Transcriptional activation and repression by Fos are independent functions: the C terminus represses immediate-early gene expression via CArG elements

The Fos-Jun complex has been shown to activate transcription through the regulatory element known as the AP-1 binding site. We show that Fos down regulates several immediate-early genes (c-fos, Egr-1, and Egr-2) after mitogenic stimulation. Specifically, we demonstrate that the target for this repression is a sequence of the form CC(A/T)6GG, also known as a CArG box. Whereas Fos bound to the AP-1 site through a domain rich in basic amino acids and associated with Jun via a leucine zipper interaction, mutant Fos proteins lacking these structures were still capable of causing repression. Furthermore, Jun neither enhanced nor inhibited down regulation by Fos. Critical residues required for repression are located within the C-terminal 27 amino acids of c-Fos, since v-Fos and C-terminal truncations of c-Fos did not down regulate. In addition, transfer of 180 c-Fos C-terminal amino acids to Jun conferred upon it the ability to repress. Finally, Fra-1, a Fos-related protein which has striking similarity to Fos in its C-terminal 40 amino acids, also down regulated Egr-1 expression. Thus, Fos is a transcriptional regulator that can activate or repress gene expression by way of two separate functional domains that act on distinct regulatory elements.

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Transcriptional activation and repression by Fos are independent functions: the C terminus represses immediate-early gene expression via CArG elements.

Molecular and Cellular Biology ◽

10.1128/mcb.10.8.4243 ◽

1990 ◽

Vol 10 (8) ◽

pp. 4243-4255 ◽

Cited By ~ 119

Author(s):

D Gius ◽

X M Cao ◽

F J Rauscher ◽

D R Cohen ◽

T Curran ◽

...

Keyword(s):

Gene Expression ◽

Amino Acids ◽

Transcriptional Activation ◽

Leucine Zipper ◽

Regulatory Element ◽

Regulatory Elements ◽

Early Gene ◽

Immediate Early ◽

Striking Similarity ◽

Independent Functions

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Small Internal Deletions in the Human Cytomegalovirus IE2 Gene Result in Nonviable Recombinant Viruses with Differential Defects in Viral Gene Expression

Journal of Virology ◽

10.1128/jvi.78.4.1817-1830.2004 ◽

2004 ◽

Vol 78 (4) ◽

pp. 1817-1830 ◽

Cited By ~ 63

Author(s):

Elizabeth A. White ◽

Charles L. Clark ◽

Veronica Sanchez ◽

Deborah H. Spector

Keyword(s):

Gene Expression ◽

Amino Acids ◽

Human Cytomegalovirus ◽

Viral Gene Expression ◽

Artificial Chromosome ◽

Early Gene ◽

Immediate Early ◽

Viral Gene ◽

Recombinant Viruses ◽

Late Genes

ABSTRACT The human cytomegalovirus (HCMV) IE2 86-kDa protein is a key viral transactivator and an important regulator of HCMV infections. We used the HCMV genome cloned as a bacterial artificial chromosome (BAC) to construct four HCMV mutants with disruptions in regions of IE2 86 that are predicted to be important for its transactivation and autoregulatory functions. Three of these mutants have mutations that remove amino acids 356 to 359, 427 to 435, and 505 to 511, which disrupts a region of IE2 86 implicated in the activation of HCMV early promoters, a predicted zinc finger domain, and a putative helix-loop-helix motif, respectively, while the fourth carries three arginine-to-alanine substitution mutations in the region of amino acids 356 to 359. The resulting recombinant viruses are not viable, and by using quantitative real-time reverse transcription-PCR and immunofluorescence we have determined the location of the block in their replicative cycles. The IE2 86Δ356-359 mutant is able to support early gene expression, as indicated by the presence of UL112-113 transcripts and UL112-113 and UL44 proteins in cells transfected with the mutant BAC. This mutant does not express late genes and behaves nearly indistinguishably from the IE2 86R356/7/9A substitution mutant. Both exhibit detectable upregulation of major immediate-early transcripts at early times. The IE2 86Δ427-435 and IE2 86Δ505-511 recombinant viruses do not activate the early genes examined and are defective in repression of the major immediate-early promoter. These two mutants also induce the expression of selected delayed early (UL89) and late genes at early times in the infection. We conclude that these three regions of IE2 86 are necessary for productive infections and for differential control of downstream viral gene expression.

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A CCaMK/Cyclops response element in the promoter of L. japonicus Calcium-Binding Protein 1 (CBP1) mediates transcriptional activation in root symbioses

10.1101/2021.08.11.455944 ◽

2021 ◽

Author(s):

Xiaoyun Gong ◽

Simone Bucerius ◽

Elaine Jensen ◽

Martin Parniske

Keyword(s):

Gene Expression ◽

Transcriptional Activation ◽

Calcium Binding ◽

Regulatory Element ◽

Expression Patterns ◽

Lotus Japonicus ◽

Gus Expression ◽

Early Gene ◽

Dna Hypermethylation ◽

Spatio Temporal

Early gene expression in arbuscular mycorrhiza (AM) and the nitrogen-fixing root nodule symbiosis (RNS) is governed by a shared regulatory complex. Yet many symbiosis-induced genes are specifically activated in only one of the two symbioses. The Lotus japonicus T-DNA insertion line T90, carrying a promoterless uidA (GUS) gene in the promoter of Calcium Binding Protein1 (CBP1) is exceptional as it exhibits GUS activity in both root endosymbioses. To identify the responsible cis- and trans-acting factors, we subjected deletion/modification series of CBP1 promoter:reporter fusions to transactivation and spatio-temporal expression analysis and screened EMS-mutagenized T90 populations for aberrant GUS expression. We identified one cis-regulatory element required for GUS expression in the epidermis and a second element, necessary and sufficient for transactivation by the Calcium and Calmodulin-dependent protein kinase (CCaMK) in combination with the transcription factor Cyclops and conferring gene expression during both AM and RNS. Lack of GUS expression in T90 white mutants could be traced to DNA hypermethylation detected in and around this element. We concluded that the CCaMK/Cyclops complex can contribute to at least three distinct gene expression patterns on its direct target promoters NIN (RNS), RAM1 (AM), and CBP1 (AM and RNS), calling for yet-to-be identified specificity-conferring factors.

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Mad1 Function Is Regulated through Elements within the Carboxy Terminus

Molecular and Cellular Biology ◽

10.1128/mcb.20.12.4253-4264.2000 ◽

2000 ◽

Vol 20 (12) ◽

pp. 4253-4264 ◽

Cited By ~ 4

Author(s):

Gonzalo Barrera-Hernandez ◽

Constance M. Cultraro ◽

Stefania Pianetti ◽

Shoshana Segal

Keyword(s):

Amino Acids ◽

Transcriptional Activation ◽

Transcriptional Repression ◽

Leucine Zipper ◽

Regulatory Elements ◽

Carboxy Terminus ◽

Helix Loop Helix ◽

Inhibitory Function ◽

Growth Inhibitory ◽

Differentiation Block

ABSTRACT Myc and Mad are basic helix-loop-helix leucine zipper (bHLH-LZ) proteins that heterodimerize with Max to bind DNA and thereby influence the transcription of Myc-responsive genes. Myc-Max dimers transactivate whereas Mad-Max-mSin3 complexes repress Myc-mediated transcriptional activation. We have previously shown that the N-terminal mSin3 binding domain and the centrally located bHLH-LZ are required for Mad1 to function during a molecular switch from proliferation to differentiation. Here we demonstrate that the carboxy terminus (CT) of Mad1 contains previously unidentified motifs necessary for the regulation of Mad1 function. We show that removal of the last 18 amino acids of Mad1 (region V) abolishes the growth-inhibitory function of the protein and the ability to reverse a Myc-imposed differentiation block. Moreover, deletion of region V results in a protein that binds DNA weakly and no longer represses Myc-dependent transcriptional activation. In contrast, deletion of the preceding 24 amino acids (region IV) together with region V restores DNA binding and transcriptional repression, suggesting a functional interplay between these two regions. Furthermore, phosphorylation within region IV appears to mediate this interplay. These findings indicate that novel regulatory elements are present in the Mad1 CT.

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