Efficient nuclear localization and immortalizing ability, two functions dependent on the adenovirus type 5 (Ad5) E1A second exon, are necessary for cotransformation with Ad5 E1B but not with T24ras

Douglas, Janet L.; Quinlan, Margaret P.

doi:10.1128/jvi.69.12.8061-8065.1995

Cited by 22 publications

(10 citation statements)

References 36 publications

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“…There are several viruses/viral proteins that can immortalize mammalian cells in culture (provide capacity for unlimited replication 17 ), including Epstein Barr virus, 18 SV40 T antigen, 19 adenoviruses E1A and E1b, 20 and human papilloma virus 16 (E6 and E7 proteins). 21 Although these processes are relatively reliable, they work with only certain cell types and require use of pathogenic agents.…”

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confidence: 99%

Immortalization of human normal and NF1 neurofibroma Schwann cells

Chang

Neubauer

et al. 2016

Laboratory Investigation

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Neurofibromas, which are benign Schwann cell tumors, are the hallmark feature in the autosomal dominant condition neurofibromatosis 1 (NF1) and are associated with biallelic loss of NF1 gene function. There is a need for effective therapies for neurofibromas, particularly the larger, plexiform neurofibromas. Tissue culture is an important tool for research. However, it is difficult to derive enriched human Schwann cell cultures, and most enter replicative senescence after 6-10 passages, impeding cell-based research in NF1. Through exogenous expression of human telomerase reverse transcriptase and murine cyclin-dependent kinase (mCdk4), normal (NF1 wild-type), neurofibroma-derived Schwann cells heterozygous for NF1 mutation, and neurofibroma-derived Schwann cells homozygous for NF1 mutation were immortalized, including some matched samples from the same NF1 patient. Initial experiments employed retroviral vectors, while subsequent work utilized lentiviral vectors carrying these genes because of improved efficiency. Expression of both transgenes was required for immortalization. Molecular and immunohistochemical analysis indicated that these cell lines are of Schwann cell lineage and have a range of phenotypes, many of which are consistent with their primary cultures. This is the first report of immortalization and detailed characterization of multiple human NF1 normal nerve and neurofibroma-derived Schwann cell lines, which will be highly useful research tools to study NF1 and other Schwann tumor biology and conditions.

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confidence: 99%

Immortalization of human normal and NF1 neurofibroma Schwann cells

Chang

Neubauer

et al. 2016

Laboratory Investigation

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“…All of the v-src-transformed cells tested had the ability to grow as soft agar colonies, including the rare cells transformed by v-src alone (Table 1). This cooperative transformation was not abrogated by mutations in the second exon of E1A, indicating that immortalization by E1A (which requires the second exon) is not necessary for v-src transformation, in contrast to E1A cooperation with Ad E1B (14,15,81). However, mutations that have been shown to interfere with E1A's ability to stimulate cell cycle progression in quiescent cells also interfered with v-src cotransformation.…”

Section: Resultsmentioning

confidence: 99%

“…An NH 2 -terminal point mutant, pm563, which lacks the ability to bind p300 (89), was able to enhance v-src transformation, indicating that the requirements for v-src cooperation are less stringent than those for E1B or Ha-ras cotransformation (14,79,88). Indeed, neither E1B, Ha-ras, nor pmT, which activates c-src (5,10,39), is able to transform primary cells alone, but each requires multiple but different functions encoded by E1A (14,71,79,81,88). Nevertheless, v-src alone is able to transform primary epithelial kidney cells, albeit inefficiently.…”

Section: Discussionmentioning

confidence: 99%

“…Functions encoded by the second exon of E1A have been shown to down-modulate Ha-ras transformation of primary epithelial cells, such that they retain some of their epithelial morphology and characteristics (25). Deletion of the regions encoding these functions leads to a marked increase in transformation with ras (13, 80), but not E1B (14). This hypertransformation is concomitant with dramatic alterations in cell growth rates, adhesion, and actin cytoskeleton organization (20a).…”

Section: Cell Linementioning

confidence: 99%

“…E1A has been shown to immortalize primary cells, such that they maintain many of their differentiated characteristics (35,64,65). In addition, E1A can cooperate with Ha-ras and Ad E1B, as well as polyomavirus mT (pmT), to transform primary cells (14,71,81,88). The pmT binds to and activates the c-Src protein (5,10).…”

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confidence: 99%

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Expression of the pRb-Binding Regions of E1A Enables Efficient Transformation of Primary Epithelial Cells by v- src

Fischer

Quinlan

1998

J Virol

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Primary cultures of rat embryo fibroblasts have been shown to be resistant to transformation by dominant oncogenes such as v-src. We sought to determine if similar resistance is displayed by primary epithelial cells, and, if so, whether an immortalizing oncogene such as E1A could enhance transformation of primary epithelial cells by v-src. Transformation of primary rat epithelial cells by v-src was synergistically enhanced when E1A expression plasmids were cotransfected with a v-src expression plasmid. Foci were more numerous and observed earlier (9 to 14 days) with E1A plus v-src than with v-src alone (18 to 28 days). This cotransformation ability was abrogated by deletions in CR1 or CR2 of E1A, which encode the binding regions for the pRb family and are responsible for E1A-mediated cell cycle activation. Mutations in the p300 binding site or the second exon, which abolish immortalization, did not affect v-src cooperation, in contrast to ras and adenovirus E1B. While kinase activation was required for growth in soft agar, differential activation of Src kinase did not correlate with transformation efficiency. Cell morphology and actin structures were not dramatically impacted by E1A expression; thus, hypertransformation, as previously described for ras cotransformation, was not observed with v-src and second-exon mutants of E1A. However, growth rates for cells expressing both E1A and v-Src were higher than those for cells expressing only v-Src. These results suggest that functions involved in cell cycle activation encoded by E1A first exon can enhance v-src transformation of primary epithelial cells.

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Cell transformation by the adenovirus oncogenes E1 and E4

Dobner

2019

FEBS Letters

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Extensive studies on viral-mediated oncogenic transformation by human adenoviruses have revealed much of our current understanding on the molecular mechanisms that are involved in the process. To date, these studies have shown that cell transformation is a multistep process regulated by the cooperation of several adenoviral gene products encoded in the early regions 1 (E1) and 4 (E4). Early region 1A immortalizes primary rodent cells, whereas coexpression of early region protein 1B induces full manifestation of the transformed phenotype. Beside E1 proteins, also some E4 proteins have partial transforming activities through regulating many cellular pathways. Here, we summarize recent data of how adenoviral oncoproteins may contribute to viral transformation and discuss the challenge of pinpointing the underlying mechanisms.

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Efficient nuclear localization and immortalizing ability, two functions dependent on the adenovirus type 5 (Ad5) E1A second exon, are necessary for cotransformation with Ad5 E1B but not with T24ras

Cited by 22 publications

References 36 publications

Immortalization of human normal and NF1 neurofibroma Schwann cells

Immortalization of human normal and NF1 neurofibroma Schwann cells

Expression of the pRb-Binding Regions of E1A Enables Efficient Transformation of Primary Epithelial Cells by v- src

Cell transformation by the adenovirus oncogenes E1 and E4

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