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Biomedical subjects

Johan Jakobsson

Publications and source records attributed to Johan Jakobsson.

9 recordsLinked to original sources
PubMed2026

Activation of transposable elements is linked to a region- and cell type-specific interferon response in Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder involving a neuroinflammatory response, the cause of which remains unclear. Transposable elements (TEs) have been linked to inflammation, but their potential role in PD remains unexplored. Using bulk- and single-nuclei RNA-seq of postmortem brain tissue from four brain regions, we studied TE transcription and its correlation with PD neuroinflammation. Over a thousand TEs, including LINE-1 s and ERVs, were expressed in a cell type- and region-specific manner in the human brain. Increased TE expression was found in microglia and neurons in the substantia nigra and putamen of PD brains, but not amygdala or prefrontal cortex, compared to controls. This TE activation correlated with an innate immune response in the same brain regions. The link between an interferon response and TE activation was mechanistically confirmed using human pluripotent stem cell-derived microglia and neurons. Our findings provide insights into TE transcription in the PD brain and suggest that TEs may contribute to neuroinflammation and pathological progression in PD.

Humans↗
PubMed2006

Lentiviral vectors for use in the central nervous system.

Lentiviral vectors have been used extensively as gene transfer tools for the central nervous system throughout the past decade since they transduce most cell types in the brain, resulting in high-level and long-term transgene expression. This review discusses some of the recent progress in this field, including preclinical gene therapy experiments in disease models, development of regulated vectors, and the application of siRNA's using lentiviral vectors. We also describe some of the features that make lentiviral vectors a likely candidate for human gene therapy in the brain.

Animals↗
PubMed2006

Evidence for disease-regulated transgene expression in the brain with use of lentiviral vectors.

In this study we have developed and validated a novel approach of transgene regulation in the brain. By using lentiviral vectors that incorporate promoters of genes that are up-regulated during different pathological states, we were able to regulate transgene expression in accordance with the disease process. When using a glial fibrillary acidic protein promoter, efficient disease regulation in glial cells was achieved after an excitotoxic lesion or a 6-hydroxydopamine (6-OHDA) lesion. Transgene expression was physiologically regulated and displayed a dose-dependent increase depending on the severity of lesion. Efficient regulation was also achieved in neurons when using a preproenkephlin promoter in 6-OHDA-lesioned rats, allowing combined regulation and targeting. This disease-regulated approach allows control of transgene expression in the brain without the use of inducer molecules and without overexpression of transactivator proteins.

Animals↗
PubMed2005

Inhibition of chromatin condensation prevents transgene silencing in a neural progenitor cell line transplanted to the rat brain.

The use of ex vivo gene therapy in the central nervous system has so far suffered from transgene downregulation. Condensation of the transgenic sequences has been proposed to be a mechanism involved in this silencing. In this study we inhibited either histone deacetylation or DNA methylation in neural progenitor cell lines, transduced with a lentiviral vector carrying green fluorescent protein (GFP), prior to grafting them into the rat striatum. The expression of GFP was significantly higher in grafts pretreated with either of the inhibitors. After 1 week in vivo we detected an 11-fold increase in the number of GFP-expressing cells due to the inhibition of DNA methylation in vitro with azadeoxycytidine and a ninefold increase when inhibiting histone deacetylation with trichostatin A. This suggests that a pretreatment paradigm could be used to increase efficacy of ex vivo delivery of a therapeutic protein locally in the brain.

Animals↗
PubMed2004

Dynamics of transgene expression in a neural stem cell line transduced with lentiviral vectors incorporating the cHS4 insulator.

Transplantation of genetically manipulated cells to the central nervous system holds great promise for the treatment of several severe neurological disorders. The success of this strategy relies on sufficient levels of transgene expression after transplantation. This has been difficult to achieve, however, due to transgene silencing. In this study, we transduced the neural stem cell line RN33B with self-inactivating lentiviral vectors and analyzed transgenic expression of green fluorescent protein (GFP) in several different settings both in vitro and after transplantation to the brain. We found that the transgene was affected of silencing both when transduced cells were proliferating and after differentiation. To prevent silencing, the cHS4 insulator was incorporated into the lentiviral vector. We found that a vector carrying the cHS4 insulator was partially protected against differentiation-dependent downregulation in vitro and in vivo. However, in proliferating cells, we found evidence for variegation and positional effects that were not prevented by the cHS4 insulator, suggesting that the mechanism behind silencing in proliferating cells is not the same mechanism influencing differentiation-dependent silencing. Taken together, these findings favor vector optimization as a strategy for achieving efficient ex vivo gene transfer in the central nervous system.

Animals↗
PubMed2004

Regulated delivery of glial cell line-derived neurotrophic factor into rat striatum, using a tetracycline-dependent lentiviral vector.

In this study, a tetracycline-regulated lentiviral vector system, based on the tetracycline-dependent transactivator rtTA2(S)-M2, was developed for controlled expression of glial cell line-derived neurotrophic factor (GDNF) in the rat brain. Expression of the marker gene green fluorescent protein (GFP) and GDNF was tightly regulated in a dose-dependent manner in neural cell lines in vitro. Injection of high-titer lentiviral vectors into the rat striatum resulted in a 7-fold induction of GDNF tissue levels (1060 pg/mg tissue), when doxycycline (a tetracycline analog) was added to the drinking water. However, low levels of GDNF (150 pg/mg tissue) were also detected in animals that did not receive doxycycline, indicating a significant background leakage from the vector system in vivo. The level of basal expression was markedly reduced when a 10-fold lower dose of the tetracycline-regulated GDNF vector was injected into the striatum (3-11 pg/mg tissue), and doxycycline-induced GDNF tissue levels obtained in these animals were about 190 pg/mg tissue. Doxycycline-induced expression of GDNF resulted in a significant downregulation of the tyrosine hydroxylase (TH) protein in the intact striatum. Removal of doxycycline from the drinking water rapidly (within 3 days) turned off transgenic GDNF mRNA expression and GDNF protein levels in the tissue were completely reduced by 2 weeks, demonstrating the dynamics of the system in vivo. Accordingly, TH protein expression returned to normal by 2-8 weeks after removal of doxycycline, indicating that GDNF-induced downregulation of TH is a reversible event.

Animals↗
PubMed2004

Lesion-dependent regulation of transgene expression in the rat brain using a human glial fibrillary acidic protein-lentiviral vector.

The ability to regulate transgene expression will be crucial for development of gene therapy to the brain. The most commonly used systems are based on a transactivator in combination with a drug, e.g. the tetracycline-regulated system. Here we describe a different method of transgene regulation by the use of the human glial fibrillary acidic protein (GFAP) promoter. We constructed a lentiviral vector that directs transgene expression to astrocytes. Using toxin-induced lesions we investigated to what extent transgene expression could be regulated in accordance with the activation of the endogenous GFAP gene. In animals receiving excitotoxic lesions of the striatum we detected an eightfold increase of green fluorescent protein (GFP)-expressing cells. The vast majority of these cells did not divide, suggesting that the transgene was indeed regulated in a similar fashion as the endogenous GFAP gene. This finding will lead to the development of lentiviral vectors with autoregulatory capacities that may be very useful for gene therapy to the brain.

Animals↗
PubMed2003

Targeted transgene expression in rat brain using lentiviral vectors.

Direct gene transfer to the adult brain is dependent on vectors that transduce non-dividing cells, such as lentiviral vectors. Another aspect of the development of gene therapy to the brain is the need for cell-specific transgene expression. Expression from vesicular stomatitis virus G-protein (VSV-G) pseudotyped lentiviral vectors has been reported to be mainly neuron specific in the brain. We constructed cell-specific lentiviral vectors using the neuron-specific enolase (rNSE) or the glial fibrillary acidic protein (hGFAP) promoters and compared them to the ubiquitous human cytomegalovirus promoter (hCMV), a hybrid CMV/beta-actin promoter (CAG) and the promoter for human elongation factor 1 alpha (EF1 alpha). Our results showed that the hGFAP promoter was expressed only in glial cells, whereas rNSE was purely neuron specific, showing that VSV-G is pantropic in the rat striatum. We conclude that the VSV-G allows transduction of both glial and neuronal cells and the promoter dictates in what cell type the transgene will be expressed. The expression of transgenes exclusively in astrocytes would allow for local delivery of secreted transgene products, such as glial cell line-derived neurotrophic factor (GDNF), circumventing the anterograde transport that may induce unwanted side effects.

Analysis of Variance↗