Increasing Gene Editing Efficiency via CRISPR/Cas9- or Cas12a-Mediated Knock-In in Primary Human T Cells.

T lymphocytes represent a promising target for genome editing. They are primarily modified to recognize and kill tumor cells or to withstand HIV infection. In most studies, T cell genome editing is performed using the CRISPR/Cas technology. Although this technology is easily programmable and widely accessible, its efficiency of T cell genome editing was initially low. Several crucial improvements were made in the components of the CRISPR/Cas technology and their delivery methods, as well as in the culturing conditions of T cells, before a reasonable editing level suitable for clinical applications was achieved. In this review, we summarize and describe the aforementioned parameters that affect human T cell editing efficiency using the CRISPR/Cas technology, with a special focus on gene knock-in.

Advances of Genome Editing with CRISPR/Cas9 in Neurodegeneration: The Right Path towards Therapy.

The rate of neurodegenerative disorders (NDDs) is rising rapidly as the world's population ages. Conditions such as Alzheimer's disease (AD), Parkinson's disease (PD), and dementia are becoming more prevalent and are now the fourth leading cause of death, following heart disease, cancer, and stroke. Although modern diagnostic techniques for detecting NDDs are varied, scientists are continuously seeking new and improved methods to enable early and precise detection. In addition to that, the present treatment options are limited to symptomatic therapy, which is effective in reducing the progression of neurodegeneration but lacks the ability to target the root cause-progressive loss of neuronal functioning. As a result, medical researchers continue to explore new treatments for these conditions. Here, we present a comprehensive summary of the key features of NDDs and an overview of the underlying mechanisms of neuroimmune dysfunction. Additionally, we dive into the cutting-edge treatment options that gene therapy provides in the quest to treat these disorders.

Factors That Affect the Formation of Chromosomal Translocations in Cells.

Chromosomal translocations are products of the illegitimate repair of DNA double-strand breaks (DSBs). Their formation can bring about significant structural and molecular changes in the cell that can be physiologically and pathologically relevant. The induced changes may lead to serious and life-threatening diseases such as cancer. As a growing body of evidence suggests, the formation of chromosomal translocation is not only affected by the mere close spatial proximity of gene loci as potential translocation partners. Several factors may affect formation of chromosomal translocations, including chromatin motion to the potential sources of DSBs in the cell. While these can be apparently random events, certain chromosomal translocations appear to be cell-type-specific. In this review, we discuss how chromosomal translocations are formed and explore how different cellular factors contribute to their formation.

Engineering T-Cell Resistance to HIV-1 Infection via Knock-In of Peptides from the Heptad Repeat 2 Domain of gp41.

Previous studies suggest that short peptides from the heptad repeat 2 (HR2) domain of gp41 expressed on the cell surface are more potent inhibitors of HIV-1 entry than soluble analogs. However, their therapeutic potential has only been examined using lentiviral vectors. Here, we aimed to develop CRISPR/Cas9-based fusion inhibitory peptide knock-in (KI) technology for the generation and selection of HIV-1-resistant T cells. First, we embedded a series of HIV-1 fusion inhibitory peptides in CD52, the shortest glycosylphosphatidylinositol (GPI)-anchored protein, which efficiently delivers epitope tags to the cell surface and maintains a sufficient level of KI. Among the seven peptides tested, MT-C34, HP-23L, and 2P23 exhibited significant activity against both cell-free and cell-to-cell HIV-1 infection. The shed variant of MT-C34 provided insufficient protection against HIV-1 due to its low concentration in the culture medium. Using Cas9 plasmids or ribonucleoprotein electroporation and peptide-specific antibodies, we sorted CEM/R5 cells with biallelic KI of MT-C34 and 2P23 peptides at the CXCR4 locus. In combination, these peptides provided a higher level of protection than individual KI. By extending homology arms and cloning donor DNA into a plasmid containing signals for nuclear localization, we achieved KI of MT-C34 into the CXCR4 locus and HIV-1 proviral DNA at levels of up to 35% in the T-cell line and up to 4 to 5% in primary CD4 lymphocytes. Compared to lentiviral delivery, KI resulted in the higher MT-C34 surface expression and stronger protection of lymphocytes from HIV-1. Thus, we demonstrate that KI is a viable strategy for peptide-based therapy of HIV infection. IMPORTANCE HIV is a human lentivirus that infects CD4-positive immune cells and, when left untreated, manifests in the fatal disease known as AIDS. Antiretroviral therapy (ART) does not lead to viral clearance, and HIV persists in the organism as a latent provirus. One way to control infection is to increase the population of HIV-resistant CD4 lymphocytes via entry molecule knockout or expression of different antiviral genes. Peptides from the heptad repeat (HR) domain of gp41 are potent inhibitors of HIV-1 fusion, especially when designed to express on the cell surface. Individual gp41 peptides encoded by therapeutic lentiviral vectors have been evaluated and some have entered clinical trials. However, a CRISPR/Cas9-based gp41 peptide delivery platform that operates through concomitant target gene modification has not yet been developed due to low knock-in (KI) rates in primary cells. Here, we systematically evaluated the antiviral activity of different HR2 peptides cloned into the shortest carrier molecule, CD52. The resulting small-size transgene constructs encoding selected peptides, in combination with improvements to enhance donor vector nuclear import, helped to overcome precise editing restrictions in CD4 lymphocytes. Using KI into CXCR4, we demonstrated different options for target gene modification, effectively protecting edited cells against HIV-1.

A gel-less isolation of untagged plasmid DNA insert from vector backbone in homogeneous format.

Agarose gel electrophoresis with subsequent DNA extraction from gel is routinely used for DNA fragment isolation after plasmid DNA digestion. We describe a gel-less method for DNA fragment isolation after plasmid DNA digestion which is based on in-solution negative selection through depletion of vector backbone bearing LoxP sites by sorption on solid phase-immobilized mutated Cre recombinase. The method might be especially useful in preparation of DNA fragments for transgenic animal generation where residual agarose presence is a concern, and DNA fragments are frequently large in size and thus might be mechanically damaged during purification with conventional affinity-based gel extraction methods.

hTERT and BIRC5 gene promoters for cancer gene therapy: A comparative study.

Human telomerase reverse transcriptase (hTERT) and survivin (BIRC5) gene promoters are frequently used for transcriptional targeting of tumor cells, yet there is no comprehensive comparative analysis allowing rational choice of a promoter for a particular therapy. In the current study, the transcriptional activity of hTERT, human BIRC5 and mouse Birc5 promoters and their modifications were compared in 10 human cancer cell lines using the luciferase reporter gene activity assay. The results revealed that BIRC5- and hTERT-based promoters had strikingly different cell specificities with comparable activities in only 40% of cell lines. Importantly, relative hTERT and BIRC5 transcript abundance cannot be used to predict the most potent promoter. Among the hTERT-based promoters that were assessed, modification with the minimal cytomegalovirus promoter generally resulted in the most potent activity. Mouse Birc5 and modified human BIRC5 promoters were superior to the unmodified human survivin promoter; however, their tumor specificities must be investigated further. In summary, the present results emphasize the desirability for construction of more universal tumor-specific promoters to efficiently target a wide spectrum of tumor cells.

LY294002 enhances expression of proteins encoded by recombinant replication-defective adenoviruses via mTOR- and non-mTOR-dependent mechanisms.

Adenovirus-based drugs are efficient when combined with other anticancer treatments. Here we show that treatment with LY294002 and LY303511 upregulates expression of recombinant proteins encoded by replication-defective adenoviruses, including expression of therapeutically valuable combination of herpes simplex virus thymidine kinase controlled by human telomerase reverse transcriptase promoter (Ad-hTERT-HSVtk). In line with this, treatment with LY294002 synergized with Ad-hTERT-HSVtk infection in the presence of gancyclovir prodrug on Calu-I lung cancer cell death. The effect of LY294002 and LY303511 on adenovirus-delivered transgene expression was demonstrated in 4 human lung cancer cell lines. LY294002-induced upregulation of adenovirally delivered transgene is mediated in part by direct inhibition of mTOR protein kinase in mTORC2 signaling complex thus suggesting that anticancer drugs targeting mTOR will also enhance expression of transgenes delivered with adenoviral vectors. As both LY294002 and LY303511 are candidate prototypic anticancer drugs, and many mTOR inhibitors for cancer treatment are under development, our results have important implication for development of future therapeutic strategies with adenoviral gene delivery.

The RHOV gene is overexpressed in human non-small cell lung cancer.

Rho family GTPases act as molecular switches to regulate numerous cellular processes, including malignant transformation. Commonly, overexpression of Rho GTPases contributes to tumorigenesis. Elevated expression of several Rho GTPases has been reported in lung cancer and is associated with poor prognosis. The RHOV gene encodes the atypical Rho family GTPase Chp/RhoV, which is capable of transforming fibroblasts, although other functions of Chp remain largely elusive. RHOV is expressed in normal lung tissue in rats, but not in humans. RHOV expression was found in several human cancer cell lines, including non-small-cell lung cancer (NSCLC) cell line A549, but expression of RHOV in NSCLC tumors has never been investigated. Here we studied the expression of the RHOV gene in lung cancer cell lines and in 29 matched pairs of NSCLC tumors and adjacent nontumorous tissues. We found that RHOV is expressed in lung cancer cell lines and is upregulated in the majority of studied lung tumors. Analysis of the Oncomine database revealed correlation between elevated RHOV level and poor patient survival. We propose that the RHOV gene could be validated as a diagnostic or prognostic marker for NSCLC, and that observed overexpression of RHOV might contribute to tumorigenesis.

Rho family GTPase Chp/RhoV induces PC12 apoptotic cell death via JNK activation.

Rho GTPases regulate numerous cellular processes including apoptosis. Chp/RhoV is an atypical Rho GTPase which functions are poorly understood. Here we investigated the role of Chp in regulation of cell viability using PC12 cells with inducible expression of Chp as a model. We found that expression of Chp results in apoptosis in PC12 cells. Chp-induced apoptosis was accompanied by activation of JNK signaling and both death receptor-mediated and mitochondrial apoptotic pathways as justified by caspase-8 and caspase-9 activation, respectively. Moreover, inhibition of JNK by SP600125 rescued PC12 cells from Chp-triggered cell death and attenuated activation of caspases-9 and -3/7 suggesting that activation of JNK mediates pro-apoptotic effect of Chp. Expression of Chp resulted in increased phosphorylation of c-Jun in PC12 cells, and Chp expression in HE K293 cells upregulated AP-1-dependent transcription in a JNK-dependent manner. Together results of our study reveal the role of Chp GTPase as a putative regulator of JNK-dependent apoptotic death in PC12 cells, similarly to previously described pro-apoptotic activity of the related Cdc42 and Rac1 GTPases.

The genetics of Pak.

p21-activated kinases (Paks) are a highly conserved family of enzymes that bind to and are activated by small GTPases of the Cdc42 and Rac families. With the notable exception of plants, nearly all eukaryotes encode one or more Pak genes, indicating an ancient origin and important function for this family of enzymes. Genetic approaches in many different experimental systems, ranging from yeast to mice, are beginning to decipher the different functions of Paks. Although some of these functions are unique to a given organism, certain common themes have emerged, such as the activation of mitogen-activated protein kinase (MAPK) cascades and the regulation of cytoskeletal structure through effects on the actin and tubulin cytoskeletons.