Translational control in heat-shocked Drosophila embryos. Evidence for the inactivation of initiation factor(s) involved in the recognition of mRNA cap structure.

Maroto, Federico García; Sierra, J M

doi:10.1016/s0021-9258(19)37647-1

Cited by 41 publications

(12 citation statements)

References 45 publications

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“…Some evidence for a ribosomal fraction lesion has also been obtained (Scott & Pardue, 1980), the differences likely resulting from stringency of salt-wash removal of ribosomal-associated proteins. Recent work from Sierra and colleagues strongly implicates alterations in Drosophila eIF-4E and eIF-4F activity in preferential translation (Maroto et al, 1989;Zapata et al, 1991Zapata et al, ,1994) and supports the model for preferential translation of HSP mRNAs based on capindependent translation (Lindquist, 1987; Lindquist & Petersen, 1990; Maroto & Sierra, 1988;Zapata et al, 1991Zapata et al, , 1994. The Drosophila cap binding protein complex (Maroto & Sierra, 1989) may dissociate during heat shock at 37 °C (Zapata et al, 1991; but see discussion below), which likely would result in its inactivation.…”

Section: Discussionmentioning

confidence: 79%

“…To address the consequences of inactivation, antibody-mediated inhibition of eIF-4F was demonstrated to repress translation of normal mRNAs in vitro, but have relatively little inhibitory effect on HSP mRNAs (ibid.). Similarly, blocking eIF-4F by m7GTP cap analogue inhibition preferentially inhibits normal mRNA translation while HSP mRNA translation is relatively spared (Maroto & Sierra, 1988). Heat-Induced elF Phosphorylation Changes and Their Modest Scope.…”

Section: Discussionmentioning

confidence: 99%

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Heat Shock Effects on Phosphorylation of Protein Synthesis Initiation Factor Proteins eIF-4E and eIF-2.alpha. in Drosophila

Duncan

Cavener

1995

Biochemistry

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Heat shock of mammalian cells causes changes in initiation factor phosphorylation that likely contribute to or cause the translation reprogramming characteristic of heat shock. In these investigations we have carried out a parallel analysis of Drosophila, focusing on eIF-4E and eIF-2 alpha. eIF-4E plus associated proteins was purified from lysates by m7GTP-Sepharose chromatography. A minor fraction (< 10%) of eIF-4E is phosphorylated under normal growth conditions, and phosphorylation decreases during heat shock. Drosophila eIF-2 alpha has been identified by in vitro translation of T7 RNA polymerase-transcribed mRNA, and immunoblotting with anti-Drosophila eIF-2 alpha antiserum. 32P-labeling analysis (unfractionated cell lysates and immunoprecipitates) detects phosphorylated eIF-2 alpha, whose amount increases approximately 2-3-fold upon heat shock. Immunoblotting analysis of two-dimensional gel-resolved proteins to determine the mass fraction of eIF-2 alpha phosphorylated detects a single eIF-2 alpha spot in both normal temperature and heat shocked cells, indicating less than 5% phosphorylation after and before heat shock. Staining quantification is consistent with this low prevalence. A major phosphoprotein which copurifies with eIF-4E on m7GTP-Sepharose shows decreased overall phosphorylation and decreased association with eIF-4E following heat shock. Several distinctive characteristics of this phosphoprotein suggest it is Drosophila eIF-4B.

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Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Heat Shock Effects on Phosphorylation of Protein Synthesis Initiation Factor Proteins eIF-4E and eIF-2.alpha. in Drosophila

Duncan

Cavener

1995

Biochemistry

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“…The secondary structures of the Cx43 IRES and most of the other described IRES elements have a semi-conserved Y-like structure, which is suggested to have role in the IRES mediated translation in eukaryotic cells in Stress conditions. Inhibition of cap-dependent translation is one of the cellular responses to stress [71]. This inhibition allows continuation of synthesis of proteins essential for survival and stops the synthesis of non-essential proteins.…”

Section: Ires Mediated Regulation Of Connexin 43mentioning

confidence: 99%

Implication of Connexin 43 as a Tumor Suppressor in Pathogenesis of Breast Cancer

Rashid¹,

Ali²,

Mahboob-Ul-Hussain³

2021

Global Women's Health

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Breast cancer (BC) is a global public health burden, constituting the highest cancer incidence in women worldwide. Connexins 43 proteins propagate intercellular communication, gap junction intercellular communication (GJIC), remarkably expressed in several tumor types including liver, prostate, and breast. This domain of Cx43 possesses functionally critical sites identical to those involved in gating of channel and phosphorylation sites for various kinases. However, the mechanism by which Cx43 down regulation occurs in breast cancer is far from clear. Several mechanisms like Cx43 promoter hyper-methylation or a cancer-specific reduction of Cx43 expression/trafficking by the modulation of various components of the Cx43 life cycle give the idea to be involved in the down regulation of Connexins in mammary glands, but irreversible mutational alterations have not yet been proved to be among them. Summarily, the efficacy or specificity of these drugs can be increased by a combinatory approach considering an effect on both the Connexins and their regulatory molecules. This chapter will summarize the knowledge about the connexins and gap junction activities in breast cancer highlighting the differential expression and functional dynamics of connexins in the pathogenesis of the disease.

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“…Several observations, including the isolation of CBP complexes lacking eIF-4A (10,11,13,32), the differential association of CBP I and 220-kDa polypeptide with ribosomal initiation complexes (33), and the estimates of the relative abundances of the CBP II polypeptides in mammalian cells (11,17), support the notion (2, 33, The data obtained from lower eucaryotes are still scarce, but recent reports have claimed an involvement of eIF-4E and eIF-4F in the control of the yeast cell cycle (8) and the early embryogenesis of sea urchin (22), respectively. In addition, recent results from our laboratory (23) have suggested that cap recognition is involved in translational control during heat shock in Drosophila embryos. However, to enable detailed study of mechanism of this control, the need to characterize the CBPs from this organism became evident (23).…”

mentioning

confidence: 94%

“…In addition, recent results from our laboratory (23) have suggested that cap recognition is involved in translational control during heat shock in Drosophila embryos. However, to enable detailed study of mechanism of this control, the need to characterize the CBPs from this organism became evident (23). Such studies would also be of interest in elucidating the translational initiation mechanism in a eucaryote evolution-2182 MAROTO AND SIERRA ary distant from mammals, a goal we have already begun to pursue (24,25).…”

mentioning

confidence: 94%

Purification and Characterization of mRNA Cap-Binding Protein from Drosophila melanogaster Embryos

Maroto

Sierra

1989

Molecular and Cellular Biology

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A protein with specific affinity for the mRNA cap structure was purified both from the postribosomal supernatant and from the ribosomal high-salt wash of Drosophila melanogaster embryos by m7GTP-Sepharose chromatography. This protein had an apparent molecular mass of 35 kilodaltons (kDa) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a size very different from those of the cap-binding proteins that have been characterized thus far. Drosophila 35-kDa cap-binding protein (CBP) could also be isolated from the ribosomal high-salt wash as part of a salt-stable protein complex consisting of polypeptides of 35, 72, and 140 to 180 kDa. Polyclonal antibodies against Drosophila 35-kDa CBP neither reacted with eucaryotic initiation factor 4E from rabbit reticulocytes nor affected mRNA translation in a rabbit reticulocyte cell-free system. However, in a cell-free system from Drosophila embryos, mRNA translation was specifically inhibited by these antibodies. The requirement of 35-kDa CBP for mRNA translation in Drosophila was diminished under ionic conditions in which the importance of mRNA cap structure recognition was reduced. Despite the structural differences between Drosophila 35-kDa CBP and mammalian initiation factor 4E, both proteins were functionally interchangeable in the in vitro translation system from Drosophila embryos.

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Translational control in heat-shocked Drosophila embryos. Evidence for the inactivation of initiation factor(s) involved in the recognition of mRNA cap structure.

Cited by 41 publications

References 45 publications

Heat Shock Effects on Phosphorylation of Protein Synthesis Initiation Factor Proteins eIF-4E and eIF-2.alpha. in Drosophila

Heat Shock Effects on Phosphorylation of Protein Synthesis Initiation Factor Proteins eIF-4E and eIF-2.alpha. in Drosophila

Implication of Connexin 43 as a Tumor Suppressor in Pathogenesis of Breast Cancer

Purification and Characterization of mRNA Cap-Binding Protein from Drosophila melanogaster Embryos

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