Different intracellular distributions of heat-shock and arsenite-induced proteins in Drosophila Kc cells (original) (raw)
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Biochemical and Immunocytochemical Localization of Heat-Shock Proteins in Drosophila Cultured Cells
Annals of the New York Academy of Sciences, 1985
Treatment of living cells at supraoptimal temperatures or with various chemical or physical aggressors induces the synthesis of a group of proteins known as heat-shock proteins (HSP).'.2 The function of these ubiquitous proteins is unclear although a role in cellular protection has been ~uggested.~ In Drosophila cultured cells, biochemical fractionation of HS cells shows an enrichment of most HSPs (with the exception of HSP 82) in the nuclear pellet following HS.4,' In the course of studies on the characterization of a major intermediate filament-like cytoskeletal protein of 46,000 in these we observed that the group of low molecular weight HSPs tended to copurify with a Triton-high salt insoluble' cytoskeletal fraction (FIGURE 1). In order to investigate the significance of this finding and to elucidate the function of HSPs, we prepared polyclonal antibodies against HSP 82, 70, 68, and 23 and studied their intracellular distribution by immunofluorescence techniques following heat shock and during recovery. The antibodies were purified by affinity and their specificity checked by immunoblotting. The results are summarized in FIGURE 2.
Changes in nuclear proteins induced by heat shock in Drosophila culture cells
FEBS Letters, 1985
Nuclear proteins of normal and heat-shocked Drosophila cells were analysed by two-dimensional electrophoresis. The computerized processing of the gels allowed us to detect 6 proteins strongly induced by the heat treatment, but which were different from the usually described heat-shock proteins. The possible role of these proteins in genetic regulation is discussed, as is the value of this type of approach for the study of other genetic regulation phenomena.
Steroid and high-temperature induction of the small heat-shock protein genes in Drosophila
Journal of Molecular Biology, 1984
Transcription of the four small heat-shock protein genes of Drosophila rrwlnnogaater ('an be induced in cultured cells by high-temperature shock, or b? physiological doses of the moulting hormone. ecdyst,erone. We have characterized and compared the two induction events, f&using on hspdd and hsp23. in terms of rates of heat-shock protein synthesis, transcription rate, messenger RXA abundance and mRr\'A half-life. The results indicate that relative t,o hspB2, thti ratv of hs$3 synthesis is significantly greater during recovery from heat shock and during rvdgsterone induction. This difference is not, due to differences in transcription rate. but rather reflects differences in mRN.4 stabilitv and translational efficiency. One intriguing finding is that hsp message stability is temperature-dependent; hsp transcripts are two to three times more stable at 35°C t,han at, A?"(:. The Ix)ssiblr mechanism and significance of this phenomenon arr tliscussrtl.
Small heat shock proteins of Drosophila associate with the cytoskeleton
Proceedings of the National Academy of Sciences, 1986
Fractionation of heat-shocked Drosophila melanogaster Kc cells reveals that both the small heat shock proteins (hsp28, -26, -23, and -22) and vimentin-like intermediate filament proteins (IFPs) are abundantly represented in the nuclear fraction. Cofractionation of the IFPs with nuclei is due to the collapse of the IFP network against the nucleus upon heat shock, raising the possibility that cofractionation of the small hsps is by a similar mechanism. Indirect immunofluorescence supports this possibility. In salivary glands, both the hsps and the IFPs are cytoplasmic after mild-to-moderate heat shocks and only enter the nucleus upon severe--indeed, lethal--shocks. Double-label experiments with Schneider line 2 cells show that the IFPs and small hsps colocalize to the same perinuclear aggregates in 70% of the cells examined. Thus, the small hsps are associated with the cytoskeleton rather than with nuclear structures.
Molecular & general genetics : MGG, 1979
The effect of a ts-mutation belonging to the cell-lethal type on protein and RNA synthesis under heat shock conditions has been investigated. The mutation studied, l(l)ts-403, localized in the X-chromosome has significant effect on the kinetics of protein synthesis in salivary gland subjected to heat treatment under in vivo and in vitro conditions. The animals homozygous for l(l)ts-403 are characterized by a rapid drop of label incorporation into heat shock proteins. It is shown that the mutation affects not only the kinetics of heat-shock proteins synthesis but their electrophoretic pattern as well. The experiments performed enable us to conclude that the presumptive regulatory gene realized its action at the level of transcription of heat shock loci.
Genetic regulation during heat shock and function of heat-shock proteins: a review
Biochemistry and Cell Biology, 1983
The induction by thermal stress of certain specific genes (heat-shock genes) first described in Drosophila has recently been observed in a wide variety of unicellular and multicellular organisms, emphasizing the basic importance of this ubiquitous response. Recent data dealing with the molecular mechanisms involved in the intensive transcriptional and posttranscriptional regulation during heat shock is reviewed with emphasis on the induction of the response and the putative function of the heat-shock proteins. A model showing the various interactions of cellular regulatory mechanisms operating in the heat-shocked cell is presented. While the list of agents or treatments inducing heat-shock proteins (hsp's) in various organisms is increasing, the identification of a hypothetical common inducing factor is elusive. The recently described reorganization of some cytoskeletal elements upon heat shock is discussed both in terms of its potential involvement in transcriptional and (or) t...
Regulation of heat shock gene induction and expression during Drosophila development
Cellular and Molecular Life Sciences, 1997
Some heat shock genes are expressed in the absence of stress during embryogenesis and metamorphosis in the fruit fly Drosophila melanogaster. Their functions in these processes are unknown. During development, each of the four members of the small heat shock protein family (Hsp27, Hsp26, Hsp23 and Hsp22), which are coordinately induced in response to a heat stress, shows a specific pattern of expression in diverse tissues and cells. This expression is driven through cell-specific enhancers in the promoter regions of their genes. In addition, some of the Hsps show cell-specific induction by heat shock. Hsp23, for example, is only inducible in a single cell type (cone cells) of the eye ommatidium, while the other small Hsps are inducible in all cells of the eye unit. In germ line tissues such as testes, Hsp23 and 27 are both readily expressed in the absence of stress (albeit in distinct cell lineages) and cannot be further induced by heat shock. Hsp27 is expressed throughout oogenesis, but its intracellular localization is stage-specific, being nuclear from germarium to stage 6 and cytoplasmic from stage 8 onwards. Finally the small Hsps show tissue-specific post-translational modifications. Thus the function(s) of the small Hsps may be modulated by different cell and developmental stage-specific mechanisms operating either on their expression, their cellular localization or their structure by post-translational modifications.
Integration, transcription, and control of a Drosophila heat shock gene in mouse cells
Proceedings of the National Academy of Sciences, 1981
Mouse L cells were transformed with a cloned 3.6-kilobase (kb) segment of Drosophila melanogaster DNA carrying the 2.25-kb transcribed sequence for the Drosophila 70,000dalton heat shock protein (hsp70) and 1.1 kb and 0.2 kb of 5' and 3' flanking DNA, respectively. Heat shock of one of three such transformed cell lines containing multiple copies ofthe intact Drosophila segment induced the abundant accumulation oftranscripts of the Drosophila gene, with correct or nearly correct 5' and 3' termini. This provides evidence, in accord with earlier indications, that diverse eukaryotes, including vertebrates, have heat shock systems similar to that studied extensively in Drosophila. Our results suggest that the signals for heat shock transcription and the chromosomal sites with which they interact have been highly conserved in evolution and that the regulatory sequences controlling transcription ofthe gene for hsp70 lie within the 3.6-kb Drosophila segment.