Overview of Genetically Engineered Mouse Models of Papillary and Anaplastic Thyroid Cancers: Enabling Translational Biology for Patient Care Improvement.

The prognosis from thyroid cancer subtypes in humans covers a spectrum from "cured at almost 90%" to "100% lethal." Invasive and poorly differentiated forms of thyroid cancer are among the most aggressive human cancers, and there are few effective therapeutic options. Genetically engineered mice, based on mutations observed in patients, can accurately recapitulate the human disease and its progression, providing invaluable tools for the preclinical evaluation of novel therapeutic approaches. This overview details models developed to date as well as their uses for identifying novel anticancer agents. © 2015 by John Wiley & Sons, Inc.

Sphingosine kinase 2 deficiency increases proliferation and migration of renal mouse mesangial cells and fibroblasts

Both of the sphingosine kinase (SK) subtypes SK-1 and SK-2 catalyze the production of the bioactive lipid molecule sphingosine 1-phosphate (S1P). However, the subtype-specific cellular functions are largely unknown. In this study, we investigated the cellular function of SK-2 in primary mouse renal mesangial cells (mMC) and embryonic fibroblasts (MEF) from wild-type C57BL/6 or SK-2 knockout (SK2ko) mice. We found that SK2ko cells displayed a significantly higher proliferative and migratory activity when compared to wild-type cells, with concomitant increased cellular activities of the classical extracellular signal regulated kinase (ERK) and PI3K/Akt cascades, and of the small G protein RhoA. Furthermore, we detected an upregulation of SK-1 protein and S1P3 receptor mRNA expression in SK-2ko cells. The MEK inhibitor U0126 and the S1P1/3 receptor antagonist VPC23019 blocked the increased migration of SK-2ko cells. Additionally, S1P3ko mesangial cells showed a reduced proliferative behavior and reduced migration rate upon S1P stimulation, suggesting a crucial involvement of the S1P3 receptor. In summary, our data demonstrate that SK-2 exerts suppressive effects on cell growth and migration in renal mesangial cells and fibroblasts, and that therapeutic targeting of SKs for treating proliferative diseases requires subtype-selective inhibitors.

In vitro differentiation of mouse granulocytes. Programmed Cell Death: Methods and Protocols

Granulocytes are central players of the immune system and, once activated, a tightly controlled balance between effector functions and cell removal by apoptosis guarantees maximal host benefit with least possible collateral damage to healthy tissue. Granulocytes are end-differentiated cells that cannot be maintained in culture for prolonged times. Isolating primary granulocytes is inefficient and challenging when working with mice, and especially so for the lowly abundant eosinophil and basophils subtypes. Here we describe an in vitro protocol to massively expand mouse derived myeloid progenitors and to differentiate them ‘on demand’ and in large numbers into mature neutrophils or basophils.

Variable phenotypic expressivity in inbred retinal degeneration mouse lines: A comparative study of C3H/HeOu and FVB/N rd1 mice

PURPOSE Recent advances in optogenetics and gene therapy have led to promising new treatment strategies for blindness caused by retinal photoreceptor loss. Preclinical studies often rely on the retinal degeneration 1 (rd1 or Pde6b(rd1)) retinitis pigmentosa (RP) mouse model. The rd1 founder mutation is present in more than 100 actively used mouse lines. Since secondary genetic traits are well-known to modify the phenotypic progression of photoreceptor degeneration in animal models and human patients with RP, negligence of the genetic background in the rd1 mouse model is unwarranted. Moreover, the success of various potential therapies, including optogenetic gene therapy and prosthetic implants, depends on the progress of retinal degeneration, which might differ between rd1 mice. To examine the prospect of phenotypic expressivity in the rd1 mouse model, we compared the progress of retinal degeneration in two common rd1 lines, C3H/HeOu and FVB/N. METHODS We followed retinal degeneration over 24 weeks in FVB/N, C3H/HeOu, and congenic Pde6b(+) seeing mouse lines, using a range of experimental techniques including extracellular recordings from retinal ganglion cells, PCR quantification of cone opsin and Pde6b transcripts, in vivo flash electroretinogram (ERG), and behavioral optokinetic reflex (OKR) recordings. RESULTS We demonstrated a substantial difference in the speed of retinal degeneration and accompanying loss of visual function between the two rd1 lines. Photoreceptor degeneration and loss of vision were faster with an earlier onset in the FVB/N mice compared to C3H/HeOu mice, whereas the performance of the Pde6b(+) mice did not differ significantly in any of the tests. By postnatal week 4, the FVB/N mice expressed significantly less cone opsin and Pde6b mRNA and had neither ERG nor OKR responses. At 12 weeks of age, the retinal ganglion cells of the FVB/N mice had lost all light responses. In contrast, 4-week-old C3H/HeOu mice still had ERG and OKR responses, and we still recorded light responses from C3H/HeOu retinal ganglion cells until the age of 24 weeks. These results show that genetic background plays an important role in the rd1 mouse pathology. CONCLUSIONS Analogous to human RP, the mouse genetic background strongly influences the rd1 phenotype. Thus, different rd1 mouse lines may follow different timelines of retinal degeneration, making exact knowledge of genetic background imperative in all studies that use rd1 models.

Sleep-Wake Cycle Dysfunction in the TgCRND8 Mouse Model of Alzheimer's Disease: From Early to Advanced Pathological Stages.

In addition to cognitive decline, individuals affected by Alzheimer's disease (AD) can experience important neuropsychiatric symptoms including sleep disturbances. We characterized the sleep-wake cycle in the TgCRND8 mouse model of AD, which overexpresses a mutant human form of amyloid precursor protein resulting in high levels of β-amyloid and plaque formation by 3 months of age. Polysomnographic recordings in freely-moving mice were conducted to study sleep-wake cycle architecture at 3, 7 and 11 months of age and corresponding levels of β-amyloid in brain regions regulating sleep-wake states were measured. At all ages, TgCRND8 mice showed increased wakefulness and reduced non-rapid eye movement (NREM) sleep during the resting and active phases. Increased wakefulness in TgCRND8 mice was accompanied by a shift in the waking power spectrum towards fast frequency oscillations in the beta (14-20 Hz) and low gamma range (20-50 Hz). Given the phenotype of hyperarousal observed in TgCRND8 mice, the role of noradrenergic transmission in the promotion of arousal, and previous work reporting an early disruption of the noradrenergic system in TgCRND8, we tested the effects of the alpha-1-adrenoreceptor antagonist, prazosin, on sleep-wake patterns in TgCRND8 and non-transgenic (NTg) mice. We found that a lower dose (2 mg/kg) of prazosin increased NREM sleep in NTg but not in TgCRND8 mice, whereas a higher dose (5 mg/kg) increased NREM sleep in both genotypes, suggesting altered sensitivity to noradrenergic blockade in TgCRND8 mice. Collectively our results demonstrate that amyloidosis in TgCRND8 mice is associated with sleep-wake cycle dysfunction, characterized by hyperarousal, validating this model as a tool towards understanding the relationship between β-amyloid overproduction and disrupted sleep-wake patterns in AD.

The bona fide mouse U7 snRNA gene maps to a different chromosome than two U7 pseudogenes.

The U7 snRNA, together with both common and unique snRNP proteins, forms the U7 snRNP particle. This particle is a major component of the 3' processing machinery that converts histone pre-mRNA into mature mRNA in the eukaryotic nucleus. The genes for many snRNAs are present in multiple copies and often have many pseudogenes. Southern blot experiments using U7 oligonucleotide and gene probes have identified only one strongly hybridizing band and three weakly hybridizing bands in mouse genomic DNA. Previously, two laboratories isolated genomic clones encoding one functional U7 gene and three presumed pseudogenes. Since all the genes were isolated on separate, nonoverlapping genomic fragments, the four genes are not tightly clustered in the mouse genome. In this study, we use fluorescence in situ hybridization to determine the chromosomal locations of these clones and their possible linkage to histone loci. Two of the pseudogenes map to mouse Chromosome 1, but are many megabases apart, whereas the active U7 gene maps to Chromosome 6. Possible mechanisms for this localization pattern are discussed.

3' end processing of mouse histone pre-mRNA: evidence for additional base-pairing between U7 snRNA and pre-mRNA.

We have analysed the extent of base-pairing interactions between spacer sequences of histone pre-mRNA and U7 snRNA present in the trans-acting U7 snRNP and their importance for histone RNA 3' end processing in vitro. For the efficiently processed mouse H4-12 gene, a computer analysis revealed that additional base pairs could be formed with U7 RNA outside of the previously recognised spacer element (stem II). One complementarity (stem III) is located more 3' and involves nucleotides from the very 5' end of U7 RNA. The other, more 5' located complementarity (stem I) involves nucleotides of the Sm binding site of U7 RNA, a part known to interact with snRNP structural proteins. These potential stem structures are separated from each other by short internal loops of unpaired nucleotides. Mutational analyses of the pre-mRNA indicate that stems II and III are equally important for interaction with the U7 snRNP and for processing, whereas mutations in stem I have moderate effects on processing efficiency, but do not impair complex formation with the U7 snRNP. Thus nucleotides near the processing site may be important for processing, but do not contribute to the assembly of an active complex by forming a stem I structure. The importance of stem III was confirmed by the ability of a complementary mutation in U7 RNA to suppress a stem III mutation in a complementation assay using Xenopus laevis oocytes. The main role of the factor(s) binding to the upstream hairpin loop is to stabilise the U7-pre-mRNA complex. This was shown by either stabilising (by mutation) or destabilising (by increased temperature) the U7-pre-mRNA base-pairing under conditions where hairpin factor binding was either allowed or prevented (by mutation or competition). The hairpin dependence of processing was found to be inversely related to the strength of the U7-pre-mRNA interaction.

Analysis of left ventricular function of the mouse heart during experimentally induced hyperthyroidism and recovery

Many of the clinical manifestations of hyperthyroidism are due to the ability of thyroid hormones to alter myocardial contractility and cardiovascular hemodynamics, leading to cardiovascular impairment. In contrast, recent studies highlight also the potential beneficial effects of thyroid hormone administration for clinical or preclinical treatment of different diseases such as atherosclerosis, obesity and diabetes or as a new therapeutic approach in demyelinating disorders. In these contexts and in the view of developing thyroid hormone-based therapeutic strategies, it is, however, important to analyze undesirable secondary effects on the heart. Animal models of experimentally induced hyperthyroidism therefore represent important tools for investigating and monitoring changes of cardiac function. In our present study we use high-field cardiac MRI to monitor and follow-up longitudinally the effects of prolonged thyroid hormone (triiodothyronine) administration focusing on murine left ventricular function. Using a 9.4 T small horizontal bore animal scanner, cinematographic MRI was used to analyze changes in ejection fraction, wall thickening, systolic index and fractional shortening. Cardiac MRI investigations were performed after sustained cycles of triiodothyronine administration and treatment arrest in adolescent (8 week old) and adult (24 week old) female C57Bl/6 N mice. Triiodothyronine supplementation of 3 weeks led to an impairment of cardiac performance with a decline in ejection fraction, wall thickening, systolic index and fractional shortening in both age groups but with a higher extent in the group of adolescent mice. However, after a hormonal treatment cessation of 3 weeks, only young mice are able to partly restore cardiac performance in contrast to adult mice lacking this recovery potential and therefore indicating a presence of chronically developed heart pathology.

Modeling immune functions of the mouse blood-cerebrospinal fluid barrier in vitro: primary rather than immortalized mouse choroid plexus epithelial cells are suited to study immune cell migration across this brain barrier.

BACKGROUND The blood-cerebrospinal fluid barrier (BCSFB) established by the choroid plexus (CP) epithelium has been recognized as a potential entry site of immune cells into the central nervous system during immunosurveillance and neuroinflammation. The location of the choroid plexus impedes in vivo analysis of immune cell trafficking across the BCSFB. Thus, research on cellular and molecular mechanisms of immune cell migration across the BCSFB is largely limited to in vitro models. In addition to forming contact-inhibited epithelial monolayers that express adhesion molecules, the optimal in vitro model must establish a tight permeability barrier as this influences immune cell diapedesis. METHODS We compared cell line models of the mouse BCSFB derived from the Immortomouse(®) and the ECPC4 line to primary mouse choroid plexus epithelial cell (pmCPEC) cultures for their ability to establish differentiated and tight in vitro models of the BCSFB. RESULTS We found that inducible cell line models established from the Immortomouse(®) or the ECPC4 tumor cell line did not express characteristic epithelial proteins such as cytokeratin and E-cadherin and failed to reproducibly establish contact-inhibited epithelial monolayers that formed a tight permeability barrier. In contrast, cultures of highly-purified pmCPECs expressed cytokeratin and displayed mature BCSFB characteristic junctional complexes as visualized by the junctional localization of E-cadherin, β-catenin and claudins-1, -2, -3 and -11. pmCPECs formed a tight barrier with low permeability and high electrical resistance. When grown in inverted filter cultures, pmCPECs were suitable to study T cell migration from the basolateral to the apical side of the BCSFB, thus correctly modelling in vivo migration of immune cells from the blood to the CSF. CONCLUSIONS Our study excludes inducible and tumor cell line mouse models as suitable to study immune functions of the BCSFB in vitro. Rather, we introduce here an in vitro inverted filter model of the primary mouse BCSFB suited to study the cellular and molecular mechanisms mediating immune cell migration across the BCSFB during immunosurveillance and neuroinflammation.

Dose-dependent effects of experimental infection with the virulent Neospora caninum Nc-Spain7 isolate in a pregnant mouse model.

Pregnant BALB/c mice have been widely used as an in vivo model to study Neospora caninum infection biology and to provide proof-of-concept for assessments of drugs and vaccines against neosporosis. The fact that this model has been used with different isolates of variable virulence, varying infection routes and differing methods to prepare the parasites for infection, has rendered the comparison of results from different laboratories impossible. In most studies, mice were infected with similar number of parasites (2 × 10(6)) as employed in ruminant models (10(7) for cows and 10(6) for sheep), which seems inappropriate considering the enormous differences in the weight of these species. Thus, for achieving meaningful results in vaccination and drug efficacy experiments, a refinement and standardization of this experimental model is necessary. Thus, 2 × 10(6), 10(5), 10(4), 10(3) and 10(2) tachyzoites of the highly virulent and well-characterised Nc-Spain7 isolate were subcutaneously inoculated into mice at day 7 of pregnancy, and clinical outcome, vertical transmission, parasite burden and antibody responses were compared. Dams from all infected groups presented nervous signs and the percentage of surviving pups at day 30 postpartum was surprisingly low (24%) in mice infected with only 10(2) tachyzoites. Importantly, infection with 10(5) tachyzoites resulted in antibody levels, cerebral parasite burden in dams and 100% mortality rate in pups, which was identical to infection with 2 × 10(6) tachyzoites. Considering these results, it is reasonable to lower the challenge dose to 10(5) tachyzoites in further experiments when assessing drugs or vaccine candidates.

A vaccine formulation combining rhoptry proteins NcROP40 and NcROP2 improves pup survival in a pregnant mouse model of neosporosis.

Currently there are no effective vaccines for the control of bovine neosporosis. During the last years several subunit vaccines based on immunodominant antigens and other proteins involved in adhesion, invasion and intracellular proliferation of Neospora caninum have been evaluated as targets for vaccine development in experimental mouse infection models. Among them, the rhoptry antigen NcROP2 and the immunodominant NcGRA7 protein have been assessed with varying results. Recent studies have shown that another rhoptry component, NcROP40, and NcNTPase, a putative dense granule antigen, exhibit higher expression levels in tachyzoites of virulent N. caninum isolates, suggesting that these could be potential vaccine candidates to limit the effects of infection. In the present work, the safety and efficacy of these recombinant antigens formulated in Quil-A adjuvant as monovalent vaccines or pair-wise combinations (rNcROP40+rNcROP2 and rNcGRA7+rNcNTPase) were evaluated in a pregnant mouse model of neosporosis. All the vaccine formulations elicited a specific immune response against their respective native proteins after immunization. Mice vaccinated with rNcROP40 and rNcROP2 alone or in combination produced the highest levels of IFN-γ and exhibited low parasite burdens and low IgG antibody levels after the challenge. In addition, most of the vaccine formulations were able to increase the median survival time in the offspring. However, pup survival only ensued in the groups vaccinated with rNcROP40+rNcROP2 (16.2%) and rNcROP2 (6.3%). Interestingly, vertical transmission was not observed in those survivor pups immunized with rNcROP40+rNcROP2, as shown by PCR analyses. These results show a partial protection against N. caninum infection after vaccination with rNcROP40+rNcROP2, suggesting a synergistic effect of the two recombinant rhoptry antigens.

MOUSE MAMMARY TUMOR VIRUS-RELATED PROTEINS: ISOLATION AND CHARACTERIZATION OF A UNIQUE GLYCOPROTEIN

Mouse mammary tumor virus (MMTV) contained six major proteins, identified as gp55, gp33, p25, pp20, p12, and p10. Immunoprecipitation of cytoplasmic extracts from MMTV-infected, pulse-labeled cells identified three MMTV core-specific precursor proteins, termed Pr78('gag), Pr110('gag), Pr110('gag), and Pr180('gag+). The major intracellular core-specific precursor polyprotein, Pr78('gag), contained antigenic determinants and tryptic peptides characteristic of p25, p12, and p10. Pr110('gag) contained all but one of the leucine-containing tryptic peptides of Pr78('gag), plus several additional peptides. In addition to Pr78('gag) and Pr110('gag), monospecific antisera to virion p12 and p25 also precipitated from pulse-labeled cells a small amount of Pr180('gag+). This large polyprotein contained nearly all of the leucine-containing tryptic peptides of Pr78('gag) and Pr110('gag) plus several additional peptides. By analogy to type-C viral systems, Pr180('gag+) is presumed to represent a gag-pol-specific common precursor which is the major translation product in the synthesis of MMTV RNA-dependent-DNA polymerase. Immunoprecipitation of cytoplasmic extracts from pulse-labeled cells with antisera to gp55 identified two envelope-specific proteins, designated gPr76('env) and gP79('env). The major envelope-specific precursor, gPr76('env), could be labeled with radioactive glucosamine and contained antigenic determinants and tryptic peptides characteristic of gp55 and gp33. A quantitatively minor glycoprotein, gP79('env), contained both fucose and glucosamine and was precipitable from cytoplasmic extracts with monospecific serum to gp55. It is suggested that gP79('env) represents fucosylated gPr76('env) which is transiently synthesized and cleaved rapidly into gp55 and gp33.^ A glycoprotein of 130,00 molecular weight (gP130) was precipitable from the cytoplasm of GR-strain mouse mammary tumor cells by a rabbit antiserum (anti-MMTV) to Gr-strain mouse mammary tumors virus (GR-MMTV). Two dimensional thin layer analysis of ('35)S-methionine-containing peptides revealed that five of nine gp33 peptides and one of seven gp55 peptides were shared by gP130 and gPr76('env). Six of ten p25 peptides and four more core-related peptides were shared by Pr78('gag) and gP130. Protein gP130 also contained several tryptic peptides not found in gPr76('env), or in the core protein precursors Pr78('gag), Pr110('gag), or Pr180('gag+). both gP130 and a second protein, p30, were found in immunoprecipitates of detergent disrupted, isotopically labeled GR-MMTV treated with anti-MMTV serum. Results suggest that antibodies to gP130 in the anti-MMTV serum are capable of recognizing those protein sequences which are not related to viral structural proteins. These gP130-unique peptides are evidently host specific. Polyproteins consisting of juxtaposed host- and virus-related protein tracts have been implicated in the process of cell transformation in other mammalian systems. Therefore, gP130 may be instrinsic to the oncogenic potential of MMTV. ^

THE MICROCELL-MEDIATED TRANSFER OF SINGLE HUMAN CHROMOSOMES INTO RECIPIENT MOUSE CELLS

Microcell-mediated chromosome transfer is a method of gene transfer which allows for the introduction of single or small groups of intact chromosomes into recipient host cells. Microcell transfer was first performed by Fournier and Ruddle using rodent microcells and various recipient cells. Expansion of this technology to include the transfer of normal human genetic material has been hindered because large micronucleate populations from diploid human cells have been unobtainable. This dissertation research describes, however, the methods for production of micronuclei in 40-60% of normal human fibroblasts. Once micronucleate cells were obtained, they were enucleated by centrifugation in the presence of Cytochalasin B; the microcells were then purified and fused to recipient mouse (LMTK('-)) cells using a new fusion protocol employing polyethylene glycol containing phytohemagglutinin. Microcell clones were isolated from the HAT selection system. Alkaline Giemsa staining performed on these hybrids indicated the presence of a single human chromosome in each of seven microcell clones from three separate experiments. That chromosome was further identified by G banding analysis to be human chromosome #17, which codes for thymidine kinase. The time course for production of these hybrids from fusion to karyotypic analysis was 6 weeks. The viability of the transferred human genetic material was assessed by electrophoretic isozyme analysis.^ Subsequent experiments were performed in an attempt to optimize the transfer frequency for the thymidine kinase gene using this system. Results indicated that the frequency could be increased from < 1 x 10('-6) in initial experiments to 2 x 10('-5) in the latest experiment. Analyses were also conducted to determine the number of chromosomes per isolated microcell as well as to investigate the stability of the transferred human chromosome in the mouse genome. ^

HETEROGENEITY IN VIRUS EXPRESSION, TUMORIGENICITY, AND IN VITRO GROWTH PROPERTIES OF DRUG-RESISTANT CLONES OF AN RIII MOUSE MAMMARY TUMOR CELL LINE

Four 8-azaguanine (AG)-resistant and 5-bromodeoxyuridine (BUdR)-resistant clones of a mouse mammary adenocarcinoma cell line, RIII 7387, were developed and analyzed for their tumorigenic properties, in vitro characteristics, and virus expression. These characteristics were analyzed for relationships of any of the cellular parameters and the ability of these lines to produce tumors in syngeneic animals.^ The results of this study demonstrated that the parental line consists of a heterogeneous population of cells. Doubling times, saturation densities, and 2-deoxy-D-glucose uptake varied between sublines. In addition, while all sublines were found to express both B-type and C-type viral antigenic markers, levels of the major B-type and C-type viral proteins varied in the subclones. The sublines also differed markedly in their response to the presence of dexamethasone, glutathione, and insulin in the tissue culture medium.^ Variations in retrovirus expression were convirmed by electron microscopy. Budding and extracellular virus particles were seen in the majority of the cell lines. Virus particles in one of the BUdR-resistant lines, BUD9, were found however, only in inclusions and vacuoles. The AG-resistant subline AGE11 was observed to be rich in intracytoplasmic A particles. The examination of these cell lines for the presence of retroviral RNA-dependent DNA polymerase (RT) activity revealed that some B-type RT activity could be found in the culture fluid of most of the cell lines but that little C-type RT activity could be found suggesting that the C-type virus particles expressed by these RIII clones contain a defective RT.^ Tumor clones also varied in their ability to form tumors in syngeneic RIII mice. Tumor incidence ranged from 50% to 100%. The majority of the tumors regressed within 30 days post infection.^ Statistical analysis indicated that while these clones varied in their characteristics, there was no correlation between the ability of these cell lines to form tumors in syngeneic mice and any of the other characteristics examined.^ These studies have confirmed and extended the growing evidence that tumors, regardless of their natural origin, consist of heterogeneous subpopulations of cells which may vary widely in their in vitro growth behavior, their antigenic expression, and their malignant properties. ^