Biomedical subjects

G Rotman

Publications and source records attributed to G Rotman.

39 records · Page 3Linked to original sources

PubMed1986

Promoter and enhancer activities of long terminal repeats associated with cellular retrovirus-like (VL30) elements.

LTR units associated with cellular retrovirus-like elements are abundantly present in chromosomal DNA of animal cells. We have analyzed the promoter and enhancer activities of diverse LTR units associated with different members of the murine retrovirus-like family known as VL30. We report here that the structurally heterogenous VL30 LTRs displayed highly variable promoter/enhancer activities. The most active VL30 LTR (designated VL3) promoted CAT activity to levels six-fold higher than the LTR of the strongly transforming retrovirus, MSV. This VL30 transcription unit, containing a unique U3 region, was further characterized by S1 nuclease mapping. VL3 LTR functioned as an enhancer in CAT constructs containing a SV40 promoter. In addition, a defined U3 segment was shown to augment expression of CAT in an orientation independent manner. VL3 LTR also served as an efficient promoter and enhancer in heterologous monkey cells. These results suggest that certain resident LTRs possess promoter and enhancer capacities greater than those possessed by LTRs of infectious retroviruses.

Acetyltransferases↗

PubMed1984

'Solo' large terminal repeats (LTR) of an endogenous retrovirus-like gene family (VL30) in the mouse genome.

VL30 genetic elements constitute a murine multicopy gene family that is retrovirus-like, despite the lack of sequence homology with any known retrovirus. Over one hundred copies of VL30 units are dispersed throughout the mouse genome. We report here that the mouse genome also contains 'solo' VL30 long terminal repeats (LTRs). These are structures which contain the LTR detached from the rest of the VL30 sequences. The isolation of solo LTRs from a mouse embryonic gene library with the aid of sub-genomic VL30 probes is described. Direct DNA sequencing established that the solo LTR unit is grossly similar to a standard VL30 LTR and that the LTR is flanked by a 4-base pair duplication. The analogy to the occurrence of solitary LTR units of transposable elements is discussed.

Animals↗

PubMed1983

Conservation patterns of mouse "virus-like" (VL30) DNA sequences.

VL30 sequences are a murine dispersed multigene family with several "retrovirus-like" characteristics. Notably, they share basic structural features with retrovirus proviruses and 30S RNA transcripts of these genes are capable of efficient packaging in C-type virions and may be subsequently transmitted to other cells. It is not known whether VL30 information is genetically related to endogenous proviruses or to cellular elements. We extended our studies concerning evolutionary conservation and genetic relationships of VL30 sequences within and outside the genus Mus. The following observations were made: (i) Although VL30 DNA sequences were detected in all mice examined, analysis of VL30 reiteration disclosed up to a 100-fold difference among different Mus species. For example, only 1-3 VL30 copies were detected in M. pahari compared to approximately 200 VL30 copies in certain strains of M. musculus. (ii) Using low-stringency hybridization conditions, nucleotide sequences homologous to mouse VL30 DNA were detected in the DNAs of other animal cells such as rat and human. (iii) The cross-hybridization between mouse VL30 DNA and rat genomic DNA was fully accounted for by the cross-homology between the respective VL30 elements. The homologous regions were mapped and were found confined within a small fragment (less than 1kb) in both mouse VL30 and rat 30S DNA (as well as in Ha-MSV). The data suggested differential conservation of subsets of VL30 information. (iv) A subset of VL30 information was found in the mouse genome in molecular linkages other than "standard" VL30 units (that is a segment of VL30 DNA flanked by non-VL30 sequences). Results are discussed in terms of the possible evolution of VL30 sequences.

Animals↗