Transgenic mouse models enabling photolabeling of individual neurons in vivo.
Ontology highlight
ABSTRACT:
SUBMITTER: Peter M
PROVIDER: S-EPMC3633923 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Ventral tegmental area (VTA) dopamine (DA) neurons have been implicated in reward, aversion, salience, cognition, and several neuropsychiatric disorders. Optogenetic approaches involving transgenic Cre-driver mouse lines provide powerful tools for dissecting DA-specific functions. However, the emerging complexity of VTA circuits requires Cre-driver mouse lines that restrict transgene expression to a precisely defined cell population. Because of recent work reporting that VTA DA neurons projecting to the lateral habenula release GABA, but not DA, we performed an extensive anatomical, molecular, and functional characterization of prominent DA transgenic mouse driver lines. We find that transgenes under control of the tyrosine hydroxylase, but not the dopamine transporter, promoter exhibit dramatic non-DA cell-specific expression patterns within and around VTA nuclei. Our results demonstrate how Cre expression in unintentionally targeted cells in transgenic mouse lines can confound the interpretation of supposedly cell-type-specific experiments. This Matters Arising paper is in response to Stamatakis et al. (2013), published in Neuron. See also the Matters Arising Response paper by Stuber et al. (2015), published concurrently with this Matters Arising in Neuron.
| S-EPMC5037114 | biostudies-literature
Project description:Liver cancer is a complex multistep process requiring genetic alterations in multiple proto-oncogenes and tumor suppressor genes. Although hundreds of genes are known to play roles in hepatocarcinogenesis, oncogenic collaboration among these genes is still largely unknown. Here, we report a simple methodology by which oncogenic cooperation between cancer-related genes can be efficiently investigated in the liver. We developed various non-germline transgenic mouse models using hydrodynamics-based transfection which express HrasG12V, SmoM2, and a short-hairpin RNA down-regulating p53 (shp53) individually or in combination in the liver. In this transgenic system, firefly luciferase was co-expressed with the oncogenes as a reporter, allowing tumor growth in the liver to be monitored over time without an invasive procedure. Very strong bioluminescence imaging (BLI) signals were observed at 4 weeks post-hydrodynamic injection (PHI) in mice co-expressing HrasG12V and shp53, while only background signals were detected in other double or single transgenic groups until 30 weeks PHI. Consistent with the BLI data, tumors were observed in the HrasG12V plus shp53 group at 4 weeks PHI, while other transgenic groups failed to exhibit a hyperplastic nodule at 30 weeks PHI. In the HrasG12V plus shp53 transgenic group, BLI signals were well-correlated with actual tumor growth in the liver, confirming the versatility of BLI-based monitoring of tumor growth in this organ. The methodology described here is expected to accelerate and facilitate in vivo studies of the hepatocarcinogenic potential of cancer-related genes by means of oncogenic cooperation.
| S-EPMC3610734 | biostudies-literature
Project description:BackgroundTransgenic mice have proven to be a powerful system to study normal and pathological gene functions. Here we describe an attempt to generate a transgenic mouse model for choroideremia (CHM), a slow-onset X-linked retinal degeneration caused by mutations in the Rab Escort Protein-1 (REP1) gene. REP1 is part of the Rab geranylgeranylation machinery, a modification that is essential for Rab function in membrane traffic. The loss of REP1 in CHM patients may trigger retinal degeneration through its effects on Rab proteins. We have previously reported that Rab27a is the Rab most affected in CHM lymphoblasts and hypothesised that the selective dysfunction of Rab27a (and possibly a few other Rab GTPases) plays an essential role in the retinal degenerative process.ResultsTo investigate this hypothesis, we generated several lines of dominant-negative, constitutively-active and wild-type Rab27a (and Rab27b) transgenic mice whose expression was driven either by the pigment cell-specific tyrosinase promoter or the ubiquitous beta-actin promoter. High levels of mRNA and protein were observed in transgenic lines expressing wild-type or constitutively active Rab27a and Rab27b. However, only modest levels of transgenic protein were expressed. Pulse-chase experiments suggest that the dominant-negative proteins, but not the constitutively-active or wild type proteins, are rapidly degraded. Consistently, no significant phenotype was observed in our transgenic lines. Coat-colour was normal, indicating normal Rab27a activity. Retinal function as determined by fundoscopy, angiography, electroretinography and histology was also normal.ConclusionsWe suggest that the instability of the dominant-negative mutant Rab27 proteins in vivo precludes the use of this approach to generate mouse models of disease caused by Rab27 GTPases.
| S-EPMC137576 | biostudies-literature
Project description:Research efforts over the past decades have unraveled both genetic and environmental factors, which contribute to the development of autism spectrum disorders (ASD). It is, to date, largely unknown how different underlying causes result in a common phenotype. However, the individual course of development and the different comorbidities might reflect the heterogeneous genetic and non-genetic contributions. Therefore, it is reasonable to identify commonalities and differences in models of these disorders at the different hierarchical levels of brain function, including genetics/environment, cellular/synaptic functions, brain regions, connectivity, and behavior. To that end, we investigated Shank3 transgenic mouse lines and compared them with a prenatal zinc-deficient (PZD) mouse model of ASD at the level of brain structural alterations in an 11,7 T small animal magnetic resonance imaging (MRI). Animals were measured at 4 and 9 weeks of age. We identified a decreased total brain volume (TBV) and hippocampal size of Shank3 -/- mice but a convergent increase of basal ganglia (striatum and globus pallidus) in most mouse lines. Moreover, Shank3 transgenic mice had smaller thalami, whereas PZD mice had this region enlarged. Intriguingly, Shank3 heterozygous knockout mice mostly showed minor abnormalities to full knockouts, which might reflect the importance of proper Shank3 dosage in neuronal cells. Most reported volume changes seemed to be more pronounced at younger age. Our results indicate both convergent and divergent brain region abnormalities in genetic and non-genetic models of ASD. These alterations of brain structures might be mirrored in the reported behavior of both models, which have not been assessed in this study.
| S-EPMC6395436 | biostudies-literature
Project description:Growth and invasion of breast cancer require extracellular proteolysis in order to physically restructure the tissue microenvironment of the mammary gland. This pathological tissue remodeling process depends on a collaboration of epithelial and stromal cells. In fact, the majority of extracellular proteases are provided by stromal cells rather than cancer cells. This distinct expression pattern is seen in human breast cancers and also in transgenic mouse models of breast cancer. The similar expression patterns suggest that transgenic mouse models are ideally suited to study the role of extracellular proteases in cancer progression. Here we give a status report on protease intervention studies in transgenic models. These studies demonstrate that proteases are involved in all stages of breast cancer progression from carcinogenesis to metastasis. Transgenic models are now beginning to provide vital mechanistic insight that will allow us to combat breast cancer invasion and metastasis with new protease-targeted drugs.
| S-EPMC1820839 | biostudies-other
Project description:Understanding the evolution of development in large part relies on the study of phylogenetically old organisms. Cnidarians, such as Hydra, have become attractive model organisms for these studies. However, despite long-term efforts, stably transgenic animals could not be generated, severely limiting the functional analysis of genes. Here we report the efficient generation of transgenic Hydra lines by embryo microinjection. One of these transgenic lines expressing EGFP revealed remarkably high motility of individual endodermal epithelial cells during morphogenesis. We expect that transgenic Hydra will become important tools to dissect the molecular mechanisms of development at the base of the Metazoan tree.
| S-EPMC1458856 | biostudies-literature
Project description:Embryonic stem cells (ESCs) hold great potential for replacing neurons following injury or disease. The therapeutic and diagnostic potential of ESCs may be hindered by heterogeneity in ESC-derived populations. Drug selection has been used to purify ESC-derived cardiomyocytes and endothelial cells but has not been applied to specific neural lineages. In this study we investigated positive selection of progenitor motor neurons (pMNs) through transgenic expression of the puromycin resistance enzyme, puromycin N-acetyl-transferase (PAC), under the Olig2 promoter. The protein-coding region in one allele of Olig2 was replaced with PAC to generate the P-Olig2 cell line. This cell line provided specific puromycin resistance in cells that express Olig2, while Olig2(-) cells were killed by puromycin. Positive selection significantly enriched populations of Olig2(+) pMNs. Committed motoneurons (MNs) expressing Hb9, a common progeny of pMNs, were also enriched by the end of the selection period. Selected cells remained viable and differentiated into mature cholinergic MNs and oligodendrocyte precursor cells. Drug resistance may provide a scalable and inexpensive method for enriching desired neural cell types for use in research applications.
| S-EPMC3319638 | biostudies-literature
Project description:Attempts to model inherited human prion disorders such as familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker (GSS) disease, and fatal familial insomnia (FFI) using genetically modified mice have produced disappointing results. We recently demonstrated that transgenic (Tg) mice expressing wild-type bank vole prion protein (BVPrP) containing isoleucine at polymorphic codon 109 develop a spontaneous neurodegenerative disorder that exhibits many of the hallmarks of prion disease. To determine if mutations causing inherited human prion disease alter this phenotype, we generated Tg mice expressing BVPrP containing the D178N mutation, which causes FFI; the E200K mutation, which causes familial CJD; or an anchorless PrP mutation similar to mutations that cause GSS. Modest expression levels of mutant BVPrP resulted in highly penetrant spontaneous disease in Tg mice, with mean ages of disease onset ranging from ~120 to ~560 days. The brains of spontaneously ill mice exhibited prominent features of prion disease-specific neuropathology that were unique to each mutation and distinct from Tg mice expressing wild-type BVPrP. An ~8-kDa proteinase K-resistant PrP fragment was found in the brains of spontaneously ill Tg mice expressing either wild-type or mutant BVPrP. The spontaneously formed mutant BVPrP prions were transmissible to Tg mice expressing wild-type or mutant BVPrP as well as to Tg mice expressing mouse PrP. Thus, Tg mice expressing mutant BVPrP exhibit many of the hallmarks of heritable prion disorders in humans including spontaneous disease, protease-resistant PrP, and prion infectivity.
| S-EPMC5152593 | biostudies-literature
Project description:Data from Integration-independent Transgenic Huntington Disease
Fragment Mouse Models Reveal Distinct Phenotypes and Life
Span in Vivo
CoIP of HTT full length and fragment proteins from mouse cortical lysates. Controlled with preimmune mouse IgG IP.
2015-06-30 | MSV000079178 | MassIVE
Project description:Melanoma differentiation associated gene-7/Interleukin-24 (MDA-7/IL-24) is a novel member of the IL-10 gene family that selectively induces apoptosis and toxic autophagy in a broad spectrum of human cancers, including breast cancer, without harming normal cells or tissues. The ability to investigate the critical events underlying cancer initiation and progression, as well as the capacity to test the efficacy of novel therapeutics, has been significantly advanced by the development of genetically engineered mice (GEMs) that accurately recapitulate specific human cancers. We utilized three transgenic mouse models to better comprehend the in vivo role of MDA-7/IL-24 in breast cancer. Using the MMTV-PyMT spontaneous mammary tumor model, we confirmed that exogenously introducing MDA-7/IL-24 using a Cancer Terminator Virus caused a reduction in tumor burden and also produced an antitumor "bystander" effect. Next we performed xenograft studies in a newly created MMTV-MDA-7 transgenic model that over-expresses MDA-7/IL-24 in the mammary glands during pregnancy and lactation, and found that MDA-7/IL-24 overexpression delayed tumor growth following orthotopic injection of a murine PDX tumor cell line (mPDX) derived from a tumor formed in an MMTV-PyMT mouse. We also crossed the MMTV-MDA-7 line to MMTV-Erbb2 transgenic mice and found that MDA-7/IL-24 overexpression delayed the onset of mammary tumor development in this model of spontaneous mammary tumorigenesis as well. Finally, we assessed the role of MDA-7/IL-24 in immune regulation, which can potentially contribute to tumor suppression in vivo. Our findings provide further direct in vivo evidence for the role of MDA-7/IL-24 in tumor suppression in breast cancer in immune-competent transgenic mice.
| S-EPMC4741906 | biostudies-other