Cytoplasmic retention of Xenopus nuclear factor 7 before the mid blastula transition uses a unique anchoring mechanism involving a retention domain and several phosphorylation sites

Li, Xiaoxia; Shou, Weinian; Kloc, Małgorzata; Reddy, Bramham A.; Etkin, Laurence D.

doi:10.1083/jcb.124.1.7

Cited by 61 publications

(44 citation statements)

References 38 publications

(34 reference statements)

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“…Such a mechanism has been described, for example, in the block to nuclear import of phosphorylated Pho4 in yeast (26). Alternatively, phosphorylation could strengthen binding of mPER1 to a cytoplasmic anchoring protein, as occurs with the Xenopus transcription factor Xnf7 (33,51). In the case of Xnf7, addition of an exogenous NLS is unable to overcome the cytoplasmic binding, and NLS-Xnf7 remains in the cytoplasm.…”

Section: Resultsmentioning

confidence: 99%

“…It has become increasingly clear that proteins whose functions are tightly regulated by phosphorylation are often maintained in close proximity to their regulatory kinases and phosphatases, either by colocalization (e.g., binding to common anchoring proteins) or by direct association (22,38). Protein phosphorylation controls the nuclear import of a number of proteins, including Cdc25 and Pho4 in yeast and SV40 large T antigen, Dorsal, Cdc25C, Xnf7, NF-B, NF-AT4, and FKHRL1 in vertebrates (3,4,9,24,29,33,35,39,43,60). In many of these cases tight association between the kinase and the substrate has been shown.…”

Section: Discussionmentioning

confidence: 99%

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Nuclear Entry of the Circadian Regulator mPER1 Is Controlled by Mammalian Casein Kinase I ɛ

Vielhaber

Eide

Rivers

et al. 2000

Molecular and Cellular Biology

263

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The molecular oscillator that keeps circadian time is generated by a negative feedback loop. Nuclear entry of circadian regulatory proteins that inhibit transcription from E-box-containing promoters appears to be a critical component of this loop in both Drosophila and mammals. The Drosophila double-time gene product, a casein kinase I (CKI) homolog, has been reported to interact with dPER and regulate circadian cycle length. We find that mammalian CKI binds to and phosphorylates the murine circadian regulator mPER1. Unlike both dPER and mPER2, mPER1 expressed alone in HEK 293 cells is predominantly a nuclear protein. Two distinct mechanisms appear to retard mPER1 nuclear entry. First, coexpression of mPER2 leads to mPER1-mPER2 heterodimer formation and cytoplasmic colocalization. Second, coexpression of CKI leads to masking of the mPER1 nuclear localization signal and phosphorylation-dependent cytoplasmic retention of both proteins. CKI may regulate mammalian circadian rhythm by controlling the rate at which mPER1 enters the nucleus.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Nuclear Entry of the Circadian Regulator mPER1 Is Controlled by Mammalian Casein Kinase I ɛ

Vielhaber

Eide

Rivers

et al. 2000

Molecular and Cellular Biology

263

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“…The movement of p122 into the nucleus occurs as many of the maternal mRNAs to which it binds are degraded. Since the pattern of subcellular movement of p122 closely resembles that of xnf7, a protein whose control has been intensively studied (15,18,31,32,40,56), we checked for regions of homology between the two (especially for a cytoplasmic retention domain). None were apparent; thus, the cytoplasm-to-nucleus translocation of p122 is most likely regulated by a mechanism separate from that which regulates xnf7.…”

Section: Discussionmentioning

confidence: 99%

The Maternal CCAAT Box Transcription Factor Which Controls GATA-2 Expression Is Novel and Developmentally Regulated and Contains a Double-Stranded-RNA-Binding Subunit

Orford

Robinson

Haydon

et al. 1998

Molecular and Cellular Biology

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The transcription factor GATA-2 is expressed at high levels in the nonneural ectoderm of the Xenopus embryo at neurula stages, with lower amounts of RNA present in the ventral mesoderm and endoderm. The promoter of the GATA-2 gene contains an inverted CCAAT box conserved among Xenopus laevis, humans, chickens, and mice. We have shown that this sequence is essential for GATA-2 transcription during early development and that the factor binding it is maternal. The DNA-binding activity of this factor is detectable in nuclei and chromatin bound only when zygotic GATA-2 transcription starts. Here we report the characterization of this factor, which we call CBTF (CCAAT box transcription factor). CBTF activity mainly appears late in oogenesis, when it is nuclear, and the complex has multiple subunits. We have identified one subunit of the factor as p122, a Xenopus double-stranded-RNA-binding protein. The p122 protein is perinuclear during early embryonic development but moves from the cytoplasm into the nuclei of embryonic cells at stage 9, prior to the detection of CBTF activity in the nucleus. Thus, the accumulation of CBTF activity in the nucleus is a multistep process. We show that the p122 protein is expressed mainly in the ectoderm. Expression of p122 mRNA is more restricted, mainly to the anterior ectoderm and mesoderm and to the neural tube. Two properties of CBTF, its dual role and its cytoplasm-to-nucleus translocation, are shared with other vertebrate maternal transcription factors and may be general properties of these proteins.

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“…Regulation of protein import can also occur by protein phosphorylation such as in the case of MAPK [2] or by direct binding of a lipophilic hormone ligand to a steroid receptor located in the cytoplasm such as in the case of glucocorticoid receptor [3]. Additionally, an intermolecular interaction may prevent a protein from nuclear localization by actively retaining that protein in the cytoplasm such as in the case of Xenopus nuclear factor 7 (xnf7) [4]. In yet another example p53, which functions as a transcriptional activator in the cell nucleus, is exported out to the cytoplasm to be degraded [5].…”

Section: Introductionmentioning

confidence: 99%

Non-random subcellular distribution of variant EKLF in erythroid cells

Quadrini¹,

Gruzglin²,

Bieker³

2008

Experimental Cell Research

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EKLF protein plays a prominent role during erythroid development as a nuclear transcription factor. Not surprisingly, exogenous EKLF quickly localizes to the nucleus. However, using two different assays we have unexpectedly found that a substantial proportion of endogenous EKLF resides in the cytoplasm at steady state in all erythroid cells examined. While EKLF localization does not appear to change during either erythroid development or terminal differentiation, we find that the protein displays subtle yet distinct biochemical and functional differences depending on which subcellular compartment it is isolated from, with PEST sequences possibly playing a role in these differences. Localization is unaffected by inhibition of CRM1 activity and the two populations are not differentiated by stability. Heterokaryon assays demonstrate that EKLF is able to shuttle out of the nucleus although its nuclear re-entry is rapid. These studies suggest there is an unexplored role for EKLF in the cytoplasm that is separate from its well-characterized nuclear function.

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Cytoplasmic retention of Xenopus nuclear factor 7 before the mid blastula transition uses a unique anchoring mechanism involving a retention domain and several phosphorylation sites

Abstract: Abstract. Xenopus nuclear factor 7 (xnf7) is a maternally expressed protein that belongs to the B-box zinc finger gene family consisting of transcription factors, protooncogenes, and ribonucleoproteins.

Cited by 61 publications

References 38 publications

Nuclear Entry of the Circadian Regulator mPER1 Is Controlled by Mammalian Casein Kinase I ɛ

Nuclear Entry of the Circadian Regulator mPER1 Is Controlled by Mammalian Casein Kinase I ɛ

The Maternal CCAAT Box Transcription Factor Which Controls GATA-2 Expression Is Novel and Developmentally Regulated and Contains a Double-Stranded-RNA-Binding Subunit

Non-random subcellular distribution of variant EKLF in erythroid cells

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