The CArG promoter sequence is necessary for muscle-specific transcription of the cardiac actin gene in Xenopus embryos.

Mohun, Timothy J.; Taylor, Martin J.; Garrett, Nigel; Gurdon, J. B.

doi:10.1002/j.1460-2075.1989.tb03486.x

Cited by 140 publications

(90 citation statements)

References 35 publications

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“…The importance of the CArG box for the activation of the cardiac ␣-actin promoters (20,23; the present study) for muscle-specific expression and for expression in general has been extensively demonstrated (reference 30 and references therein), and the recent finding that SRF interacts with myogenic bHLH proteins might provide a molecular explanation for this phenomenon (11). Nevertheless, our data ( Fig.…”

Section: Resultsmentioning

confidence: 55%

Myogenic Basic Helix-Loop-Helix Proteins and Sp1 Interact as Components of a Multiprotein Transcriptional Complex Required for Activity of the Human Cardiac α-Actin Promoter

Biesiada

Hamamori

Kedes

et al. 1999

Molecular and Cellular Biology

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Activation of the human cardiac ␣-actin (HCA) promoter in skeletal muscle cells requires the integrity of DNA binding sites for the serum response factor (SRF), Sp1, and the myogenic basic helix-loop-helix (bHLH) family. In this study we report that activation of the HCA correlates with formation of a muscle-specific multiprotein complex on the promoter. We provide evidence that proteins eluted from the multiprotein complex specifically react with antibodies directed against myogenin, Sp1, and SRF and that the complex can be assembled in vitro by using the HCA promoter and purified MyoD, E12, SRF, and Sp1. In vitro and in vivo assays revealed a direct association of Sp1 and myogenin-MyoD mediated by the DNA-binding domain of Sp1 and the HLH motif of myogenin. The results obtained in this study indicate that protein-protein interactions and the cooperative DNA binding of transcriptional activators are critical steps in the formation of a transcriptionally productive multiprotein complex on the HCA promoter and suggest that the same mechanisms might be utilized to regulate the transcription of muscle-specific and other genes.Cooperative interactions of transcriptional activators are pivotal in ensuring the proper execution of the myogenic program. For instance, the cooperative binding to two adjacent E boxes on the muscle creatine kinase enhancer by MyoD is required for transcriptional activation (38). The transcriptional activators that bind muscle regulatory regions often establish direct contacts. In fact, protein-protein interactions govern functional cooperativity of myogenic basic helix-loop-helix (bHLH) with E proteins (17) and the myocyte enhancer factor 2 (MEF2) in directing muscle transcription (24). In addition to the E box, numerous muscle-specific regulatory regions contain binding sites for the MEF2 proteins, the serum response factor (SRF), and Sp1, suggesting that the combinatorial binding of these factors to muscle regulatory regions has been selected and is particularly favored for regulation of musclespecific transcription (25, 39). Whereas both MEF2 and SRF have been shown to interact with the myogenic bHLH (24, 11), the question of whether Sp1 can also directly associate with myogenic bHLH has not been addressed. Furthermore, it remains to be determined whether muscle and ubiquitous transcription factors found on muscle-specific regulatory regions are associated as multiprotein complexes.A region of the human cardiac ␣-actin (HCA) promoter spanning from nucleotides Ϫ110 to ϩ68 is a composite response element that directs striated muscle-specific transcription (20). Electrophoretic mobility shift assay (EMSA) and footprinting experiments revealed sites for the binding of three nuclear proteins in myogenic cells, including a CArG box for the SRF (21, 5), a GC box for Sp1 (12), and an E box for one of the myogenic bHLH proteins (33). Mutations in any of these three DNA elements result in promoter inactivation (33). Furthermore, reconstitution experiments conducted in Drosophila melanogaster-deriv...

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Section: Resultsmentioning

confidence: 55%

Myogenic Basic Helix-Loop-Helix Proteins and Sp1 Interact as Components of a Multiprotein Transcriptional Complex Required for Activity of the Human Cardiac α-Actin Promoter

Biesiada

Hamamori

Kedes

et al. 1999

Molecular and Cellular Biology

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“…These elements are 100% conserved between the four species in which the SMA promoter has been cloned (9), suggesting that they may be important regulators of SMA expression. Indeed, CArG box elements have been shown to direct developmental and tissue-specific transcriptional expression for both the skeletal and cardiac ␣-actin genes (12,15,29). As the P547, P371, and P155 constructs all include the CArG-B box, we determined whether the CArG-B box is involved in the regulation of the SMA promoter by force using a mutational approach (10).…”

Section: Sma Is Expressed In Ros17/28 Cells Aftermentioning

confidence: 99%

“…The CArG box was first described as the core sequence of the serum response element (SRE) in early response genes such as c-fos (11). CArG elements can direct developmental and tissue-specific expression of many musclespecific genes (12)(13)(14)(15) and are required for the transient transcriptional responses of immediate-early response genes such as c-fos, ␣-skeletal actin, and SMA following serum or growth factor stimulation (11,16,18,19,39).…”

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confidence: 99%

Transcriptional Regulation of a Contractile Gene by Mechanical Forces Applied through Integrins in Osteoblasts

Wang

Fan

et al. 2002

Journal of Biological Chemistry

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We examined mechanotranscriptional regulation of the contractile gene, ␣-smooth muscle actin (SMA), in osteoblastic cells. Tensile forces were applied through collagen-coated magnetite beads to ROS17/2.8 cells. These cells were desmin؊, vimentin؉ and expressed low levels of SMA. After force application (480 piconewton/ cell), SMA protein and mRNA were increased but ␤-actin was unchanged. Beads coated with bovine serum albumin or poly-L-lysine produced no change of SMA. In cells transiently transfected with plasmids containing the SMA promoter fused to ␤-galactosidase or green fluorescent protein coding sequences, SMA promoter activity was increased by ϳ60% after 4 h of force, whereas control (Rous sarcoma virus) promoter activity was unaffected. Transfections with ␤-galactosidase or green fluorescent protein reporter constructs showed that forceloaded cells exhibited higher ␤-galactosidase activity than cells without force. Cytochalasin D and latrunculin B inhibited force-induced increases of SMA promoter activity. Deletion analyses showed that SMA promoter activity was increased ϳ70% after force with a minimal construct containing 155 bp upstream of the translation start site. The force effect on the SMA promoter was abrogated in cells transfected with CArG-B box mutants. Gel mobility shift analyses of nuclear extracts showed strong binding to the CArG-B motif after force. We conclude that the CArG-B box is a force-responsive element in the SMA promoter.

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“…However, based on the correlation between the induction of these AU binding factors and the developmental regulation of mRNA destabilization, caused by the 3' AU rich region [4][5][6][7]16,25], it is tempting to suggest that AU-F2, or all three AU-binding proteins are involved either directly or indirectly in this destabilization process.…”

mentioning

confidence: 99%

Induction of cytoplasmic factors that bind to the 3' AU‐rich region of human Interferon β mRNA during early development of Xenopus laevis

Grafi

Galili

1993

FEBS Letters

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Certain endogenous Xenopus mRNAs, carrying a destabilizing 3' AU-rich sequence, are unusually very stable in oocytes and become unstable only after fertilization. In addition, heterologous short lived mRNA, containing 3' AU-rich sequences, appear to be very stable when injected into Xenopus oocytes. In the present study, a human interferon fi (hu-IFNB) mRNA, carrying the destabilizing 3' AU-rich element, was used as a probe to identify Xenopus proteins that specifically bind to the 3' AU-rich element as well as to study their relative levels during early embryonic development. While three major proteins that specifically bind to the 3' AU-rich element were detected in human SV80 cells, that naturally express hu-IFNB (proteins termed AU-Fl, F2 and F3), only two proteins, migrating similarly to the SV80 AU-F1 and AU-F3, were detected in cytoplasmic extracts from Xenopus oocytes or eggs. Following fertilization, the intensity of the Xenopus AU-F1 and AU-F3 proteins increased considerably and a new protein, corresponding to SV80 AU-F2, was also detected. Cyclohexamide applied either at the morula or at the early blastula stages reduced the intensity of the AU-binding factors, while actinomycin D did not, indicating that the levels of these factors during these stages are regulated posttranscriptionally. In contrast, application of each of these metabolic inhibitors at the late blastula stage increased the intensity of the AU-binding proteins. The possible function of these AU-binding factors in regulating the expression and half life of AU-rich mRNAs is discussed.

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The CArG promoter sequence is necessary for muscle-specific transcription of the cardiac actin gene in Xenopus embryos.

Cited by 140 publications

References 35 publications

Myogenic Basic Helix-Loop-Helix Proteins and Sp1 Interact as Components of a Multiprotein Transcriptional Complex Required for Activity of the Human Cardiac α-Actin Promoter

Myogenic Basic Helix-Loop-Helix Proteins and Sp1 Interact as Components of a Multiprotein Transcriptional Complex Required for Activity of the Human Cardiac α-Actin Promoter

Transcriptional Regulation of a Contractile Gene by Mechanical Forces Applied through Integrins in Osteoblasts

Induction of cytoplasmic factors that bind to the 3' AU‐rich region of human Interferon β mRNA during early development of Xenopus laevis

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