scholarly journals Systems-Level Dissection of the Cell-Cycle Oscillator: Bypassing Positive Feedback Produces Damped Oscillations

Cell ◽  
2005 ◽  
Vol 122 (4) ◽  
pp. 565-578 ◽  
Author(s):  
Joseph R. Pomerening ◽  
Sun Young Kim ◽  
James E. Ferrell
Science ◽  
2013 ◽  
Vol 341 (6146) ◽  
pp. 670-673 ◽  
Author(s):  
Hao Yuan Kueh ◽  
Ameya Champhekar ◽  
Stephen L. Nutt ◽  
Michael B. Elowitz ◽  
Ellen V. Rothenberg

Regulatory gene circuits with positive-feedback loops control stem cell differentiation, but several mechanisms can contribute to positive feedback. Here, we dissect feedback mechanisms through which the transcription factor PU.1 controls lymphoid and myeloid differentiation. Quantitative live-cell imaging revealed that developing B cells decrease PU.1 levels by reducing PU.1 transcription, whereas developing macrophages increase PU.1 levels by lengthening their cell cycles, which causes stable PU.1 accumulation. Exogenous PU.1 expression in progenitors increases endogenous PU.1 levels by inducing cell cycle lengthening, implying positive feedback between a regulatory factor and the cell cycle. Mathematical modeling showed that this cell cycle–coupled feedback architecture effectively stabilizes a slow-dividing differentiated state. These results show that cell cycle duration functions as an integral part of a positive autoregulatory circuit to control cell fate.


Author(s):  
Jiewei Lin ◽  
Shuyu Zhai ◽  
Siyi Zou ◽  
Zhiwei Xu ◽  
Jun Zhang ◽  
...  

Abstract Background FLVCR1-AS1 is a key regulator of cancer progression. However, the biological functions and underlying molecular mechanisms of pancreatic cancer (PC) remain unknown. Methods FLVCR1-AS1 expression levels in 77 PC tissues and matched non-tumor tissues were analyzed by qRT-PCR. Moreover, the role of FLVCR1-AS1 in PC cell proliferation, cell cycle, and migration was verified via functional in vitro and in vivo experiments. Further, the potential competitive endogenous RNA (ceRNA) network between FLVCR1-AS1 and KLF10, as well as FLVCR1-AS1 transcription levels, were investigated. Results FLVCR1-AS1 expression was low in both PC tissues and PC cell lines, and FLVCR1-AS1 downregulation was associated with a worse prognosis in patients with PC. Functional experiments demonstrated that FLVCR1-AS1 overexpression significantly suppressed PC cell proliferation, cell cycle, and migration both in vitro and in vivo. Mechanistic investigations revealed that FLVCR1-AS1 acts as a ceRNA to sequester miR-513c-5p or miR-514b-5p from the sponging KLF10 mRNA, thereby relieving their suppressive effects on KLF10 expression. Additionally, FLVCR1-AS1 was shown to be a direct transcriptional target of KLF10. Conclusions Our research suggests that FLVCR1-AS1 plays a tumor-suppressive role in PC by inhibiting proliferation, cell cycle, and migration through a positive feedback loop with KLF10, thereby providing a novel therapeutic strategy for PC treatment.


Nature ◽  
2008 ◽  
Vol 454 (7202) ◽  
pp. 291-296 ◽  
Author(s):  
Jan M. Skotheim ◽  
Stefano Di Talia ◽  
Eric D. Siggia ◽  
Frederick R. Cross

2008 ◽  
Vol 31 (3) ◽  
pp. 307-308
Author(s):  
Lucas B. Carey ◽  
Janet K. Leatherwood ◽  
Bruce Futcher

1994 ◽  
Vol 14 (7) ◽  
pp. 4779-4787
Author(s):  
F R Cross ◽  
M Hoek ◽  
J D McKinney ◽  
A H Tinkelenberg

Expression of the Saccharomyces cerevisiae CLN1 and CLN2 genes is cell cycle regulated, and the genes may be controlled by positive feedback. It has been proposed that positive feedback operates via Cln/Cdc28 activation of the Swi4/Swi6 transcription factor, leading to CLN1 and CLN2 transcription due to Swi4 binding to specific sites (SCBs) in the CLN1 and CLN2 promoters. To test this proposal, we have examined the effects of deletion either of the potential SCBs in the CLN2 promoter or of the SWI4 gene on CLN2 transcriptional control. Deletion of a restriction fragment containing the identified SCBs from the promoter does not prevent cell cycle regulation of CLN2 expression, although expression is lowered at all cell cycle positions. A promoter containing a 5.5-kb plasmid insertion or an independent 2.5-kb insertion at the point of deletion of the SCB-containing restriction fragment also exhibits cell cycle regulation, so involvement of unidentified upstream SCBs is unlikely. Neither Swi4 nor the related Mbp1 transcription factor is required for cell cycle regulation of the intact CLN2 promoter. In contrast, Swi4 (but not Mbp1) is required for correct cell cycle regulation of the insertion/deletion promoter lacking SCB sites. We have extended previous genetic evidence for involvement of Swi4 in some aspect of CLN2 function: a mutant hunt for CLN2 positive regulatory factors yielded only swi4 mutations at saturation. Swi4 may bind to nonconsensus sequences in the CLN2 promoter (possibly in addition to consensus sites), or it may act indirectly to regulate CLN2 expression.


1994 ◽  
Vol 14 (7) ◽  
pp. 4779-4787 ◽  
Author(s):  
F R Cross ◽  
M Hoek ◽  
J D McKinney ◽  
A H Tinkelenberg

Expression of the Saccharomyces cerevisiae CLN1 and CLN2 genes is cell cycle regulated, and the genes may be controlled by positive feedback. It has been proposed that positive feedback operates via Cln/Cdc28 activation of the Swi4/Swi6 transcription factor, leading to CLN1 and CLN2 transcription due to Swi4 binding to specific sites (SCBs) in the CLN1 and CLN2 promoters. To test this proposal, we have examined the effects of deletion either of the potential SCBs in the CLN2 promoter or of the SWI4 gene on CLN2 transcriptional control. Deletion of a restriction fragment containing the identified SCBs from the promoter does not prevent cell cycle regulation of CLN2 expression, although expression is lowered at all cell cycle positions. A promoter containing a 5.5-kb plasmid insertion or an independent 2.5-kb insertion at the point of deletion of the SCB-containing restriction fragment also exhibits cell cycle regulation, so involvement of unidentified upstream SCBs is unlikely. Neither Swi4 nor the related Mbp1 transcription factor is required for cell cycle regulation of the intact CLN2 promoter. In contrast, Swi4 (but not Mbp1) is required for correct cell cycle regulation of the insertion/deletion promoter lacking SCB sites. We have extended previous genetic evidence for involvement of Swi4 in some aspect of CLN2 function: a mutant hunt for CLN2 positive regulatory factors yielded only swi4 mutations at saturation. Swi4 may bind to nonconsensus sequences in the CLN2 promoter (possibly in addition to consensus sites), or it may act indirectly to regulate CLN2 expression.


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