Small Interference RNA Research Articles

GATAD1 is involved in sphingosylphosphorylcholine-attenuated myocardial ischemia-reperfusion injury by modulating myocardial fatty acid oxidation and glucose oxidation

Modulating the equilibrium between glucose metabolism and lipid metabolism represents highly promising novel strategies for therapy of myocardial ischemia/reperfusion (I/R) injury. Sphingosylphosphorylcholine (SPC), an intermediate metabolite of sphingolipids, has shown cardioprotective roles during myocardial infarction by regulating the activities of various transcript factors. Gene microarray revealed that SPC significantly upregulated the expression of GATA zinc finger domain protein 1 (GATAD1), which is a vital transcript factor affecting heart development and various heart diseases. However, it remains unclear whether SPC is involved in the regulation of cardiac fatty acid and glucose metabolism via GATAD1. In this study, we found that myocardium-specific Gatad1 knockout (Gatad1 CKO) significantly increased the myocardial infarct size, impaired cardiac function in I/R mice, and disrupted the protective effect of SPC on the hearts of I/R mice. Immunofluorescence experiment and western blot evaluation of the nuclear-cytoplasmic fractionation sample showed that GATAD1 acted as a transcription factor and was regulated by SPC. Double fluorescence reporting experiment and quantitative polymerase chain reaction (qPCR) revealed that GATAD1 could inhibit the expression of genes involved in fatty acid oxidation (FAO), i.e., acetyl-coenzyme A acyltransferase 2 (Acaa2) and medium-chain acyl-CoA dehydrogenase (Acadm), and promoted the expression of genes involved in glucose oxidation, i.e., pyruvate dehydrogenase E1 α subunit (Pdha1). Small interfering RNA (SiRNA) or overexpression strategies confirmed the pro-apoptotic roles of Acaa2 and Acadm and anti-apoptotic role of Pdha1 in cardiac myocytes challenged with I/R treatment. In summary, our findings suggest that SPC can be used as a candidate to prevent I/R injury by reshaping fatty acid and glucose metabolism. Transcription factor GATAD1 plays a crucial role in regulating fatty acid oxidation and glucose oxidation homeostasis and is involved in SPC-mediated cardioprotection during I/R of the heart. Our study identifies GATAD1 as a new therapeutic target for clinical treatment of myocardial I/R injury.

Small Interference RNA Encapsulated in Liposomes: An Effective Strategy for In vitro Inhibition of SARS-CoV-2 Load

Background: The pressing need for effective SARS-CoV-2 antiviral medicines has driven research into innovative therapeutic techniques. RNA interference with small interfering RNAs (siRNAs) has shown promise as an antiviral treatment. Objective: We evaluated the effectiveness of lipid-based nanoparticles as a viable delivery platform for siRNA-based approach against SARS-CoV-2 in vitro infection. Methods: Liposomes were fabricated by microfluidics to incorporate SARS-CoV-2-specific siRNAs based on conserved sections of the Spike protein coding sequence. Nanoparticle tracking analysis was used to evaluate the nanoparticles' physicochemical features. VERO cell lines infected with SARS-CoV-2 were used to test the efficiency of siRNA-loaded liposomes. RT-PCR was used to determine the viral load by quantifying the SARS-CoV-2 genome. Results: The results showed that liposomes efficiently decreased viral load in infected cells with good physicochemical features, such as a mean particle size of about 180 nm, zeta potential of +2.5 mV and encapsulation efficiency (53.6%). Conclusion: These findings imply that lipid-based nanoparticles might be a targeted delivery strategy for siRNA-based approaches.

Harnessing antiviral RNAi therapeutics for pandemic viruses: SARS-CoV-2 and HIV.

Using the knowledge from decades of research into RNA-based therapies, the COVID-19 pandemic response saw the rapid design, testing and production of the first ever mRNA vaccines approved for human use in the clinic. This breakthrough has been a significant milestone for RNA therapeutics and vaccines, driving an exponential growth of research into the field. The development of novel RNA therapeutics targeting high-threat pathogens, that pose a substantial risk to global health, could transform the future of health delivery. In this review, we provide a detailed overview of the two RNA interference (RNAi) pathways and how antiviral RNAi therapies can be used to treat acute or chronic diseases caused by the pandemic viruses SARS-CoV-2 and HIV, respectively. We also provide insights into short-interfering RNA (siRNA) delivery systems, with a focus on how lipid nanoparticles can be functionalized to achieve targeted delivery to specific sites of disease. This review will provide the current developments of SARS-CoV-2 and HIV targeted siRNAs, highlighting strategies to advance the progression of antiviral siRNA along the clinical development pathway.

Kidney Arteriolar Responses to Liver-Targeted Small Interference RNA Targeting Angiotensinogen in Diabetic Rats: Comparison With Other Renin-Angiotensin System Blockers.

Kidney Arteriolar Responses to Liver-Targeted Small Interference RNA Targeting Angiotensinogen in Diabetic Rats: Comparison With Other Renin-Angiotensin System Blockers.

Potential role of signal transducer and activator of transcription 3 in the amygdala in mitigating stress-induced high blood pressure via exercise in rats.

Chronic stress elevates blood pressure, whereas regular exercise exerts antistress and antihypertensive effects. However, the mechanisms of stress-induced hypertension and preventive effects through exercise remain unknown. Thus, we investigated the molecular basis involved in autonomic blood pressure regulation within the amygdala. The effects of a 3-week restraint stress and daily voluntary exercise against stress on cardiovascular parameters and gene expression profiles in the amygdala were examined using a microarray method. Candidate genes were selected from differentially expressed genes; the localization of their expression within the central nucleus of the amygdala and their roles in cardiovascular regulation were examined using small-interfering RNA transfection and radiotelemetry. Chronic restraint stress caused an increase in blood pressure levels; however, with voluntary exercise, the blood pressure levels remained comparable to those of the controls. Compared with the controls, chronic restraint stress decreased signal transducer and activator of transcription 3 expression in the amygdala, whereas voluntary exercise improved its expression to normal levels. Immunohistochemical staining revealed the expression of signal transducer and activator of transcription 3 in neurons of the amygdala; inhibition of this expression using small-interfering RNA increased the arterial pressure. However, spontaneous baroreflex gain and low- and high-frequency components of heart rate variability remained unaffected by the inhibition of signal transducer and activator of transcription 3. In the amygdala, signal transducer and activator of transcription 3 regulates the blood pressure levels and is possibly involved in blood pressure elevation in response to chronic stress and its improvement by voluntary exercise.

A pipeline for validation of Serendipita indica effector-like sRNA suggests cross-kingdom communication in the symbiosis with Arabidopsis.

Bidirectional communication between pathogenic microbes and their plant hosts via small (s)RNA-mediated cross-kingdom RNA interference (ckRNAi) is a key element for successful host colonisation. Whether mutualistic fungi of the Serendipitaceae family, known for their extremely broad host range, use sRNAs to colonize plant roots is still under debate. To address this question, we developed a pipeline to validate the accumulation, translocation, and activity of fungal sRNAs in post-transcriptional silencing of Arabidopsis thaliana genes. Using stem-loop RT-qPCR, we detected the expression of a specific set of Serendipita indica (Si)sRNAs, targeting host genes involved in cell wall organization, hormonal signalling regulation, immunity, and gene regulation. To confirm the gene silencing activity of these sRNAs in plant cells, SisRNAs were transiently expressed in protoplasts. Stem-loop PCR confirmed sRNAs expression and accumulation, while qPCR validated post-transcriptional gene silencing of their predicted target genes. Furthermore, Arabidopsis ARGONAUTE 1 immunoprecipitation (AtAGO1-IP) revealed the loading of fungal SisRNAs into the plant RNAi machinery, suggesting the translocation of SisRNA from the fungus into root cells. In conclusion, this study provides a blueprint for rapid selection and analysis of sRNA effectors and further supports the model of cross-kingdom communication in the Sebacinoid symbiosis.

IL-33/ST2 axis mediates diesel exhaust particles-induced mast cell activation

BackgroundMast cells are implicated in the pathogenesis and severity of asthma in children and adults. The release of proinflammatory mediators and cytokines from activated mast cells (MC) is associated with Type 2 (T2) cell-skewed inflammation.MethodsWe obtained the airway tissues of Balb/c mice with or without intra-tracheal diesel exhaust particles (DEP) instillation to measure the extent of tryptase+ MCs infiltration and interleukin (IL)-33 expression. Cultured human mast cells (HMC-1) were stimulated with DEP to determine the role of aryl hydrocarbon receptor (AhR) in mediating the synthesis and release of IL-33 and type-2 cytokines.ResultsIn the control animals, most of the MC accumulated in the submucosal vessels without expression of IL-33. Intra-tracheal DEP installation increased the number of IL-33+ MC infiltrating in the epithelial and sub-epithelial areas of mice. Human MC exposed to DEP upregulated mRNA and protein expression of IL-33. These effects were abolished by knockdown of expression of the AhR or AhR nuclear translocator (ARNT) by small interfering (si)RNA transfection. DEP also activated nuclear factor-kappa B (NF-κB) to facilitate nuclear translocation of the AhR. DEP increased MC migration and induced the synthesis and release of IL-4, IL-5, and IL-13 in MCs, and these effects were abolished by anti-ST2 antibodies.ConclusionsAirborne pollutants may activate MCs to produce IL-33 via the AhR/NF-κB pathway, leading to type 2 cytokines production and enhancing MC airway epithelium-shifted migration through the autocrine or paracrine IL-33/ST2 axis.

SPRR1A is a potential therapeutic target for osteosarcoma: in vitro and in vivo evaluations using generated artificial osteosarcoma cancer stem cell‑like cells.

Cancer stem cells (CSCs) have been implicated as critical mediators in the progression, chemoresistance and metastatic capabilities of diverse malignancies, including osteosarcoma (OS). The authors have succeeded in generating CSC‑like cells (MG‑OKS) from the OS cell line MG‑63 by transducing defined factors. A significant increase in small proline‑rich protein 1A (SPRR1A) expression, a cross‑linked envelope protein in keratinocytes, was observed in MG‑OKS cells. Therefore, SPRR1A could be involved in tumor initiation, growth and poor OS progression. However, its specific role in OS remains unclear. The present study aimed to evaluate the role of SPRR1A in OS both in vitro and in vivo using MG‑OKS cells. Three experimental groups were established: MG‑OKS cells transfected with SPRR1A small interfering (si)RNA (siMG‑OKS), untransfected MG‑OKS cells and MG‑OKS cells transfected with scrambled siRNA (scMG‑OKS) as controls. SPRR1A expression, morphological changes, cell proliferation and migration were assessed in these groups. RNA sequencing was performed to examine the genetic changes caused by SPRR1A suppression. To evaluate tumorigenicity in vivo, cells from each group were subcutaneously transplanted into the backs of nude mice. Tumor volume and Ki‑67 expression were assessed and compared among the three groups at four weeks post‑transplantation. The siMG‑OKS group exhibited altered cell morphology, reduced cell proliferation and decreased migratory abilities in vitro. RNA sequencing revealed suppression of genes involved in cell adhesion in the siMG‑OKS group. Furthermore, the in vivo tumorigenicity of siMG‑OKS was lower than that of the other two experimental groups. These findings suggest that SPRR1A is one of the key cell adhesion‑related molecules involved in OS progression, potentially serving as a therapeutic target for this refractory tumor. However, further research is needed to fully elucidate the mechanisms by which SPRR1A influences OS pathogenesis and to explore its clinical potential.

Bioengineered Nanomaterials for siRNA Therapy of Chemoresistant Cancers.

Chemoresistance remains a long-standing challenge after cancer treatment. Over the last two decades, RNA interference (RNAi) has emerged as a gene therapy modality to sensitize cancer cells to chemotherapy. However, the use of RNAi, specifically small-interfering RNA (siRNA), is hindered by biological barriers that limit its intracellular delivery. Nanoparticles can overcome these barriers by protecting siRNA in physiological environments and facilitating its delivery to cancer cells. In this review, we discuss the development of nanomaterials for siRNA delivery in cancer therapy, current challenges, and future perspectives for their implementation to overcome cancer chemoresistance.

Augmented epigenetic repression of hepatitis B virus covalently closed circular DNA by interferon-α and small-interfering RNA synergy.

Since there are currently no approved drugs targeting and silencing covalently closed circular DNA (cccDNA), achieving a "functional cure" remains difficult. This study aims to comprehensively compare the effects of IFNα, small-interfering RNA targeting hepatitis B virus (HBV), and their combination on the activity, accessibility, and epigenetic modifications of cccDNA minichromosomes in cell models. A more durable and stable inhibition of HBV RNAs and antigens expression by IFNα and HBx-targeting siRNA (siHBx) synergy was observed, associated with augmented epigenetic repression of the cccDNA minichromosome. Besides, in an extracellular humanized IFNAR mouse model harboring recombinant cccDNA with an intact response to human IFNα, the synergistic effect of clinically used pegylated IFNα2 and in-house-developed GalNac-siHBx was further clarified.

High resistance barrier and prophylactic protection in preclinical models of SARS-CoV-2 with two siRNA combination.

RNA interference is a natural antiviral mechanism that could be harnessed to combat SARS-CoV-2 infection by targeting and destroying the viral RNA. We identified potent lipophilic smallinterfering RNA (siRNA) conjugates targeting highly conserved regions ofSARS-CoV-2 outside of the spike-encoding region capable of achieving≥3-log viral reduction. Serial passaging studies demonstrated that a two-siRNA combination prevented development of resistance compared to a singlesiRNA approach. Viral resistance to single siRNA treatment occurred due to emergence of point mutations at critical positions required for siRNA-mediated target binding and cleavage, which led to a loss of siRNA efficacy. With a two-siRNA combination, emergence of mutations within the siRNA binding site was abolished. When delivered intranasally, two-siRNA combination protected Syrian hamsters from weight loss and lung pathology by viral infection upon prophylactic administration but not following onset of infection. Together, the data support potential utility of RNAi as a prophylactic approach with high resistance barrier to counteract SARS-CoV-2 emergent variants and complement vaccination. Most importantly, given that the siRNAs can be rapidly developed from a new pathogen sequence, this strategy has implications as a new type of preventive medicinethat may protect against future coronavirus pandemics.

Investigational RNA Interference Agents for Hepatitis B.

Functional cure of chronic hepatitis B (CHB)-defined as sustained seroclearance of hepatitis B surface antigen (HBsAg) with unquantifiable hepatitis B virus (HBV) DNA at 24 weeks off treatment, is an optimal treatment endpoint. Nonetheless, it cannot be consistently attained by current treatment modalities. RNA interference (RNAi) is a novel treatment strategy using small-interfering RNA (siRNA) or antisense oligonucleotide (ASO) to target HBV post-transcriptional RNA, in turn suppressing viral protein production and replication. Hence, RNAi has indirect effects in promoting host immune reconstitution against HBV. Multiple RNAi therapeutics have entered phase II/III clinical trials, demonstrating potent, dose-dependent, and sustainable effects in suppressing HBsAg. Incidences of HBsAg seroclearance, particularly with the use of ASO, have also been documented. The combination of RNAi with other antivirals/immunomodulators (e.g. pegylated interferon), have shown promising results in potentiating RNAi effects and enhancing treatment durability. Further research will be required to establish predictors of response, optimal treatment protocols, and long-term outcomes in patients on RNAi. RNAi therapeutics have shown promising results and will likely be the keystone of future HBV treatment.

Nanomedicine based on chemotherapy-induced immunogenic death combined with immunotherapy to enhance antitumor immunity.

Chemo-immunotherapy based on inducing tumor immunogenic cell death (ICD)with chemotherapy drugs has filled the gaps between traditional chemotherapy and immunotherapy. It is verified that paclitaxel (PTX) can induce breast tumor ICD. From this basis, a kind of nanoparticle that can efficiently deliver different drug components simultaneously is constructed. The purpose of this study is for the sake of exploring the scheme of chemotherapy-induced ICD combined with other immunotherapy to enhance tumor immunogenicity and inhibit the growth, metastasis, and recurrence of breast tumors, so as to provide a research basis for solving the tough problem of breast cancer treatment. Nanomedicine loaded with PTX, small interference RNA that suppresses CD47 expression (CD47siRNA, siCD47), and immunomodulator R848 were prepared by the double emulsification method. The hydrodynamic diameter and zeta potential of NP/PTX/siCD47/R848 were characterized. Established the tumor-bearing mice model of mouse breast cancer cell line (4T1) in situ and observed the effect of intravenous injection of NP/PTX/siCD47/R848 on the growth of 4T1 tumor in situ. Flow cytometry was used to detect the effect of drugs on tumor immune cells. NP/PTX/siCD47/R848 nano-drug with tumor therapeutic potential were successfully prepared by double emulsification method, with particle size of 121.5 ± 4.5nm and surface potential of 36.1 ± 2.5mV. The calreticulin on the surface of cell membrane and extracellular ATP or HMGB1 of 4T1 cells increased through treatment with NPs. NP/PTX-treated tumor cells could cause activation of BMDCs and BMDMs. After intravenous injection, NP/PTX could quickly reach the tumor site and accumulate for 24h. The weight and volume of tumor in situ in the breast cancer model mice injected with nanomedicine through the tail vein were significantly lower than those in the PBS group. The ratio of CD8+/CD4+ T cells in the tumor microenvironment and the percentage of dendritic cells in peripheral blood increased significantly in breast cancer model mice injected with nano-drugs through the tail vein. Briefly, the chemotherapeutic drug paclitaxel can induce breast cancer to induce ICD. The nanomedicine which can deliver PTX, CD47siRNA, and R848 at the same time was prepared by double emulsification. NP/PTX/siCD47/R848 nano-drug can be enriched in the tumor site. The experiment of 4T1 cell tumor-bearing mice shows that the nano-drug can enhance tumor immunogenicity and inhibit breast tumor growth, which provides a new scheme for breast cancer treatment. (Graphical abstract).

Acid-sensing ion channel-1 contributes to the failure of myelin sheath regeneration following spinal cord injury by transcellular delivery of PGE2

BackgroundTraumatic injuries to spinal cord lead to severe motor, sensory, and autonomic dysfunction. The accumulation of inhibitory compounds plays a pivotal role in the secondary damage to sparing neural tissue and the failure of axonal regeneration and remyelination. Acid-sensing ion channel-1(ASIC1A) is widely activated following neurotrauma, including spinal cord injury (SCI). However, its role in SCI remains elusive.MethodsThe effects of acidic environment on the differentiation and genes changes of neural stem cells (NSCs) were assessed by immunofluorescence staining and RNA-sequencing analysis, respectively. The expression of ASIC1A and prostaglandin endoperoxide synthase 2 (PTGS2) were detected by western blot and immunofluorescence staining. The concentration of prostaglandin E2 (PGE2) within NSC-derived extracellular vesicles were evaluated by ELISA. Small-interfering RNAs (siRNAs) were used to knock down Asic1a and Ptgs2 expression in NSCs. The myelin sheath regeneration and axonal remyelination in rats and Asic1a-KO mice were assessed by immunofluorescence staining.ResultsFollowing injury to the spinal cord, ASIC1A was found to be colocalized and upregulated in NSCs. ASIC1A activation prevents the differentiation of NSCs into oligodendrocytes by upregulating PTGS2, which leads to increased production and release of PGE2 within extracellular vesicles (EVs). ASIC1A or PTGS2 deficiency in NSCs counters the ASIC1A-related effects on mediating NSC differentiation by reducing PGE2 expression within NSC-derived EVs. Furthermore, intervention in ASIC1A signaling by administration of ASIC1A inhibitors or genetic deletion of ASIC1A demonstrated a pronounced advantage in enhancing myelin sheath regeneration and axonal remyelination.ConclusionsThe activation of ASIC1A prevents NSC differentiation into oligodendrocytes via the transcellular NSC-to-NSC delivery of PGE2, resulting in the failure of myelin sheath regeneration and axonal remyelination following SCI. The inhibition of ASIC1A presents a promising therapeutic strategy for the treatment of SCI.Graphical

Wild-Type p53 Regulates Apoptosis of Human Breast Cancer Cells.

The tumor suppressor wild-type p53 is known for its role in inducing apoptosis in tumor cells. This study investigated the relationship between wild-type p53 and protein phosphatase 1 (PP1) and caspase in promoting apoptosis of breast cancer cells. Human breast cancer cell lines MCF-7 and MDA-MB-231 obtained from the American Type Culture Collection were used in this study. Small interference RNAs (Si-RNA) and plasmids were used to regulate wild-type p53 expression in these two tumor cell lines through liposome-mediated transfection. GSK-2830371 (PP1 inhibitor) and zVAD (Caspase inhibitor) were employed to further verify the PP1 activating function of wild-type p53 in Caspase-dependent MCF-7 and MDA-MB-231 apoptosis. PP1 activity was quantitatively detected by phosphorus colorimetric assay. Co-immunoprecipitation (Co-IP), flow cytometry assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, Western blot, the real-time reverse transcriptase-polymerase chain reaction (RT-qPCR), and immunofluorescence staining were used to analyze cell apoptosis degree and marker protein expression. The expression level of PP1 in the breast cancer cells was successfully regulated by cell transfection. The phosphatase activity was increased, and obvious apoptotic cytological characteristics were observed in p53-overexpressed breast cancer cells. p53 knockdown/overexpression increased/decreased the level of B cell lymphoma 2 (Bcl-2), and decreased/increased levels of Caspase-3, cleaved Caspase-3, cleaved Caspase-8, Cytochrome C (Cyt-C), Truncated BID (tBid), Bcl-2-associated X (Bax), and cell apoptosis (p < 0.01). The promotion of proteins and apoptosis induced by p53 overexpression was reversed by GSK-2830371 or zVAD. Wild-type p53 might promote Caspase-dependent apoptosis of human breast cancer cells through PP1 activation.

Correlation of NAT10 expression with clinical data and survival profiles in esophageal squamous cell carcinoma patients, and its impact on cell proliferation and apoptosis.

This study investigates the association between NAT10 expression and clinical parameters while assessing prognostic outcomes in esophageal squamous cell carcinoma (ESCC) patients. Furthermore, the study seeks to elucidate the functional role of NAT10 in neoplastic cell proliferation and apoptosis. NAT10 expression was assessed in ESCC tissue microarrays through immunohistochemistry (IHC) tests. We employed SPSS software to analyze the correlation between NAT10 staining data, clinical indicators, and their implications for patient prognosis. Small interference RNA (siRNA) was utilized to inhibit NAT10 expression in two esophageal cancer cell lines, TE-1 and KYSE150. Subsequently, we meticulously quantified and compared cellular proliferation and apoptotic ratios among experimental groups. NAT10, Ki67, and Caspase3 expression levels in different groups were evaluated using quantitative polymerase chain reaction (qPCR) and Western blot (WB) assays. Statistical analyses were conducted using GraphPad Prism software, with significance at P<0.05. Our findings indicate that NAT10 is overexpressed in ESCC tissues and exhibits a significant correlation with tumor diameter and overall patient survival. Decreasing NAT10 expression led to the inhibition of tumor cell proliferation and the promotion of apoptosis. Furthermore, siRNA-mediated NAT10 inhibition resulted in the downregulation of Ki67 expression and the concomitant upregulation of Caspase3. The observed overexpression of NAT10 in ESCC tissues is associated with larger tumor diameters and reduced patient survival. NAT10 appears to play a pivotal role in the progression of esophageal cancer by influencing cell proliferation and apoptosis. These findings suggest potential clinical implications, with Ki67 and Caspase3 potentially participating in this intricate molecular biological process.

Linoleic Acid Enhances Renal Tubular Epithelial Cells Autophagy Caused by Calcium Oxalate Monohydrate Crystals.

High intake of dietary linoleic acid may increase the incidence of many diseases. The aim of this research is to examine the impact of linoleic acid on the damage caused by calcium oxalate kidney stones on renal tubular epithelial cells. Calcium oxalate monohydrate (COM) crystals were prepared and used to treat HK-2 cells, which were further treated with different concentrations of linoleic acid invitro. Also, a small-interfering RNA lentiviral vector of milk fat globule epidermal growth factor 8 (MFGE8) was constructed and transfected into HK-2 cells. The cell viability, level of intracellular ROS and autophagy were tested. Invivo experiments were also carried out with a rat model for renal urolithiasis treated with linoleic acid. The results indicated that COM crystals promoted crystal deposition and apoptosis, increased levels of intracellular Ca2+ and ROS levels and inhibited the proliferation of HK-2 cells. Linoleic acid exacerbated the damage of COM crystal-treated HK-2 cells and renal tubular epithelial cells of the rat model for renal urolithiasis, which can be partially reversed by downregulation of MFGE8. These results collectively suggest that linoleic acid might enhance the damage of renal tubular epithelial cells caused by COM crystals.

Cross-species RNAi therapy via AAV delivery alleviates neuropathic pain by targeting GCH1.

Tetrahydrobiopterin (BH4) expression is normally strictly controlled; however, its intracellular levels increase considerably following nerve damage. GTP cyclohydrolase I (GCH1) plays a crucial role in regulating BH4 concentration, with an upregulation observed in the dorsal root ganglion in cases of neuropathic pain. In this study, we aimed to develop and evaluate the clinical potential of an RNA interference-based adeno-associated virus (AAV) targeting GCH1 across various species to decrease BH4 levels and, consequently, alleviate neuropathic pain symptoms. We identified universal small-interfering RNA sequences effective across species and developed an AAV-u-shRNA that successfully suppressed GCH1 expression with minimal off-target effects. Male Sprague Dawley rats were divided into four groups: normal, spared nerve injury, AAV-shCON, and AAV-u-shGCH1. The rats were sacrificed on post-injection day 28 to collect blood for BH4 level assessment. The AAV-u-shGCH1 group demonstrated remarkable improvement in the mechanical withdrawal threshold by PID 28, significantly outperforming the normal, spared nerve injury, and AAV-shCON groups. Plasma BH4 levels confirmed that AAV-u-shGCH1 effectively reduced neuropathic pain by inhibiting BH4 synthesis in vivo, introducing a novel, multispecies-compatible therapeutic strategy. Our results suggest that a single application of AAV-u-shGCH1 could offer a viable solution for neuropathic pain relief.

UBR1 Promotes Sex-Dependent ACE2 Ubiquitination in Hypertension.

Ang-II (angiotensin II) impairs the function of the antihypertensive enzyme ACE2 (angiotensin-converting enzyme 2) by promoting its internalization, ubiquitination, and degradation, thus contributing to hypertension. However, few ACE2 ubiquitination partners have been identified, and their role in hypertension remains unknown. Proteomics and bioinformatic analyses were used to identify ACE2 ubiquitination partners in the brain, heart, and kidney of hypertensive C57BL6/J mice of both sexes. The interaction between UBR1 (ubiquitin protein ligase E3 component N-recognin) and ACE2 was validated in cells. Central and peripheral UBR1 knockdown was then performed in male mice to investigate its role in the maintenance of hypertension. Proteomics analysis of the hypothalamus identified UBR1 as a potential E3 (ubiquitin protein ligase) ligase promoting ACE2 ubiquitination. Enhanced UBR1 expression, associated with ACE2 reduction, was confirmed in various tissues from hypertensive male mice and human samples. Treatment of endothelial and smooth muscle cells with testosterone, but not 17β-estradiol, confirmed a sex-specific regulation of UBR1. In vivo silencing of UBR1 using chronic administration of small interference RNA resulted in the restoration of ACE2 levels in hypertensive male mice. A transient decrease in blood pressure after intracerebroventricular, but not systemic, infusion was also observed. Interestingly, UBR1 knockdown increased brain activation of Nedd4-2 (neural precursor cell expressed developmentally downregulated protein 4), an E3 ligase promoting ACE2 ubiquitination, and reduced expression of serum and glucocorticoid-regulated kinase 1, the kinase that inactivates Nedd4-2. These data demonstrate that UBR1 is a novel E3 ubiquitin ligase targeting ACE2 in hypertension. UBR1 and Nedd4-2 appear to work synergistically to ubiquitinate ACE2. Targeting these ubiquitin ligases may represent a novel strategy to restore ACE2 compensatory activity in hypertension.

Zerlasiran—A Small-Interfering RNA Targeting Lipoprotein(a)

Elevated lipoprotein(a) increases the risk of atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis. To evaluate the effects of zerlasiran, a small-interfering RNA targeting hepatic synthesis of apolipoprotein(a), on lipoprotein(a) serum concentration. A multicenter trial in patients with stable ASCVD with serum lipoprotein(a) concentrations greater than or equal to 125 nmol/L at 26 sites in Europe and South Africa between January 3, 2023, and April 27, 2023, with last follow-up on July 1, 2024. Participants randomized to receive a subcutaneous dose of placebo every 16 weeks for 3 doses (n = 23) or every 24 weeks for 2 doses (n = 24) or zerlasiran 450 mg every 24 weeks for 2 doses (n = 45), 300 mg every 16 weeks for 3 doses (n = 42), or 300 mg every 24 weeks for 2 doses (n = 44). The primary outcome was the time-averaged percent change in lipoprotein(a) concentration from baseline to 36 weeks, with follow-up to 60 weeks. Among 178 patients, mean (SD) age was 63.7 (9.4) years, 46 (25.8%) were female, with a median (IQR) baseline lipoprotein(a) concentration of 213 (177-282) nmol/L; 172 patients completed the trial. Compared with the pooled placebo group, the least-squares mean time-averaged percent change in lipoprotein(a) concentration from baseline to week 36 was -85.6% (95% CI, -90.9% to -80.3%), -82.8% (95% CI, -88.2% to -77.4%), and -81.3% (95% CI, -86.7% to -76.0%) for the 450 mg every 24 weeks, 300 mg every 16 weeks, and 300 mg every 24 weeks groups, respectively. Median (IQR) percent change in lipoprotein(a) concentration at week 36 was -94.5% (-97.3% to -84.2%) for the 450 mg every 24 weeks group, -96.4% (-97.7% to -92.3%) for the 300 mg every 16 weeks group, and -90.0% (-93.7% to -81.3%) for the 300 mg every 24 weeks group. The most common treatment-related adverse effects were injection site reactions, with mild pain occurring in 2.3% to 7.1% of participants in the first day following drug administration. There were 20 serious adverse events in 17 patients, none considered related to the study drug. Zerlasiran was well-tolerated and reduced time-averaged lipoprotein(a) concentration by more than 80% during 36 weeks of treatment in patients with ASCVD. ClinicalTrials.gov Identifier: NCT05537571.