Researchers from UC San Diego have engineered human zinc finger-containing fusion proteins that target and can destroy or modify human RNA transcripts that contain expanded G4C2 hexanucleotide repeats. This approach, which they have termed zinc fingerdirected RNA targeting, provides a means to, depending on the fusion protein, 1) target and degrade disease-causing RNA transcripts containing G4C2 expansions and to 2) target, label, and track the same transcripts in living cells.

Reseachers from UC San Diego demonstrated a proof of principle for a CAGEX RNA-targeting CRISPR–Cas13d system as a potential allele-sensitive therapeutic approach for HD, a strategy with broad implications for the treatment of other neurodegenerative disorders.

The strategy employed by the invention is inspired by splicing factors, a category of RNA-binding protein that influence alternative splicing outcomes. These splicing factors are trans-acting, and act to enhance or silence exon inclusion by binding near or on the target exon and promoting or repressing the activity of splicing machinery. Scientifically, a highly programmable, minimally disruptive system to increase exon inclusion could allow for higher-throughput identification of functional roles of specific exons than have been previously shown.

Alternative splicing accounts for a considerable portion of transcriptomic diversity, as most protein-coding genes are spliced into multiple mRNA isoforms. However, errors in splicing patterns can give rise to mis-splicing with pathological consequences, such as the congenital diseases familial dysautonomia, Duchenne muscular dystrophy, and spinal muscular atrophy. Small nuclear RNA (snRNA) components of the U snRNP family have been proposed as a therapeutic modality for the treatment of mis-splicing. U1 snRNAs offer great promise, with prior studies demonstrating in vivo efficacy, suggesting additional preclinical development is merited. Improvements in enabling technologies, including screening methodologies, gene delivery vectors, and relevant considerations from gene editing approaches justify further advancement of U1 snRNA as a therapeutic and research tool.

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a predominantly genetic-based heart disease characterized by right but also recently left ventricular dysfunction, fibrofatty replacement of the myocardium leading to fatal/severe ventricular arrhythmias leading to sudden cardiac death in young people and athletes. ARVC is responsible for 10% of sudden cardiac deaths in people ≥65 years of age and 24% in people ≤30 years of age. ARVC is thought to be a rare disease as it occurs in 1 in 1000-5000 people, although the prevalence may be higher as some patients are undiagnosed or misdiagnosed due to poor diagnostic markers. Growing evidence also reveals earlier onset since pediatric populations ranging from infants to children in their teens are also particularly vulnerable to ARVC, highlighting the critical need to identify and treat patients at an earlier stage of the disease. At present there are no effective treatments for ARVC nor has there been any randomized clinical trials conducted to examine treatment modalities, screening regimens, or medications specific for ARVC. As a result, treatment strategies for ARVC patients are directed at symptomatic relief of electrophysiological defects, based on clinical expertise, results of retrospective registry-based studies, and the results of studies on model systems. The current standard of care is the use of anti-arrhythmic drugs (sotalol, amniodarone and beta-blockers) that transition into more invasive actions, which include implantable cardioverter defibrillators and cardiac catheter ablation, if the patient becomes unresponsive or intolerant to anti-arrhythmic therapies. However, current therapeutic modalities have limited effectiveness in managing the disease, 40% of ARVC patients (a young heart disease) die within 10-11 years after initial diagnosis, highlighting the need for development of more effective therapies for patients with ARVC.

Present strategies aimed to target and manipulate RNA in living cells mainly rely on the use of antisense oligonucleotides (ASO) or engineered RNA binding proteins (RBP). Although ASO therapies have been shown great promise in eliminating pathogenic transcripts or modulating RBP binding, they are synthetic in construction and thus cannot be encoded within DNA. This complicates potential gene therapy strategies, which would rely on regular administration of ASOs throughout the lifetime of the patient. Furthermore, they are incapable of modulating the genetic sequence of RNA. Although engineered RBPs such as PUF proteins can be designed to recognize target transcripts and fused to RNA modifying effectors to allow for specific recognition and manipulation, these constructs require extensive protein engineering for each target and may prove to be laborious and costly. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0in; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

NK cells possess a native ability to kill tumors and virally infected cells without prior antigen priming. Furthermore, NK cells can be administered to patients across HLA allotypes, unlike T cells which require HLA matching to avoid graft-versus-host disease. Many trials utilizing adoptive transfer of allogeneic NK cells demonstrated complete remissions in patients with acute myelogenous leukemia (AML) who are refractory to standard chemotherapy. Another recent clinical study demonstrated effective treatment of lymphoid malignancies using allogeneic CAR-expressing NK cells, with minimal side effects. Thus, NK cells possess a number of advantages over T cells that enables them to be used as safe, effective, “off-the-shelf” adoptive cell therapy product to treat diverse malignancies. Antibody-dependent cellular cytotoxicity (ADCC) is a key pathway that mediates natural killer (NK) cell cytotoxicity against antibody-opsonized target cells. This process helps mediate the therapeutic efficacy of anti-tumor antibodies. On NK cells, ADCC occurs via engagement of antibody-coated target cells with activating receptor leading to proinflammatory cytokine upregulation, degranulation, and target cell death. Upon cellular activation, the     is cleaved from the NK cell surface. Cleavage of the ectodomain prevents further antibody binding and signaling, which dampens NK cell activity. Blocking activation-induced cleavage has been previously demonstrated to augment ADCC activity and provides a novel strategy to improve efficacy of therapeutic antibodies in combination with adoptive transfer of engineered NK cells. 

Heart failure (HF) is a disease of epidemic portions in the United States affecting over 6 million patients with heart failure in the US, with 400,000 new cases per year. It is the most common cause of non-elective admission to the hospital in subjects 65 yrs and older. The introduction of new drugs over the last 30 years that target pathways critical to progression of HF, along with implantable cardiac defibrillators and resynchronization devices have shown some successes, however, both the morbidity and mortality associated with heart failure remains at unacceptable levels, with as many as 30-40% of affected individuals dying within 5 years of diagnosis. Recently, preclinical and clinical trials have tested gene transfer to increase left ventricular (LV) function, especially in heart failure with reduced ejection fraction.

The National Center for Advancing Translational Sciences and Genetic and Rare Diseases Information Center characterizes Pigmented villonodular synovitis (PVNS) as a rare disease estimated to occur in ~ 5-6 people out of 100,000. This locally invasive tumor most often occurs in younger adults and causes severe damage to joints. The first line of treatment is surgery but at least 50% of patients require multiple surgeries over many years due to re-growth of the tumor.

Control of gene expression is a general approach to treat diseases where there is too much or too little of a gene product. However, while there are many methods which are available to downregulate the expression of messenger RNA transcripts, very few strategies can upregulate the endogenous gene product. The vast majority of gene regulatory drugs which are commercially available or being developed are designed to knockdown gene expression (i.e. siRNAs, miRNAs, anti-sense, etc.). There exist some methods to enhance gene expression, such as the delivery of messenger RNAs; although, therapeutic delivery of such large and charged RNA molecules is technically challenging, inefficient, and may not be practical. There are also classical gene therapy approaches where a gene product is delivered as viral-encoded products (AAV or lentivirus-packaged). However, these methods suffer from not being able to accurately reproduce the correct alternatively spliced isoforms in the right ratios in cells.  

Currently, alleles at multiple loci in the mouse genome must be combined by Mendelian genetics in crosses of animals to one another to produce a desired compound mutant genotype. For example, to combine homozygous mutations at two loci, animals that are heterozygous for each gene must be produced by breeding, and these are subsequently crossed to one another. Since the frequency of homozygosity for each allele is 1:4 the frequency of homozygosity for both genes is 1:16. Since the average litter of mice is approximately 10 pups, and the generation time from conception to reproductive age is about 3 months, this requires a substantial number of animals and time. With the addition of each new locus (three, four, etc), the cost measured in animals, time, and money increases exponentially. These factors increase substantially more if two or more loci are genetically linked, which requires rare recombination events to combine engineered alleles on the same chromosome. The CRISPR-Cas9 gene drive system stands to revolutionize rodent breeding. If each desired allele is encoded as a gene drive element that contains an sgRNA designed to target the same genomic location in the wild type homologous chromosome, each locus will be “driven” to homozygosity in the presence of Cas9. Therefore, in order to combine three alleles, for example, a mouse with one gene drive element (A) would be crossed to a mouse that encodes Cas9. Offspring of this cross would then be crossed to mice carrying gene drive element B, and these offspring would be crossed to mice carrying gene drive element C. In the presence of Cas9 at each generation, these gene drive elements at three distinct loci will be converted to homozygosity such that 50% of offspring, those that inherit Cas9, will be triple homozygous after three generations, even if they are genetically linked loci. A CRISPR-Cas9 mediated gene drive leverages the native cellular mechanism of homology directed repair to copy a desired allele from one chromosome to another. This process can convert a heterozygous genotype to homozygosity in a single generation. While CRISPR-Cas9 gene drives have been implemented in two species of insects, flies and mosquitos, it has not been reported in any non-insect animal species. 

Hematopoietic stem cell (HSC) transplants are used to treat patients with a broad spectrum of hematological malignancies, immune disorders and genetic blood diseases. Unfortunately, even after decades of use and research, there is a significant shortage of histocompatible HSCs available for transplants. Transplanting larger numbers of HSCs increases the likelihood and speed of successful engraftment, which can reduce the risk of complications such as anemia and infection, and more effectively treat underlying disease. The inability to efficiently maintain adult HSCs ex vivo is also a significant barrier for the wider development and implementation of gene therapies for diverse blood diseases and a major obstacle for engineering HSC derived cellular products for immunotherapy. One approach to overcome this challenge is to develop a means to maintain and expand HSCs in culture. Unfortunately, there is no well-defined reproducible means to maintain or expand HSCs. Even short culture times in optimized conditions are deleterious to HSCs. Ex vivo HSC maintenance and expansion could significantly enhance their clinical utility in a wide range of human diseases, providing a new platform for testing drugs, enabling more efficient gene editing within stem cells, and developing into a widely-used tool for the research community.

Gene editing in cells involves the use of sequence-specific nucleases that generate double-strand DNA breaks (DSBs) at specifically targeted sites in the genome. The DSBs are then repaired by non-homologous end joining (NHEJ) or, much less efficiently, by homology directed repair (HDR). In NHEJ, the two free DNA ends are joined together. This commonly results in small DNA deletions or insertions that inactivate the target gene. In HDR, the DSB is repaired by a mechanism that converts the DNA into the specific sequence that is provided by a DNA donor template. Thus, HDR enables genes to be modified or inserted at specifically desired sites.  The main drawback to HDR is the low efficiency of the process.

Cellular therapies are becoming well established within the medical community. However, the degree of cellular activation can be an unknown factor, and the risk of off-target effects remains. Cells may be delivered, but may not be therapeutically effective, or effective cells may elicit activity in an undesired location. The delivery of a cell therapy where a known quantity of cell activation occurs at a specific, selected site may therefore be advantageous. UC San Diego researchers have recently developed the methods and materials for remote control of cellular activation, to dynamically manipulate molecular events for immunotherapeutic effect.

Heart failure is the most common cause of non-elective admission to the hospital in subjects 65 years and older. Despite optimal drug and device therapy, prognosis in heart failure is dismal. Many clinical trials of drugs that increase heart function (“inotropes”) have failed, possibly due to the deleterious effects of agents that increase cAMP. An alternative strategy is to alter myocardial calcium handling or myofilament response to calcium using agents that do not affect cAMP. Expression of a catalytically impaired adenylate cyclase type 6 mutant molecule (AC6mut), one that markedly reduces cAMP production, is associated with normal cardiac function in response to β-adrenergic receptor stimulation. The mechanism is through enhanced effects of AC6mut on Ca2+ handling - effects that do not require cAMP. These data are important in clinical settings for two reasons: 1) the results provide additional insight regarding the interplay between Ca2+ handling and βAR signaling vis-à-vis LV function; and 2) AC6mut may provide inotropic support free from the potentially deleterious effects of increased cAMP.

CAP (Cbl associated protein) is an adapter protein that is ubiquitously expressed. CAP acts in concert with Cbl to stimulate glucose uptake in skeletal muscle and adipose tissue as well as to induce the proliferation and migration of macrophages. Whole body CAP gene deletion in mice results in a protection from insulin resistance induced by high fat diet. However, exercise capacity is severely blunted in these mice.

The ability to capture and study circulating tumor cells is an emerging field with implications for early detection, diagnosis, determining prognosis, and monitoring of cancer, as well as for understanding the fundamental biology of metastasis. Current techniques of identifying and isolating such cells usually involve flowing cells in a chip across an antibody coated surface. However, these devices usually require complex geometries to ensure effective contact of the target cells with the functionalized surfaces. Such a problem can be avoided by using micro/nanoscale motors that can be programmed to scower an entire static sample as many times as needed. Further, the movement of the nano/microscale motor increases the solution convection thereby improving the diffusion of the target antigen, making for a quicker and more favorable recognition reaction. This also helps eliminate non-specific binding of the antigen while on its way to a clean environment for post-capture analysis.

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