G-quadruplexes Stabilization Upregulates CCN1 and Accelerates Aging in Cultured Cerebral Endothelial Cells

Senescence in the cerebral endothelium has been proposed as a mechanism that can drive dysfunction of the cerebral vasculature, which precedes vascular dementia. Cysteine-rich angiogenic inducer 61 (Cyr61/CCN1) is a matricellular protein secreted by cerebral endothelial cells (CEC). CCN1 induces senescence in fibroblasts. However, whether CCN1 contributes to senescence in CEC and how this is regulated requires further study. Aging has been associated with the formation of four-stranded Guanine-quadruplexes (G4s) in G-rich motifs of DNA and RNA. Stabilization of the G4 structures regulates transcription and translation either by upregulation or downregulation depending on the gene target. Previously, we showed that aged mice treated with a G4-stabilizing compound had enhanced senescence-associated (SA) phenotypes in their brains, and these mice exhibited enhanced cognitive deficits. A sequence in the 3′-UTR of the human CCN1 mRNA has the ability to fold into G4s in vitro. We hypothesize that G4 stabilization regulates CCN1 in cultured primary CEC and induces endothelial senescence. We used cerebral microvessel fractions and cultured primary CEC from young (4-months old, m/o) and aged (18-m/o) mice to determine CCN1 levels. SA phenotypes were determined by high-resolution fluorescence microscopy in cultured primary CEC, and we used Thioflavin T to recognize RNA-G4s for fluorescence spectra. We found that cultured CEC from aged mice exhibited enhanced levels of SA phenotypes, and higher levels of CCN1 and G4 stabilization. In cultured CEC, CCN1 induced SA phenotypes, such as SA β-galactosidase activity, and double-strand DNA damage. Furthermore, CCN1 levels were upregulated by a G4 ligand, and a G-rich motif in the 3′-UTR of the Ccn1 mRNA was folded into a G4. In conclusion, we demonstrate that CCN1 can induce senescence in cultured primary CEC, and we provide evidence that G4 stabilization is a novel mechanism regulating the SASP component CCN1.

Biocompatible FePO4 Nanoparticles: Drug Delivery, RNA Stabilization, and Functional Activity

FePO4 NPs are of special interest in food fortification and biomedical imaging because of their biocompatibility, high bioavailability, magnetic property, and superior sensory performance that do not cause adverse organoleptic effects. These characteristics are desirable in drug delivery as well. Here, we explored the FePO4 nanoparticles as a delivery vehicle for the anticancer drug, doxorubicin, with an optimum drug loading of 26.81% ± 1.0%. This loading further enforces the formation of Fe3+ doxorubicin complex resulting in the formation of FePO4-DOX nanoparticles. FePO4-DOX nanoparticles showed a good size homogeneity and concentration-dependent biocompatibility, with over 70% biocompatibility up to 80 µg/mL concentration. Importantly, cytotoxicity analysis showed that Fe3+ complexation with DOX in FePO4-DOX NPs enhanced the cytotoxicity by around 10 times than free DOX and improved the selectivity toward cancer cells. Furthermore, FePO4 NPs temperature-stabilize RNA and support mRNA translation activity showing promises for RNA stabilizing agents. The results show the biocompatibility of iron-based inorganic nanoparticles, their drug and RNA loading, stabilization, and delivery activity with potential ramifications for food fortification and drug/RNA delivery.

CAF Proteins Help SOT1 Regulate the Stability of Chloroplast ndhA Transcripts

Protein-mediated RNA stabilization plays profound roles in chloroplast gene expression. Genetic studies have indicated that chloroplast ndhA transcripts, encoding a key subunit of the NADH dehydrogenase-like complex that mediates photosystem I cyclic electron transport and facilitates chlororespiration, are stabilized by PPR53 and its orthologs, but the underlying mechanisms are unclear. Here, we report that CHLOROPLAST RNA SPLICING 2 (CRS2)-ASSOCIATED FACTOR (CAF) proteins activate SUPPRESSOR OF THYLAKOID FORMATION 1 (SOT1), an ortholog of PPR53 in Arabidopsis thaliana, enhancing their affinity for the 5′ ends of ndhA transcripts to stabilize these molecules while inhibiting the RNA endonuclease activity of the SOT1 C-terminal SMR domain. In addition, we established that SOT1 improves the splicing efficiency of ndhA by facilitating the association of CAF2 with the ndhA intron, which may be due to the SOT1-mediated stability of the ndhA transcripts. Our findings shed light on the importance of PPR protein interaction partners in moderating RNA metabolism.

Practical strategies for SARS-CoV-2 RT-PCR testing in resource-constrained settings

ABSTRACTBackgrounStandard nasopharyngeal swab testing for SARS-CoV-2 detection by PCR is not always feasible due to limitations in trained personnel, personal protective equipment, swabs, PCR reagents, and access to cold chain and biosafety hoods.MethodWe piloted the collection of nasal mid-turbinate swabs amenable to self-testing, including both standard polyester flocked swabs as well as 3D printed plastic lattice swabs, placed into either viral transport media or an RNA stabilization agent. Quantitative SARS-CoV-2 viral detection by RT-qPCR was compared to that obtained by nasopharyngeal sampling as the reference standard. Pooling specimens in the lab versus pooling swabs at the point of collection was also evaluated.ResultsAmong 275 participants, flocked nasal swabs identified 104/121 individuals who were PCR-positive for SARS-CoV-2 by nasopharyngeal sampling (sensitivity 87%, 95% CI 79-92%), mostly missing those with low viral load (<10^3 viral copies/uL). 3D-printed nasal swabs showed similar sensitivity. When nasal swabs were placed directly into an RNA stabilizer, the mean 1.4 log decrease in viral copies/uL compared to nasopharyngeal samples was reduced to <1 log, even when samples were left at room temperature for up to 7 days. Pooling sample specimens or swabs both successfully detected samples >102viral copies/uL.ConclusionsNasal swabs are likely adequate for clinical diagnosis of acute infections to help expand testing capacity in resource-constrained settings. When collected into an RNA preservative that also inactivates infectious virus, nasal swabs yielded quantitative viral loads approximating those obtained by nasopharyngeal sampling.

homeRNA: A self-sampling kit for the collection of peripheral blood and stabilization of RNA

ABSTRACTGene expression analysis (e.g., targeted small gene panels, transcriptomics) from whole blood can elucidate mechanisms of immune function and aid in the discovery of biomarkers. Conventional in-clinic venipuncture offers only a small snapshot of our broad immune landscape as immune responses may occur outside of the time and location parameters available for conventional venipuncture. A self-operated method that enables flexible sampling of liquid whole blood coupled with an immediate stabilization of cellular RNA is instrumental in facilitating capture and preservation of acute or transient immune fluxes. To this end, we developed homeRNA: a kit that allows for self-collection of peripheral blood (∼0.5 mL) and immediate stabilization of cellular RNA, using the Tasso-SST™ blood collection device paired with a specially designed stabilizer tube containing RNAlater™. To assess the usability and feasibility of homeRNA for self-collection and stabilization of whole blood RNA, we conducted a pilot study (n = 41 participants) where we sent homeRNA to participants aged 21-69, located across 10 US states (94% successful blood collections, n = 51). Among participants who successfully collected blood, 91% reported no or minimal pain/discomfort using the kit (n = 35), and 77% reported easy or somewhat easy stabilization protocol. Total RNA yield from the stabilized samples ranged between 0.24 µg and 5.99 µg (mean = 1.65 µg), while RNA Integrity Number (RIN) values were above 7.0 (mean = 7.9), indicating limited RNA degradation. Results from this study demonstrate the self-collection and RNA stabilization of whole blood with homeRNA by participants themselves, in their own home.

COVID-19 Diagnostic Testing For All - Using Non-Dilutive Saliva Sample Collection, Stabilization and Ambient Transport Devices

COVID-19 testing is not accessible for millions during this pandemic despite our best efforts. Without greatly expanded testing of asymptomatic individuals, contact tracing and subsequent isolation of spreaders remains as a means for control. In an effort to increase RT-PCR assay testing for the presence of the novel beta-coronavirus SARS-CoV-2 as well as improve sample collection safety, GenTegra LLC has introduced two products for saliva collection and viral RNA stabilization: GTR-STM™ (GenTegra Saliva Transport Medium) and GTR-STMdk™ (GenTegra Saliva Transport Medium Direct to PCR). Both products contain a proprietary formulation based on GenTegra’s novel “Active Chemical Protection™” (ACP) technology that gives non-dilutive, error-free saliva sample collection using RNA stabilization chemicals already dried in the collection tube.GTR-STM can be used for safer saliva-based sample collection at home (or at a test site). Following saliva collection, the sample-containing GTR-STM can be kept at ambient temperature during shipment to an authorized CLIA lab for analysis. SARS-CoV-2 viral RNA in GTR-STM is stable for over a month at ambient temperature, easily surviving the longest transit times from home to lab. GTR-STM enhances patient comfort, convenience, compliance and reduces infectious virus exposure to essential medical and lab professionals.Alternatively, the GTR-STMdk direct-into-PCR product can be used to improve lab throughput and reduce reagent costs for saliva sample collection and testing at any lab site with access to refrigeration. GTR-STMdk reduces lab process time by 25% and reagent costs by 30% compared to other approaches. Since GTR-STMdk retains SARS-CoV-2 viral RNA stability for three days at ambient temperature, it is optimized for lab test site rather than at home saliva collection. SARS-COV-2 viral RNA levels as low as 0.4 genome equivalents/uL are detected in saliva samples using GTR-STMdk. The increased sensitivity of SARS-CoV-2 detection can expand COVID-19 testing to include asymptomatic individuals using pooled saliva.One Sentence SummaryGTR-STM and Direct-into-PCR GTR-STMdk offer substantive improvements in SARS-CoV-2 viral RNA stability, safety, and RT-PCR process efficiency for COVID-19 testing by using a non-dilutive saliva sample collection system for individuals at home or onsite respectively.

RNA stabilization by a poly(A) tail 3ʹ-end binding pocket and other modes of poly(A)-RNA interaction

Poly(A) tail addition to the 3ʹ end of a wide range of RNAs is a highly conserved modification that plays a central role in cellular RNA function. Elements for nuclear expression (ENEs) are cis-acting RNA elements that stabilize poly(A) tails by sequestering them in RNA triplex structures. A 2.89-Å resolution crystal structure of a double ENE from a rice hAT transposon mRNA complexed with poly(A)28 reveals multiple modes of interaction with poly(A), including major-groove triple helices, extended minor-groove interactions with RNA double helices, a quintuple-base motif that transitions poly(A) from minor-groove associations to major-groove triple helices, and a poly(A) 3ʹ-end binding pocket. Our findings both expand the repertoire of motifs involved in long-range RNA interactions and provide insights into how polyadenylation can protect an RNA’s extreme 3ʹ end.

Inhibition of HDAC Enzymes Contributes to Differential Expression of Pro-Inflammatory Proteins in the TLR-4 Signaling Cascade

Class I and II histone deacetylases (HDAC) are considered important regulators of immunity and inflammation. Modulation of HDAC expression and activity is associated with altered inflammatory responses but reports are controversial and the specific impact of single HDACs is not clear. We examined class I and II HDACs in TLR-4 signaling pathways in murine macrophages with a focus on IκB kinase epsilon (IKKε) which has not been investigated in this context before. Therefore, we applied the pan-HDAC inhibitors (HDACi) trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA) as well as HDAC-specific siRNA. Administration of HDACi reduced HDAC activity and decreased expression of IKKε although its acetylation was increased. Other pro-inflammatory genes (IL-1β, iNOS, TNFα) also decreased while COX-2 expression increased. HDAC 2, 3 and 4, respectively, might be involved in IKKε and iNOS downregulation with potential participation of NF-κB transcription factor inhibition. Suppression of HDAC 1–3, activation of NF-κB and RNA stabilization mechanisms might contribute to increased COX-2 expression. In conclusion, our results indicate that TSA and SAHA exert a number of histone- and HDAC-independent functions. Furthermore, the data show that different HDAC enzymes fulfill different functions in macrophages and might lead to both pro- and anti-inflammatory effects which have to be considered in therapeutic approaches.

Use of alternative RNA storage and extraction reagents and development of a hybrid PCR-based method for SARS-CoV-2 detection

The COVID-19 pandemic has presented multiple healthcare challenges, one of which is adequately meeting the need for large-scale diagnostic testing. The most commonly used assays for detection of SARS-CoV-2, including those recommended by the Center for Disease Control and Prevention (CDC), rely on a consistent set of core reagents. This has put a serious strain on the reagent supply chain, resulting in insufficient testing. It has also led to restricted animal testing, even though there are now multiple reports of animals, particularly cats, ferrets and minks, contracting the disease. We aimed to address the diagnostic bottleneck by developing a PCR-based SARS-CoV-2 detection assay for cats (and, potentially, other animals) which avoids the use of most common reagents, such as collection kits optimized for RNA stabilization, RNA isolation kits and TaqMan-based RT-PCR reagents. We demonstrated that an inexpensive solid-phase reversible immobilization (SPRI) method can be used for RNA extraction from feline samples collected with DNAGenotek’s ORAcollect RNA OR-100 and PERFORMAgene DNA PG-100 sample collection kits, optimized for RNA or DNA stabilization, respectively. We developed a dual method SARS-CoV-2 detection assay relying on SYBR RT-PCR and Sanger sequencing, using the same set of custom synthesized oligo primers. We validated our test’s specificity with a commercially available SARS-CoV-2 plasmid positive control, as well as two in-house positive control RNA samples. Our assay’s sensitivity was determined to be 10 viral copies per reaction. Our results suggest that a simple SPRI-dependent RNA extraction protocol and certain sample collection kits not specifically optimized for RNA stabilization could potentially be used in cases where reagent shortages are hindering adequate COVID-19 testing. These ‘alternative’ reagents could be used in combination with our COVID-19 testing method, which relies on inexpensive and readily available SYBR RT-PCR and non-fluorescent PCR reagents. Depending on the detection goals and the laboratory setup available, the SYBR RT-PCR method and the Sanger sequencing based method can be used alone or in conjunction, for improved accuracy. Although the test is intended for animal use, it is, in theory, possible to use it with human samples, especially those with higher viral loads.