scholarly journals Intron-independent Association of Splicing Factors with Active Genes

1999 ◽  
Vol 145 (6) ◽  
pp. 1133-1143 ◽  
Author(s):  
Caroline Jolly ◽  
Claire Vourc'h ◽  
Michel Robert-Nicoud ◽  
Richard I. Morimoto

The cell nucleus is organized as discrete domains, often associated with specific events involved in chromosome organization, replication, and gene expression. We have examined the spatial and functional relationship between the sites of heat shock gene transcription and the speckles enriched in splicing factors in primary human fibroblasts by combining immunofluorescence and fluorescence in situ hybridization (FISH). The hsp90α and hsp70 genes are inducibly regulated by exposure to stress from a low basal level to a high rate of transcription; additionally the hsp90α gene contains 10 introns whereas the hsp70 gene is intronless. At 37°C, only 30% of hsp90α transcription sites are associated with speckles whereas little association is detected with the hsp70 gene, whose constitutive expression is undetectable relative to the hsp90α gene. Upon exposure of cells to heat shock, the heavy metal cadmium, or the amino acid analogue azetidine, transcription at the hsp90α and hsp70 gene loci is strongly induced, and both hsp transcription sites become associated with speckles in >90% of the cells. These results reveal a clear disconnection between the presence of intervening sequences at specific gene loci and the association with splicing factor–rich regions and suggest that subnuclear structures containing splicing factors are associated with sites of transcription.

1989 ◽  
Vol 9 (8) ◽  
pp. 3166-3173
Author(s):  
N G Theodorakis ◽  
D J Zand ◽  
P T Kotzbauer ◽  
G T Williams ◽  
R I Morimoto

Hemin-induced differentiation of the human erythroleukemia cell line K562 results in the expression and accumulation of erythroid-specific gene products such as embryonic and fetal hemoglobins and the elevated synthesis of the major heat shock protein HSP70. This activity was suggested to represent activation of a heat shock gene during erythroid maturation independent of stress induction. In this study, we demonstrate that hemin induces the transcription of two members of the human HSP70 gene family, HSP70 and GRP78 (BiP). However, the induction of HSP70 by hemin showed characteristics consistent with the molecular events associated with a heat shock or stress response. The increase in HSP70 gene transcription was accompanied by induction of the stress-induced form of the heat shock transcription factor. Moreover, a heat shock element was required for the hemin responsiveness of chimeric heat shock promoter-chloramphenicol acetyltransferase genes transiently expressed in transfected K562 cells.


1989 ◽  
Vol 9 (8) ◽  
pp. 3166-3173 ◽  
Author(s):  
N G Theodorakis ◽  
D J Zand ◽  
P T Kotzbauer ◽  
G T Williams ◽  
R I Morimoto

Hemin-induced differentiation of the human erythroleukemia cell line K562 results in the expression and accumulation of erythroid-specific gene products such as embryonic and fetal hemoglobins and the elevated synthesis of the major heat shock protein HSP70. This activity was suggested to represent activation of a heat shock gene during erythroid maturation independent of stress induction. In this study, we demonstrate that hemin induces the transcription of two members of the human HSP70 gene family, HSP70 and GRP78 (BiP). However, the induction of HSP70 by hemin showed characteristics consistent with the molecular events associated with a heat shock or stress response. The increase in HSP70 gene transcription was accompanied by induction of the stress-induced form of the heat shock transcription factor. Moreover, a heat shock element was required for the hemin responsiveness of chimeric heat shock promoter-chloramphenicol acetyltransferase genes transiently expressed in transfected K562 cells.


1988 ◽  
Vol 8 (11) ◽  
pp. 4736-4744
Author(s):  
D D Mosser ◽  
N G Theodorakis ◽  
R I Morimoto

Activation of human heat shock gene transcription by heat shock, heavy metal ions, and amino acid analogs required the heat shock element (HSE) in the HSP70 promoter. Both heat shock- and metal ion-induced HSP70 gene transcription occurred independently of protein synthesis, whereas induction by amino acid analogs required protein synthesis. We identified a HSE-binding activity from control cells which was easily distinguished by a gel mobility shift assay from the stress-induced HSE-binding activity which appeared following heat shock or chemically induced stress. The kinetics of HSP70 gene transcription paralleled the rapid appearance of stress-induced HSE-binding activity. During recovery from heat shock, both the rate of HSP70 gene transcription and stress-induced HSE-binding activity levels declined and the control HSE-binding activity reappeared. The DNA contacts of the control and stress-induced HSE-binding activities deduced by methylation interference were similar but not identical. While stable complexes with HSE were formed with extracts from both control and stressed cells in vitro at 25 degrees C, only the stress-induced complex was detected when binding reactions were performed at elevated temperatures.


1990 ◽  
Vol 10 (12) ◽  
pp. 6362-6373
Author(s):  
R E Susek ◽  
S Lindquist

hsp26, the small heat shock protein of Saccharomyces cerevisiae, accumulates in response to heat and other types of stress. It also accumulates during the normal course of development, as cells enter stationary phase growth or begin to sporulate (S. Kurtz, J. Rossi, L. Petko, and S. Lindquist, Science 231:1154-1157, 1986). Analysis of deletion and insertion mutations demonstrated that transcriptional control plays a critical role in regulating HSP26 expression. The HSP26 promoter was found to be complex and appears to contain repressing elements as well as activating elements. Several upstream deletion mutations resulted in strong constitutive expression of HSP26. Furthermore, upstream sequences from the HSP26 gene repressed the constitutive expression of a heterologous heat shock gene. We propose that basal repression and heat-induced depression of transcription play major roles in regulating the expression of HSP26. None of the recombinant constructs that we analyzed separated cis-regulatory sequences responsible for heat shock regulation from those responsible for developmental regulation of HSP26. Depression of HSP26 transcription may be the general mechanism of HSP26 induction in yeast cells. This regulatory scheme is very different from that described for the regulation of most other heat shock genes.


1986 ◽  
Vol 6 (11) ◽  
pp. 3984-3989 ◽  
Author(s):  
D S Gilmour ◽  
J T Lis

By using a protein-DNA cross-linking method (D. S. Gilmour and J. T. Lis, Mol. Cell. Biol. 5:2009-2018, 1985), we examined the in vivo distribution of RNA polymerase II on the hsp70 heat shock gene in Drosophila melanogaster Schneider line 2 cells. In heat shock-induced cells, a high level of RNA polymerase II was detected on the entire gene, while in noninduced cells, the RNA polymerase II was confined to the 5' end of the hsp70 gene, predominantly between nucleotides -12 and +65 relative to the start of transcription. This association of RNA polymerase II was apparent whether the cross-linking was performed by a 10-min UV irradiation of chilled cells with mercury vapor lamps or by a 40-microsecond irradiation of cells with a high-energy xenon flash lamp. We hypothesize that RNA polymerase II has access to, and a high affinity for, the promoter region of this gene before induction, and this poised RNA polymerase II may be critical in the mechanism of transcription activation.


1988 ◽  
Vol 8 (11) ◽  
pp. 4736-4744 ◽  
Author(s):  
D D Mosser ◽  
N G Theodorakis ◽  
R I Morimoto

Activation of human heat shock gene transcription by heat shock, heavy metal ions, and amino acid analogs required the heat shock element (HSE) in the HSP70 promoter. Both heat shock- and metal ion-induced HSP70 gene transcription occurred independently of protein synthesis, whereas induction by amino acid analogs required protein synthesis. We identified a HSE-binding activity from control cells which was easily distinguished by a gel mobility shift assay from the stress-induced HSE-binding activity which appeared following heat shock or chemically induced stress. The kinetics of HSP70 gene transcription paralleled the rapid appearance of stress-induced HSE-binding activity. During recovery from heat shock, both the rate of HSP70 gene transcription and stress-induced HSE-binding activity levels declined and the control HSE-binding activity reappeared. The DNA contacts of the control and stress-induced HSE-binding activities deduced by methylation interference were similar but not identical. While stable complexes with HSE were formed with extracts from both control and stressed cells in vitro at 25 degrees C, only the stress-induced complex was detected when binding reactions were performed at elevated temperatures.


1990 ◽  
Vol 10 (12) ◽  
pp. 6362-6373 ◽  
Author(s):  
R E Susek ◽  
S Lindquist

hsp26, the small heat shock protein of Saccharomyces cerevisiae, accumulates in response to heat and other types of stress. It also accumulates during the normal course of development, as cells enter stationary phase growth or begin to sporulate (S. Kurtz, J. Rossi, L. Petko, and S. Lindquist, Science 231:1154-1157, 1986). Analysis of deletion and insertion mutations demonstrated that transcriptional control plays a critical role in regulating HSP26 expression. The HSP26 promoter was found to be complex and appears to contain repressing elements as well as activating elements. Several upstream deletion mutations resulted in strong constitutive expression of HSP26. Furthermore, upstream sequences from the HSP26 gene repressed the constitutive expression of a heterologous heat shock gene. We propose that basal repression and heat-induced depression of transcription play major roles in regulating the expression of HSP26. None of the recombinant constructs that we analyzed separated cis-regulatory sequences responsible for heat shock regulation from those responsible for developmental regulation of HSP26. Depression of HSP26 transcription may be the general mechanism of HSP26 induction in yeast cells. This regulatory scheme is very different from that described for the regulation of most other heat shock genes.


Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 921-932 ◽  
Author(s):  
B. Billoud ◽  
M.L. Rodriguez-Martin ◽  
L. Berard ◽  
N. Moreau ◽  
N. Angelier

We isolated and characterized a sequence coding for heat-shock protein 70 (HSP70) of the amphibian Pleurodeles waltl. Results from S1 nuclease protection assays led us to conclude that an hsp70 gene, strictly inducible in somatic cells during heat shock, is constitutively active during oogenesis. By quantitative northern and western blot analysis, we showed that both hsp70 mRNA and HSP70-related protein levels increased in oocytes from stage II to stage VI under physiological conditions. Furthermore, by in situ hybridization to the nascent transcripts of lampbrush chromosome loops, we provided evidence for a clear-cut relationship between this increase in hsp70 mRNA and transcriptional activity during the lampbrush stage of oogenesis. These results strongly suggest that hsp70 genes are actively transcribed throughout oogenesis. HSP70-related proteins localized in the cytoplasm of young oocytes are progressively transferred to the nucleus in the course of oogenesis and preferentially accumulated in the nuclei of some stage VI oocytes.


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