Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pregnancy-dependent mammary tumors (PDMT) of GR/A mice and transplantable PDMT (TPDMT-4 line) in DDD mice, are exceptionally stable in hormone dependence, continue to grow until parturition and regress soon after delivery. In order to study the regression mechanism of PDMT and TPDMT-4, morphological and biochemical changes were examined in the tumors removed on day 18 (TPDMT-4) or day 20 (PDMT) of pregnancy, and on the expected parturient and the following postpartum days. DNA fragmentation occurred from day 18 (TPDMT-4) or day 20 (PDMT) of pregnancy to the day after parturition. Apoptotic cells were demonstrated by an in situ 3'-end labeling method, and the plateau of the number of apoptotic cells was observed on the parturient day in PDMT and on the day after parturition in TPDMT-4. Reverse transcriptase polymerase chain reaction showed that expression of Fas was slightly increased but that of bcl-2 was decreased during the process of involution of TPDMT-4 and PDMT. These results suggest that both an increase in expression of Fas and decrease in expression of bcl-2 are involved in the apoptosis of pregnancy-dependent mammary tumor cells after parturition.
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PMID:Apoptosis of pregnancy-dependent mammary tumor and transplantable pregnancy-dependent mammary tumor in mice. 901 89

A novel common integration site for the mouse mammary tumor virus (MMTV) was identified (designated Int7) in five independently arising mouse mammary tumors. The insertion sites all cluster within a 1-kb region that is 2 to 3 kb 5' of the transcription initiation site of a gene, 2610028F08RIK, whose gene product contains furin-like and thrombospondin-like sequences. Expression of Int7 is normally very low or silent during various stages of mammary gland development, but MMTV integration at this site results in the activation of high steady-state levels of expression of the gene. These five tumors were also found to have two or three additional viral insertions, which in each case occurred flanking a member of either the Wnt and/or FGF gene family. Reverse transcriptase PCR results demonstrated that each of the viral insertions led to elevated expression of the presumed target flanking genes.
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PMID:A new common integration site, Int7, for the mouse mammary tumor virus in mouse mammary tumors identifies a gene whose product has furin-like and thrombospondin-like sequences. 1601 73

Retroviruses express Gag and Pol proteins by translation of unspliced genome-length viral RNA. For some retroviruses, transport of unspliced viral RNA to the cytoplasm is mediated by small regulatory proteins such as human immunodeficiency virus Rev, while other retroviruses contain constitutive transport elements in their RNAs that allow transport without splicing. In this study, we found that the betaretrovirus Jaagsiekte sheep retrovirus (JSRV) encodes within the env gene a trans-acting factor (Rej) necessary for the synthesis of Gag protein from unspliced viral RNA. Deletion of env sequences from a JSRV proviral expression plasmid (pTN3) abolished its ability to produce Gag polyprotein in transfected 293T cells, and Gag synthesis could be restored by cotransfection of an env expression plasmid (DeltaGP). Deletion analysis localized the complementing activity (Rej) to the putative Env signal peptide, and a signal peptide expression construct showed Rej activity. Two other betaretroviruses, mouse mammary tumor virus (MMTV) and human endogenous retrovirus type K, encode analogous factors (Rem and Rec, respectively) that are encoded from doubly spliced env mRNAs. Reverse transcriptase-PCR cloning and sequencing identified alternate internal splicing events in the 5' end of JSRV env that could signify analogous doubly spliced Rej mRNAs, and cDNA clones expressing two of them also showed Rej activity. The predicted Rej proteins contain motifs similar to those found in MMTV Rem and other analogous retroviral regulatory proteins. Interestingly, in most cell lines, JSRV expression plasmids with Rej deleted showed normal transport of unspliced JSRV RNA to the cytoplasm; however, in 293T cells Rej modestly enhanced export of unspliced viral RNA (2.8-fold). Metabolic labeling experiments with [(35)S]methionine indicated that JSRV Rej is required for the synthesis of viral Gag polyprotein. Thus, in most cell lines, the predominant function of Rej is to facilitate translation of unspliced viral mRNA.
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PMID:Jaagsiekte sheep retrovirus encodes a regulatory factor, Rej, required for synthesis of Gag protein. 1977 24