Overexpression of 5-methylcytosine DNA glycosylase in human embryonic kidney cells EcR293 demethylates the promoter of a hormone-regulated reporter gene

We have shown that the DNA demethylation complex isolated from chicken embryos has a G(.)T mismatch DNA glycosylase that also possesses 5-methylcytosine DNA glycosylase (5-MCDG) activity. Herein we show that human embryonic kidney cells stably transfected with 5-MCDG cDNA linked to a cytomegalovirus promoter overexpress 5-MCDG. A 15- to 20-fold overexpression of 5-MCDG results in the specific demethylation of a stably integrated ecdysone-retinoic acid responsive enhancer-promoter linked to a beta-galactosidase reporter gene. Demethylation occurs in the absence of the ligand ponasterone A (an analogue of ecdysone). The state of methylation of the transgene was investigated by Southern blot analysis and by the bisulfite genomic sequencing reaction. Demethylation occurs downstream of the hormone response elements. No genome-wide demethylation was observed. The expression of an inactive mutant of 5-MCDG or the empty vector does not elicit any demethylation of the promoter-enhancer of the reporter gene. An increase in 5-MCDG activity does not influence the activity of DNA methyltransferase(s) when tested in vitro with a hemimethylated substrate. There is no change in the transgene copy number during selection of the clones with antibiotics. Immunoprecipitation combined with Western blot analysis showed that an antibody directed against 5-MCDG precipitates a complex containing the retinoid X receptor alpha. The association between retinoid receptor and 5-MCDG is not ligand dependent. These results suggest that a complex of the hormone receptor with 5-MCDG may target demethylation of the transgene in this system.

Targeted overexpression of IGF-I in smooth muscle cells of transgenic mice enhances neointimal formation through increased proliferation and cell migration after intraarterial injury

The response of arterial smooth muscle cells to injury is governed by a complex series of events. Significant among them is the paracrine production of peptide growth factors. To determine the impact of local IGF-I gene expression on vascular injury, the left carotid arteries of SMP8-IGF-I mice (in which IGF-I is selectively overexpressed in smooth muscle cells by means of a smooth muscle alpha-actin promoter) and wild-type controls were injured mechanically with an epon resin probe. After 7 and 14 d, a progressive increase in medial area was seen in both SMP8-IGF-I and wild-type mice, but they were not significantly different from each other. However, by 14 d there was a more than 4-fold increase in neointimal area in transgenic vs. wild-type. The intima/media ratios were also strikingly increased at 14 d in the IGF-I-overexpressing animals. The mitotic index, determined in animals injected daily with bromodeoxyuridine for 3 d before death, was markedly elevated in both the media and neointima 7 d after injury in SMP8-IGF-I mice, but the effect had subsided by 14 d. Despite a higher rate of cell division, the relative increase in medial area was less in the SMP8-IGF-I mice than in wild-type mice at both 7 and 14 d, consistent with a stimulation of cell migration to the neointima. The experiments reported here provide compelling evidence that paracrine expression of IGF-I is a powerful stimulus for smooth muscle cell proliferation and migration in vivo.

Total synthesis of epothilone A

[reaction: see text]Epothilones A (1) and B (2) are potent antitumor natural products with a Taxol-like mechanism of action. A total synthesis of epothilone A (1) is reported, which utilized chiral silane-based bond construction methodology to introduce the key C-6 and C-7 stereocenters of fragment 4. The C-15 stereocenter of fragment 5 was established by a lipase-mediated kinetic resolution. The fragments were assembled with a Suzuki coupling reaction and an aldol condensation and cyclized with a Yamaguchi-type macrolactonization reaction.

A head-to-head comparison of ixekizumab vs. guselkumab in patients with moderate-to-severe plaque psoriasis: 24-week efficacy and safety results from a randomized, double-blinded trial

Background

Significantly more patients with moderate‐to‐severe plaque psoriasis treated with the interleukin (IL)‐17A inhibitor ixekizumab vs. the IL‐23p19 inhibitor guselkumab in the IXORA‐R head‐to‐head trial achieved 100% improvement in Psoriasis Area and Severity Index (PASI 100) at week 12.

Objectives

To compare skin and nail clearance and patient‐reported outcomes for ixekizumab vs. guselkumab, up to week 24.

Methods

IXORA‐R enrolled adults with moderate‐to‐severe plaque psoriasis, defined as static Physician’s Global Assessment ≥ 3, PASI ≥ 12 and involved body surface area ≥ 10%. Statistical comparisons were performed using the Cochran–Mantel–Haenszel test stratified by pooled site. Time‐to‐first‐event comparisons were performed using Kaplan–Meier analysis, and P‐values were generated using adjusted log‐rank tests stratified by treatment group. Cumulative days at clinical and patient‐reported responses were compared by ancova. The trial was registered with ClinicalTrials.gov (NCT03573323).

Results

Of the 1027 patients randomly assigned, 90% completed the trial (465 of 520 ixekizumab and 459 of 507 guselkumab). As early as week 2 and through week 16, more patients on ixekizumab achieved PASI 100 (P < 0·01). At week 24, ixekizumab was noninferior to guselkumab (50% vs. 52%, difference −2·3%), with no statistically significant difference in PASI 100 (P = 0·41). More patients receiving ixekizumab showed completely clear nails at week 24 (52% vs. 31%, P = 0·007). The median time to first PASI 50/75/90 and PASI 100 were 2 and 7·5 weeks shorter, respectively, for patients on ixekizumab vs. guselkumab (P < 0·001). Patients on ixekizumab also had a greater cumulative benefit, with more days at PASI 90 and 100, with Dermatology Life Quality Index of 0 or 1, and itch free (P < 0·05). The frequency of serious adverse events was 3% for each group, with no new safety signals.

Conclusions

Ixekizumab was noninferior to guselkumab in complete skin clearance and superior in clearing nails at week 24. Ixekizumab cleared skin more rapidly in patients with moderate‐to‐severe plaque psoriasis, with a greater cumulative benefit, than guselkumab. Overall, the safety findings were consistent with the known safety profile for ixekizumab.

What is already known about this topic?

Patients with plaque psoriasis desire both high levels of clearance and rapid onset of treatment effects.

Ixekizumab is a high‐affinity monoclonal antibody that selectively targets interleukin (IL)‐17A.

In the 12‐week report of the IXORA‐R study, ixekizumab demonstrated significantly higher efficacy at early timepoints than the IL‐23p19 inhibitor guselkumab, with more patients achieving 100% improvement in Psoriasis Area and Severity Index (PASI 100) and improved quality of life as early as week 4.

What does this study add?

Patients on ixekizumab vs. guselkumab achieved similar levels of skin clearance and superior efficacy in the resolution of nail psoriasis at week 24.

Patients on ixekizumab vs. guselkumab had a greater cumulative benefit, with more days at PASI 90 and 100, more days when psoriasis did not impact their quality of life, and more itch‐free days.

The safety profiles of both drugs were consistent with those in previous studies.

Linked Comment: Puig. Br J Dermatol 2021; 184:992–993.

A highly selective surface coating for enhanced membrane rejection of endocrine disrupting compounds: Mechanistic insights and implications

We designed a highly selective surface coating to achieve enhanced rejection of endocrine disrupting compounds (EDCs) by nanofiltration membranes. A commercial NF90 membrane was first coated with polydopamine (PDA) followed by in situ immobilization of silver nanoparticles (AgNPs). This PDA/AgNPs coating greatly improved EDC rejection at the expense of slight water permeability loss (4-10%). This improvement in rejection can be attributed to a combination of enhanced size exclusion and suppressed hydrophobic interaction. A resistance-in-series analysis further reveals that the coating was highly permeable to water but highly resistant to EDCs, leading to an EDC selectivity that was an order of magnitude greater than those of the bare PDA coating and the base membrane NF90. The current study provides important insights into the design of highly selective coatings for effective retention of targeted trace organic contaminants.

Inhibition of tumorigenesis by intratumoral delivery of the circadian gene mPer2 in C57BL/6 mice

Biological clocks are intrinsic time-keeping systems that regulate behavior and physiological functions in most living organisms. Previous works suggested a possible link between the endogenous circadian clock and cell cycle regulation. The mammalian Period-2 gene (mPer2), an important component of the circadian clock mechanism, is recently demonstrated to play an important role in repressing tumor growth. In this study, we found that polyethylenimine-mediated intratumoral Per2 gene delivery had significant antitumor effects in C57BL/6 mice transplanted with Lewis lung carcinoma. Our data illustrated that the Per2 gene delivery inhibited PCNA expression and induced apoptosis. Our results support the emerging role of the circadian clock in critical aspects of tumorigenesis. These findings underscore the potential use of Per2 gene delivery as a novel therapeutic intervention for the treatment of malignant tumors.

Assessment of cytochrome P450 activity by a five-drug cocktail approach

OBJECTIVES

Our goal was to establish and validate a modified cocktail approach including probe drugs caffeine, chlorzoxazone, mephenytoin, metoprolol, and midazolam for simultaneous phenotyping of CYP1A2, CYP2E1, CYP2C19, CYP2D6, and CYP3A.

METHODS

The study was conducted in 14 healthy, nonsmoking male volunteers with a cocktail of 5 drugs consisting of 100 mg caffeine, 200 mg chlorzoxazone, 100 mg mephenytoin, 100 mg metoprolol, and 7.5 mg midazolam in a randomized manner with a 7 x 7 Latin square design. Plasma was obtained at 1, 4, and 6 hours, and urine was collected from 0 to 8 hours after oral drug administration.

RESULTS

The phenotypic indexes determined for caffeine, chlorzoxazone, mephenytoin, metoprolol, and midazolam were not significantly different when the drugs were given in different combinations. There were no metabolic interactions or analytic interference of these probe drugs.

CONCLUSIONS

This cocktail approach can simultaneously provide independent in vivo phenotypic measures for the cytochrome P450 (CYP) enzymes CYP1A2, CYP2E1, CYP2C19, CYP2D6, and CYP3A.

Boosting the signal-to-noise of low-field MRI with deep learning image reconstruction

Recent years have seen a resurgence of interest in inexpensive low magnetic field (< 0.3 T) MRI systems mainly due to advances in magnet, coil and gradient set designs. Most of these advances have focused on improving hardware and signal acquisition strategies, and far less on the use of advanced image reconstruction methods to improve attainable image quality at low field. We describe here the use of our end-to-end deep neural network approach (AUTOMAP) to improve the image quality of highly noise-corrupted low-field MRI data. We compare the performance of this approach to two additional state-of-the-art denoising pipelines. We find that AUTOMAP improves image reconstruction of data acquired on two very different low-field MRI systems: human brain data acquired at 6.5 mT, and plant root data acquired at 47 mT, demonstrating SNR gains above Fourier reconstruction by factors of 1.5- to 4.5-fold, and 3-fold, respectively. In these applications, AUTOMAP outperformed two different contemporary image-based denoising algorithms, and suppressed noise-like spike artifacts in the reconstructed images. The impact of domain-specific training corpora on the reconstruction performance is discussed. The AUTOMAP approach to image reconstruction will enable significant image quality improvements at low-field, especially in highly noise-corrupted environments.

Apolipoprotein E inhibits neointimal hyperplasia after arterial injury in mice

The potential cytostatic function of apolipoprotein (apo) E in vivo was explored by measuring neointimal hyperplasia in response to vascular injury in apoE-deficient and apoE-overexpressing transgenic mice. Results showed a significant increase in medial thickness, medial area, and neointimal formation after vascular injury in both apoE knockout and wild-type C57BL/6 mice. Immunochemical analysis with smooth muscle alpha-actin-specific antibodies revealed that the neointima contained proliferating smooth muscle cells. Neointimal area was 3.4-fold greater, and the intima/medial ratio as well as stenotic luminal area was more pronounced in apoE(-/-) mice than those observed in control mice (P < 0.05). The human apoE3 transgenic mice in FVB/N genetic background were then used to verify a direct effect of apoE in protection against neointimal hyperplasia in response to mechanically induced vascular injury. Results showed that neointimal area was reduced threefold to fourfold in mice overexpressing the human apoE3 transgene (P < 0.05). Importantly, suppression of neointimal formation in the apoE transgenic mice also abolished the luminal stenosis observed in their nontransgenic FVB/N counterparts. These results documented a direct role of apoE in modulating vascular response to injury, suggesting that increasing apoE level may be beneficial in protection against restenosis after vascular surgery.

FasL promoter activation by IL-2 through SP1 and NFAT but not Egr-2 and Egr-3

Recently activated peripheral T cells treated with IL-2 for 4 days expressed Fas ligand (FasL)-mediated cytotoxicity. These IL-2-treated T cells had high nuclear expression of SP1 and NFAT, but lacked the Egr-2 and Egr-3 that could be induced by anti-CD3 stimulation and had been implicated in FasL gene activation. A minimal promoter region that responded to IL-2 was identified by transient transfection assays using deletion mutants. The data suggests that the GGGCGGAAA site present in the 5' end of the minimal FasL promoter is critical to IL-2-induced FasL gene activation. The GGGCGGAAA sequence contains an overlapping site used by two transcription factor families, one (GGGCGG) for the SP1 family and the other (GGAAA) for the NFAT family. FasL promoter activity was partially but statistically significantly reduced with constructs mutated at either site. More activity was lost with a construct mutated at both sites. In contrast, mutation at the Egr site had no effect on IL-2-induced FasL promoter activity. Our study identified a new FasL promoter site responding to IL-2-induced SP1 and NFAT factors. Furthermore, the nuclei of IL-2-treated cells express SP1 and NFAT, but not Egr-2 and Egr-3, for FasL gene activation.

Cardiorespiratory, hormonal and haematological responses to submaximal cycling performed 2 days after eccentric or concentric exercise bouts

Eccentric muscle actions are known to induce delayed-onset muscle soreness (DOMS) and muscle weakness (reduced static strength and dynamic peak power output) that may persist for several days. The aim of the present study was to determine whether DOMS-inducing exercise affects physiological responses to subsequent submaximal dynamic exercise. Physiological and metabolic responses to a standardized exercise task were measured 2 days after the performance of an eccentric or concentric exercise bout. Six healthy, untrained male subjects aged 30 +/- 7 years (mean +/- S.D.) performed repeated eccentric contractions during 30 min of bench stepping (47-cm step, 15 steps min-1). On another occasion, they performed concentric contractions by walking uphill (8% incline) for 30 min at 5 km h-1, which elicited a similar heart rate response to bench stepping. Two days after the eccentric or concentric exercise, the subjects cycled for 15 min on an electrically braked cycle ergometer at a work rate (172 +/- 37 W) equivalent to 80% VO2 max. The order of the preceding treatments was randomized and the treatments were carried out 2 weeks apart. Two days after the eccentric exercise, all subjects reported leg muscle soreness and exhibited elevated levels of serum creatine kinase activity (P < 0.01) and plasma cortisol concentration (P < 0.05). After uphill walking, the subjects were not sore and serum creatine kinase activity was unchanged. Minute volume, breathing frequency, respiratory exchange ratio, heart rate, rating of perceived exertion, venous blood lactate concentration and plasma cortisol concentration were all higher (P < 0.05) during cycling after eccentric exercise compared with after uphill walking. Increases in plasma catecholamine concentrations and numbers of circulating leucocytes after cycling at 80% VO2 max for 15 min were similar under both experimental conditions, but the delayed leucocytosis (at 150 min post-exercise) was significantly greater (P < 0.01) for the post-eccentric exercise condition. We conclude that dynamic submaximal exercise performed 2 days following exercise with a large eccentric component produces physiological responses that are indicative of a higher relative exercise stress. It is likely that such effects will significantly limit the level and duration of exercise that can be achieved in subsequent training bouts over several days.

COMT rs4680 Met is not always the 'smart allele': Val allele is associated with better working memory and larger hippocampal volume in healthy Chinese

Catechol-O-methyltransferase (COMT) Val158Met (rs4680) polymorphism plays a crucial role in regulating brain dopamine level. Converging evidence from Caucasian samples showed that, compared with rs4680 Val allele, the Met allele was linked to lower COMT activity, which in turn was linked to better cognitive performance such as working memory (WM) and to a larger hippocampus (a brain region important for WM). However, some behavioral studies have shown that the function of rs4680 appears to vary across different ethnic groups, with Chinese subjects showing an opposite pattern as that for Caucasians (i.e. the Val allele is linked to better cognitive functions related to WM in Chinese). Using a sample of healthy Han Chinese college students (ages from 19 to 21 years), this study investigated the association of COMT Val158Met genotype with behavioral data on a two-back WM task (n = 443, 189M/254F) and T1 MRI data (n = 320, 134M/186F). Results showed that, compared to the Met allele, the Val allele was associated with larger hippocampal volume (the right hippocampus: β = -0.118, t = -2.367, P = 0.019, and the left hippocampus: β = -0.099, t = -1.949, P = 0.052) and better WM performance (β = -0.110, t = -2.315, P = 0.021). These results add to the growing literature on differentiated effects of COMT rs4680 polymorphism on WM across populations and offer a brain structural mechanism for such population-specific genetic effects.

An early stage mechanism of the age-associated mitochondrial dysfunction in the brain of SAMP8 mice; an age-associated neurodegeneration animal model

In order to characterize the early stage of mitochondrial dysfunction, we investigated the redox state and oxidative phosphorylation of the brain mitochondria from 2-month-old Senescence-accelerated mouse (SAM)P8 and SAMR1 mice; SAMP8 mice exhibit various signs of age-associated neurodegeneration and rapid mitochondrial dysfunction, although SAMR1 mice do not. The redox state was estimated as the reduction rate of Cu-pyruvaldehyde-bis (N4-methylthiosemicarbazone) (Cu-PTSM), the reduction of which is closely related to the electron leakage from the mitochondrial electron transport system in the brain, using electron spin resonance spectrometry (ESRS). The oxidative phosphorylation was measured polarographically. The SAMP8 mouse brain mitochondria demonstrated higher redox state and a higher activity of mitochondrial respiration with lower respiration control ratio than the mitochondria of SAMR1 mouse brains. This indicates that an inefficient hyperactive state can exist in the mitochondrial electron transport system before the age-associated mitochondrial dysfunction develops.

Itching is a significant problem and a mediator between disease severity and quality of life for patients with psoriasis: results from a randomized controlled trial

BACKGROUND

In patients with moderate-to-severe psoriasis, health-related quality of life (HRQOL) has been shown to improve in parallel with improvement in disease severity.

OBJECTIVES

To evaluate the role of pruritus (itch) in mediating the relationship between improvements in disease severity and HRQOL.

METHODS

Data from a phase 2 clinical trial, in which 142 patients with moderate-to-severe plaque psoriasis received ixekizumab or placebo, were used for this posthoc analysis. Relationships between improvement in Psoriasis Area and Severity Index (PASI), Itch Visual Analogue Scale (VAS) and Dermatology Life Quality Index (DLQI), as well as in individual DLQI domains (symptoms and feelings, treatment, work and school, daily activities, leisure, and personal relationships) from baseline to week 16 were determined. Multiple hierarchical linear regressions and Sobel tests were conducted to evaluate the results.

RESULTS

Improvement in PASI was highly correlated with pruritus improvement and improvements in DLQI total and domain scores at week 16 (P < 0·01). Multiple hierarchical linear regression analyses showed a statistically significant (P < 0·01) association between improvement in pruritus and improvement in DLQI total score and each of the six DLQI domain scores after adjusting for improvement in PASI. Sobel tests indicated that pruritus had a significant mediation effect (P < 0·05) on the association of PASI improvement with improvement in DLQI total score and all domains except the personal relationships score.

CONCLUSIONS

Pruritus appears to be an important mediator of the association between improvements in disease severity and HRQOL in patients with moderate-to-severe psoriasis.

Effect of paternal heat stress on the development in vitro of preimplantation embryos in the mouse

This study was conducted to investigate the effects of paternal heat stress on the development in vitro of preimplantation embryos in the mouse. Female C57/CBA mice were superovulated using eCG/hCG and mated either to an untreated (control) male mouse or to one that had been exposed for 24 h to an ambient temperature of 36 +/- 0.1 degrees C and 62 +/- 0.4% relative humidity, between 3 and 42 days previously. Putative zygotes were collected from the oviducts of mated mice, 25-28 h after hCG injection, and cultured in vitro. Embryo development was evaluated at 24-h intervals for up to 120 h. Paternal heat stress significantly reduced the proportion of embryos that developed normally during 24-120 h of in vitro culture, when zygotes were sired by males which had been heat stressed between 7 and 35 days prior to mating. Maximum impairment to development (including nondevelopment, abnormal and dying/dead embryos) occurred in those embryos sired by males at days 14 and 21 after heating. Embryo development returned to control levels by day 42 after heat stress. Furthermore, whilst all stages of embryo development were affected by paternal heat stress, the proportion of embryos at the two-cell stage appeared to be most severely affected. Four-cell to morula stages and the morula to blastocyst stage also demonstrated impairment at days 14, 21, 28 and 35 after heating. These results demonstrate that a single episode of paternal heat stress significantly reduces the development of preimplantation embryos, and this is not recovered until day 42 after heating. The present results also support previous work demonstrating that sperm from the epididymis as well as germ cells in the testis are susceptible to damage by heat stress, with both spermatids and spermatocytes being the most vulnerable.

Treatment with BBB022A or rolipram stabilizes the blood-brain barrier in experimental autoimmune encephalomyelitis: an additional mechanism for the therapeutic effect of type IV phosphodiesterase inhibitors

We examined the treatment effects of two structurally distinct phosphodiesterase type IV (PDE IV) inhibitors, BBB022 and rolipram, in murine and rat models of experimental autoimmune encephalomyelitis (EAE). Based on our data, we propose a mechanism of action which may supplement immunomodulatory effects of PDE IV inhibitors. In particular, PDE inhibitors promote elevation of intracellular cAMP levels, increasing the electrical resistance of endothelial monolayers by stabilizing intercellular junctional complexes. Such an effect on central nervous system (CNS) vascular endothelium has the potential to reduce disease severity in EAE, because both inflammatory cells and humoral factors readily cross a disrupted blood-brain barrier (BBB). In this report, we demonstrate the capacity of BBB022 and rolipram to decrease clinical severity of EAE. further, PDE IV inhibitors significantly reduced BBB permeability in the spinal cords of mice with EAE. These results provide evidence that PDE IV-inhibitors may exert therapeutic effects in EAE by modifying cerebrovascular endothelial permeability, reducing tissue edema as well as entry of inflammatory cells and factors.

Improving antifouling ability and hemocompatibility of poly(vinylidene fluoride) membranes by polydopamine-mediated ATRP

A versatile strategy for the preparation of polymer membranes with remarkably improved antifouling properties and hemocompatibility is developed through a simple blending process and secondary treatments.

Evidence for involvement of polymorphic CYP2C19 and 2C9 in the N-demethylation of sertraline in human liver microsomes

AIMS

The present study was designed to define the kinetic behaviour of sertraline N-demethylation in human liver microsomes and to identify the isoforms of cytochrome P450 involved in this metabolic pathway.

METHODS

The kinetics of the formation of N-demethylsertraline were determined in human liver microsomes from six genotyped CYP2C19 extensive (EM) and three poor metabolisers (PM). Selective inhibitors of and specific monoclonal antibodies to various cytochrome P450 isoforms were also employed.

RESULTS

The kinetics of N-demethylsertraline formation in all EM liver microsomes were fitted by a two-enzyme Michaelis-Menten equation, whereas the kinetics in all PM liver microsomes were best described by a single-enzyme Michaelis-Menten equation similar to the low-affinity component found in EM microsomes. Mean apparent Km values for the high-and low-affinity components were 1.9 and 88 microm and V max values were 33 and 554 pmol min-1 mg-1 protein, respectively, in the EM liver microsomes. Omeprazole (a CYP2C19 substrate) at high concentrations and sulphaphenazole (a selective inhibitor of CYP2C9) substantially inhibited N-demethylsertraline formation. Of five monoclonal antibodies to various cytochrome P450 forms tested, only anti-CYP2C8/9/19 had any inhibitory effect on this reaction. The inhibition of sertraline N-demethylation by anti-CYP2C8/9/19 was greater in EM livers than in PM livers at both low and high substrate concentrations. However, anti-CYP2C8/9/19 did not abolish the formation of N-demethylsertraline in the microsomes from any of the livers.

CONCLUSIONS

The polymorphic enzyme CYP2C19 catalyses the high-affinity N-demethylation of sertraline, while CYP2C9 is one of the low-affinity components of this metabolic pathway.

Alternative splicing of the 5'-sequences of the mouse EAAT2 glutamate transporter and expression in a transgenic model for amyotrophic lateral sclerosis

Glutamate-mediated neurotoxicity and a reduced expression of the excitatory amino acid transporter 2 (EAAT2) have been described in the pathogenesis of several acute and chronic neurological conditions. EAAT2 is the major carrier of glutamate in the mammalian brain. However, the principles of EAAT2 expression regulation are not fully understood. For the human brain, extensive alternative splicing of the EAAT2 RNA has been shown. To delineate the complex RNA regulation of EAAT2 we investigated whether the murine species is a suitable model for the study of EAAT2 splicing events. We identified five splice variants (mEAAT2/5UT1-5) encoding different 5'-untranslated sequences and two distinct N-termini of the putative EAAT2 polypeptide. In the murine CNS we found a region-specific expression pattern of the novel 5'-variants of EAAT2 as shown by in situ hybridization, dot blotting and competitive reverse transcription polymerase chain reaction. Furthermore, we performed an expression analysis of the EAAT2 splice variants in the spinal cord of a transgenic model (SOD1G93A) of amyotrophic lateral sclerosis, a motor neurone disease for which altered splicing of EAAT2 has been discussed. We found an increased expression of mEAAT2/5UT4 and a reduction of mEAAT2/5UT5 in the early course of the disease. We conclude that alternative splicing of 5'-sequences may contribute to the regional expression of the EAAT2 RNA and was altered in the pre-symptomatic stage of the SOD1G93A-mouse model for amyotrophic lateral sclerosis.