The DnaJ domain of polyomavirus large T antigen is required to regulate Rb family tumor suppressor function

Sheng, Qing; Denis, Deborah; Ratnofsky, Mara; Roberts, Thomas M.; DeCaprio, James A.; Schaffhausen, Brian

doi:10.1128/jvi.71.12.9410-9416.1997

Cited by 81 publications

(37 citation statements)

References 66 publications

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“…Hsc70 also interacts with oncoproteins and helps to release E2F from pRb as a molecular chaperone. (33) Notably, we showed in vitro that the D326V mutation selectively perturbed the direct interaction with E2F2 ⁄ 3 (Fig. 7).…”

Section: Discussionmentioning

confidence: 81%

Novel retinoblastoma mutation abrogating the interaction to E2F2/3, but not E2F1, led to selective suppression of thyroid tumors

et al. 2014

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Mutant mouse models are indispensable tools for clarifying gene functions and elucidating the pathogenic mechanisms of human diseases. Here, we describe novel cancer models bearing point mutations in the retinoblastoma gene (Rb1) generated by N-ethyl-N-nitrosourea mutagenesis. Two mutations in splice sites reduced Rb1 expression and led to a tumor spectrum and incidence similar to those observed in the conventional Rb1 knockout mice. The missense mutant, Rb1D326V/+, developed pituitary tumors, but thyroid tumors were completely suppressed. Immunohistochemical analyses of thyroid tissue revealed that E2F1, but not E2F2/3, was selectively inactivated, indicating that the mutant Rb protein (pRb) suppressed thyroid tumors by inactivating E2F1. Interestingly, Rb1D326V/+ mice developed pituitary tumors that originated from the intermediate lobe of the pituitary, despite selective inactivation of E2F1. Furthermore, in the anterior lobe of the pituitary, other E2F were also inactivated. These observations show that pRb mediates the inactivation of E2F function and its contribution to tumorigenesis is highly dependent on the cell type. Last, by using a reconstitution assay of synthesized proteins, we showed that the D326V missense pRb bound to E2F1 but failed to interact with E2F2/3. These results reveal the effect of the pRb N-terminal domain on E2F function and the impact of the protein on tumorigenesis. Thus, this mutant mouse model can be used to investigate human Rb family-bearing mutations at the N-terminal region.

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Section: Discussionmentioning

confidence: 81%

Novel retinoblastoma mutation abrogating the interaction to E2F2/3, but not E2F1, led to selective suppression of thyroid tumors

et al. 2014

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“…pCMV-LT (62) and pCMV-Rb Ϫ -LT, which contains two point mutations in the L-X-C-X-E motif of PyLT (32), have been described previously. The J domain mutants H42Q and P43S were also described earlier (70). Both mutants were used in each assay with similar results.…”

Section: Methodsmentioning

confidence: 99%

“…A functional J domain is not required for PyLT to induce apoptosis. Previous work showed that LT required both an intact pRb binding site and a functional J domain to activate E2F (70). However, a critical question is whether a requirement for J function is universal or if it is limited to certain pRb functions such as E2F regulation.…”

Section: Fig 1 Lt-induced Apoptosis In Differentiating C2c12 Cellsmentioning

confidence: 99%

“…Much of what LT does to cells depends upon its interactions with the Rb tumor suppressor family through an LXCXE motif starting at residue 141 (17,32). Immortalization (22,34,41), induction of cell DNA synthesis (70), overcoming p53-induced cell cycle arrest (16), and prevention of differentiation (52) can all depend on Rb family binding. Transactivation of the thymidine kinase, polymerase ␣, PCNA, dihydrofolate reductase, and thymidylate synthase genes (54) as well as regulation of interferon-inducible gene expression (80) also requires an intact pRb/p107 binding site on LT and is mediated via the cellular transcription factor E2F.…”

mentioning

confidence: 99%

“…For SV40 they contribute, for example, to DNA replication (10). However, the most striking aspect of their function was that mutation of the J domain prevented its interaction with hsc70, a DnaK, thereby blocking LT functions related to Rb family member binding (27,70,72,86). Since many of the effects of the Rb family are mediated through interactions with the E2F family, these results have been interpreted in terms of effects on protein complexes containing Rb and E2F family members.…”

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confidence: 99%

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J Domain-Independent Regulation of the Rb Family by Polyomavirus Large T Antigen

Sheng¹,

Love²,

Schaffhausen³

2000

J. Virol.

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The ability of polyomavirus large T antigen (LT) to promote cell cycling, to immortalize primary cells, and to block differentiation has been linked to its effects on tumor suppressors of the retinoblastoma susceptibility (Rb) gene family. Our previous studies have shown that LT requires an intact N-terminal DnaJ domain, in addition to an Rb binding site, for activation of simple E2F-containing promoters and stimulation of cell cycle progression. Here we show that some LT effects dependent on interaction with the Rb family are largely DnaJ independent. In differentiating C2C12 myoblasts, overexpression of LT caused apoptosis. Although this activity of LT completely depended on Rb binding, LTs with mutations in the J domain remained able to kill. Comparisons of Rb ؊ and J ؊ LTs revealed additional differences. Wild-type but not Rb ؊ LT activated the cyclin A promoter under serum starvation conditions. Genetic analysis of the promoter linked the Rb requirement to an E2F site in the promoter. LTs with mutations in the J domain were still able to activate the promoter. Finally, J mutant LTs caused changes in phosphorylation of both pRb and p130. In the case of p130, Thr-986 was shown to be a site that is regulated by J mutant LT. Taken together, these observations reveal that LT regulation of Rb function can be separated into both DnaJ-dependent and DnaJ-independent pathways.

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Cross‐talk between T‐Ag presence and pRb family and p53/p73 signaling in mouse and human medulloblastoma

Caracciolo

Macaluso

D’Agostino

et al. 2010

J of Cellular Biochemistry

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The formation and progression of mudulloblastoma (MB) is poorly understood. However, somatic inactivation of pRb/p105, in combination with a somatic or a germ-line TP53 inactivation, leads to MB in a mouse model. Presently, there is no specific evidence of pathway/s alterations for the other two members of the retinoblastoma family, pRb2/p130 and/or p107 in MB. JC virus (JCV) is a human polyomavirus. Although there is no firm evidence that this virus plays a causal role in human neoplasia, it has been clearly proven that JCV is highly oncogenic when injected into the brain of experimental animals. The mechanism of JCV-induced tumorigenesis is not entirely clear. However, several studies relate the oncogenic properties of JCV mainly to its early protein large T-antigen (T-Ag), which is able to bind and inactivate both TP53 and Rb family proteins. Here, we compared the protein expression profiles of p53, p73, pRb family proteins, and PCNA, as main regulators of cell proliferation and death, in different cell lines of mouse primitive neuroectodermal tumors (PNET), either T-Ag-positive or -negative, and in human MB cell lines. Our goal was to determine if changes in the relative expression of these regulators could trigger molecular perturbations underlying MB pathogenesis in mouse and human cells. Our results support that the presence of JCV T-Ag may interfere with the expression of pRb family proteins, specific p73 isoforms, and p53. In turn, this "perturbation" may trigger a network of signals strictly connected with survival and apoptosis. Keywords MEDULLOBLASTOMA; LARGE T-ANTIGEN; JC VIRUS; SV40; pRb FAMILY; p53/p73Embryonal tumors of the central nervous system (CNS) include medulloblastomas (MB), primitive neuroectodermal tumors of the CNS (PNET), and atypical teratoid/rabdoid tumors (ATRT) [Louis et al., 2007]. The mechanism of MB tumorigenesis is poorly understood. Genetic alterations associated with this disease include loss of chromosome p17 and gain of 17q, losses on chromosomes 10q and 11, gains on chromosome 7, and rearrangements of chromosome 1 [Trojanek et al., 2006]. c-Myc and n-Myc amplification, constitutive Sonic hedgehog (SHH) signaling activation, and TP53 pathway alteration have also been reported [Rossi et al., 2008]. TP73 is a member of the p53 family and it has been indicated that overexpression of TP73 isoforms could have a role in the growth and treatment response in Castellino et al., 2007]. pRb/p105, p107, and pRb2/p130 form the retinoblastoma family [Caracciolo et al., 2006;Macaluso et al., 2006]. pRb/p105 mutations are common in several cancers but not in human MB [Giacinti and Giordano, 2006]. However, somatic inactivation of pRb/p105, in combination with a somatic or a germ-line TP53 inactivation, leads to MB in a mouse model. Presently, there is no specific evidence of pRb2/p130 and/or p107 pathway/s alterations in MB, but a role for pRb2/p130 in glioblastoma has been suggested [Pucci et al., 2002].JC virus (JCV) is a human polyomavirus of the polyomaviridae family, which a...

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The DnaJ domain of polyomavirus large T antigen is required to regulate Rb family tumor suppressor function

Cited by 81 publications

References 66 publications

Novel retinoblastoma mutation abrogating the interaction to E2F2/3, but not E2F1, led to selective suppression of thyroid tumors

Novel retinoblastoma mutation abrogating the interaction to E2F2/3, but not E2F1, led to selective suppression of thyroid tumors

J Domain-Independent Regulation of the Rb Family by Polyomavirus Large T Antigen

Cross‐talk between T‐Ag presence and pRb family and p53/p73 signaling in mouse and human medulloblastoma

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