The DNA-binding activity of mouse DNA methyltransferase 1 is regulated by phosphorylation with casein kinase 1δ/ε

2010 ◽  
Vol 427 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Yasunori Sugiyama ◽  
Naoya Hatano ◽  
Noriyuki Sueyoshi ◽  
Isao Suetake ◽  
Shoji Tajima ◽  
...  

Dnmt1 (DNA methyltansferase 1) is an enzyme that recognizes and methylates hemimethylated DNA during DNA replication to maintain methylation patterns. The N-terminal region of Dnmt1 is known to form an independent domain structure that interacts with various regulatory proteins and DNA. In the present study, we investigated protein kinases in the mouse brain that could bind and phosphorylate the N-terminal regulatory domain of Dnmt1. A protein fraction containing protein kinase activity for phosphorylation of Dnmt1(1–290) was prepared using Dnmt1(1–290)-affinity, DNA–cellulose and gel-filtration columns. When the proteins in this fraction were analysed by LC-MS/MS (liquid chromatography tandem MS), CK1δ/ε (casein kinase 1δ/ε) was the only protein kinase identified. Recombinant CK1δ/ε was found to bind to the N-terminal domain of Dnmt1 and significantly phosphorylated this domain, especially in the presence of DNA. Phosphorylation analyses using various truncation and point mutants of Dnmt1 revealed that the major priming site phosphorylated by CK1δ/ε was Ser146, and that subsequent phosphorylation at other sites may occur after phosphorylation of the priming site. When the DNA-binding activity of phosphorylated Dnmt1 was compared with that of the non-phosphorylated form, phosphorylation of Dnmt1 was found to decrease the affinity for DNA. These results suggest that CK1δ/ε binds to and phosphorylates the N-terminal domain of Dnmt1 and regulates Dnmt1 function by reducing the DNA-binding activity.

2011 ◽  
Vol 437 (1) ◽  
pp. 141-148 ◽  
Author(s):  
Isao Suetake ◽  
Yuichi Mishima ◽  
Hironobu Kimura ◽  
Young-Ho Lee ◽  
Yuji Goto ◽  
...  

The Dnmt3a gene, which encodes de novo-type DNA methyltransferase, encodes two isoforms, full-length Dnmt3a and Dnmt3a2, which lacks the N-terminal 219 amino acid residues. We found that Dnmt3a showed higher DNA-binding and DNA-methylation activities than Dnmt3a2. The N-terminal sequence from residues 1 to 211 was able to bind to DNA, but could not distinguish methylated and unmethylated CpG. Its binding to DNA was inhibited by a major groove binder. Four basic amino acid residues, Lys51, Lys53, Arg177 and Arg179, in the N-terminal region were crucial for the DNA-binding activity. The ectopically expressed N-terminal sequence (residues 1–211) was localized in nuclei, whereas that harbouring mutations at the four basic amino acid residues was also detected in the cytoplasm. The DNA-methylation activity of Dnmt3a with the mutations was suppressed under physiological salt conditions, which is similar that of Dnmt3a2. In addition, ectopically expressed Dnmt3a with mutations, as well as Dnmt3a2, could not be retained efficiently in nuclei on salt extraction. We conclude that the DNA-binding activity of the N-terminal domain contributes to the DNA-methyltransferase activity via anchoring of the whole molecule to DNA under physiological salt conditions.


2007 ◽  
Vol 282 (14) ◽  
pp. 10299-10310 ◽  
Author(s):  
Caterina Grillo ◽  
Chiara D'Ambrosio ◽  
Valerio Consalvi ◽  
Roberta Chiaraluce ◽  
Andrea Scaloni ◽  
...  

2002 ◽  
Vol 364 (3) ◽  
pp. 875-879 ◽  
Author(s):  
Lisa O'ROURKE ◽  
Peter R. SHEPHERD

Activation of the transcription factor signal transducer and activator of transcription 3 (STAT3) requires dimerization that is induced by phosphorylation of Tyr705, but its activity can be further modulated by phosphorylation at Ser727 in a manner that is dependent on cell context and the stimulus used. The role of STAT3 Ser727 phosphorylation in leptin signalling is currently not known. While cells transfected with the signalling-competent long form of the leptin receptor (ObRb) have been used to study leptin signalling, these are likely to be of limited use in studying STAT3 Ser727 phosphorylation due to the importance of cell background in determining the nature of the response. However, we have recently found that J774.2 macrophages endogenously express high levels of ObRb, and using these cells we find that leptin stimulates STAT3 phosphorylation on both Tyr705 and Ser727. The phosphorylation of Ser727 was not affected by rapamycin or the protein kinase C inhibitor H7 [1-(5-isoquinolinylsulphonyl)-2-methylpiperazine dihydrochloride]. While the MEK-1 [mitogen-activated protein kinase (MAP kinase)/extracellular-signal-related kinase (ERK) kinase-1] inhibitor PD98059 [(2-amino-3′-methoxyphenyl)oxanaphthalen-4-one] had no effect on leptin-stimulated phosphorylation of STAT3 Tyr705, it greatly attenuated leptin's effects on STAT3 Ser727 phosphorylation. Further, Ob's effect on the DNA binding activity of STAT3 was also greatly reduced at all time points by PD98059. Leptin-induced ERK activation in J774.2 cells shows a biphasic pattern, with an initial reduction in ERK phosphorylation for up to 10min following leptin stimulation, while at later time points phosphorylation of ERK was increased above basal levels. The increase in ERK activity corresponded with an increase in both phosphorylation of Ser727 and STAT3 DNA binding activity. These data provide the first evidence that ERK-mediated phosphorylation of Ser727 is required for full stimulation of STAT3 by leptin.


1990 ◽  
Vol 173 (3) ◽  
pp. 862-871 ◽  
Author(s):  
Odile Filhol ◽  
Claude Cochet ◽  
Edmond M. Chambaz

1997 ◽  
Vol 272 (21) ◽  
pp. 13489-13495 ◽  
Author(s):  
Susan A. Armstrong ◽  
Denise A. Barry ◽  
Robert W. Leggett ◽  
Christopher R. Mueller

2004 ◽  
Vol 24 (7) ◽  
pp. 2797-2807 ◽  
Author(s):  
Pablo Gómez-del Arco ◽  
Kazushige Maki ◽  
Katia Georgopoulos

ABSTRACT Ikaros is a key regulator of lymphocyte proliferative responses. Inactivating mutations in Ikaros cause antigen-mediated lymphocyte hyperproliferation and the rapid development of leukemia and lymphoma. Here we show that Ikaros's ability to negatively regulate the G1-S transition can be modulated by phosphorylation of a serine/threonine-rich conserved region (p1) in exon 8. Ikaros phosphorylation in p1 is induced during the G1-S transition. Mutations that prevent phosphorylation in p1 increase Ikaros's ability to impede cell cycle progression and its affinity for DNA. Casein kinase II, whose increased activity in lymphocytes leads to transformation, is a key player in Ikaros p1 phosphorylation. We thus propose that Ikaros's activity as a regulator of the G1-S transition is controlled by phosphorylation in response to signaling events that downmodulate its DNA binding activity.


1992 ◽  
Vol 12 (10) ◽  
pp. 4694-4705 ◽  
Author(s):  
S J Baker ◽  
T K Kerppola ◽  
D Luk ◽  
M T Vandenberg ◽  
D R Marshak ◽  
...  

c-jun is a member of the family of immediate-early genes whose expression is induced by factors such as serum stimulation, phorbol ester, and differentiation signals. Here we show that increased Jun synthesis after serum stimulation is accompanied by a concomitant increase in phosphorylation. Several serine-threonine kinases were evaluated for their ability to phosphorylate Jun in vitro. p34cdc2, protein kinase C, casein kinase II, and pp44mapk phosphorylated Jun efficiently, whereas cyclic AMP-dependent protein kinase and glycogen synthase kinase III did not. The sites phosphorylated by p34cdc2 were similar to those phosphorylated in vivo after serum induction. The major sites of phosphorylation were mapped to serines 63, 73, and 246. Phosphorylation of full-length Jun with several kinases did not affect the DNA-binding activity of Jun homodimers or Fos-Jun heterodimers. Comparison of the DNA binding and in vitro transcription properties of wild-type and mutated proteins containing either alanine or aspartic acid residues in place of Ser-63, -73, and -246 revealed only minor differences among homodimeric complexes and no differences among Fos-Jun heterodimers. Thus, phosphorylation of Jun did not produce a significant change in dimerization, DNA-binding, or in vitro transcription activity. The regulatory role of phosphorylation in the modulation of Jun function is likely to be considerably more complex than previously suggested.


2000 ◽  
Vol 279 (2) ◽  
pp. C326-C334 ◽  
Author(s):  
Hong Jin Kim ◽  
B. Mark Evers ◽  
David A. Litvak ◽  
Mark R. Hellmich ◽  
Courtney M. Townsend

The hormone bombesin (BBS) and its mammalian equivalent gastrin-releasing peptide (GRP) act through specific GRP receptors (GRP-R) to affect multiple cellular functions in the gastrointestinal tract; the intracellular signaling pathways leading to these effects are not clearly defined. Previously, we demonstrated that the human gastric cancer SIIA possesses GRP-R and that BBS stimulates activator protein-1 (AP-1) gene expression. The purpose of our present study was to determine the signaling pathways leading to AP-1 induction in SIIA cells. A rapid induction of c- jun and jun-B gene expression was noted after BBS treatment; this effect was blocked by specific GRP-R antagonists, indicating that BBS is acting through the GRP-R. The signaling pathways leading to increased AP-1 gene expression were delineated using phorbol 12-myristate 13-acetate (PMA), which stimulates protein kinase C (PKC)-dependent pathways, by forskolin (FSK), which stimulates protein kinase A (PKA)-dependent pathways, and by the use of various protein kinase inhibitors. Treatment with PMA stimulated AP-1 gene expression and DNA binding activity similar to the effects noted with BBS; FSK stimulated jun-B expression but produced only minimal increases of c- jun mRNA and AP-1 binding activity. Pretreatment of SIIA cells with either H-7 or H-8 (primarily PKC inhibitors) inhibited the induction of c- jun and jun-B mRNAs in response to BBS, whereas H-89 (PKA inhibitor) exhibited only minimal effects. Pretreatment with tyrphostin-25, a protein tyrosine kinase (PTK) inhibitor, attenuated the BBS-mediated induction of c- jun and jun-B, but the effect was not as pronounced as with H-7. Collectively, our results demonstrate that BBS acts through its receptor to produce a rapid induction of both c- jun and jun-B mRNA and AP-1 DNA binding activity in the SIIA human gastric cancer. Moreover, this induction of AP-1, in response to BBS, is mediated through both PKC- and PTK-dependent signal transduction pathways with only minimal involvement of PKA.


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