Structural analysis of type II variants within the mouse intracisternal A-particle sequence family

Lueders, Kira K.; Mietz, Judy A.

doi:10.1093/nar/14.3.1495

Cited by 23 publications

(13 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The genome of Mus musculus contains -700 full-sized IAP (type I) elements 7.1 kilobases (kb) long and several hundred shorter elements defined by various internal deletions (19,20). This group includes the type IA elements, characterized by a single internal deletion of 1.9 kb, and the type TI elements, which have both a major deletion and a novel insertion of 270 base pairs (bp) (19).…”

Section: Resultsmentioning

confidence: 99%

Tissue and strain-specific patterns of endogenous proviral hypomethylation analyzed by two-dimensional gel electrophoresis.

Mietz

Kuff

1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Proviral sequences related to the intracisternal A particle (IAP) are amplified and dispersed in the mouse genome. Their expression is associated with hypomethylation at CpG sites in the 5' long terminal repeat. We have used two-dimensional agarose gel electrophoresis to examine patterns of LAP hypomethylation in mouse DNA. The method is sensitive to both the methylation status of a conserved Hae II site in the 5' long teiminal repeat and the location of the closest BamtII site in the flanking DNA upstream of each hypomethylated long terminal repeat. The method also detects restriction fragments derived from UAP elements that are themselves methylated but have an unmethylated Hae II site in their 5' adjacent DNA. DNAs from each of four inbred mouse strains (BALB/c, C3H/He, C57BL/6, and DBA/2) gave distinctive two-dimensional patterns of BamHl/Hae II restriction fragments detected by hybridization with an LAP probe. This constitutive pattern was largely conserved among several tissues of each strain, but some tissue-specific variations were observed. The site-specific hypomethylations reflected in the two-dimensional patterns were heritable properties, since DNA from progeny of an interstrain cross contained both parental sets of fragments. UAP elements may be useful endogenous reporters of genomic methylation patterns.DNA methylation is thought to have an important, perhaps determining, role in maintaining specific patterns of gene expression in eukaryotic cells (1, 2). In the genome, hypomethylated domains corresponding to active genetic loci are thought to be interspersed among regions of more heavily methylated inactive DNA. Major alterations in cell programming associated with normal differentiation or neoplastic transformation may involve widespread changes in patterns of DNA methylation (3, 4).Intracisternal A particles (lAPs) are defective retroviruses seen in many mouse tumors, in preimplantation embryos, and in certain normal tissues (reviewed in ref. 5). They are encoded by endogenous proviral elements, which are abundant (1000 copies per haploid genome) and distributed over the entire chromosome complement (6, 7). Transpositions of IAP elements have resulted in phenotypic alterations, such as loss of immunoglobulin light chain expression (8), constitutive oncogene activation (9), and growth factor production (10, 11). Although intracisternal expression has no apparent consequence for the producing cell, particle proteins that gain access to the cell exterior can behave as neoantigens (12).These IAP-associated effects could be related to the expression of particular proviral elements that are transposition-prone or encode strongly antigenic variants of IAP proteins. However, detection of individual active IAP elements has been difficult because of the large number of homologous copies. In the present study, we have used a two-dimensional (2-D) gel electrophoresis technique to detect 1AP elements that are hypomethylated in their 5' long terminal repeats (LTRs). This approach is based on the obse...

show abstract

Section: Resultsmentioning

confidence: 99%

Tissue and strain-specific patterns of endogenous proviral hypomethylation analyzed by two-dimensional gel electrophoresis.

Mietz

Kuff

1990

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…For Northern blot analysis, 10 g of total RNA/lane were fractionated on agarose/formaldehyde gels. RNAs were transferred to a nylon membrane (Hybond N, Amersham) in 0.15 M NH 4 Ac buffer and hybridized with riboprobes or DNA probes. Loading of equal amounts of RNA in each lane was assessed with the BET-stained ribosomal RNAs upon UV illumination of the membrane.…”

Section: Methodsmentioning

confidence: 99%

“…These sequences, 3.5-7.2 kb long, have been classified into different subgroups, each represented by a few hundred copies (3,4), depending on the presence of various internal deletions (class I and I⌬1-4) and of one specific 0.3-kb insertion (class IIA-C). Like retroviruses, they contain two long terminal repeats (LTRs) with a U3-R-U5 organization, bordering gag-pol-like open reading frames.…”

mentioning

confidence: 99%

Characterization of Two Age-induced Intracisternal A-particle-related Transcripts in the Mouse Liver

Puech

Dupressoír

Loireau

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

Intracisternal A-particle (IAP) sequences are endogenous retrovirus-like elements present at 1,000 copies in the mouse genome. We had previously identified IAPrelated transcripts of unusual size (6 and 10 kilobases (kb)), which are observed exclusively in the liver of the aging mouse. In this report, using cDNA libraries that we have constructed from the liver mRNAs of an aged DBA/2 mouse, we have cloned and entirely sequenced the corresponding cDNAs. Both are initiated within the 5 long terminal repeat of a type I⌬1 IAP sequence, and correspond to a read-through into a unique flanking cellular sequence containing a 966-nucleotide open reading frame, located 3 to the IAP sequence. The 6-kb IAP-related transcript corresponds to a post-transcriptional modification of the 10-kb mRNA, and is generated by a splicing event with the donor site in the IAP sequence, and the acceptor site 5 to the open reading frame. This open reading frame is located on chromosome 3, is evolutionarily conserved, and discloses significant similarity to the yeast CCR4 transcription factor at the amino acid level. The specific expression of these age-induced transcripts, which account for more than 50% of the IAP-related transcripts in the liver of old mice, is therefore entirely consistent with the induction of a single genomic locus, thus strengthening the importance of position effects for the expression of transposable elements. Characterization of this locus should now allow studies on its chromatin and methylation status, and on the "molecular factors of senescence" possibly involved in its induction.

show abstract

“…These discrepancies may be indicative of the presence of a truncated TAP, missing a 2-kb DNA segment overlapping the two known BamHI sites. The precise identification of the LAP by Southern blotting is complicated by the relative high degree of sequence heterogeneity amongst IAPs sequenced to date (49,69). Nevertheless, taken together, these results strongly suggest that mdr3 overexpression in P388/ADM-2 cells is linked to the presence of a retroviral TAP inserted in the promoter region of the gene.…”

Section: Methodsmentioning

confidence: 99%

Activation of the mouse mdr3 gene by insertion of retroviruses in multidrug-resistant P388 tumor cells.

1993

View full text Add to dashboard Cite

In multidrug-resistant (MDR) derivatives of the mouse lymphoid tumor P388, the emergence of MDR is associated with overexpression and transcriptional activation of the mdr3 gene, either in the absence of (P388/VCR-10) or concomitant with (P388/ADM-2) gene amplification. In both instances, Northern (RNA) blotting analyses have suggested the presence of altered mdr3 transcripts in these cells, possibly originating from novel transcription initiation sites. The mechanisms underlying mdr3 overexpression in these cells have been investigated. In P388/VCR-10 cells, Southern blotting analyses together with genomic DNA cloning and nucleotide sequencing have demonstrated the presence of an intact mouse mammary tumor virus (MMTV) within the boundaries of intron 1 of mdr3. cDNA cloning and nucleotide sequencing indicated that this integration event results in the synthesis and overexpression of a hybrid MMTV-mdr3 mRNA which initiates within the U3 region of the 5' long terminal repeat (LTR) of the provirus. Consequently, this mRNA lacks the normal exon 1 of mdr3 but contains (i) MMTV LTR-derived sequences at its 5' end, (ii) a novel mdr3 exon, mapping within the boundaries of intron 1 downstream of the MMTV integration site and generated by alternative splicing, and (iii) an otherwise intact 3' portion ofmdr3 starting at exon 2. A similar type of analysis of P388/ADM-2 cells revealed that mdr3 overexpression in these cells is associated with the integration of an intracisternal A particle (IAP) within an LlMd repetitive element, immediately upstream of mdr3. The IAP insertion results in the overexpression of hybrid AP-mdr3 mRNA transcripts that initiate within the 3' LTR of the IAP and which contain TAP LTR-derived sequences at the 5' end spliced 14 nucleotides upstream of the normal exon 1 of mdr3. Taken together, these results indicate that independent retroviral insertions were the initial mutagenic event responsible for mdr3 overexpression and survival during drug selection of these cell lines. Amplification of the rearranged and activated mdr3 gene copy occurred during further selection for high-level drug resistance in P388/ADM-2 cells.Expression of P-glycoprotein (P-gp), a phosphoglycoprotein of 170 kDa, causes multidrug resistance (MDR) in cultured cells in vitro and cancer cells in vivo (23,28). P-gps are encoded by a small family of closely related genes, with two members MDRI and MDR2 (also called MDR3) in humans and three members, mdrl, mdr2, and mdr3, in mice (7,19,30,31,76). The MDR phenotype is linked to an ATP-dependent decrease in cellular drug accumulation and increased drug efflux (18). The functional role of P-gps in drug resistance has been established in transfection experiments, in which sensitive cells acquire the MDR phenotype after expression of full-length cDNAs for either the mouse mdrl, mouse mdr3, or human MDR1 gene (19,29,73). Human MDR2 and mouse mdr2 genes do not seem to play any role in MDR, as transfection and overexpression of these genes do not confer drug resistance (31, 67). Highly...

show abstract

Structural analysis of type II variants within the mouse intracisternal A-particle sequence family

Cited by 23 publications

References 45 publications

Tissue and strain-specific patterns of endogenous proviral hypomethylation analyzed by two-dimensional gel electrophoresis.

Tissue and strain-specific patterns of endogenous proviral hypomethylation analyzed by two-dimensional gel electrophoresis.

Characterization of Two Age-induced Intracisternal A-particle-related Transcripts in the Mouse Liver

Activation of the mouse mdr3 gene by insertion of retroviruses in multidrug-resistant P388 tumor cells.

Contact Info

Product

Resources

About