myocardial fibrosis and the corresponding molecular mechanisms remain elusive. In this study, we aim to elucidate whether ASMase contributes to diabetic myocardial fibrosis through the phosphorylation mediated by MAPK, thereby culminating in the development of diabetic cardiomyopathy (DCM). In vitro experiments utilized cardiac fibroblasts (CFs) isolated from wild-type mice (WT). For in vivo studies, ASMase knockout mice were generated through TALEN gene editing technology. Additionally, a diabetes mellitus model was established by intraperitoneal injection of Streptozotocin (STZ), involving both ASMase knockdown mice (ASMase+/--STZ) and WT mice. CFs were subjected to incubation with amitriptyline (AMP) (2.5μM), advanced glycation end products (AGEs), and small interfering RNA (siRNA) over a duration of 24h. Experimental assessments encompassed EdU incorporation, transwell assays, and fluorescence staining, aimed at elucidating the functional characteristics of cardiac fibroblasts. The quantification of collagen I, phosphorylated MAPK levels within both cellular and murine cardiac contexts was accomplished through Western blot analysis. In the ASMase±-STZ group, mice exhibited attenuated myocardial fibrosis and ameliorated cardiac diastolic function in comparison to the WT-STZ group. Furthermore, treatment of CFs with AMP and siRNA demonstrated a suppressive effect on the proliferation and fibrotic expression induced by AGEs in CFs. Our investigation unveiled that ASMase modulates myocardial fibrosis through the TGF-β-Smad3 and MAPK pathways, elucidating the intricate molecular mechanisms underlying the observed effects. Our findings indicate that ASMase plays a vital role in myocardial fibrosis in DCM, providing a foundation for developing new therapeutic strategies for the prevention and control of DCM.

A novel model of central precocious puberty disease: Paternal MKRN3 gene-modified rabbit.

Makorin ring finger protein 3 gene (MKRN3) gene mutation is the most common genetic cause of central precocious puberty (CPP) in children. Due to the lack of ideal MKRN3-modified animal model (MKRN3-modified mice enter puberty only 4-5 days earlier than normal mice), the related research is limited. Therefore, the MKRN3-modified rabbit was developed using CRISPR (clustered regularly interspaced short palindromic repeats) gene editing technology. The genotype identification and phenotype evaluation of MKRN3-modified rabbits were carried out. The first estrus of MKRN3-modified female rabbits was observed ~27 days earlier than that of wild-type female rabbits, with a typical CPP phenotype. This study found increased gonadotropin releasing hormone (GnRH) and decreased gonadotropin inhibiting hormone (GnIH) in the hypothalamus of the CPP rabbit model with MKRN3 gene mutation. Although this study failed to fully clarify the pathogenesis of CPP caused by MKRN3 mutation, it found some differentially expressed genes and potential pathways through transcriptome sequencing. This study established a novel CPP model: paternal MKRN3 gene-modified rabbit. It is hoped that the establishment of this model will help researchers better understand, treat, and prevent CPP in the future.

The role of mitochondrial dysfunction in Huntington's disease: Implications for therapeutic targeting.

Huntington's disease (HD) is a progressive, autosomal dominant neurodegenerative disorder characterized by cognitive decline, motor dysfunction, and psychiatric disturbances. A common feature of neurodegenerative disorders is mitochondrial dysfunction, which affects the brain's sensitivity to oxidative damage and its high oxygen demand. This dysfunction may plays a significant role in the pathogenesis of Huntington's disease. HD is caused by a CAG repeat expansion in the huntingtin gene, which leads to the production of a toxic mutant huntingtin (mHTT) protein. This disruption in mitochondrial function compromises energy metabolism and increases oxidative stress, resulting in mitochondrial DNA abnormalities, impaired calcium homeostasis, and altered mitochondrial dynamics. These effects ultimately may contribute to neuronal dysfunction and cell death, underscoring the importance of targeting mitochondrial function in developing therapeutic strategies for HD. This review discusses the mechanistic role of mitochondrial dysfunction in Huntington's disease. Mitochondrial dysfunction is a crucial factor in HD, making mitochondrial-targeted therapies a promising approach for treatment. We explore therapies that address bioenergy deficits, antioxidants that reduce reactive oxygen species, calcium modulators that restore calcium homeostasis, and treatments that enhance mitochondrial dynamics to rejuvenate mitochondrial function. We also highlight innovative treatment approaches such as gene editing and stem cell therapy, which offer hope for more personalized strategies. In conclusion, understanding mitochondrial dysfunction in Huntington's disease may guide potential treatment strategies. Targeting this dysfunction may help to slow disease progression and enhance the quality of life for individuals affected by Huntington's disease.

Stipulations of cell and gene therapy and the ties to biomanufacturing.

Cell and gene therapy (CGT) products are emerging and innovative biopharmaceuticals that hold promise for treating diseases that are otherwise beyond the scope of conventional medicines. The evolution of CGT from a research idea to a promising therapeutic product is due to the complementary advancements across various scientific disciplines. First, the innovations and advancements in gene editing and delivery technology have provided fundamental tools to manipulate genes and cells for therapeutic pursuits. Second, advancements in applied and translational research, including how clinical trials are designed, performed, evaluated, and analyzed, have transformed the technology into a potential therapeutic product. Third, advancements in scaling up the production of CGT products have been critical in delivering the product for preclinical studies, clinical trials, and approved treatments. In parallel, regulatory requirements have continuously evolved, with lessons learned from translational studies and biomanufacturing. These combined efforts have transformed CGT products from a promising concept into a reality with the potential to treat a wide range of diseases. However, continued R&D and regulatory oversight are crucial to further improve the safety, efficacy, and accessibility of CGT products.

Jan and mini-Jan, a model system for potato functional genomics.

Potato (Solanum tuberosum) is the third-most important food crop in the world. Although the potato genome has been fully sequenced, functional genomics research of potato lags behind that of other major food crops, largely due to the lack of a model experimental potato line. Here, we present a diploid potato line, 'Jan,' which possesses all essential characteristics for facile functional genomics studies. Jan exhibits a high level of homozygosity after seven generations of self-pollination. Jan is vigorous, highly fertile and produces tubers with outstanding traits. Additionally, it demonstrates high regeneration rates and excellent transformation efficiencies. We generated a chromosome-scale genome assembly for Jan, annotated its genes and identified syntelogs relative to the potato reference genome assembly DMv6.1 to facilitate functional genomics. To miniaturize plant architecture, we developed two 'mini-Jan' lines with compact and dwarf plant stature through CRISPR/Cas9-mediated mutagenesis targeting the Dwarf and Erecta genes involved in growth. One mini-Jan mutant, mini-JanE, is fully fertile and will permit higher-throughput studies in limited growth chamber and greenhouse space. Thus, Jan and mini-Jan offer a robust model system that can be leveraged for gene editing and functional genomics research in potato.

Transgene-free genome editing in poplar.

Precise gene-editing methods are valuable tools to enhance genetic traits. Gene editing is commonly achieved via stable integration of a gene-editing cassette in the plant's genome. However, this technique is unfavorable for field applications, especially in vegetatively propagated plants, such as many commercial tree species, where the gene-editing cassette cannot be segregated away without breaking the genetic constitution of the elite variety. Here, we describe an efficient method for generating gene-edited Populus tremula × P. alba (poplar) trees without incorporating foreign DNA into its genome. Using Agrobacterium tumefaciens, we expressed a base-editing construct targeting CCoAOMT1 along with the ALS genes for positive selection on a chlorsulfuron-containing medium. About 50% of the regenerated shoots were derived from transient transformation and were free of T-DNA. Overall, 7% of the chlorsulfuron-resistant shoots were T-DNA free, edited in the CCoAOMT1 gene and nonchimeric. Long-read whole-genome sequencing confirmed the absence of any foreign DNA in the tested gene-edited lines. Additionally, we evaluated the CodA gene as a negative selection marker to eliminate lines that stably incorporated the T-DNA into their genome. Although the latter negative selection is not essential for selecting transgene-free, gene-edited Populus tremula × P. alba shoots, it may prove valuable for other genotypes or varieties.

Application of Multiple Base-Editing Mediated by Polycistronic tRNA-gRNA-Processing System in Pig Cells.

Gene edited pigs have extensive and important application value in the fields of agriculture and biomedicine. With the increasing demand in medical research and agricultural markets, more and more application scenarios require gene edited pigs to possess two or even more advantageous phenotypes simultaneously. The current production of multi gene edited pigs is inefficient, time-consuming, and costly, and there is an urgent need to develop efficient and accurate multi gene editing application technologies. The polycistronic tRNA-gRNA-processing system (PTG), developed based on endogenous tRNA self-processing systems, has been shown to exhibit efficient multi gene editing in plants. This study aims to combine a PTG strategy with multiple gRNA production functions with an adenine base editor (ABE) to test its feasibility for efficient and precise multi gene base editing in pig cells. The results indicate that the PTG based integrated ABE plasmid can perform efficient base editing at multiple gene loci in pig cells. And while the gene editing efficiency was significantly improved, no indel and sgRNA dependent off target effects caused by DSB were detected. This work permit will provide a solid foundation for the production of multi gene edited pigs with agricultural and medical applications.

A Rapid and Reversible Molecular "Switch" Regulating Protein Expression in Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii, a prominent chassis in synthetic biology, faces limitations in regulating the expression of exogenous genes. A destabilization domain (DD)/Shield-1 system, originally derived from mammals, offers a ligand-dependent control of stability, making it a valuable tool. This system utilises the destabilization domain to induce rapid degradation of target protein unless stabilised by Shield-1, a synthetic ligand. Upon the addition of Shield-1,the degradation is halted, leading to the accumulation and stabilisation of the target protein. This system has demonstrated successful regulation of foreign protein expression in mammals, parasites, and plants. In this study, the DD/Shield-1 system was harnessed to regulate the expression of the paromomycin resistance gene and luciferase encoding gene in Chlamydomonas, revealing its capability for rapid, stable, and reversible protein expression regulation in microalgae, serving as a molecular switch. Furthermore, this regulation exhibits reagent dependency, enhancing its applicability in practical production. A strain with induced expression of the gene-editing protein, LbCas12a, was successfully constructed and then tested for gene editing. The findings not only enrich the toolkit for Chlamydomonas molecular studies but offer a promising technique for regulating the expression and validating the functionality of exogenous proteins in microalgae.

Plant secondary metabolites against biotic stresses for sustainable crop protection.

Sustainable agriculture practices are indispensable for achieving a hunger-free world, especially as the global population continues to expand. Biotic stresses, such as pathogens, insects, and pests, severely threaten global food security and crop productivity. Traditional chemical pesticides, while effective, can lead to environmental degradation and increase pest resistance over time. Plant-derived natural products such as secondary metabolites like alkaloids, terpenoids, phenolics, and phytoalexins offer promising alternatives due to their ability to enhance plant immunity and inhibit pest activity. Recent advances in molecular biology and biotechnology have improved our understanding of how these natural compounds function at the cellular level, activating specific plant defense through complex biochemical pathways regulated by various transcription factors (TFs) such as MYB, WRKY, bHLH, bZIP, NAC, and AP2/ERF. Advancements in multi-omics approaches, including genomics, transcriptomics, proteomics, and metabolomics, have significantly improved the understanding of the regulatory networks that govern PSM synthesis. These integrative approaches have led to the discovery of novel insights into plant responses to biotic stresses, identifying key regulatory genes and pathways involved in plant defense. Advanced technologies like CRISPR/Cas9-mediated gene editing allow precise manipulation of PSM pathways, further enhancing plant resistance. Understanding the complex interaction between PSMs, TFs, and biotic stress responses not only advances plant biology but also provides feasible strategies for developing crops with improved resistance to pests and diseases, contributing to sustainable agriculture and food security. This review emphasizes the crucial role of PSMs, their biosynthetic pathways, the regulatory influence of TFs, and their potential applications in enhancing plant defense and sustainability. It also highlights the astounding potential of multi-omics approaches to discover gene functions and the metabolic engineering of genes associated with secondary metabolite biosynthesis. Taken together, this review provides new insights into research opportunities for enhancing biotic stress tolerance in crops through utilizing plant secondary metabolites.

Past and future of cytoplasmic male sterility and heterosis breeding in crop plants.

Plant breeding needs to embrace genetic innovations to ensure stability in crop yields under fluctuating climatic conditions. Development of commercial hybrid varieties has proven to be a sustainable and economical alternative to deliver superior yield, quality and resistance with uniformity in a number of food crops. Cytoplasmic male sterility (CMS), a maternally inherited inability to produce functional pollen, facilitates a three-line system for efficient hybrid seed production strategies in crops. The CMS system has illustrated its potential as a robust pollination control mechanism to support the billion-dollar seed industry. In plants, CMS arises due to a genomic conflict between mitochondrial open reading frames (orfs) and nuclear-encoding restoration-of-fertility (Rf) genes, leading to floral abnormalities and pollen sterility. Research on pollen sterility and fertility restoration provides deeper insights into cytoplasmic-nuclear interplay in plants and elucidates key molecular targets for hybrid breeding in crops. More recently, programmable gene editing (e.g., TALEN, CRISPR-Cas) has emerged as a promising tool to functionally validate CMS and Rf genes and obviate the need for pollen donors or Rf-genes for hybrid breeding. Modern genomic prediction models have allowed establishment of high-performing heterotic groups and patterns for sustaining long-term gain in hybrid breeding. This article reviews latest discoveries elucidating the molecular mechanisms behind CMS and fertility restoration in plants. We then present our perspective on how evolving genetic technologies are contributing to advance fundamental knowledge of the CMS-Rf genetic system for producing crop hybrids with high heterosis.

Promotion or inhibition? This is a question in gene editing.

Promotion or inhibition? This is a question in gene editing.

Multi-gene precision editing tool using CRISPR-Cas12a/Cpf1 system in Ogataea polymorpha

BackgroundOgataea polymorpha, a non-conventional methylotrophic yeast, has demonstrated significant potential for heterologous protein expression and the production of high-value chemicals and biopharmaceuticals. However, the lack of precise and efficient genome editing tools severely hinders the construction of cell factories. Although the CARISP-Cas9 system has been established in Ogataea polymorpha, the gene editing efficiency, especially for multiple genes edition, needs to be further improved.ResultsIn this study, we developed an efficient CRISPR-Cpf1-mediated genome editing system in O. polymorpha that exhibited high editing efficiency for single gene (98.1 ± 1.7%), duplex genes (93.9 ± 2.4%), and triplex genes (94.0 ± 6.0%). Additionally, by knocking out non-homologous end joining (NHEJ) related genes, homologous recombination (HR) efficiency was increased from less than 30% to 90 ~ 100%, significantly enhancing precise genome editing capabilities. The increased HR rates enabled over 90% integration efficiency of triplex genes, as well as over 90% deletion rates of large DNA fragments up to 20 kb. Furthermore, using this developed CRISPR-Cpf1 system, triple genes were precisely integrated into the genome by one-step, enabling lycopene production in O. polymorpha.ConclusionsThis novel multiplexed genome-editing tool mediated by CRISPR-Cpf1 can realize the deletion and integration of multiple genes, which holds great promise for accelerating engineering efforts on this non-conventional methylotrophic yeast for metabolic engineering and genomic evolution towards its application as an industrial cell factory.

Emerging Delivery Systems for Enabling Precision Nucleic Acid Therapeutics.

Nucleic acid therapeutics represent a highly promising treatment approach in modern medicine, treating diseases at the genetic level. However, these therapeutics face numerous challenges in practical applications, particularly regarding their stability, effectiveness, cellular uptake efficiency, and limitations in delivering them specifically to target tissues. To overcome these obstacles, researchers have developed various innovative delivery systems, including viral vectors, lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, protein carriers, exosomes, antibody oligonucleotide conjugates, and DNA nanostructure-based delivery systems. These systems enhance the therapeutic efficacy of nucleic acid drugs by improving their stability, targeting specificity, and half-life in vivo. In this review, we systematically discuss different types of nucleic acid drugs, analyze the major barriers encountered in their delivery, and summarize the current research progress in emerging delivery systems. We also highlight the latest advancements in the application of these systems for treating genetic diseases, infectious diseases, cancer, brain diseases, and wound healing. This review aims to provide a comprehensive overview of nucleic acid drug delivery systems' current status and future directions by integrating the latest advancements in nanotechnology, biomaterials science, and gene editing technologies, emphasizing their transformative potential in precision medicine.

Identifying and targeting key driver genes for collagen production within the 11q13/14 breast cancer amplicon.

Breast cancers of the IntClust-2 type, characterized by amplification of a small portion of chromosome 11, have a median survival of only five years. Several cancer-relevant genes occupy this portion of chromosome 11, and it is thought that overexpression of a combination of driver genes in this region is responsible for the poor outcome of women in this group. In this study we used a gene editing method to knock out, one by one, each of 198 genes that are located within the amplified region of chromosome 11 and determined how much each of these genes contributed to the survival of breast cancer cells. In addition to well-known drivers such as CCND1 and PAK1, we identified two different genes (SERPINH1 and P4HA3), that encode proteins involved in collagen synthesis and organization. Using both in vitro and in vivo functional analyses, we determined that P4HA3 and/or SERPINH1 provide a critical driver function on IntClust-2 basic processes, such as viability, proliferation, and migration. Inhibiting these enzymes via genetic or pharmacologic means reduced collagen synthesis and impeded oncogenic signaling transduction in cell culture models, and a small-molecule inhibitor of P4HA3 was effective in treating 11q13 tumor growth in an animal model. As collagen has a well-known association with tissue stiffness and aggressive forms of breast cancer, we believe that the two genes we identified provide an opportunity for a new therapeutic strategy in IntClust-2 breast cancers. Implications: Breast cancers with 11q13/14 chromosomal amplifications may be vulnerable to inhibitors of collagen synthesis.

Generation and propagation of high fecundity gene edited fine wool sheep by CRISPR/Cas9

CRISPR/Cas9 technology has been widely utilized to enhance productive performance, increase disease resistance and generate medical models in livestock. The FecB allele in sheep is a mutation in the BMPRIB gene, recognized as the first major gene responsible for the high fecundity trait in sheep, leading to an increased ovulation rate in ewe. In this study, we employed CRISPR/Cas9-mediated homologous-directed repair (HDR) to introduce a defined point mutation (c.746 A > G) using single-stranded oligonucleotides (ssODN) and the ligase IV inhibitor (SCR7) into the BMPRIB gene of fine wool sheep. A total of nine gene-edited sheep were produced, six of which carried the targeted point mutation, with a precise base substitution efficiency (A > G) of 31.6%. Based on the six targeted founders (F0), we expanded the BMPRIB-targeted population, which included F1 heterozygous (B+) and F2 homozygous(BB) or heterozygous offspring. The average litter size of F1 ewes carrying the B + allele reached 170%, comparable to that of heterozygous native Australian Booroola sheep. Gene-edited ewes with B + and BB genotype produced 0.62 and 0.42 more lambs, respectively, compared to wide-type ewes (p < 0.01). Our results also indicated that the parity signification, our data demonstrate that highly efficient introduction of the intended base mutation into the sheep genome can be achieved by combining the CRISPR/Cas9 system with ssODN and SCR7. The offspring of BMPR/B edited sheep with the defined mutation exhibited high fecundity performance. Compared to conventional sheep breeding strategies, genetic improvement through gene editing offered significant advantages without compromising the fine wool traits of Merino sheep, which are often affected by routine cross-breeding methods.

Modified Shenqi Dihuang Decoction inhibits prostate cancer metastasis by disrupting TCA cycle energy metabolism via NF-kB/p65-mediated OGDH regulation.

Prostate cancer (PCa) is a significant malignancy in men, particularly challenging in the metastatic stage due to poor prognosis and limited treatment efficacy. Traditional Chinese Medicine, particularly Modified Shenqi Dihuang Decoction (MSDD), has demonstrated promise in inhibiting PCa metastasis, although its mechanisms remain unclear. The efficacy of MSDD was evaluated using migration assays and a nude mouse model. Metabolomics was employed to identify the biological processes affected by MSDD. Systematic pharmacology, bioinformatics, and molecular dynamics were utilized to determine direct action targets of MSDD. Additionally, luciferase reporter assays, ChIP-qPCR, and gene editing were applied to elucidate the pharmacological mechanisms. MSDD effectively inhibited prostate metastasis both in vivo and in vitro, without significant adverse events reported. Metabolomics and molecular biology experiments indicated that MSDD transcriptionally represses OGDH, affecting energy metabolism associated with the tricarboxylic acid cycle (TCA) in PCa. The active components of MSDD were found to potentially bind to the transcription factor RELA (NF-kB-p65), and further experiments demonstrated that RELA regulates OGDH transcription. Further experiments revealed that the anti-metastatic effects of MSDD are RELA-dependent, indicating the crucial role of the NF-kB/OGDH axis in this process. These findings support the clinical use of MSDD in metastatic PCa, emphasizing its potential to address current treatment gaps. The identified NF-kB/OGDH-dependent mechanism not only underpins MSDD's anti-metastatic effects but also reflects OGDH as a potential therapeutic target. Further research into the role of TCA in PCa progression is imperative.

Full sequencing of 100mer sgRNA via tandem mass spectrometry by targeted RNase H digestion with customized probes.

The use of single-guide RNA (sgRNA) for gene editing using the CRISPR Cas9 system has become a powerful technique in various fields, especially with the growing interest in such molecules as therapeutic options in the last years. An important parameter for the use of these molecules is the verification of the correct sgRNA oligonucleotide sequence. Apart from next-generation sequencing protocols, mass spectrometry (MS) has been proven as a powerful technique for this purpose. The protocol and investigations presented in this work show an optimal digestion and 100% sequence coverage of sgRNA, while top-down approaches or other ribonuclease (RNase) digestion strategies obtain a sequence coverage of up to 80-90% utilizing multiple RNases. The results in this publication were obtained by utilizing DNA-RNA hybrid GAPmer-like probes and RNase H, an enzyme which specifically hydrolyzes RNA in DNA-RNA double strands. We assessed the optimal length of the DNA segment of these hybrid probes to maximize the specificity of the RNase H digestion and to achieve complete sequence confirmation by tandem MS analysis of the resulting digestion products. Furthermore, we showed that the approach is applicable for the identification of common synthesis-related impurities, like truncations and elongations. Despite the fact that the accessibility of this approach for highly modified molecules is limited to nucleotides which are not 2'-O-methylated, the optimized sequence coverage makes it a viable method.

Emerging Role of Noncovalent Interactions and Disulfide Bond Formation in the Cellular Uptake of Small Molecules and Proteins.

Intracellular delivery of proteins is an important barrier in the development of strategies to deliver functional proteins and protein therapeutics into the cells to realize their full potential in biotechnology, biomedicine, cell-based therapies, and gene editing protein systems. Most of the intracellular protein delivery strategies involve the conjugation of cell penetrating peptides to enable and enhance the permeability of plasma membrane of mammalian cells to allow proteins to enter cytosol. Small molecules conjugations such as (p-methylphenyl) glycine, pyrenebutyrate and cysteines are used for the same purpose. The molecular level interactions are governed mostly by ionic (cationic/anionic), covalent and non-covalent interactions with various molecular entities of glycocalyx matrix on plasma membrane lipid bilayer. Although the role of non-covalent interactions is not fully understood, it is intriguing to see the recent advances in the non-covalent interaction-based strategies of intracellular delivery of small molecules and proteins into mammalian cells. These are achieved by simple modification of proteins' surface with chemical moieties which can form non-covalent interactions other than hydrogen bonding. In this review, we describe the recent advances and the mechanistic aspects of intracellular delivery and role of non-covalent interactions during the cellular uptake of proteins and small molecules.