Showing papers on "Transgene published in 2005"
TL;DR: It is shown that overexpression of Klotho in mice extends life span and it is suggested that Klotha-mediated inhibition of insulin and IGF1 signaling contributes to its anti-aging properties.
Abstract: A defect in Klotho gene expression in mice accelerates the degeneration of multiple age-sensitive traits. Here, we show that overexpression of Klotho in mice extends life span. Klotho protein functions as a circulating hormone that binds to a cell-surface receptor and represses intracellular signals of insulin and insulin-like growth factor 1 (IGF1), an evolutionarily conserved mechanism for extending life span. Alleviation of aging-like phenotypes in Klotho-deficient mice was observed by perturbing insulin and IGF1 signaling, suggesting that Klotho-mediated inhibition of insulin and IGF1 signaling contributes to its anti-aging properties. Klotho protein may function as an anti-aging hormone in mammals.
1,583 citations
TL;DR: Evidence is provided that environmental enrichment leads to reductions in steady-state levels of cerebral Abeta peptides and amyloid deposition and selective upregulation in levels of specific transcripts in brains of transgenic mice.
843 citations
TL;DR: The results suggest that miRNAs have functional roles for plants to cope with fluctuations in mineral-nutrient availability in the soil and downregulates UBC mRNA accumulation by targeting the 5' UTR, and this regulation is important for plant responses to Pi starvation.
812 citations
TL;DR: It is reported that epidermal keratinocytes in psoriatic lesions are characterized by activated Stat3, and targeting Stat3 may be potentially therapeutic in the treatment of psoriasis.
Abstract: Here we report that epidermal keratinocytes in psoriatic lesions are characterized by activated Stat3. Transgenic mice with keratinocytes expressing a constitutively active Stat3 (K5.Stat3C mice) develop a skin phenotype either spontaneously, or in response to wounding, that closely resembles psoriasis. Keratinocytes from K5.Stat3C mice show upregulation of several molecules linked to the pathogenesis of psoriasis. In addition, the development of psoriatic lesions in K5.Stat3C mice requires cooperation between Stat3 activation in keratinocytes and activated T cells. Finally, abrogation of Stat3 function by a decoy oligonucleotide inhibits the onset and reverses established psoriatic lesions in K5.Stat3C mice. Thus, targeting Stat3 may be potentially therapeutic in the treatment of psoriasis.
695 citations
TL;DR: A "safety switch" that can be stably and efficiently expressed in human T cells without impairing phenotype, function, or antigen specificity is described, based on a modified human caspase 9 fused to a human FK506 binding protein to allow conditional dimerization using a small molecule pharmaceutical.
647 citations
TL;DR: The data establish a direct link between Pgp and Abeta metabolism in vivo and suggest that Pgp activity at the BBB could affect risk for developing AD as well as provide a novel diagnostic and therapeutic target.
Abstract: Accumulation of amyloid-beta (Abeta) within extracellular spaces of the brain is a hallmark of Alzheimer disease (AD). In sporadic, late-onset AD, there is little evidence for increased Abeta production, suggesting that decreased elimination from the brain may contribute to elevated levels of Abeta and plaque formation. Efflux transport of Abeta across the blood-brain barrier (BBB) contributes to Abeta removal from the brain. P-glycoprotein (Pgp) is highly expressed on the luminal surface of brain capillary endothelial cells and contributes to the BBB. In Pgp-null mice, we show that [I]Abeta40 and [I]Abeta42 microinjected into the CNS clear at half the rate that they do in WT mice. When amyloid precursor protein-transgenic (APP-transgenic) mice were administered a Pgp inhibitor, Abeta levels within the brain interstitial fluid significantly increased within hours of treatment. Furthermore, APP-transgenic, Pgp-null mice had increased levels of brain Abeta and enhanced Abeta deposition compared with APP-transgenic, Pgp WT mice. These data establish a direct link between Pgp and Abeta metabolism in vivo and suggest that Pgp activity at the BBB could affect risk for developing AD as well as provide a novel diagnostic and therapeutic target.
604 citations
TL;DR: It is shown that increased dosage of Sirt1, the mammalian Sir2 ortholog, in pancreatic beta cells improves glucose tolerance and enhances insulin secretion in response to glucose in beta cell-specific Sirt 1-overexpressing (BESTO) transgenic mice.
601 citations
TL;DR: A novel transgenic mouse that closely mimics human tauopathy is described and may represent an important model for the future study of tau-related neurodegenerative disease.
Abstract: Here, we describe the generation of a novel transgenic mouse model of human tauopathy. The rTg(tauP301L)4510 mouse expresses the P301L mutation in tau (4R0N) associated with frontotemporal dementia and parkinsonism linked to chromosome 17. Transgene expression was driven by a forebrain-specific Ca2+ calmodulin kinase II promoter system resulting in high levels of expression in the hippocampus and neocortex. Importantly, transgene expression in this model is induced via the tetracycline-operon responsive element and is suppressed after treatment with doxycycline. Continued transgene expression in rTg(tauP301L)4510 mice results in age-dependent development of many salient characteristics of hereditary human dementia. From an early age, immunohistochemical studies demonstrated abnormal biochemical processing of tau and the presence of pathological conformation- and phosphorylation-dependent epitopes. Neurofibrillary tangle (NFT) pathology was first observed in the neocortex and progressed into the hippocampus and limbic structures with increasing age. Consistent with the formation of NFTs, immunoblots indicated an age-dependent transition of accumulating tau species from Sarkosyl soluble 55 kDa to insoluble hyperphosphorylated 64 kDa. Ultrastructural analysis revealed the presence of straight tau filaments. Furthermore, the effects of tauP301L expression on spatial reference memory were longitudinally tested using the Morris water maze. Compared with nontransgenic age-matched control littermates, rTg(tauP301L)4510 mice developed significant cognitive impairments from 4 months of age. Memory deficits were accompanied by gross forebrain atrophy and a prominent loss of neurons, most strikingly in hippocampal subdivision CA1. Collectively, these data describe a novel transgenic mouse that closely mimics human tauopathy and may represent an important model for the future study of tau-related neurodegenerative disease.
572 citations
TL;DR: Transgenic mice generate transgenic mice that demonstrate that TSLP can initiate a cascade of allergic inflammation in the skin and provide a valuable animal model for future study of this common disease.
Abstract: The cytokine thymic stromal lymphopoietin (TSLP) has recently been implicated in the pathogenesis of atopic dermatitis (AD) and other allergic diseases in humans. To further characterize its role in this disease process, transgenic mice were generated that express a keratinocyte-specific, tetracycline-inducible TSLP transgene. Skin-specific overexpression of TSLP resulted in an AD-like phenotype, with the development of eczematous lesions containing inflammatory dermal cellular infiltrates, a dramatic increase in Th2 CD4 + T cells expressing cutaneous homing receptors, and elevated serum levels of IgE. These transgenic mice demonstrate that TSLP can initiate a cascade of allergic inflammation in the skin and provide a valuable animal model for future study of this common disease.
565 citations
TL;DR: Cerebellar granule cell progenitors are fated at an early stage to produce granule cells with axonal projections limited to specific sublayers of the cerebellar cortex, showing that interchromosomal recombination can be induced efficiently in vivo in both mitotic and postmitotic cells in all tissues examined.
515 citations
TL;DR: Angptl3 and Angptl4 function to regulate circulating triglyceride levels during different nutritional states and therefore play a role in lipid metabolism during feeding/fasting through differential inhibition of LPL.
Abstract: Lipoprotein lipase (LPL) is a key regulator of triglyceride clearance. Its coordinated regulation during feeding and fasting is critical for maintaining lipid homeostasis and energy supply. Angiopoietin-like (Angptl)3 and Angptl4 are secreted proteins that have been demonstrated to regulate triglyceride metabolism by inhibiting LPL. We have taken a targeted genetic approach to generate Angptl4- and Angptl3-deficient mice as well as transgenic mice overexpressing human Angptl4 in the liver. The Angptl4 transgenic mice displayed elevated plasma triglycerides and reduced postheparin plasma (PHP) LPL activity. A purified recombinant Angptl4 protein inhibited mouse LPL and recombinant human LPL activity in vitro. In contrast to the transgenic mice, Angptl4-deficient mice displayed hypotriglyceridemia and increased PHP LPL activity, with greater effects in the fasted compared with the fed state. Angptl3-deficient mice also displayed hypotriglyceridemia with elevated PHP LPL activity, but these mice showed a greater effect in the fed state. Mice deficient in both Angptl proteins showed an additive effect on plasma triglycerides and did not survive past 2 months of age. Our results show that Angptl3 and Angptl4 function to regulate circulating triglyceride levels during different nutritional states and therefore play a role in lipid metabolism during feeding/fasting through differential inhibition of LPL.
TL;DR: Results indicate that NH1 may be involved in the regulation of SA in response to environmental changes, and indicates that rice has a disease-resistance pathway similar to the Arabidopsis SAR pathway.
Abstract: Arabidopsis NPR1/NIM1 is a key regulator of systemic acquired resistance (SAR), which confers lasting broad-spectrum resistance. Previous reports indicate that rice has a disease-resistance pathway similar to the Arabidopsis SAR pathway. Here we report the isolation and characterization of a rice NPR1 homologue (NH1). Transgenic rice plants overexpressing NH1 (NH1ox) acquire high levels of resistance to Xanthomonas oryzae pv. oryzae. The resistance phenotype is heritable and correlates with the presence of the transgene and reduced bacterial growth. Northern analysis shows that NH1ox rice spontaneously activates defense genes, contrasting with NPR1-overexpressing Arabidopsis, where defense genes are not activated until induction. Wildtype NH1, but not a point mutant corresponding to npr1-1, interacts strongly with the rice transcription factor rTGA2.2 in yeast two-hybrid. Greenhouse-grown NH1ox plants develop lesion-mimic spots on leaves at preflowering stage although no other developmental effects are observed. However, when grown in growth chambers (GCs) under low light, NH1ox plants are dwarfed, indicating elevated sensitivity to light. The GC-grown NH1ox plants show much higher salicylic acid (SA) levels than the wild type, whereas greenhouse-grown NH1ox plants contain lower SA. These results indicate that NH1 may be involved in the regulation of SA in response to environmental changes.
TL;DR: A triple transgenic mouse system, which combines the tissue specificity of any Cre-transgenic line with the inducibility of the reverse tetracycline transactivator (rtTA)/tetracyCline-responsive element (tet-O)-driven transgenes, that will be useful for studying genes in which temporal control of expression is necessary for the discovery of the full spectrum of functions.
Abstract: Here we describe a triple transgenic mouse system, which combines the tissue specificity of any Cre-transgenic line with the inducibility of the reverse tetracycline transactivator (rtTA)/tetracycline-responsive element (tet-O)-driven transgenes. To ensure reliable rtTA expression in a broad range of cell types, we have targeted the rtTA transgene into the ROSA26 locus. The rtTA expression, however, is conditional to a Cre recombinase-mediated excision of a STOP region from the ROSA26 locus. We demonstrate the utility of this technology through the inducible expression of the vascular endothelial growth factor (VEGF-A) during embryonic development and postnatally in adult mice. Our results of adult induction recapitulate several different hepatic and immune cell pathological phenotypes associated with increased systemic VEGF-A protein levels. This system will be useful for studying genes in which temporal control of expression is necessary for the discovery of the full spectrum of functions. The presented approach abrogates the need to generate tissue-specific rtTA transgenes for tissues where well-characterized Cre lines already exist.
TL;DR: It is shown that brain-specific leptin signaling is sufficient to reverse the obesity, diabetes, and infertility of db/db mice.
Abstract: We have generated mice that carry a neuron-specific leptin receptor (LEPR) transgene whose expression is driven by the rat synapsin I promoter synapsin-LEPR B (SYN-LEPR-B). We have also generated mice that are compound hemizygotes for the transgenes SYN-LEPR-B and neuron-specific enolase-LEPR B (NSE-LEPR-B). We observed a degree of correction in db/db mice that are hemizygous (Syn db/db) and homozygous (Syn/Syn db/db) for the SYN-LEPR-B transgene similar to that previously reported for the NSE-LEPR-B transgene. We also show complete correction of the obesity and related phenotypes of db/db mice that are hemizygous for both NSE-LEPR-B and SYN-LEPR-B transgenes (Nse+Syn db/db). Body composition, insulin sensitivity, and cold tolerance were completely normalized in Nse+Syn db/db mice at 12 weeks of age compared with lean controls. In situ hybridization for LEPR B isoform expression in Nse+Syn db/db mice showed robust expression in the energy homeostasis-relevant regions of the hypothalamus. Expression of 3 neuropeptide genes, agouti-related peptide (Agrp), neuropeptide Y (Npy), and proopiomelanocortin (Pomc), was fully normalized in dual transgenic db/db mice. The 2 transgenes in concert conferred normal fertility to male and female db/db mice. Male mice with partial peripheral deletion of Lepr, induced in the periweaning phase, did not show alterations in body composition or mass. In summary, we show that brain-specific leptin signaling is sufficient to reverse the obesity, diabetes, and infertility of db/db mice.
TL;DR: The positional cloning of Ter is reported, revealing a point mutation that introduces a termination codon in the mouse orthologue (Dnd1) of the zebrafish dead end (dnd) gene that may adversely affect essential aspects of RNA biology during PGC development.
Abstract: The phenotype of Ter testicular germ cell tumour susceptibility gene was first described more than 30 years ago, but it has taken until now for the identity of the gene to be discovered. Ter is a mutation inducing a termination codon on the mouse version of the dead end gene, known from zebrafish embryos. It encodes a protein with an RNA recognition motif, thus implicating RNA biology in testicular tumour development. In mice, the Ter mutation causes primordial germ cell (PGC) loss in all genetic backgrounds1. Ter is also a potent modifier of spontaneous testicular germ cell tumour (TGCT) susceptibility in the 129 family of inbred strains, and markedly increases TGCT incidence in 129-Ter/Ter males2,3,4. In 129-Ter/Ter mice, some of the remaining PGCs transform into undifferentiated pluripotent embryonal carcinoma cells2,3,4,5,6, and after birth differentiate into various cells and tissues that compose TGCTs. Here, we report the positional cloning of Ter, revealing a point mutation that introduces a termination codon in the mouse orthologue (Dnd1) of the zebrafish dead end (dnd) gene. PGC deficiency is corrected both with bacterial artificial chromosomes that contain Dnd1 and with a Dnd1-encoding transgene. Dnd1 is expressed in fetal gonads during the critical period when TGCTs originate. DND1 has an RNA recognition motif and is most similar to the apobec complementation factor, a component of the cytidine to uridine RNA-editing complex. These results suggest that Ter may adversely affect essential aspects of RNA biology during PGC development. DND1 is the first protein known to have an RNA recognition motif directly implicated as a heritable cause of spontaneous tumorigenesis. TGCT development in the 129-Ter mouse strain models paediatric TGCT in humans. This work will have important implications for our understanding of the genetic control of TGCT pathogenesis and PGC biology.
TL;DR: A better understanding of the cellular and molecular basis of non-viral vector trafficking from the extracellular compartment into the nucleus may provide strategies to overcome those obstacles that limit the efficiency of gene delivery.
TL;DR: Evidence is provided that the pharmacological induction of NF‐κB‐dependent transcription and bcl‐2 gene expression is neuroprotective in ALS mice by inhibiting programmed cell death and Phenylbutyrate may provide a novel therapeutic approach for the treatment of patients with ALS.
Abstract: Multiple molecular defects trigger cell death in amyotrophic lateral sclerosis (ALS). Among these, altered transcriptional activity may perturb many cellular functions, leading to a cascade of secondary pathological effects. We showed that pharmacological treatment, using the histone deacetylase inhibitor sodium phenylbutyrate, significantly extended survival and improved both the clinical and neuropathological phenotypes in G93A transgenic ALS mice. Phenylbutyrate administration ameliorated histone hypoacetylation observed in G93A mice and induced expression of nuclear factor-kappaB (NF-kappaB) p50, the phosphorylated inhibitory subunit of NF-kappaB (pIkappaB) and beta cell lymphoma 2 (bcl-2), but reduced cytochrome c and caspase expression. Curcumin, an NF-kappaB inhibitor, and mutation of the NF-kappaB responsive element in the bcl-2 promoter, blocked butyrate-induced bcl-2 promoter activity. We provide evidence that the pharmacological induction of NF-kappaB-dependent transcription and bcl-2 gene expression is neuroprotective in ALS mice by inhibiting programmed cell death. Phenylbutyrate acts to phosphorylate IkappaB, translocating NF-kappaB p50 to the nucleus, or to directly acetylate NF-kappaB p50. NF-kappaB p50 transactivates bcl-2 gene expression. Up-regulated bcl-2 blocks cytochrome c release and subsequent caspase activation, slowing motor neuron death. These transcriptional and post-translational pathways ultimately promote motor neuron survival and ameliorate disease progression in ALS mice. Phenylbutyrate may therefore provide a novel therapeutic approach for the treatment of patients with ALS.
TL;DR: Initial characterization of the PR‐Cre mouse underscores the utility of this model to precisely ablate floxed target genes specifically in cell lineages that express the PR.
Abstract: Using gene-targeting methods, a progesterone receptor Cre knockin (PR-Cre) mouse was generated in which Cre recombinase was inserted into exon 1 of the PR gene. The insertion positions the Cre gene downstream (and under the specific control) of the endogenous PR promoter. As for heterozygotes for the progesterone receptor knockout (PRKO) mutation, mice heterozygous for the Cre knockin insertion are phenotypically indistinguishable from wildtype. Crossing the PR-Cre with the ROSA26R reporter revealed that Cre excision activity is restricted to cells that express PR in progesterone-responsive tissues such as the uterus, ovary, oviduct, pituitary gland, and mammary gland. Initial characterization of the PR-Cre mouse underscores the utility of this model to precisely ablate floxed target genes specifically in cell lineages that express the PR. In the wider context of female reproductive tissue ontology, this model will be indispensable in tracing the developmental fate of cell lineages that descend from PR positive progenitors.
TL;DR: It is demonstrated that cellular senescence and organismal aging are intimately linked and that these processes are mediated by p63 loss, and that p63 deficiency accelerates this process.
Abstract: The p53 tumor suppressor plays a key role in organismal aging. A cellular mechanism postulated to drive the aging process is cellular senescence, mediated in part by p53. Although senescent cells accumulate in elderly individuals, most studies have relied on correlating in vitro senescence assays with in vivo phenotypes of aging. Here, using two different mouse models in which the p53-related protein p63 is compromised, we demonstrate that cellular senescence and organismal aging are intimately linked and that these processes are mediated by p63 loss. We found that p63(+/-) mice have a shortened life span and display features of accelerated aging. Both germline and somatically induced p63 deficiency activates widespread cellular senescence with enhanced expression of senescent markers SA-beta-gal, PML, and p16(INK4a). Using an inducible tissue-specific p63 conditional model, we further show that p63 deficiency induces cellular senescence and causes accelerated aging phenotypes in the adult. Our results thus suggest a causative link between cellular senescence and aging in vivo, and demonstrate that p63 deficiency accelerates this process.
TL;DR: It is suggested that infiltration of BM-derived monocytic cells into the brain contributes to the development of microglial reaction in AD.
TL;DR: A Bmp4-Bmpr1a genetic pathway that functions in lip fusion is uncovered, and the function of Bmp signaling in orofacial clefting is dissected, revealing that BMP signaling has distinct roles in lip and palate fusion.
Abstract: Previous work suggested that cleft lip with or without cleft palate (CL/P) is genetically distinct from isolated cleft secondary palate (CP). Mutations in the Bmp target gene Msx1 in families with both forms of orofacial clefting has implicated Bmp signaling in both pathways. To dissect the function of Bmp signaling in orofacial clefting, we conditionally inactivated the type 1 Bmp receptor Bmpr1a in the facial primordia, using the Nestin cre transgenic line. Nestin cre ; Bmpr1a mutants had completely penetrant, bilateral CL/P with arrested tooth formation. The cleft secondary palate of Nestin cre ; Bmpr1a mutant embryos was associated with diminished cell proliferation in maxillary process mesenchyme and defective anterior posterior patterning. By contrast, we observed elevated apoptosis in the fusing region of the Nestin cre ; Bmpr1a mutant medial nasal process. Moreover, conditional inactivation of the Bmp4 gene using the Nestin cre transgenic line resulted in isolated cleft lip. Our data uncover a Bmp4-Bmpr1a genetic pathway that functions in lip fusion, and reveal that Bmp signaling has distinct roles in lip and palate fusion.
TL;DR: The studies indicate the existence of a Cyt c- and apoptosome-independent but Apaf-1-dependent mechanism(s) for caspase activation and fibroblasts from the KA/KA mice were resistant to apoptosis, their thymocytes were markedly more sensitive to death stimuli than Apaf.
TL;DR: The overexpression of brain-derived neurotrophic factor accounts for an important component of this phenotype, and the contribution of the most prominent candidate genes revealed by the screening, namely prodynorphin, BDNF, and MHC class I molecules, to the facilitated LTP of VP16-CREB mice is explored.
TL;DR: The data suggest that reduction of active GCs exclusively in adipose tissue is an important determinant of a favorable metabolic phenotype with respect to energy homeostasis and the metabolic syndrome.
Abstract: Local glucocorticoid (GC) action depends on intracellular GC metabolism by 11β-hydroxysteroid dehydrogenases (11βHSDs) 11βHSD1 activates GCs, while 11βHSD2 inactivates GCs Adipocyte-specific amplification of GCs through transgenic overexpression of 11βHSD1 produces visceral obesity and the metabolic syndrome in mice To determine whether adipocyte-specific inactivation of GCs protects against this phenotype, we created a transgenic model in which human 11βHSD2 is expressed under the control of the murine adipocyte fatty acid binding protein (aP2) promoter (aP2-h11βHSD2) Transgenic mice have increased 11βHSD2 expression and activity exclusively in adipose tissue, with the highest levels in subcutaneous adipose tissue, while systemic indexes of GC exposure are unchanged Transgenic mice resist weight gain on high-fat diet due to reduced fat mass accumulation This improved energy balance is associated with decreased food intake, increased energy expenditure, and improved glucose tolerance and insulin sensitivity Adipose tissue gene expression in transgenic mice is characterized by decreased expression of leptin and resistin and increased expression of adiponectin, peroxisome proliferator–activated receptor γ, and uncoupling protein 2 These data suggest that reduction of active GCs exclusively in adipose tissue is an important determinant of a favorable metabolic phenotype with respect to energy homeostasis and the metabolic syndrome
TL;DR: For the efficient production of transgenic barley plants, with stable transgene expression and reduced silencing, the Agrobacterium-mediated method appears to offer significant advantages over particle bombardment.
Abstract: Two barley transformation systems, Agrobacterium-mediated and particle bombardment, were compared in terms of transformation efficiency, transgene copy number, expression, inheritance and physical structure of the transgenic loci using fluorescence in situ hybridisation (FISH). The efficiency of Agrobacterium-mediated transformation was double that obtained with particle bombardment. While 100% of the Agrobacterium-derived lines integrated between one and three copies of the transgene, 60% of the transgenic lines derived by particle bombardment integrated more than eight copies of the transgene. In most of the Agrobacterium-derived lines, the integrated T-DNA was stable and inherited as a simple Mendelian trait. Transgene silencing was frequently observed in the T1 populations of the bombardment-derived lines. The FISH technique was able to reveal additional details of the transgene integration site. For the efficient production of transgenic barley plants, with stable transgene expression and reduced silencing, the Agrobacterium-mediated method appears to offer significant advantages over particle bombardment.
TL;DR: It is shown that leukemias from this transgenic line are highly penetrant and render animals moribund by 80.7 ± 17.6 days of life, providing an essential step in preparing this model for chemical and genetic screens designed to identify modifiers of Myc-induced T-ALL.
Abstract: We have created a stable transgenic rag2-EGFP-mMyc zebrafish line that develops GFP-labeled T cell acute lymphoblastic leukemia (T-ALL), allowing visualization of the onset and spread of this disease. Here, we show that leukemias from this transgenic line are highly penetrant and render animals moribund by 80.7 ± 17.6 days of life (±1 SD, range = 50-158 days). These T cell leukemias are clonally aneuploid, can be transplanted into irradiated recipient fish, and express the zebrafish orthologues of the human T-ALL oncogenes tal1/scl and lmo2, thus providing an animal model for the most prevalent molecular subgroup of human T-ALL. Because T-ALL develops very rapidly in rag2-EGFP-mMyc transgenic fish (in which “mMyc” represents mouse c-Myc), this line can only be maintained by in vitro fertilization. Thus, we have created a conditional transgene in which the EGFP-mMyc oncogene is preceded by a loxed dsRED2 gene and have generated stable rag2-loxP-dsRED2-loxP-EGFP-mMyc transgenic zebrafish lines, which have red fluorescent thymocytes and do not develop leukemia. Transgenic progeny from one of these lines can be induced to develop T-ALL by injecting Cre RNA into one-cell-stage embryos, demonstrating the utility of the Cre/lox system in the zebrafish and providing an essential step in preparing this model for chemical and genetic screens designed to identify modifiers of Myc-induced T-ALL.
TL;DR: It is shown that intracellular Aβ42 directly activated the p53 promoter, resulting in p53‐dependent apoptosis, and that intrusion of Aβ40 had a similar but lesser effect.
Abstract: The amyloid beta-protein (Abeta) ending at 42 plays a pivotal role in Alzheimer's disease (AD). We have reported previously that intracellular Abeta42 is associated with neuronal apoptosis in vitro and in vivo. Here, we show that intracellular Abeta42 directly activated the p53 promoter, resulting in p53-dependent apoptosis, and that intracellular Abeta40 had a similar but lesser effect. Moreover, oxidative DNA damage induced nuclear localization of Abeta42 with p53 mRNA elevation in guinea-pig primary neurons. Also, p53 expression was elevated in brain of sporadic AD and transgenic mice carrying mutant familial AD genes. Remarkably, accumulation of both Abeta42 and p53 was found in some degenerating-shape neurons in both transgenic mice and human AD cases. Thus, the intracellular Abeta42/p53 pathway may be directly relevant to neuronal loss in AD. Although neurotoxicity of extracellular Abeta is well known and synaptic/mitochondrial dysfunction by intracellular Abeta42 has recently been suggested, intracellular Abeta42 may cause p53-dependent neuronal apoptosis through activation of the p53 promoter; thus demonstrating an alternative pathogenesis in AD.
TL;DR: It is demonstrated that hepatocyte growth factor receptor, c-Met, is also a coreceptor for AAV2 infection by facilitating AAV1 internalization into the cytoplasm and the physical interaction between A AV2 and the β subunit of c- met.
Abstract: After the first attachment of virus to the cell surface through a primary receptor, efficient entry of virus requires the presence of a coreceptor. For adeno-associated virus type 2 (AAV2) infection, heparan sulfate proteoglycan is supposed as the primary receptor, and αvβ5 integrin and FGFR1 are reported to act as coreceptors. In this study, we were able to demonstrate that hepatocyte growth factor receptor, c-Met, is also a coreceptor for AAV2 infection. AAV2-mediated transgene analyses revealed that c-Met expression significantly up-regulated transgene expression without increasing AAV2 cell binding. Moreover, a viral overlay assay elucidated the physical interaction between AAV2 and the β subunit of c-Met. These data suggest that c-Met plays the role of coreceptor for AAV2 infection by facilitating AAV2 internalization into the cytoplasm.
TL;DR: It is demonstrated that the unfolded protein response (UPR) is activated in macrophages derived from the bone marrow of HLA-B27 transgenic rats with inflammatory disease, the first demonstration, to the authors' knowledge, that HLA -B27 misfolding is associated with ER stress that results in activation of the UPR.
Abstract: The mechanism by which the MHC class I allele, HLA-B27, contributes to spondyloarthritis pathogenesis is unknown. In contrast to other alleles that have been examined, HLA-B27 has a tendency to form high m.w. disulfide-linked H chain complexes in the endoplasmic reticulum (ER), bind the ER chaperone BiP/Grp78, and undergo ER-associated degradation. These aberrant characteristics have provided biochemical evidence that HLA-B27 is prone to misfold. Recently, similar biochemical characteristics of HLA-B27 were reported in cells from HLA-B27/human β 2 -microglobulin transgenic (HLA-B27 transgenic) rats, an animal model of spondyloarthritis, and correlated with disease susceptibility. In this study, we demonstrate that the unfolded protein response (UPR) is activated in macrophages derived from the bone marrow of HLA-B27 transgenic rats with inflammatory disease. Microarray analysis of these cells also reveals an IFN response signature. In contrast, macrophages derived from premorbid rats do not exhibit a strong UPR or evidence of IFN exposure. Activation of macrophages from premorbid HLA-B27 transgenic rats with IFN-γ increases HLA-B27 expression and leads to UPR induction, while no UPR is seen in cells from nondisease-prone HLA-B7 transgenic or wild-type (nontransgenic) animals. This is the first demonstration, to our knowledge, that HLA-B27 misfolding is associated with ER stress that results in activation of the UPR. These observations link HLA-B27 expression with biological effects that are independent of immunological recognition, but nevertheless may play an important role in the pathogenesis of inflammatory diseases associated with this MHC class I allele.
TL;DR: Apart from being a general GFP reporter, the ROSA26‐GFP‐DTA mouse line should provide a useful resource for genetic ablation of specific groups of cells.
Abstract: We generated a ROSA26-eGFP-DTA mouse line by introducing an eGFP-DTA (enhanced green fluorescent protein - diphtheria toxin fragment A) cassette into the ROSA26 locus by homologous recombination in ES cells. This mouse expresses eGFP ubiquitously, but DTA expression is prevented by the presence of eGFP, a Neo cassette, and a strong transcriptional stop sequence. Mice carrying this construct are normal and fertile, indicating the absence of DTA expression. However, upon Cre-mediated excision of the floxed region DTA expression is activated, resulting in the specific ablation of Cre-expressing cells. As an example of this approach, we ablated Nkx2.5 and Wnt1-expressing cells by using the Nkx2.5-Cre and Wnt1-Cre mouse lines, respectively. We observed loss of the precise tissues in which Nkx2.5 and Wnt1 are expressed. Apart from being a general GFP reporter, the ROSA26-GFP-DTA mouse line should provide a useful resource for genetic ablation of specific groups of cells.