scholarly journals Expression of Murine APOBEC3 Alleles in Different Mouse Strains and Their Effect on Mouse Mammary Tumor Virus Infection

2009 ◽  
Vol 83 (7) ◽  
pp. 3029-3038 ◽  
Author(s):  
Chioma M. Okeoma ◽  
Josiah Petersen ◽  
Susan R. Ross
Keyword(s):  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Inbred Mouse ◽  
Mouse Strains ◽  
Inbred Mouse Strains ◽  
Mammary Tumor Virus ◽  
Susceptibility To Infection ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

ABSTRACT Recent work has shown that mouse APOBEC3 restricts infection by mouse mammary tumor virus (MMTV) and murine leukemia virus (MLV) and that there are polymorphic APOBEC3 alleles found in different inbred mouse strains. For example, C57BL/6 mice, which are resistant to Friend MLV (F-MLV), encode a APOBEC3 gene different from that encoded by F-MLV-susceptible BALB/c mice; the predominant RNA produced in C57BL/6 mice lacks exon 5 (mA3−5) and encodes a protein with 15 polymorphic amino acids. It has also been reported that BALB/c mice produce only a variant RNA that lacks exon 2 (mA3−2). In this study, we examined the effect of these polymorphic APOBEC3 proteins on MMTV infection. We found that the major RNA made in C57BL/6 and B10.BR mice lacks exon 5 but that BALB/c and C3H/HeN mice predominantly express an RNA that contains all nine exons. In addition to producing the splice variant, C57BL/6 and B10.BR cells and tissues had levels of mA3 RNA fivefold higher than those from BALB/c and C3H/HeN mice. A cloned C57BL/6-derived mA3 protein lacking exon 5 inhibited MMTV infection better than a cloned full-length protein derived from 129/Ola RNA when packaged into MMTV virions. We also tested dendritic cells derived from different inbred mouse strains for their abilities to be infected by MMTV and showed that susceptibility to infection correlated with the presence of the exon 5-encoding allele. In vivo susceptibility to infection cosegregated with the inherited mA3 allele in a C57BL/6 × BALB/c backcross analysis. Moreover, virus produced in vivo in the mammary tissue of mA3 knockout and BALB/c mice was more infectious than that produced in the tissue of C57BL/6 mice. These data indicate that mA3 plays a role in the genetics of susceptibility and resistance to MMTV infection.

scholarly journals Heregulin Co-opts PR Transcriptional Action Via Stat3 Role As a Coregulator to Drive Cancer Growth

2015 ◽  
Vol 29 (10) ◽  
pp. 1468-1485 ◽  
Author(s):  
Cecilia J. Proietti ◽  
Franco Izzo ◽  
María Celeste Díaz Flaqué ◽  
Rosalía Cordo Russo ◽  
Leandro Venturutti ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Signaling Pathways ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Cancer Growth ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Virus Promoter

Abstract Accumulated findings have demonstrated the presence of bidirectional interactions between progesterone receptor (PR) and the ErbB family of receptor tyrosine kinases signaling pathways in breast cancer. We previously revealed signal transducer and activator of transcription 3 (Stat3) as a nodal convergence point between said signaling pathways proving that Stat3 is activated by one of the ErbBs' ligands, heregulin (HRG)β1 via ErbB2 and through the co-option of PR as a signaling molecule. Here, we found that HRGβ1 induced Stat3 recruitment to the promoters of the progestin-regulated cell cycle modulators Bcl-XL and p21CIP1 and also stimulated Stat3 binding to the mouse mammary tumor virus promoter, which carries consensus progesterone response elements. Interestingly, HRGβ1-activated Stat3 displayed differential functions on PR activity depending on the promoter bound. Indeed, Stat3 was required for PR binding in bcl-X, p21CIP1, and c-myc promoters while exerting a PR coactivator function on the mouse mammary tumor virus promoter. Stat3 also proved to be necessary for HRGβ1-induced in vivo tumor growth. Our results endow Stat3 a novel function as a coregulator of HRGβ1-activated PR to promote breast cancer growth. These findings underscore the importance of understanding the complex interactions between PR and other regulatory factors, such as Stat3, that contribute to determine the context-dependent transcriptional actions of PR.

scholarly journals Nucleosome-mediated disruption of transcription factor-chromatin initiation complexes at the mouse mammary tumor virus long terminal repeat in vivo.

1994 ◽  
Vol 14 (1) ◽  
pp. 32-41 ◽  
Author(s):  
H L Lee ◽  
T K Archer
Keyword(s):  
Mammary Tumor ◽  
Dna Sequences ◽  
Mouse Mammary Tumor Virus ◽  
Binding Protein ◽  
Tata Binding Protein ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Nuclear Factor 1

Glucocorticoid induction of mouse mammary tumor virus (MMTV) is short lived, returning to base levels within 24 h despite the continued presence of hormone. MMTV DNA sequences assembled as chromatin require hormone for binding by nuclear factor 1 (NF1) and octamer proteins (OCT). However, in the same cells, NF1 and OCT factors are bound to transiently introduced DNA in the absence of hormone. In contrast, recruitment of the TATA-binding protein and a novel DNA-binding protein, which we have designated FDT, for factor downstream of the TATA-binding protein, is hormone dependent for both stable and transient templates. Furthermore, transient DNA templates, but not nucleosomal templates, retain these transcription factors over the course of 24 h. This finding suggests that MMTV chromatin structure contributes to activation and cessation of transcription in vivo.

scholarly journals Bone marrow stromal cell antigen 2 (BST-2) restricts mouse mammary tumor virus (MMTV) replication in vivo

Retrovirology ◽  
2012 ◽  
Vol 9 (1) ◽  
pp. 10 ◽  
Author(s):  
Philip H Jones ◽  
Harshini V Mehta ◽  
Martina Maric ◽  
Richard J Roller ◽  
Chioma M Okeoma
Keyword(s):  
Bone Marrow ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Stromal Cell ◽  
Bone Marrow Stromal Cell ◽  
Mammary Tumor Virus ◽  
Marrow Stromal Cell ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

scholarly journals Peripheral T cell activation and deletion induced by transfer of lymphocyte subsets expressing endogenous or exogenous mouse mammary tumor virus.

1993 ◽  
Vol 177 (5) ◽  
pp. 1359-1366 ◽  
Author(s):  
G A Waanders ◽  
A N Shakhov ◽  
W Held ◽  
O Karapetian ◽  
H Acha-Orbea ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Lymphocyte Subsets ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Cell Deletion

Murine T cell reactivity with products of the minor lymphocyte stimulatory (Mls) locus correlates with the expression of particular variable (V) domains of the T cell receptor (TCR) beta chain. It was recently demonstrated that Mls antigens are encoded by an open reading frame (ORF) in the 3' long terminal repeat of either endogenous or exogenous mouse mammary tumor virus (MMTV). Immature thymocytes expressing reactive TCR-V beta domains are clonally deleted upon exposure to endogenous Mtv's. Mature T cells proliferate vigorously in response to Mls-1a (Mtv-7) in vivo, but induction of specific anergy and deletion after exposure to Mtv-7-expressing cells in the periphery has also been described. We show here that B cells and CD8+ (but not CD4+) T cells from Mtv-7+ mice efficiently induce peripheral deletion of reactive T cells upon transfer to Mtv-7- recipients, whereas only B cells stimulate specific T cell proliferation in vivo. In contrast to endogenous Mtv-7, transfer of B, CD4+, or CD8+ lymphocyte subsets from mice maternally infected with MMTV(SW), an infectious homologue of Mtv-7, results in specific T cell deletion in the absence of a detectable proliferative response. Finally, we show by secondary transfers of infected cells that exogenous MMTV(SW) is transmitted multidirectionally between lymphocyte subsets and ultimately to the mammary gland. Collectively our data demonstrate heterogeneity in the expression and/or presentation of endogenous and exogenous MMTV ORF by lymphocyte subsets and emphasize the low threshold required for induction of peripheral T cell deletion by these gene products.

scholarly journals A Novel Block to Mouse Mammary Tumor Virus Infection of Lymphocytes in B10.BR Mice

2007 ◽  
Vol 82 (3) ◽  
pp. 1314-1322 ◽  
Author(s):  
Chioma M. Okeoma ◽  
Ming Shen ◽  
Susan R. Ross
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Cell Activation ◽  
Mouse Strains ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Mhc Locus

ABSTRACT Classic studies on C57BL-derived mouse strains showed that they were resistant to mouse mammary tumor virus (MMTV) infection. Although one form of resistance mapped to the major histocompatibility complex (MHC) locus, at least one other, unknown gene was implicated in this resistance. We show here that B10.BR mice, which are derived from C57BL mice but have the same MHC locus (H-2 k ) as susceptible C3H/HeN mice, are resistant to MMTV, and show a lack of virus spread in their lymphoid compartments but not their mammary epithelial cells. Although in vivo virus superantigen (Sag)-mediated activation of T cells was similar in C3H/HeN and B10.BR mice, T cell-dependent B-cell and dendritic cell activation was diminished in the latter. Ex vivo, B10.BR T cells showed a diminished capacity to proliferate in response to the MMTV Sag. The genetic segregation of the resistance phenotype indicated that it maps to a single allele. These data highlight the role of Sag-dependent T-cell responses in MMTV infection and point to a novel mechanism for the resistance of mice to retroviral infection that could lead to a better understanding of the interplay between hosts and pathogens.

scholarly journals Transcription factor access is mediated by accurately positioned nucleosomes on the mouse mammary tumor virus promoter.

1991 ◽  
Vol 11 (2) ◽  
pp. 688-698 ◽  
Author(s):  
T K Archer ◽  
M G Cordingley ◽  
R G Wolford ◽  
G L Hager
Keyword(s):  
Mammary Tumor ◽  
Transcription Initiation ◽  
Mouse Mammary Tumor Virus ◽  
Initiation Complex ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Nuclear Factor 1

A fragment of the mouse mammary tumor virus (MMTV) promoter was reconstituted from pure histones into a dinucleosome with uniquely positioned octamer cores. Core boundaries for the in vitro-assembled dinucleosome corresponded to the observed in vivo phasing pattern for long terminal repeat nucleosomes A and B. Nuclear factor 1 (NF1), a constituent of the MMTV transcription initiation complex, was excluded from the assembled dinucleosome, whereas the glucocorticoid receptor was able to bind. During transcription of MMTV in vivo, displacement of nucleosome B was necessary to permit assembly of the initiation complex. These results indicate that the nucleoprotein structure of the promoter can provide differential access to sequence-specific DNA-binding proteins and that active chromatin remodeling can occur during transcription activation.

scholarly journals Histone H1 Phosphorylation by Cdk2 Selectively Modulates Mouse Mammary Tumor Virus Transcription through Chromatin Remodeling

2001 ◽  
Vol 21 (16) ◽  
pp. 5417-5425 ◽  
Author(s):  
Rabindra N. Bhattacharjee ◽  
Geoffrey C. Banks ◽  
Kevin W. Trotter ◽  
Huay-Leng Lee ◽  
Trevor K. Archer
Keyword(s):  
Chromatin Remodeling ◽  
Mammary Tumor ◽  
Mouse Mammary Tumor Virus ◽  
Histone H1 ◽  
Necessary Condition ◽  
Mammary Tumor Virus ◽  
Mouse Mammary Tumor ◽  
Tumor Virus ◽  
Mmtv Promoter

ABSTRACT Transcriptional activation of the mouse mammary tumor virus (MMTV) promoter by ligand-bound glucocorticoid receptor (GR) is transient. Previously, we demonstrated that prolonged hormone exposure results in displacement of the transcription factor nuclear factor 1 (NF1) and the basal transcription complex from the promoter, the dephosphorylation of histone H1, and the establishment of a repressive chromatin structure. We have explored the mechanistic link between histone H1 dephosphorylation and silencing of the MMTV promoter by describing the putative kinase responsible for H1 phosphorylation. Both in vitro kinase assays and in vivo protein expression studies suggest that in hormone-treated cells the ability of cdk2 to phosphorylate histone H1 is decreased and the cdk2 inhibitory p21 protein level is increased. To address the role of cdk2 and histone H1 dephosphorylation in the silencing of the MMTV promoter, we used potent cdk2 inhibitors, Roscovitine and CVT-313, to generate an MMTV promoter which is associated predominantly with the dephosphorylated form of histone H1. Both Roscovitine and CVT-313 block phosphorylation of histone H1 and, under these conditions, the GR is unable to remodel chromatin, recruit transcription factors to the promoter, or stimulate MMTV mRNA accumulation. These results suggest a model where cdk2-directed histone H1 phosphorylation is a necessary condition to permit GR-mediated chromatin remodeling and activation of the MMTV promoter in vivo.

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