Identification of distinct roles for separate E1A domains in disruption of E2F complexes

1993 ◽  
Vol 13 (11) ◽  
pp. 7029-7035
Author(s):  
M A Ikeda ◽  
J R Nevins
Keyword(s):  
Transcription Factor ◽  
Gene Product ◽  
Protein Complexes ◽  
Cyclin A ◽  
Regulatory Proteins ◽  
Retinoblastoma Gene ◽  
Adenovirus E1a ◽  
E2f Transcription Factor ◽  
Cdk2 Complex ◽  
Equilibrium Dissociation

The adenovirus E1A protein can disrupt protein complexes containing the E2F transcription factor in association with cellular regulatory proteins such as the retinoblastoma gene product (Rb) and the Rb-related p107 protein. Previous experiments have shown that the CR1 and CR2 domains of E1A are required for this activity. We now demonstrate that the CR2 domain is essential for allowing E1A to interact with the E2F-Rb or the E2F-p107-cyclin A-cdk2 complex. Multimeric complexes containing E1A can be detected when the CR1 domain has been rendered inactive by mutation. In addition, the E1A CR1 domain, but not the CR2 domain, is sufficient to prevent the interaction of E2F with Rb or p107. On the basis of these results, we suggest a model whereby the CR2 domain brings E1A to the E2F complexes and then, upon a normal equilibrium dissociation of Rb or p107 from E2F, the E1A CR1 domain is able to block the site of interaction on Rb or p107, thereby preventing the re-formation of the complexes.

scholarly journals Identification of distinct roles for separate E1A domains in disruption of E2F complexes.

1993 ◽  
Vol 13 (11) ◽  
pp. 7029-7035 ◽  
Author(s):  
M A Ikeda ◽  
J R Nevins
Keyword(s):  
Transcription Factor ◽  
Gene Product ◽  
Protein Complexes ◽  
Cyclin A ◽  
Regulatory Proteins ◽  
Retinoblastoma Gene ◽  
Adenovirus E1a ◽  
E2f Transcription Factor ◽  
Cdk2 Complex ◽  
Equilibrium Dissociation

The adenovirus E1A protein can disrupt protein complexes containing the E2F transcription factor in association with cellular regulatory proteins such as the retinoblastoma gene product (Rb) and the Rb-related p107 protein. Previous experiments have shown that the CR1 and CR2 domains of E1A are required for this activity. We now demonstrate that the CR2 domain is essential for allowing E1A to interact with the E2F-Rb or the E2F-p107-cyclin A-cdk2 complex. Multimeric complexes containing E1A can be detected when the CR1 domain has been rendered inactive by mutation. In addition, the E1A CR1 domain, but not the CR2 domain, is sufficient to prevent the interaction of E2F with Rb or p107. On the basis of these results, we suggest a model whereby the CR2 domain brings E1A to the E2F complexes and then, upon a normal equilibrium dissociation of Rb or p107 from E2F, the E1A CR1 domain is able to block the site of interaction on Rb or p107, thereby preventing the re-formation of the complexes.

scholarly journals Independent regions of adenovirus E1A are required for binding to and dissociation of E2F-protein complexes.

1993 ◽  
Vol 13 (12) ◽  
pp. 7267-7277 ◽  
Author(s):  
A R Fattaey ◽  
E Harlow ◽  
K Helin
Keyword(s):  
Transcription Factor ◽  
Protein Complexes ◽  
Susceptibility Gene ◽  
Cyclin A ◽  
Cellular Proteins ◽  
Adenovirus E1a ◽  
E2f Transcription Factor ◽  
E1a Gene

The transcription factor E2F is present in independent complexes with the product of the retinoblastoma susceptibility gene, pRB, and a related gene product, p107, in association with the cyclin A-cdk2 or the cyclin E-cdk2 kinase complex. pRB and p107 can negatively regulate E2F activity, since overexpression of pRB or p107 in cells lacking a functional pRB leads to the repression of E2F activity. The products of the adenovirus E1A gene can disrupt E2F complexes and result in free and presumably active E2F transcription factor. The regions of E1A required for this function are also essential for binding to a number of cellular proteins, including pRB and p107. Through the use of a number of glutathione S-transferase fusion proteins representing different regions of E1A, as well as in vivo expression of E1A proteins containing deletions of either conserved region 1 (CR1) or CR2, we find that CR2 of E1A can form stable complexes with E2F. E1A proteins containing both CR1 and CR2 also associate with E2F, although the presence of these proteins results in the release of free E2F from its complexes. In vitro reconstitution experiments indicate that E1A-E2F interactions are not direct and that pRB can serve to facilitate these interactions. Complexes containing E1A, p107, cyclin A, and E2F were identified in vivo, which indicates that E1A may associate with E2F through either p107 or pRB. Peptide competition experiments demonstrate that the pRB-binding domain of the human E2F-1 protein can compete with the CR1 but not CR2 domain of E1A for binding to pRB. These results indicate that E1A CR1 and E2F-1 may bind to the same or overlapping sites on pRB and that E1A CR2 binds to an independent region. On the basis of our results, we propose a two-step model for the release of E2F from pRB and p107 cellular proteins.

Independent regions of adenovirus E1A are required for binding to and dissociation of E2F-protein complexes

1993 ◽  
Vol 13 (12) ◽  
pp. 7267-7277
Author(s):  
A R Fattaey ◽  
E Harlow ◽  
K Helin
Keyword(s):  
Transcription Factor ◽  
Protein Complexes ◽  
Susceptibility Gene ◽  
Cyclin A ◽  
Cellular Proteins ◽  
Adenovirus E1a ◽  
E2f Transcription Factor ◽  
E1a Gene

The transcription factor E2F is present in independent complexes with the product of the retinoblastoma susceptibility gene, pRB, and a related gene product, p107, in association with the cyclin A-cdk2 or the cyclin E-cdk2 kinase complex. pRB and p107 can negatively regulate E2F activity, since overexpression of pRB or p107 in cells lacking a functional pRB leads to the repression of E2F activity. The products of the adenovirus E1A gene can disrupt E2F complexes and result in free and presumably active E2F transcription factor. The regions of E1A required for this function are also essential for binding to a number of cellular proteins, including pRB and p107. Through the use of a number of glutathione S-transferase fusion proteins representing different regions of E1A, as well as in vivo expression of E1A proteins containing deletions of either conserved region 1 (CR1) or CR2, we find that CR2 of E1A can form stable complexes with E2F. E1A proteins containing both CR1 and CR2 also associate with E2F, although the presence of these proteins results in the release of free E2F from its complexes. In vitro reconstitution experiments indicate that E1A-E2F interactions are not direct and that pRB can serve to facilitate these interactions. Complexes containing E1A, p107, cyclin A, and E2F were identified in vivo, which indicates that E1A may associate with E2F through either p107 or pRB. Peptide competition experiments demonstrate that the pRB-binding domain of the human E2F-1 protein can compete with the CR1 but not CR2 domain of E1A for binding to pRB. These results indicate that E1A CR1 and E2F-1 may bind to the same or overlapping sites on pRB and that E1A CR2 binds to an independent region. On the basis of our results, we propose a two-step model for the release of E2F from pRB and p107 cellular proteins.

Cyclin A and the retinoblastoma gene product complex with a common transcription factor

Nature ◽  
1991 ◽  
Vol 352 (6332) ◽  
pp. 249-251 ◽  
Author(s):  
Lasantha R. Bandara ◽  
Jörg P. Adamczewski ◽  
Tim Hunt ◽  
Nicholas B. La Thangue
Keyword(s):  
Transcription Factor ◽  
Gene Product ◽  
Cyclin A ◽  
Retinoblastoma Gene ◽  
Common Transcription Factor ◽  
Retinoblastoma Gene Product

scholarly journals The Rb-related p107 protein can suppress E2F function independently of binding to cyclin A/cdk2.

1995 ◽  
Vol 15 (1) ◽  
pp. 338-344 ◽  
Author(s):  
E J Smith ◽  
J R Nevins
Keyword(s):  
Transcription Factor ◽  
Susceptibility Gene ◽  
Cyclin A ◽  
S Phase ◽  
Mutant Proteins ◽  
Independent Events ◽  
Multicomponent Complex ◽  
E2f Transcription Factor ◽  
Cdk2 Complex

The interaction of the retinoblastoma susceptibility gene product (Rb)-related p107 protein with the E2F transcription factor in S-phase cells facilitates the formation of a multicomponent complex also containing cyclin A and the p33cdk2 kinase. We have created a series of p107 mutants to assess the ability of p107 to inhibit E2F function and the role of the cyclin A/cdk2 complex in this process. We find that p107 mutants that do not bind to E2F also fail to repress E2F-dependent transcription. Moreover, we find that the ability of p107 to suppress E2F-dependent transcription is not dependent on the ability of p107 to associate with cyclin A/cdk2. Finally, an analysis of the ability of the p107 mutant proteins to suppress cell growth suggests that both E2F-dependent and E2F-independent events correlate with this activity.

Retinoblastoma gene product activates expression of the human TGF-β2 gene through transcription factor ATF-2

Nature ◽  
1992 ◽  
Vol 358 (6384) ◽  
pp. 331-334 ◽  
Author(s):  
Seong-Jin Kim ◽  
Susanne Wagner ◽  
Fang Liu ◽  
Michael A. O'Reilly ◽  
Paul D. Robbins ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Gene Product ◽  
Retinoblastoma Gene ◽  
Retinoblastoma Gene Product
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