scholarly journals Simian virus 40 and polyoma virus induce synthesis of heat shock proteins in permissive cells.

1983 ◽  
Vol 3 (1) ◽  
pp. 1-8 ◽  
Author(s):  
E W Khandjian ◽  
H Türler

During the lytic infection of monkey and mouse cells with simian virus 40 and polyoma virus, respectively, the preferentially increased synthesis of two host proteins of 92,000 and 72,000 Mr was observed by 15 to 20 h after infection besides the general stimulation of most cellular proteins. The incubation of uninfected monkey and mouse cell cultures for 30 to 60 min at 43.5 degrees C induced the enhanced synthesis of at least three proteins of 92,000, 72,000 and 70,000 Mr, the last one being the major heat shock protein of mammalian cells. Two-dimensional gel electrophoresis and partial proteolytic digestion confirmed that the same 92,000- and 72,000-Mr proteins are stimulated by virus infection and thermal treatment. In simian virus 40-infected CV-1 cells, we also observed the weak stimulation of a 70,000-Mr protein comigrating in gel electrophoresis with the major heat shock protein. The 92,000-, 72,000- and 70,000-Mr proteins of monkey cells are structurally very similar to the corresponding proteins of mouse cells. In immunoprecipitations, no specific association of these proteins to simian virus 40 T antigens was noticed.

1983 ◽  
Vol 3 (1) ◽  
pp. 1-8
Author(s):  
E W Khandjian ◽  
H Türler

During the lytic infection of monkey and mouse cells with simian virus 40 and polyoma virus, respectively, the preferentially increased synthesis of two host proteins of 92,000 and 72,000 Mr was observed by 15 to 20 h after infection besides the general stimulation of most cellular proteins. The incubation of uninfected monkey and mouse cell cultures for 30 to 60 min at 43.5 degrees C induced the enhanced synthesis of at least three proteins of 92,000, 72,000 and 70,000 Mr, the last one being the major heat shock protein of mammalian cells. Two-dimensional gel electrophoresis and partial proteolytic digestion confirmed that the same 92,000- and 72,000-Mr proteins are stimulated by virus infection and thermal treatment. In simian virus 40-infected CV-1 cells, we also observed the weak stimulation of a 70,000-Mr protein comigrating in gel electrophoresis with the major heat shock protein. The 92,000-, 72,000- and 70,000-Mr proteins of monkey cells are structurally very similar to the corresponding proteins of mouse cells. In immunoprecipitations, no specific association of these proteins to simian virus 40 T antigens was noticed.


1989 ◽  
Vol 264 (27) ◽  
pp. 16160-16164
Author(s):  
I C Taylor ◽  
W Solomon ◽  
B M Weiner ◽  
E Paucha ◽  
M Bradley ◽  
...  

1996 ◽  
Vol 16 (9) ◽  
pp. 4691-4699 ◽  
Author(s):  
C F Chen ◽  
Y Chen ◽  
K Dai ◽  
P L Chen ◽  
D J Riley ◽  
...  

A gene encoding a new heat shock protein that may function as a molecular chaperone for the retinoblastoma protein (Rb) was characterized. The cDNA fragment was isolated by using the yeast two-hybrid system and Rb as bait. The open reading frame of the longest cDNA codes for a protein with substantial sequence homology to members of the hsp90 family. Antibodies prepared against fusions between glutathione S-transferase and portions of this new heat shock protein specifically recognized a 75-kDa cellular protein, hereafter designated hsp75, which is expressed ubiquitously and located in the cytoplasm. A unique LxCxE motif in hsp75, but not in other hsp90 family members, appears to be important for binding to the simian virus 40 T-antigen-binding domain of hypophosphorylated Rb, since a single mutation changing the cysteine to methionine abolishes the binding. In mammalian cells, Rb formed complexes with hsp75 under two special physiological conditions: (i) during M phase, when the envelope that separates the nuclear and cytoplasmic compartments broke down, and (ii) after heat shock, when hsp75 moved from its normal cytoplasmic location into the nucleus. In vitro, hsp75 had a biochemical activity to refold denatured Rb into its native conformation. Taken together, these results suggest that Rb may be a physiological substrate for the hsp75 chaperone molecule. The discovery of a heat shock protein that chaperones Rb identifies a mechanism, in addition to phosphorylation, by which Rb is regulated in response to progression of the cell cycle and to external stimuli.


1994 ◽  
Vol 14 (8) ◽  
pp. 5088-5098
Author(s):  
J Yang ◽  
D B DeFranco

Nuclear import of glucocorticoid receptors (GRs) was analyzed in vitro with digitonin-permeabilized cells (S. A. Adam, R. Sterne-Marr, and L. Gerace, J. Cell Biol. 111:807-816, 1990). Indirect immunofluorescence methods were used to monitor the transport of GRs from rat hepatoma and fibroblast cell cytosol into HeLa nuclei. In vitro nuclear import of GRs was shown to be hormone dependent and to require ATP and incubation at ambient temperatures (i.e., 30 degrees C). Hormone-dependent dissociation of GR-bound proteins, such as the 90-kDa heat shock protein, hsp90, is part of an activation process that is obligatory for the expression of the receptor's DNA-binding activity. Inhibition of in vitro GR activation by Na2MoO4 blocked hormone-dependent nuclear import, demonstrating that receptor activation is required for nuclear import. The addition to GR-containing cytosol of antiserum directed against the cytosolic 70-kDa heat shock protein, hsp70, while effective in blocking the nuclear import of simian virus 40 large tumor antigen (SV40 TAg), did not affect hormone-dependent nuclear import of endogenous, full-length GRs or an exogenously added truncated GR protein (i.e., XGR556) that lacks a hormone-binding domain but possesses a constitutively active nuclear localization signal sequence (NLS). Depletion of hsp70 from HeLa cell cytosol did not affect the nuclear import of exogenously added XGR556 but led to inhibition of SV40 TAg nuclear import. Thus, two closely related NLSs, one contained within GRs and the other contained within SV40 TAg, are distinguished by their differential requirements for hsp70 in vitro.


1993 ◽  
Vol 104 (3) ◽  
pp. 629-638 ◽  
Author(s):  
H. Hattori ◽  
T. Kaneda ◽  
B. Lokeshwar ◽  
A. Laszlo ◽  
K. Ohtsuka

We have previously reported that a novel 40 kDa protein is induced by heat shock and several environmental stresses in mammalian and avian cells and that the N-terminal amino acid sequence of this 40 kDa protein has homology with the bacterial DnaJ heat-shock protein. We have purified this protein (40 kDa heat-shock protein, hsp40) from HeLa cells by modified two-dimensional gel electrophoresis and generated a polyclonal antibody against hsp40. This antibody was highly specific for human hsp40 and cross-reacted weakly with rat and Chinese hamster hsp40. Indirect immunofluorescence revealed that the hsp40 in HeLa cells accumulates in the nucleus, especially in the nucleolus, during heat shock and returns to the cytoplasm during the recovery period. The kinetics of the accumulation in the nucleoli and subsequent return to the cytoplasm of hsp40 was similar to that of hsp70. In addition, hsp40 was co-localized with hsc70(p73) in heat-shocked HeLa cells as demonstrated by double immunofluorescence staining. These results suggest that hsp40 (a DnaJ homologue) and hsp70 (a DnaK homologue) may act in concert to repair (refold) denatured proteins and protein aggregates in the nuclei and nucleoli of heat-shocked HeLa cells.


1995 ◽  
Vol 23 (03n04) ◽  
pp. 327-330 ◽  
Author(s):  
Kazuko Kobayashi

Rats were treated by moxibustion at the point of hip muscle, and intramuscular temperature was kept at 40°C for 15 minutes. The rats were sacrificed under deep anesthesia and the muscular tissues were excised immediately, three hours and 24 hours after stimulation. Proteins were extracted from the homogenized and centrifuged tissues of the stimulated rats and control rats. Two-dimensional gel electrophoresis of the proteins was carried out. Heat-shock protein (hsp) with molecular weight of 70,000 (hsp 70), 85,000 (hsp 85) and 100,000 (hsp 100) was detected in rats sacrificed three hours after the stimulation by moxibustion. Protein patterns were analyzed and the ratios of the hsps were obtained.


1995 ◽  
Vol 15 (5) ◽  
pp. 2482-2489 ◽  
Author(s):  
Y Yoon ◽  
J A Sanchez ◽  
C Brun ◽  
J A Huberman

New techniques for mapping mammalian DNA replication origins are needed. We have modified the existing nascent-strand size analysis technique (L. Vassilev and E.M. Johnson, Nucleic Acids Res. 17:7693-7705, 1989) to provide an independent means of studying replication initiation sites. We call the new method nascent-strand abundance analysis. We confirmed the validity of this method with replicating simian virus 40 DNA as a model. We then applied nascent-strand abundance and nascent-strand size analyses to mapping of initiation sites in human (HeLa) ribosomal DNA (rDNA), a region previously examined exclusively by two-dimensional gel electrophoresis methods (R.D. Little, T.H.K. Platt, and C.L. Schildkraut, Mol. Cell. Biol. 13:6600-6613, 1993). Our results partly confirm those obtained by two-dimensional gel electrophoresis techniques. Both studies suggest that replication initiates at relatively high frequency a few kilobase pairs upstream of the transcribed region and that many additional low-frequency initiation sites are distributed through most of the remainder of the ribosomal DNA repeat unit.


1994 ◽  
Vol 14 (8) ◽  
pp. 5088-5098 ◽  
Author(s):  
J Yang ◽  
D B DeFranco

Nuclear import of glucocorticoid receptors (GRs) was analyzed in vitro with digitonin-permeabilized cells (S. A. Adam, R. Sterne-Marr, and L. Gerace, J. Cell Biol. 111:807-816, 1990). Indirect immunofluorescence methods were used to monitor the transport of GRs from rat hepatoma and fibroblast cell cytosol into HeLa nuclei. In vitro nuclear import of GRs was shown to be hormone dependent and to require ATP and incubation at ambient temperatures (i.e., 30 degrees C). Hormone-dependent dissociation of GR-bound proteins, such as the 90-kDa heat shock protein, hsp90, is part of an activation process that is obligatory for the expression of the receptor's DNA-binding activity. Inhibition of in vitro GR activation by Na2MoO4 blocked hormone-dependent nuclear import, demonstrating that receptor activation is required for nuclear import. The addition to GR-containing cytosol of antiserum directed against the cytosolic 70-kDa heat shock protein, hsp70, while effective in blocking the nuclear import of simian virus 40 large tumor antigen (SV40 TAg), did not affect hormone-dependent nuclear import of endogenous, full-length GRs or an exogenously added truncated GR protein (i.e., XGR556) that lacks a hormone-binding domain but possesses a constitutively active nuclear localization signal sequence (NLS). Depletion of hsp70 from HeLa cell cytosol did not affect the nuclear import of exogenously added XGR556 but led to inhibition of SV40 TAg nuclear import. Thus, two closely related NLSs, one contained within GRs and the other contained within SV40 TAg, are distinguished by their differential requirements for hsp70 in vitro.


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