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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The MPK1 (SLT2) gene of Saccharomyces cerevisiae encodes a mitogen-activated protein kinase that is regulated by a kinase cascade whose known elements are Pkc1 (a homolog of protein kinase C), Bck1 (Slk1) (a homolog of MEK kinase), and the functionally redundant Mpk1 activators Mkk1 and Mkk2 (homologs of MEK). An activated mutation of MKK1, MKK1P386, inhibits growth when overexpressed. This growth-inhibitory effect was suppressed by the mpk1 delta mutation, suggesting that hyperactivation of the Mpk1 pathway is toxic to cells. To search for genes that interact with the Mpk1 pathway, we isolated both chromosomal mutations and dosage suppressor genes that ameliorate the growth-inhibitory effect of overexpressed Mkk1P386. One of the genes identified by the analysis of chromosomal mutations is RLM1 (resistance to lethality of MKK1P386 overexpression), which encodes a protein homologous to a conserved domain of the MADS (Mcm1, Agamous, Deficiens, and serum response factor) box family of transcription factors. Although rlm1 delta cells grow normally at any temperature, they display a caffeine-sensitive phenotype similar to that observed in mutants defective in BCK1, MKK1/MKK2, or MPK1. A gene fusion that provides Rlm1 with a transcriptional activation domain of Gal4 suppresses bck1 delta and mpk1 delta. A screening for dosage suppressors yielded the MSG5 genes, which encode a dual-specificity protein phosphatase. Our results suggest that Rlm1 functions as a transcription factor downstream of Mpk1 that is subject to activation by the Mpk1 mitogen-activated protein kinase pathway.
Mol Cell Biol 1995 Oct
PMID:Yeast RLM1 encodes a serum response factor-like protein that may function downstream of the Mpk1 (Slt2) mitogen-activated protein kinase pathway. 756 26

YY1 is a multifunctional transcription factor that acts as an activator or repressor in different contexts. YY1 binds to multiple sites in the mouse c-fos promoter, inducing at each site a sharp DNA bend. Binding of YY1 to a site situated between the cyclic AMP response element (CRE) and the TATA box bends the DNA in a way that interferes with the interaction of proteins bound at the CRE and TATA elements, resulting in repression of transcription. Here, we show that binding of YY1 to a different site in the c-fos promoter has a different result. Binding of YY1 to the c-fos serum response element (SRE) enhances the binding of serum response factor (SRF). This enhancement requires the binding of YY1 to SRE DNA. YY1 and SRF can cooccupy the SRE at least transiently. In the region of overlapping contact, YY1 contacts DNA in the major groove, while SRF contacts DNA in the minor groove. YY1 also enhances the association of SRF with the SRE in transfected insect cells. Thus, although YY1 induces similar structural changes in DNA at different binding sites, it can have distinct local effects on protein-DNA and protein-protein interactions. These data support a general role for YY1 in the building of highly organized promoter complexes.
Mol Cell Biol 1995 Nov
PMID:YY1 facilitates the association of serum response factor with the c-fos serum response element. 756 50

Protein-DNA interactions in mammalian cells can be analyzed at the nucleotide level of resolution by genomic sequencing techniques. The most sensitive genomic sequencing method uses the ligation-mediated polymerase chain reaction (LMPCR) for signal amplification to detect the positions of DNA modifications or strand breaks. Various probing methods are compatible with LMPCR, but dimethyl sulfate footprinting has most commonly been used. Here, we have examined the suitability of ultraviolet (UV) light as an in vivo footprinting agent to detect a wide variety of protein-DNA contacts. The distribution of the two major types of UV-induced DNA photoproducts (cyclobutane pyrimidine dimers and (6-4) photo-products) has been examined along the promoter sequences of three human genes. A comparison of UV-irradiated naked DNA and UV-irradiated cells reveals differences in the UV damage spectrum for both types of photoproducts. These differences can be either decreases or dramatic increases of photoproduct frequency. At the promoter of the c-jun gene, these differences ("photofootprints") co-localize with binding sites for two AP-1-like transcription factors, a CCAAT box binding protein, an SP-1 sequence, an NF-jun sequence, a related to serum response factor (RSRF) binding site and a sequence bound by an unknown factor. In the promoter of the gene coding for proliferating cell nuclear antigen (PCNA), photofootprints were seen at two SP-1 like sequences and two CCAAT boxes. The c-fos promoter is characterized by photofootprints at the serum response element (SRE), at the adjacent binding site for ternary complex factor (TCF), at an AP-1 site and at a binding site for a growth factor inducible protein (SIF). Photofootprints may be signatures of specific transcription factors or families of related factors since we noticed that the photofootprints seen at several common factor binding sites were similar or identical when the same site was analyzed in different genes. Photofootprints were not seen at sequences distant from transcription factor binding sites. A comparison of our UV photofootprinting data with data from experiments using other probing strategies shows that UV light has the potential to reveal all protein-DNA interactions provided there is a dipyrimidine sequence on either DNA strand within a factor binding site. The simplicity of using this probing agent together with its specificity for detecting a large variety of different factors should make UV light a generally useful tool for in vivo footprinting studies.
J Mol Biol 1995 Jun 16
PMID:UV light as a footprinting agent: modulation of UV-induced DNA damage by transcription factors bound at the promoters of three human genes. 760 84

The MADS box is a conserved sequence motif found in the DNA binding domain of a family of transcription factors which possess related but distinct DNA binding specificities. We investigated the basis of differential sequence recognition by the MADS-box proteins serum response factor (SRF), MCM1, and MEF2A, using chimeric proteins and site-directed mutants in conjunction with gel mobility shift and binding site selection assays. Deletion of sequences immediately N terminal to the SRF MADS box alters its preferred binding site to that of MEF2A, although the resulting protein still weakly binds SRF-specific sites: exclusive binding to MEF2 sites requires further mutations, at MADS-box residues 11 to 15. In contrast to SRF, the sequence specificity of MCM1 (and of MEF2A) is determined entirely by sequences within its MADS box, and mutation of only SRF MADS-box residue 1 is sufficient to alter its binding specificity to that of MCM1. However, changes at both MADS-box positions 1 and 11 to 15 are necessary and sufficient to alter the specificity of the MCM1 MADS box to that of MEF2, and vice versa. The role of SRF MADS-box residues which differ from those present in the other proteins was investigated by selection of functional SRF variants in yeast cells. SRF MADS-box position 1 was always a glycine in the variants, but many different sequences at the other nonconserved MADS-box residues were compatible with efficient DNA binding. We discuss potential mechanisms of DNA recognition by MADS-box proteins.
Mol Cell Biol 1995 Aug
PMID:DNA binding specificity determinants in MADS-box transcription factors. 762 3

The mouse myosin light-chain 1A (MLC1A) gene, expressed in the atria of the adult heart, is one of the first muscle genes to be activated when skeletal as well as cardiac muscles form in the embryo. It is also transcribed in skeletal muscle cell lines at the onset of differentiation. Transient transfection assays of mouse skeletal muscle cell lines with DNA constructs containing MLC1A promoter fragments fused to the chloramphenicol acetyltransferase (CAT) gene show that the first 630 bp of the promoter is sufficient to direct expression of the reporter gene during myotube formation. Two E boxes located at bp -76 and -519 are necessary for this regulation. MyoD and myogenin proteins bind to them as heterodimers with E12 protein and, moreover, transactivate them in cotransfection experiments with the MLC1A promoter in nonmuscle cells. Interestingly, the effect of mutating each E box is less striking in primary cultures than in the C2 or Sol8 muscle cell line. A DNA fragment from bp -36 to -597 confers tissue- and stage-specific activity to the herpes simplex virus thymidine kinase promoter in both orientations, showing that the skeletal muscle-specific regulation of the MLC1A gene is under the control of a muscle-specific enhancer which extends into the proximal promoter region. At bp -89 is a diverged CArG box, CC(A/T)6AG, which binds the serum response factor (SRF) in myotube nuclear extracts, as does the wild-type sequence, CC(A/T)6GG. Both types of CArG box also bind a novel myotube-enriched complex which has contact points with the AT-rich part of the CArG box and adjacent 3' nucleotides. Mutations within the CArG box distinguish between the binding of this complex and binding of SRF; only SRF binding is directly involved in the specific regulation of the MLC1A gene in skeletal muscle cell lines.
Mol Cell Biol 1995 Aug
PMID:A skeletal muscle-specific enhancer regulated by factors binding to E and CArG boxes is present in the promoter of the mouse myosin light-chain 1A gene. 762 50

The Arabidopsis AGL3 gene was previously identified on the basis of sequence similarity to the floral homeotic gene AGAMOUS (AG), which encodes a protein with a conserved MADS domain that is also found in human and yeast transcription factors (SRF and MCM1, respectively). Analysis of newly isolated full-length cDNA clones as well as genomic clones indicates that AGL3 is indeed a MADS-box gene with a general intron-exon structure similar to other plant MADS-box genes. However, unlike the others, which are expressed specifically in flowers, AGL3 is expressed in all above-ground vegetative organs, as well as in flowers, but not in roots. Furthermore, since AGL3 is MADS-domain protein, it is likely that it is also a DNA-binding protein regulating transcription. To characterize AGL3 as a DNA-binding protein in vitro, we expressed the AGL3 protein in Escherichia coli, and characterized its DNA-binding properties. We show that AGL3 binds to sequences which resemble the target sequences of SRF and MCM1, and have determined the consensus sequence to which AGL3 binds using random oligonucleotides. These results suggest that AGL3 is a widely distributed DNA-binding protein, which may be involved the transcriptional regulation of genes in many cells.
Plant Mol Biol 1995 Jun
PMID:The Arabidopsis MADS-box gene AGL3 is widely expressed and encodes a sequence-specific DNA-binding protein. 763 23

Serum induction of c-jun expression in HeLa cells requires a MEF2 site at -59 in the c-jun promoter. MEF2 sites, found in many muscle-specific enhancers, are bound by a family of transcription factors, MEF2A through -D, which are related to serum response factor in their DNA binding domains. We have found that MEF2D is the predominant protein in HeLa cells that binds to the c-jun MEF2 site. Serum induction of a MEF2 reporter gene was not observed in a line of NIH 3T3 cells which contain low MEF2 site binding activity. Transfection of MEF2D into NIH 3T3 cells reconstituted serum induction, demonstrating that MEF2D is required for the serum response. Deletion analysis of MEF2D showed that its DNA binding domain, when fused to a heterologous transcriptional activation domain, was sufficient for serum induction of a MEF2 reporter gene. This is the domain homologous to that in the serum response factor which is required for serum induction of the c-fos serum response element, suggesting that serum regulation of c-fos and c-jun may share a common mechanism.
Mol Cell Biol 1995 Jun
PMID:Regulatory role of MEF2D in serum induction of the c-jun promoter. 776 Jul 90

Cells translate extracellular signals into specific programs of gene expression that reflect their developmental history or identity. We present evidence that one way this interpretation may be performed is by cooperative interactions between serum response factor (SRF) and certain homeodomain proteins. We show that human and Drosophila homeodomain proteins of the paired class have the ability to recruit SRF to DNA sequences not efficiently recognized by SRF on its own, thereby imparting to a linked reporter gene the potential to respond to polypeptide growth factors. This activity requires both the DNA-binding activity of the homeodomain and putative protein-protein contact residues on the exposed surfaces of homeodomain helices 1 and 2. The ability of the homeodomain to impart signal responsiveness is DNA sequence specific, and this specificity differs from the simple DNA-binding specificity of the homeodomain in vitro. The homeodomain imparts response to a spectrum of signals characteristic of the natural SRF-binding site in the c-fos gene. Response to some of these signals is dependent on the secondary recruitment of SRF-dependent ternary complex factors, and we show directly that a homeodomain can promote the recruitment of one such factor, Elk1. We infer that SRF and homeodomains interact cooperatively on DNA and that formation of SRF-homeodomain complexes permits the recruitment of signal-responsive SRF accessory proteins. The ability to route extracellular signals to specific target genes is a novel activity of the homeodomain, which may contribute to the identity function displayed by many homeodomain genes.
Mol Cell Biol 1995 Jun
PMID:Sequence-specific targeting of nuclear signal transduction pathways by homeodomain proteins. 776 Aug 27

Enhanced levels of cytoplasmic Ca2+ due to membrane depolarization with elevated levels of KCl or exposure to the Ca2+ ionophore ionomycin stimulate serum response element (SRE)-dependent transcription in the pheochromocytoma cell line PC12. By using altered binding specificity mutants of transcription factors that bind to the SRE, it was demonstrated that in contrast to treatment with purified growth factors, such as nerve growth factor, the serum response factor (SRF), but not Elk-1, mediates Ca(2+)-regulated SRE-dependent transcription. Enhanced levels of cytoplasmic Ca2+ were found to trigger SRE-dependent transcription via a Ras-independent signaling pathway that appears to involve a Ca2+/calmodulin-dependent kinase (CaMK). Overexpression of a constitutively active form of CaMKIV stimulated SRF-dependent transcription. Taken together, these findings indicate that SRF is a versatile transcription factor that, when bound to the SRE, can function by distinct mechanisms and can mediate transcriptional responses to both CaMK- and Ras-dependent signaling pathways.
Mol Cell Biol 1995 Jul
PMID:Calcium activates serum response factor-dependent transcription by a Ras- and Elk-1-independent mechanism that involves a Ca2+/calmodulin-dependent kinase. 779 74

We have identified a basic sequence in the N-terminal region of the 67-kDa serum response factor (p67SRF or SRF) responsible for its nuclear localization. A peptide containing this nuclear localization signal (NLS) translocates rabbit immunoglobulin G (IgG) into the nucleus as efficiently as a peptide encoding the simian virus 40 NLS. This effect is abolished by substituting any two of the four basic residues in this NLS. Overexpression of a modified form of SRF in which these basic residues have been mutated confirms the absolute requirement for this sequence, and not the other basic amino acid sequences adjacent to it, in the nuclear localization of SRF. Since this NLS is in close proximity to potential phosphorylation sites for the cAMP-dependent protein kinase (A-kinase), we further investigated if A-kinase plays a role in the nuclear location of SRF. The nuclear transport of SRF proteins requires basal A-kinase activity, since inhibition of A-kinase by using either the specific inhibitory peptide PKIm or type II regulatory subunits (RII) completely prevents the nuclear localization of plasmid-expressed tagged SRF or an SRF-NLS-IgG conjugate. Direct phosphorylation of SRF by A-kinase can be discounted in this effect, since mutation of the putative phosphorylation sites in either the NLS peptide or the encoded full-length SRF protein had no effect on nuclear transport of the mutants. Finally, in support of an implication of A-kinase-dependent phosphorylation in a more general mechanism affecting nuclear import, we show that the nuclear transport of a simian virus 40-NLS-conjugated IgG or purified cyclin A protein is also blocked by inhibition of A-kinase, even though neither contains any potential sites for phosphorylation by A-kinase or can be phosphorylated by A-kinase in vitro.
Mol Cell Biol 1995 Jan
PMID:The serum response factor nuclear localization signal: general implications for cyclic AMP-dependent protein kinase activity in control of nuclear translocation. 779 52


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