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Generation of full-length wild-type and mutated futsch transgenes in Drosophila-efficient Gibson Assembly of ultra-large cDNAs.

Drosophila Futsch is a key microtubule-associated protein (fly homolog of MAP1B) that regulates microtubule organization, synaptic terminal growth, and neuronal development. Functional analysis of futsch has long been limited by the inability to clone and express a full-length futsch transgene, owing to its exceptional size (~16.5 kb) and extensive repetitive sequences. Here, I present an efficient and reproducible method for cloning both wild-type and mutated full-length Drosophila futsch cDNA (16,488 bp) using Gibson Assembly. These resulting cDNAs were used to generate UAS-futsch transgenes. When expressed in neurons, the wild‑type transgenic Futsch associated with microtubule and rescued the synaptic morphological defects observed in futschK68 mutants. This approach substantially reduces the time and complexity compared with traditional cloning techniques. Furthermore, I highlight common pitfalls encountered during the cloning process and provide practical solutions to enhance cloning efficiency. This protocol offers a broadly applicable and cost-effective framework for cloning otherwise intractable large cDNAs from Drosophila and other organisms.

Animals

Enhanced transgene expression from single-stranded AAV vectors in human cells in vitro and in murine hepatocytes in vivo.

We identified that distal 10 nucleotides in the D-sequence in AAV2 inverted terminal repeat (ITR) share partial sequence homology to 1/2 binding site of glucocorticoid receptor-binding element (GRE). Here, we describe that (1) purified GR binds to AAV2 D-sequence, and the D-sequence competes with GR binding to its cognate binding site; (2) dexamethasone-mediated activation of GR pathway significantly increases the transduction efficiency of AAV2 vectors in human cells; (3) human osteosarcoma cells, U2OS, which lack expression of GR, are poorly transduced by AAV2 vectors, but stable transfection with a GR expression plasmid restores vector-mediated transgene expression; (4) replacement of the distal 10 nucleotides in the D-sequence of the AAV2 ITR with a full-length GRE consensus sequence significantly enhances transgene expression in human cells in vitro and in murine hepatocytes in vivo; and (5) none of the ITRs in AAV1, AAV3, AAV4, AAV5, and AAV6 genomes contains the GRE 1/2 binding site, and insertion of a full-length GRE consensus sequence in the AAV6-ITR also significantly enhances transgene expression from AAV6 vectors, both in vitro and in vivo. These novel vectors, termed generation Y AAV vectors, which are serotype, transgene, or promoter agnostic, should be useful in human gene therapy.

AAV vectors

A Tripartite AAV System with Engineered Lox Sites Enables Efficient Delivery of the EYS Gene for Retinal Gene Therapy.

Mutations in the Eyes Shut Homolog (EYS) gene are one of the leading causes of autosomal recessive retinitis pigmentosa, a progressive retinal degenerative disease for which no effective treatment currently exists. However, the large size of the EYS coding sequence (∼9.4 kb) exceeds the packaging limit of adeno-associated virus (AAV) vectors, posing a major barrier to gene replacement therapy. To address this challenge, we developed a tripartite AAV vector system that enables delivery and reconstitution of the full-length EYS gene using a Cre-lox-based unidirectional DNA recombination strategy, Uni-directional and Site-specific Transgene Assembly by Recombination (Uni-STAR). The system consists of three AAV constructs carrying discrete EYS segments flanked by engineered, noncompatible lox sites that drive ordered and unidirectional recombination in target cells. We validated this system in vitro by demonstrating successful reconstitution and expression of full-length EYS protein in HEK293T cells. In vivo, subretinal co-injection of the three AAV vectors into mouse eyes led to precise reconstitution and expression of full-length EYS protein in the retina. These findings establish the feasibility of using a tripartite AAV system to deliver the complete EYS gene and provide a foundation for future therapeutic development targeting EYS-associated retinal degenerations.

Dependovirus

Transgenic overexpression of GmAPC7-CT improves seed yield and reduces susceptibility to soybean mosaic virus and Meloidogyne incognita in soybean.

Stable transgenic soybean lines overexpressing the GmAPC7-CT gene have demonstrated increased seed yield and reduced susceptibility to the soybean mosaic virus and Meloidogyne incognita. The Anaphase-Promoting Complex subunit 7 (APC7) is a core structural component of the anaphase-promoting complex or cyclosome (APC/C). The terminal region of this AtAPC7 gene has been shown in Arabidopsis thaliana to accumulate more transcripts than the full-length gene. The AtAPC7-CT gene (terminal region of the AtAPC7) encodes a protein with significant homology to a tobacco viral replication inhibitor (IVR). Its stable overexpression in transgenic A. thaliana lines resulted in notable improvements in biomass, seed yield, earliness of vegetative-reproductive transitions, and reduced susceptibility to viruses. In this study, we generated stable transgenic soybean lines overexpressing the GmAPC7-CT gene (terminal region or 3' portion of Glyma.15G096000, corresponding to the AtAPC7-CT) and evaluated seed yield and susceptibility of these lines to soybean mosaic virus and Meloidogyne incognita. The GmAPC7-CT gene is 624 nucleotides long and encodes a 207-amino acid protein with two tetratricopeptide repeat (TPR) domains. GmAPC7-CT showed 100% amino acid identity with full-length GmAPC7, 81.16% identity with AtAPC7-CT, and 87.94% identity with tobacco IVR. Stable transgenic lines demonstrated significant advancements in plant development and seed yield, with the top three lines producing up to 43% more pods, 44% more seeds, and a 16% increase in seed weight. Furthermore, these soybean lines showed up to a 70% reduction in susceptibility to soybean mosaic virus and M. incognita, reflected by decreased viral RNA load and nematode reproduction factor. Collectively, these results support a conserved role of GmAPC7-CT in soybean and AtAPC7-CT in A. thaliana, acting similarly to the tobacco IVR. Thus, our findings underscore the strong biotechnological potential of the GmAPC7-CT gene to improve key agronomic traits in soybean through genetic engineering approaches, including conventional breeding, transgenesis, and genome editing.

Glycine max

Self-regulating gene therapy ameliorates phenotypes and overcomes gene dosage sensitivity in a mouse model of Rett syndrome.

Conventional methods of gene transfer lead to inconsistent transgene expression within cells. This variability can be problematic, particularly in conditions like Rett syndrome (RTT), a neurological disorder caused by mutations in the MECP2 (methyl-CpG binding protein 2) gene, because overexpression of MECP2 can also cause adverse effects. To address these challenges, we devised a gene regulation system called Expression Attenuation via Construct Tuning (EXACT), which uses a self-contained, microRNA-based feed-forward loop that not only ensures more consistent transgene expression but also protects against excessive expression. Through cell-based screening assays, we demonstrated the ability of the EXACT circuit to modulate the expression of full-length human MeCP2. Compared with a conventional construct, an EXACT-MECP2 construct exhibited a narrower range of cellular protein abundance. Furthermore, the degree of regulation by the EXACT circuit increased with higher transgene doses in vitro and in wild-type mice and mice modeling RTT. On the basis of cellular and in vivo testing, we identified an optimal configuration for the adeno-associated virus serotype 9 (AAV9) construct for self-regulated MECP2 gene therapy, designated NGN-401. Delivery of NGN-401 to neonatal male Mecp2-/y hemizygous mice via intracerebroventricular injection resulted in prolonged survival and amelioration of RTT-like phenotypes compared with vehicle-treated animals. NGN-401 was also well tolerated by female Mecp2+/- mice and healthy juvenile nonhuman primates, in contrast with a conventional construct, which caused toxicity. The results from these studies underpin a first-in-human pediatric trial of NGN-401 in RTT (ClinicalTrials.gov, NCT05898620).

Animals

Overexpression of the tomato SlLEA_2-26 gene enhances the tolerance to drought and salt stresses in Arabidopsis thaliana.

Late embryogenesis abundant (LEA) proteins are pivotal in conferring cellular tolerance to abiotic stresses and sustaining plant growth and development. However, systematic functional characterization of the tomato SlLEA_2 gene family remains limited. To elucidate the role of tomato SlLEA_2-26 in abiotic stress responses, this study cloned its full-length cDNA. Quantitative real-time PCR (qRT-PCR) analysis revealed that SlLEA_2-26 exhibits predominant expression in flowers and fruits, and is strongly induced by drought, salt, Cu2+, and Pb2+ stresses. Three homozygous Arabidopsis thaliana T3 SlLEA_2-26-overexpression lines were generated and confirmed via genomic PCR. Under drought and salt stress, T3 A. thaliana lines overexpressing SlLEA_2-26 exhibited significantly enhanced seed germination rates, root elongation, and fresh weights compared to wild type (WT) plants, indicating improved stress tolerance during early seedling development. Furthermore, transgenic plants accumulated higher levels of soluble sugar and proline, and displayed elevated antioxidant enzyme activity compared to the WT, whereas contents of malondialdehyde (MDA) and reactive oxygen species (ROS) were markedly reduced relative to WT. qRT-PCR analysis confirmed the significant upregulation of SlLEA_2-26 in transgenic lines under drought and salt stress conditions, accompanied by elevated expression of AtP5CS1, AtCSD1, AtRD29A, AtRD26, and AtNCED3. Collectively, these results demonstrate that SlLEA_2-26 overexpression enhances drought and salt stress tolerance in A. thaliana by promoting the accumulation of osmoregulatory substances, augmenting antioxidant defense capacity, and activating stress-responsive gene expression. This study provides a theoretical foundation and valuable genetic resources for breeding stress-tolerant tomatoes and other crops.

SlLEA_2–26

Enhancing AAV9-UFμDys1 Gene Therapy Efficacy Through Immunosuppression in Mice with Pre-Existing Immunity and Enabling Redosing Strategies for Duchenne Muscular Dystrophy.

Significant progress has been made in gene therapy for Duchenne muscular dystrophy (DMD), a severe genetic disorder primarily affecting pediatric patients. However, the immune responses triggered by high-dose systemic delivery of adeno-associated virus (AAV) vectors remain a major challenge. These responses include the generation of long-lasting anti-capsid antibodies and potential immunity against the therapeutic transgene, rendering gene therapy ineffective. In addition, pre-existing anti-AAV antibodies exclude patients from eligibility for treatment. To address these limitations, we have developed an immunosuppression (IMS) strategy aimed at mitigating immune responses to the AAV capsid while enhancing microdystrophin expression. Using an optimized expression cassette (AAV9-UFµDys1) for sustained microdystrophin expression in striated muscle and heart, we observed a 40% improvement in muscle force compared with animals receiving a GFP-encoding control AAV9 vector. In mdx mice, a single-dose IMS regimen significantly increased microdystrophin expression in cardiac and skeletal tissues and repeat dosing further enhanced expression, an effect not observed in non-IMS-treated mdx mice. To model pre-existing immunity, we immune-challenged wild-type mice with empty AAV9 capsids and tracked antibody responses over time. The IMS regimen effectively reduced total anti-AAV antibody levels and increased microdystrophin expression in UFµDys1-treated mice. These findings highlight the potential of IMS to minimize immune barriers, facilitate repeat AAV administration, and expand the therapeutic window for DMD gene therapy. Our results support the further development of AAV-mediated approaches using either microdystrophin-expressing vectors or next-generation systems delivering full-length or near-full-length dystrophin.

Animals

Ptpn22 and Cd2 Variations Are Associated with Altered Protein Expression and Susceptibility to Type 1 Diabetes in Nonobese Diabetic Mice.

By congenic strain mapping using autoimmune NOD.C57BL/6J congenic mice, we demonstrated previously that the type 1 diabetes (T1D) protection associated with the insulin-dependent diabetes (Idd)10 locus on chromosome 3, originally identified by linkage analysis, was in fact due to three closely linked Idd loci: Idd10, Idd18.1, and Idd18.3. In this study, we define two additional Idd loci--Idd18.2 and Idd18.4--within the boundaries of this cluster of disease-associated genes. Idd18.2 is 1.31 Mb and contains 18 genes, including Ptpn22, which encodes a phosphatase that negatively regulates T and B cell signaling. The human ortholog of Ptpn22, PTPN22, is associated with numerous autoimmune diseases, including T1D. We, therefore, assessed Ptpn22 as a candidate for Idd18.2; resequencing of the NOD Ptpn22 allele revealed 183 single nucleotide polymorphisms with the C57BL/6J (B6) allele--6 exonic and 177 intronic. Functional studies showed higher expression of full-length Ptpn22 RNA and protein, and decreased TCR signaling in congenic strains with B6-derived Idd18.2 susceptibility alleles. The 953-kb Idd18.4 locus contains eight genes, including the candidate Cd2. The CD2 pathway is associated with the human autoimmune disease, multiple sclerosis, and mice with NOD-derived susceptibility alleles at Idd18.4 have lower CD2 expression on B cells. Furthermore, we observed that susceptibility alleles at Idd18.2 can mask the protection provided by Idd10/Cd101 or Idd18.1/Vav3 and Idd18.3. In summary, we describe two new T1D loci, Idd18.2 and Idd18.4, candidate genes within each region, and demonstrate the complex nature of genetic interactions underlying the development of T1D in the NOD mouse model.

Alleles