Synergism in ternary complex formation between the dimeric glycoprotein p67SRF, polypeptide p62TCF and the c-fos serum response element.

Abstract

Transcriptional regulation of the c‐fos proto‐oncogene requires the serum response element (SRE) which is complexed by a multi‐protein assembly observed both in vitro and in vivo. Two protein factors, p67SRF and p62TCF (previously called p62), are required to interact with the SRE for efficient induction of c‐fos by serum. By quantitative band shift electrophoresis we measure at least a 50‐fold increase in SRE affinity for p67SRF/p62TCF over p67SRF alone. Stoichiometrically we determine that the ternary complex with p62TCF involves p67SRF in dimeric form. We demonstrate that p67SRF is a glycosylated nuclear transcription factor carrying terminal N‐acetylglucosamine (GlcNAc) as a post‐translational modification. A proteolytic limit digestion product, approximately 13 kd in size, was generated from the p67SRF‐SRE complex. This p67SRF‐core domain binds SRE, can dimerize with p67SRF and is still able to form a ternary complex with p62TCF. Therefore, three functional activities can be ascribed to this small p67SRF‐core domain: specific DNA binding, dimerization and interaction with p62TCF. We demonstrate that these functions map within the p67SRF core fragment containing the region between amino acids 93 and 222.

The MAPK/ERK Cascade Targets Both Elk-1 and cAMP Response Element-Binding Protein to Control Long-Term Potentiation-Dependent Gene Expression in the Dentate GyrusIn Vivo

“…Elk-1 is one of the main nuclear targets of activated MAPK/ERK and has been shown to be newly phosphorylated on Ser 383 and Ser 389 by growth factors (Marais et al, 1993), leading to SRE-driven gene transcription in cell cultures (for review, see Wasylyk et al, 1998). The SRE, together with flanking DNA sequences, serves as a site of assembly of multiprotein complexes, including a dimer of the serum response factor (Treisman, 1986;Norman et al, 1988;Schröter et al, 1990) and a protein of the ternary complex factor family, such as Elk-1 (for review, see Treisman, 1995), and this site is present in the promoter region of many IEGs, including zif268. Our results, which show that inhibition of MAPK/ERK phosphorylation and the resulting inhibition of Elk-1 prevents the transcriptional activation of zif268, support the model that activation of the MAPK/ERK signaling pathway targets nuclear Elk-1 to control SRE-mediated gene expression in LTP.…”

The Smooth Muscle γ-Actin Gene Promoter Is a Molecular Target for the Mouse bagpipe Homologue, mNkx3-1, and Serum Response Factor

“…The interaction of SRF with accessory factors has been demonstrated in a number of systems. Studies of c-fos gene regulation has led to the identification of several accessory factors, including SAP-1, Elk-1, and Phox-1 (48,(63)(64)(65). These factors appear to be expressed ubiquitously and together with SRF potentiate the transcriptional activity of the c-fos gene, although the exact regulatory mechanisms are somewhat distinct.…”

Transformation by ras modifies AP1 composition and activity

“…The mitogen stimulation of c-fos transcription is a paradigm for a gene regulated via the Ras pathway. The SRE (Serum Response Element) in the c-fos promoter is continuously bound by two nuclear proteins SRF and Elk/TCF (Herrera et al, 1989;KoÈ nig, 1991;Norman et al, 1988;Prywes and Roeder, 1987;SchroÈ ter et al, 1990;Shaw et al, 1989;Treisman, 1987). Upon Ras activation Elk1 is rapidly phosphorylated by MAPK-1 and MAPK-2 (also called ERK1 and ERK2) resulting in a strong increase in its transcriptional activity (Hipskind et al, 1994;Prywes et al, 1988;Zinck et al, 1993).…”