scholarly journals Transformation of NIH 3T3 cells by cotransfection with c-src and nuclear oncogenes.

1987 ◽  
Vol 7 (10) ◽  
pp. 3582-3590 ◽  
Author(s):  
D Shalloway ◽  
P J Johnson ◽  
E O Freed ◽  
D Coulter ◽  
W A Flood

pp60c-src, the cellular homolog of the Rous sarcoma virus transforming protein, does not completely transform cells even when present at high levels, but has been shown to be involved in polyomavirus-induced transformation when activated by polyomavirus middle T (pmt)-antigen binding. Here we show that cotransfection, but not solo transfection, of expression plasmids for c-src and either adenovirus E1A, v-myc, c-myc, or the 5' half of polyomavirus large T (pltN) antigen into NIH 3T3 cells induces anchorage-independent growth, enhanced focus formation, and, for pltN cotransfection, tumorigenicity in adult NFS mice. Enhancement of transformation was not observed with polyomavirus small t (pst) antigen. Cotransfection of c-src with pltN induced modification of pp60c-src that altered its electrophoretic mobility and in vivo phosphorylation state and stimulated its in vitro kinase activity. Similar alterations were not seen after c-src-E1A cotransfection, suggesting that at least two different mechanisms of enhancement are involved.

1987 ◽  
Vol 7 (10) ◽  
pp. 3582-3590
Author(s):  
D Shalloway ◽  
P J Johnson ◽  
E O Freed ◽  
D Coulter ◽  
W A Flood

pp60c-src, the cellular homolog of the Rous sarcoma virus transforming protein, does not completely transform cells even when present at high levels, but has been shown to be involved in polyomavirus-induced transformation when activated by polyomavirus middle T (pmt)-antigen binding. Here we show that cotransfection, but not solo transfection, of expression plasmids for c-src and either adenovirus E1A, v-myc, c-myc, or the 5' half of polyomavirus large T (pltN) antigen into NIH 3T3 cells induces anchorage-independent growth, enhanced focus formation, and, for pltN cotransfection, tumorigenicity in adult NFS mice. Enhancement of transformation was not observed with polyomavirus small t (pst) antigen. Cotransfection of c-src with pltN induced modification of pp60c-src that altered its electrophoretic mobility and in vivo phosphorylation state and stimulated its in vitro kinase activity. Similar alterations were not seen after c-src-E1A cotransfection, suggesting that at least two different mechanisms of enhancement are involved.


1988 ◽  
Vol 8 (2) ◽  
pp. 704-712
Author(s):  
S Reddy ◽  
P Yaciuk ◽  
T E Kmiecik ◽  
P M Coussens ◽  
D Shalloway

Previous studies have shown that carboxyl-terminal mutation of pp60c-src can activate its transforming ability. Conflicting results have been reported for the transforming ability of pp60c-src mutants having only mutations outside its carboxyl-terminal region. To clarify the effects of such mutations, we tested the activities of chimeric v(amino)- and c(carboxyl)-src (v/c-src) proteins at different dosages in NIH 3T3 cells. The focus-forming activity of Rous sarcoma virus long terminal repeat (LTR)-src expression plasmids was significantly reduced when the v-src 3' coding region was replaced with the corresponding c-src region. This difference was masked when the Rous sarcoma virus LTR was replaced with the Moloney murine leukemia virus LTR, which induced approximately 20-fold more protein expression, but even focus-selected lines expressing v/c-src proteins were unable to form large colonies in soft agarose or tumors in NFS mice. This suggests that pp60c-src is not equally sensitive to mutations in its different domains and that there are at least two distinguishable levels of regulation, the dominant one being associated with its carboxyl terminus. v/c-src chimeric proteins expressed with either LTR had high in vitro specific kinase activity equal to that of pp60v-src but, in contrast, were phosphorylated at both Tyr-527 and Tyr-416. Total cell protein phosphotyrosine was enhanced in cells incompletely transformed by v/c-src proteins to the same extent as in v-src-transformed cells, suggesting that the carboxyl-terminal region may affect substrate specificity in a manner that is important for transformation.


2019 ◽  
Vol 19 (5) ◽  
pp. 326-334
Author(s):  
Lu Huang ◽  
Marco Tjakra ◽  
Desha Luo ◽  
Lin Wen ◽  
Daoxi Lei ◽  
...  

Background: In vertebrates, cilium is crucial for Hedgehog signaling transduction. Forkhead box transcriptional factor FoxF1 is reported to be associated with Sonic Hedgehog (Shh) signaling in many cases. However, the role of FoxF1 in cilium remains unknown. Here, we showed an essential role of FoxF1 in the regulation of ciliogenesis and in the distribution of Shh signaling components in cilium. Methods: NIH/3T3 cells were serum starved for 24h to induce cilium. Meanwhile, shRNA was used to knockdown the FoxF1 expression in the cells and CRISPR/Cas9 was used to generate the FoxF1 zebrafish mutant. The mRNA and protein expression of indicated genes were detected by the qRT-PCR and western blot, respectively. Immunofluorescence staining was performed to detect the cilium and Shh components distribution. Results: FoxF1 knockdown decreased the cilium length in NIH/3T3 cells. Meanwhile, the disruption of FoxF1 function inhibited the expression of cilium-related genes and caused an abnormal distribution of Shh components in the cilium. Furthermore, homozygous FoxF1 mutants exhibited defective development of pronephric cilium in early zebrafish embryos. Conclusion: Together, our data illustrated that FoxF1 is required for ciliogenesis in vitro and in vivo and for the proper localization of Shh signaling components in cilium.


2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 18054-18054
Author(s):  
W. J. Petty ◽  
W. R. Voelzke ◽  
V. A. Memoli ◽  
K. H. Dragnev ◽  
J. J. Urbanic ◽  
...  

18054 Background: Transcriptional repression of cyclin D1 occurs during responses to erlotinib (E) both in vitro and in vivo. Cyclin D3 has overlapping function with cyclin D1 but has distinct transcriptional regulation. Methods: The expression of cyclin D3 was compared in E sensitive cell lines (H358, H441) and an E resistant cell line (A549). Cyclins D1, D2, and D3 were independently overexpressed in E sensitive NIH 3T3 cells by plasmid transfection. Biopsy tissues from a proof-of-principal clinical trial of E were assessed for cyclin D3 expression. Results: A549 cells were resistant to E and expressed high levels of cyclin D3 RNA and protein compared to E sensitive cell lines. Overexpression of cyclin D1 and cyclin D3 conferred partial resistance to E in NIH 3T3 cells while cyclin D2 had no significant effect. Comparison of cyclin D3 immunostaining in tumor biopsies from patients before and after treatment with E revealed an increase in the percentage of cyclin D3 expressing cells following treatment with E. Conclusions: Cyclin D3 confers resistance to E in vitro and in vivo. Drugs such as retinoids and rexinoids that target cyclin D3 expression may prove useful for enhancing sensitivity to E. No significant financial relationships to disclose.


2007 ◽  
Vol 27 (13) ◽  
pp. 4980-4990 ◽  
Author(s):  
Masahiro Morita ◽  
Toru Suzuki ◽  
Takahisa Nakamura ◽  
Kazumasa Yokoyama ◽  
Takashi Miyasaka ◽  
...  

ABSTRACT The stability of mRNA influences the abundance of cellular transcripts and proteins. Deadenylases play critical roles in mRNA turnover and thus are important for the regulation of various biological events. Here, we report the identification and characterization of CCR4b/CNOT6L, which is homologous to yeast CCR4 mRNA deadenylase. CCR4b is localized mainly in the cytoplasm and displays deadenylase activity both in vitro and in vivo. CCR4b forms a multisubunit complex similar to the yeast CCR4-NOT complex. Suppression of CCR4b by RNA interference results in growth retardation of NIH 3T3 cells accompanied by elevation of both p27 Kip1 mRNA and p27Kip1 protein. Reintroduction of wild-type CCR4b, but not mutant CCR4b lacking deadenylase activity, restores the growth of CCR4b-depleted NIH 3T3 cells. The data suggest that CCR4b regulates cell growth in a manner dependent on its deadenylase activity. We also show that p27 Kip1 mRNA is stabilized and its poly(A) tail is preserved in CCR4b-depleted cells. Our findings provide evidence that CCR4b deadenylase is a constituent of the mammalian CCR4-NOT complex and regulates the turnover rate of specific target mRNAs. Thus, CCR4b may be involved in various cellular events that include cell proliferation.


1988 ◽  
Vol 8 (2) ◽  
pp. 704-712 ◽  
Author(s):  
S Reddy ◽  
P Yaciuk ◽  
T E Kmiecik ◽  
P M Coussens ◽  
D Shalloway

Previous studies have shown that carboxyl-terminal mutation of pp60c-src can activate its transforming ability. Conflicting results have been reported for the transforming ability of pp60c-src mutants having only mutations outside its carboxyl-terminal region. To clarify the effects of such mutations, we tested the activities of chimeric v(amino)- and c(carboxyl)-src (v/c-src) proteins at different dosages in NIH 3T3 cells. The focus-forming activity of Rous sarcoma virus long terminal repeat (LTR)-src expression plasmids was significantly reduced when the v-src 3' coding region was replaced with the corresponding c-src region. This difference was masked when the Rous sarcoma virus LTR was replaced with the Moloney murine leukemia virus LTR, which induced approximately 20-fold more protein expression, but even focus-selected lines expressing v/c-src proteins were unable to form large colonies in soft agarose or tumors in NFS mice. This suggests that pp60c-src is not equally sensitive to mutations in its different domains and that there are at least two distinguishable levels of regulation, the dominant one being associated with its carboxyl terminus. v/c-src chimeric proteins expressed with either LTR had high in vitro specific kinase activity equal to that of pp60v-src but, in contrast, were phosphorylated at both Tyr-527 and Tyr-416. Total cell protein phosphotyrosine was enhanced in cells incompletely transformed by v/c-src proteins to the same extent as in v-src-transformed cells, suggesting that the carboxyl-terminal region may affect substrate specificity in a manner that is important for transformation.


1987 ◽  
Vol 7 (6) ◽  
pp. 2196-2200 ◽  
Author(s):  
D Samid ◽  
D M Flessate ◽  
R M Friedman

Prolonged alpha/beta interferon (IFN-alpha/beta) treatment of NIH 3T3 cells transformed by a long terminal repeat-activated Ha-ras proto-oncogene resulted in revertants that maintained a nontransformed phenotype long after IFN treatment had been discontinued. Cloned persistent revertants (PRs) produced large amounts of the ras-encoded p21 and were refractile to transformation by EJras DNA and by transforming retroviruses which carried the v-Ha-ras, v-Ki-ras, v-abl, or v-fes oncogene. Transient treatment either in vitro or in vivo with cytidine analogs that alter gene expression by inhibiting DNA methylation resulted in transformation of PR, but not of NIH 3T3, cells. The PR retransformants reverted again with IFN, suggesting that DNA methylation is involved in IFN-induced persistent reversion.


2001 ◽  
Vol 10 (2) ◽  
pp. 209-221 ◽  
Author(s):  
Roberto Del Bo ◽  
Yvan Torrente ◽  
Stefania Corti ◽  
Maria Grazia D'angelo ◽  
Giacomo Pietro Comi ◽  
...  

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