scholarly journals A Mutant of Human Papillomavirus Type 16 E6 Deficient in Binding α-Helix Partners Displays Reduced Oncogenic Potential In Vivo

2002 ◽  
Vol 76 (24) ◽  
pp. 13039-13048 ◽  
Author(s):  
Marie Nguyen ◽  
Shiyu Song ◽  
Amy Liem ◽  
Elliot Androphy ◽  
Yun Liu ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
P53 Protein ◽  
Human Papillomaviruses ◽  
Skin Tumors ◽  
Cellular Proteins ◽  
Viral Gene ◽  
Gene Encoding ◽  
Tumor Viruses ◽  
Α Helix

ABSTRACT Human papillomaviruses (HPVs) are small DNA tumor viruses that are the causative agent of warts and are associated with many anogenital cancers. The viral gene encoding the E6 protein has been found to be involved in HPV oncogenesis. E6 is known to inactivate the cellular tumor suppressor, p53. In addition, E6 has been shown to bind to a variety of other cellular proteins. The focus of this study was to determine what role the interactions of E6 with a subset of cellular proteins which contain a common α-helical domain in their E6 binding region (α-helix partners) play in E6-mediated phenotypes. We generated transgenic mice expressing a mutant of E6, E6I128T, which is defective for binding at least a subset of the α-helix partners, including E6AP, the ubiquitin ligase that mediates E6-dependent degradation of the p53 protein, to determine whether binding of α-helix partners plays a role in E6-mediated activities in vivo. Unlike mice expressing the wild-type E6 (strain K14E6WT), the mice expressing E6I128T lacked the ability to alter the radiation-induced block to DNA synthesis and promote the formation of benign skin tumors in conjunction with chemical carcinogens. Additionally, they displayed reduced levels of skin hyperplasia, spontaneous skin tumors, and tumor progression activity compared to those of the K14E6WT mice. From these results, we conclude that a domain in E6 that mediates α-helix partner binding is critical for E6-induced phenotypes in transgenic mice.

High incidence of lung, bone, and lymphoid tumors in transgenic mice overexpressing mutant alleles of the p53 oncogene

1989 ◽  
Vol 9 (9) ◽  
pp. 3982-3991
Author(s):  
A Lavigueur ◽  
V Maltby ◽  
D Mock ◽  
J Rossant ◽  
T Pawson ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Malignant Transformation ◽  
P53 Protein ◽  
P53 Gene ◽  
Cell Types ◽  
Molecular Events ◽  
High Incidence ◽  
Transgenic Lines ◽  
Functional Inactivation

We have investigated the role of the p53 gene in oncogenesis in vivo by generating transgenic mice carrying murine p53 genomic fragments isolated from a mouse Friend erythroleukemia cell line or BALB/c mouse liver DNA. Elevated levels of p53 mRNA were detected in several tissues of two transgenic lines tested. Increased levels of p53 protein were also detected in most of the tissues analyzed by Western blotting (immunoblotting). Because both transgenes encoded p53 proteins that were antigenically distinct from wild-type p53, it was possible to demonstrate that overexpression of the p53 protein was mostly, if not entirely, due to the expression of the transgenes. Neoplasms developed in 20% of the transgenic mice, with a high incidence of lung adenocarcinomas, osteosarcomas, and lymphomas. Tissues such as ovaries that expressed the transgene at high levels were not at higher risk of malignant transformation than tissues expressing p53 protein at much lower levels. The long latent period and low penetrance suggest that overexpression of p53 alone is not sufficient to induce malignancies and that additional events are required. These observations provide direct evidence that mutant alleles of the p53 oncogene have oncogenic potential in vivo and that different cell types show intrinsic differences in susceptibility to malignant transformation by p53. Since recent data suggest that p53 may be a recessive oncogene, it is possible that the elevated tumor incidence results from functional inactivation of endogenous p53 by overexpression of the mutant transgene. The high incidence of lung and bone tumors suggests that p53 transgenic mice may provide a useful model to investigate the molecular events that underlie these malignancies in humans.

B-Catenin Signaling Regulates the In Vivo Distribution of Hepatitis B Virus Biosynthesis across the Liver Lobule

2021 ◽  
Author(s):  
Grant Tarnow ◽  
Alan McLachlan
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Viral Replication ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Central Vein ◽  
Liver Lobule ◽  
Liver Gene ◽  
Mice Liver

β-catenin (Ctnnb1) supports high levels of liver gene expression in hepatocytes in proximity to the central vein functionally defining zone 3 of the liver lobule. This region of the liver lobule supports the highest levels of viral biosynthesis in wildtype HBV transgenic mice. Liver-specific β-catenin-null HBV transgenic mice exhibit a stark loss of high levels of pericentral viral biosynthesis. Additionally, viral replication that does not depend directly on β-catenin activity appears to expand to include hepatocytes of zone 1 of the liver lobule in proximity to the portal vein, a region of the liver that typically lacks significant HBV biosynthesis in wildtype HBV transgenic mice. While the average amount of viral RNA transcripts does not change, viral DNA replication is reduced approximately three-fold. Together, these observations demonstrate that β-catenin signaling represents a major determinant of HBV biosynthesis governing the magnitude and distribution of viral replication across the liver lobule in vivo. Additionally, these findings reveal a novel mechanism for the regulation of HBV biosynthesis that is potentially relevant to the expression of additional liver-specific genes. IMPORTANCE Viral biosynthesis is highest around the central vein in the HBV transgenic mouse model of chronic infection. The associated HBV biosynthetic gradient across the liver lobule is primarily dependent upon β-catenin. In the absence of β-catenin, the gradient of viral gene expression spanning the liver lobule is absent and HBV replication is reduced. Therefore, therapeutically manipulating β-catenin activity in the liver of chronic HBV carriers may reduce circulating infectious virions without greatly modulating viral protein production. Together, these change in viral biosynthesis might limit infection of additional hepatocytes while permitting immunological clearance of previously infected cells, potentially limiting disease persistence.

scholarly journals Eosinophilia in transgenic mice expressing interleukin 5.

1990 ◽  
Vol 172 (5) ◽  
pp. 1425-1431 ◽  
Author(s):  
L A Dent ◽  
M Strath ◽  
A L Mellor ◽  
C J Sanderson
Keyword(s):  
Bone Marrow ◽  
Transgenic Mice ◽  
Lymph Nodes ◽  
Peyer's Patches ◽  
Peyer’S Patches ◽  
Mesenteric Lymph Nodes ◽  
Gene Encoding ◽  
Interleukin 5

Experiments in vitro suggest that although interleukin 5 (IL-5) stimulates the late stages of eosinophil differentiation, other cytokines are required for the generation of eosinophil progenitor cells. In this study transgenic mice constitutively expressing the IL-5 gene were established using a genomic fragment of the IL-5 gene coupled to the dominant control region from the gene encoding human CD2. Four independent eosinophilic transgenic lines have thus far been established, two of which with 8 and 49 transgene copies, are described in detail. These mice appeared macroscopically normal apart from splenomegaly. Eosinophils were at least 65- and 265-fold higher in blood from transgenics, relative to normal littermates, and approximately two- or sevenfold more numerous relative to blood from mice infected with the helminth Mesocestoides corti. Much more modest increases in blood neutrophil, lymphocyte, and monocyte numbers were noted in transgenics, relative to normal littermates (less than threefold). Thus IL-5 in vivo is relatively specific for the eosinophil lineage. Large numbers of eosinophils were present in spleen, bone marrow, and peritoneal exudate, and were highest in the line with the greatest transgene copy number. Eosinophilia was also noted in histological sections of transgenic lungs, Peyer's patches, mesenteric lymph nodes, and gut lamina propria but not in other tissues examined. IL-5 was detected in the sera of transgenics at levels comparable to those seen in sera from parasite-infected animals. IL-3 and granulocyte/macrophage colony-stimulating factor (GM-CSF) were not found. IL-5 mRNA was detected in transgenic thymus, Peyer's patches, and superficial lymph nodes, but not in heart, liver, brain, or skeletal muscle or in any tissues from nontransgenics. Bone marrow from transgenic mice was rich in IL-5-dependent eosinophil precursors. These data indicate that induction of the IL-5 gene is sufficient for production of eosinophilia, and that IL-5 can induce the full pathway of eosinophil differentiation. IL-5 may therefore not be restricted in action to the later stages of eosinophil differentiation, as suggested by earlier in vitro studies.

Overexpression of a short human seipin/BSCL2 isoform in mouse adipose tissue results in mild lipodystrophy

2012 ◽  
Vol 302 (6) ◽  
pp. E705-E713 ◽  
Author(s):  
Xin Cui ◽  
Yuhui Wang ◽  
Lingjun Meng ◽  
Weihua Fei ◽  
Jingna Deng ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Transgenic Mice ◽  
White Adipose Tissue ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Triacylglycerol Content ◽  
Adipocyte Development

Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is a recessive disorder characterized by an almost complete loss of adipose tissue, insulin resistance, and fatty liver. BSCL2 is caused by loss-of-function mutations in the BSCL2/seipin gene, which encodes seipin. The essential role for seipin in adipogenesis has recently been established both in vitro and in vivo. However, seipin is highly upregulated at later stages of adipocyte development, and its role in mature adipocytes remains to be elucidated. We therefore generated transgenic mice overexpressing a short isoform of human BSCL2 gene (encoding 398 amino acids) using the adipocyte-specific aP2 promoter. The transgenic mice produced ∼150% more seipin than littermate controls in white adipose tissue. Surprisingly, the increased expression of seipin markedly reduced the mass of white adipose tissue and the size of adipocytes and lipid droplets. This may be due in part to elevated lipolysis rates in the transgenic mice. Moreover, there was a nearly 50% increase in the triacylglycerol content of transgenic liver. These results suggest that seipin promotes the differentiation of preadipocytes but may inhibit lipid storage in mature adipocytes.

scholarly journals Deubiquitinating Function of Adenovirus Proteinase

2002 ◽  
Vol 76 (12) ◽  
pp. 6323-6331 ◽  
Author(s):  
Maxim Y. Balakirev ◽  
Michel Jaquinod ◽  
Arthur L. Haas ◽  
Jadwiga Chroboczek
Keyword(s):  
Structural Model ◽  
Proteolytic Processing ◽  
Host Cells ◽  
Cellular Proteins ◽  
Viral Gene ◽  
Cellular Processes ◽  
Infected Cells ◽  
Substrate Binding Sites

ABSTRACT The invasion strategy of many viruses involves the synthesis of viral gene products that mimic the functions of the cellular proteins and thus interfere with the key cellular processes. Here we show that adenovirus infection is accompanied by an increased ubiquitin-cleaving (deubiquitinating) activity in the host cells. Affinity chromatography on ubiquitin aldehyde (Ubal), which was designed to identify the deubiquitinating proteases, revealed the presence of adenovirus L3 23K proteinase (Avp) in the eluate from adenovirus-infected cells. This proteinase is known to be necessary for the processing of viral precursor proteins during virion maturation. We show here that in vivo Avp deubiquitinates a number of cellular proteins. Analysis of the substrate specificity of Avp in vitro demonstrated that the protein deubiquitination by this enzyme could be as efficient as proteolytic processing of viral proteins. The structural model of the Ubal-Avp interaction revealed some similarity between S1-S4 substrate binding sites of Avp and ubiquitin hydrolases. These results may reflect the acquisition of an advantageous property by adenovirus and may indicate the importance of ubiquitin pathways in viral infection.

scholarly journals Replication and Assembly of Human Papillomaviruses

2009 ◽  
Vol 88 (4) ◽  
pp. 307-317 ◽  
Author(s):  
M.J. Conway ◽  
C. Meyers
Keyword(s):  
Capsid Protein ◽  
Major Capsid Protein ◽  
Human Papillomaviruses ◽  
Icosahedral Symmetry ◽  
Raft Culture ◽  
Tumor Viruses ◽  
Etiologic Agents ◽  
Viral Structure ◽  
Transfer Vectors

Human papillomaviruses (HPVs) are small dsDNA tumor viruses, which are the etiologic agents of most cervical cancers and are associated with a growing percentage of oropharyngeal cancers. The HPV capsid is non-enveloped, having a T=7 icosahedral symmetry formed via the interaction among 72 pentamers of the major capsid protein, L1. The minor capsid protein L2 associates with L1 pentamers, although it is not known if each L1 pentamer contains a single L2 protein. The HPV life cycle strictly adheres to the host cell differentiation program, and as such, native HPV virions are only produced in vivo or in organotypic “raft” culture. Research producing synthetic papillomavirus particles—such as virus-like particles (VLPs), papillomavirus-based gene transfer vectors, known as pseudovirions (PsV), and papillomavirus genome-containing quasivirions (QV)—has bypassed the need for stratifying and differentiating host tissue in viral assembly and has allowed for the rapid analysis of HPV infectivity pathways, transmission, immunogenicity, and viral structure.

scholarly journals Interleukin-6 is necessary, but not sufficient, for induction of the humanC-reactive protein gene in vivo

1997 ◽  
Vol 325 (3) ◽  
pp. 617-621 ◽  
Author(s):  
Birgit WEINHOLD ◽  
Augustinus BADER ◽  
Valeria POLI ◽  
Ulrich RÜTHER
Keyword(s):  
Transgenic Mice ◽  
Acute Phase ◽  
Interleukin 6 ◽  
Acute Phase Reactant ◽  
Primary Hepatocytes ◽  
Cytokine Network ◽  
Gene Encoding ◽  
Reactive Protein

We have investigated the involvement of interleukin-6 (IL-6) in the induction of the gene encoding the acute-phase protein human C-reactive protein (hCRP). In transgenic mice the hCRP gene can be induced by lipopolysaccharide (LPS), but not by IL-6. In contrast, hCRP was inducible by IL-6 in primary human hepatocytes and in primary hepatocytes isolated from transgenic mice. To further evaluate the role of IL-6, we introduced the hCRP transgene into animals lacking endogenous IL-6 (IL-6-negative mice). Here, hCRP was not inducible by LPS, but was induced by a combination of LPS and IL-6. These results clearly demonstrate that IL-6 is necessary, but not sufficient, for the induction of hCRP expression. These animal models will allow further dissection of the cytokine network responsible for the regulation of the major human acute-phase reactant CRP.

scholarly journals High incidence of lung, bone, and lymphoid tumors in transgenic mice overexpressing mutant alleles of the p53 oncogene.

1989 ◽  
Vol 9 (9) ◽  
pp. 3982-3991 ◽  
Author(s):  
A Lavigueur ◽  
V Maltby ◽  
D Mock ◽  
J Rossant ◽  
T Pawson ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Malignant Transformation ◽  
P53 Protein ◽  
P53 Gene ◽  
Cell Types ◽  
Molecular Events ◽  
High Incidence ◽  
Transgenic Lines ◽  
Functional Inactivation

We have investigated the role of the p53 gene in oncogenesis in vivo by generating transgenic mice carrying murine p53 genomic fragments isolated from a mouse Friend erythroleukemia cell line or BALB/c mouse liver DNA. Elevated levels of p53 mRNA were detected in several tissues of two transgenic lines tested. Increased levels of p53 protein were also detected in most of the tissues analyzed by Western blotting (immunoblotting). Because both transgenes encoded p53 proteins that were antigenically distinct from wild-type p53, it was possible to demonstrate that overexpression of the p53 protein was mostly, if not entirely, due to the expression of the transgenes. Neoplasms developed in 20% of the transgenic mice, with a high incidence of lung adenocarcinomas, osteosarcomas, and lymphomas. Tissues such as ovaries that expressed the transgene at high levels were not at higher risk of malignant transformation than tissues expressing p53 protein at much lower levels. The long latent period and low penetrance suggest that overexpression of p53 alone is not sufficient to induce malignancies and that additional events are required. These observations provide direct evidence that mutant alleles of the p53 oncogene have oncogenic potential in vivo and that different cell types show intrinsic differences in susceptibility to malignant transformation by p53. Since recent data suggest that p53 may be a recessive oncogene, it is possible that the elevated tumor incidence results from functional inactivation of endogenous p53 by overexpression of the mutant transgene. The high incidence of lung and bone tumors suggests that p53 transgenic mice may provide a useful model to investigate the molecular events that underlie these malignancies in humans.

scholarly journals GP.02 Neuronal expression of Ubiqulin-2 mutant exacerbates TDP-43 aggregation in ALS mouse mode

2019 ◽  
Vol 46 (s1) ◽  
pp. S6
Author(s):  
V Picher-Martel ◽  
L Renaud ◽  
J Julien
Keyword(s):  
Transgenic Mice ◽  
Motor Neurons ◽  
Drug Testing ◽  
Gene Promoter ◽  
Ubiquitin Proteasome System ◽  
Gene Encoding ◽  
Ubiquitin Proteasome ◽  
Double Transgenic Mice

Background: Mutations in the gene encoding Ubiquilin-2 (UBQLN2) are linked to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). UBQLN2 plays a central role in ubiquitin proteasome system (UPS) and UBQLN2 up-regulation exacerbates TDP-43 cytoplasmic aggregates. Methods: To analyse interaction between UBQLN2 and TDP-43 and to produce a relevant ALS animal model, we have generated a new transgenic mouse expressing UBQLN2P497H under the neurofilament heavy (NFH) gene promoter. The mice were then bred with our previously described TDP-43G348C mice to generate double transgenic mice. Results: With low expression UBQLN2, the double transgenic mice developed TDP-43 cytosolic accumulations in motor neurons starting at 5 months of age. These double transgenic mice exhibited motor neuron loss, muscle atrophy, as well as motor and cognitive deficits during aging. The microglia from double transgenic mice were hyperresponsive to lipopolysaccharide (LPS). In vivo and in vitro analyses suggested that extra UBQLN2 proteins can exacerbate cytoplasmic TDP-43 accumulations by competing with the UPS for binding to ubiquitin. Thus, increasing the pool of ubiquitin promoted the UPS function with ensuing reduction of TDP-43 aggregation. Conclusions: In conclusion, the double transgenic UBQLN2P497H; TDP-43G348C mice provides a unique mouse model of ALS/FTD with enhanced TDP-43 pathology that can be exploited for drug testing.

scholarly journals MDM2 Is Required for Suppression of Apoptosis by Activated Akt1 in Salivary Acinar Cells

2006 ◽  
Vol 26 (23) ◽  
pp. 8840-8856 ◽  
Author(s):  
Kirsten H. Limesand ◽  
Kathryn L. Schwertfeger ◽  
Steven M. Anderson
Keyword(s):  
Transgenic Mice ◽  
Gamma Irradiation ◽  
Salivary Glands ◽  
P53 Protein ◽  
Acinar Cells ◽  
Dominant Negative ◽  
Common Side Effect ◽  
Protein Accumulation ◽  
Irreversible Damage

ABSTRACT Chronic damage to the salivary glands is a common side effect following head and neck irradiation. It is hypothesized that irreversible damage to the salivary glands occurs immediately after radiation; however, previous studies with rat models have not shown a causal role for apoptosis in radiation-induced injury. We report that etoposide and gamma irradiation induce apoptosis of salivary acinar cells from FVB control mice in vitro and in vivo; however, apoptosis is reduced in transgenic mice expressing a constitutively activated mutant of Akt1 (myr-Akt1). Expression of myr-Akt1 in the salivary glands results in a significant reduction in phosphorylation of p53 at serine18, total p53 protein accumulation, and p21WAF1 or Bax mRNA following etoposide or gamma irradiation of primary salivary acinar cells. The reduced level of p53 protein in myr-Akt1 salivary glands corresponds with an increase in MDM2 phosphorylation in vivo, suggesting that the Akt/MDM2/p53 pathway is responsible for suppression of apoptosis. Dominant-negative Akt blocked phosphorylation of MDM2 in salivary acinar cells from myr-Akt1 transgenic mice. Reduction of MDM2 levels in myr-Akt1 primary salivary acinar cells with small interfering RNA increases the levels of p53 protein and renders these cells susceptible to etoposide-induced apoptosis in spite of the presence of activated Akt1. These results indicate that MDM2 is a critical substrate of activated Akt1 in the suppression of p53-dependent apoptosis in vivo.

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