scholarly journals Coupled Reaction Networks for Noise Suppression

2018 ◽  
Author(s):  
Fangzhou Xiao ◽  
Meichen Fang ◽  
Jiawei Yan ◽  
John C. Doyle

AbstractNoise is intrinsic to many important regulatory processes in living cells, and often forms obstacles to be overcome for reliable biological functions. However, due to stochastic birth and death events of all components in biomolecular systems, suppression of noise of one component by another is fundamentally hard and costly. Quantitatively, a widelycited severe lower bound on noise suppression in biomolecular systems was established by Lestas et. al. in 2010, assuming that the plant and the controller have separate birth and death reactions. This makes the precision observed in several biological phenomena, e.g., cell fate decision making and cell cycle time ordering, seem impossible. We demonstrate that coupling, a mechanism widely observed in biology, could suppress noise lower than the bound of Lestas et. al. with moderate energy cost. Furthermore, we systematically investigate the coupling mechanism in all two-node reaction networks, showing that negative feedback suppresses noise better than incoherent feedforward achitectures, coupled systems have less noise than their decoupled version for a large class of networks, and coupling has its own fundamental limitations in noise suppression. Results in this work have implications for noise suppression in biological control and provide insight for a new efficient mechanism of noise suppression in biology.

2019 ◽  
Author(s):  
Madeline Smith ◽  
Khem Raj Ghusinga ◽  
Abhyudai Singh

AbstractStochastic variation in the level of a protein among cells of the same population is ubiquitous across cell types and organisms. These random variations are a consequence of low-copy numbers, amplified by the characteristically probabilistic nature of biochemical reactions associated with gene-expression. We systematically compare and contrast negative feedback architectures in their ability to regulate random fluctuations in protein levels. Our stochastic model consists of gene synthesizing pre-mRNAs in transcriptional bursts. Each pre-mRNA transcript is exported to the cytoplasm and is subsequently translated into protein molecules. In this setup, three feedbacks architectures are implemented: protein inhibiting transcription of its own gene (I), protein enhancing the nuclear pre-mRNA decay rate (II), and protein inhibiting the export of pre-mRNAs (III). Explicit analytic expressions are developed to quantify the protein noise levels for each feedback strategy. Mathematically controlled comparisons provide insights into the noise-suppression properties of these feedbacks. For example, when the protein half-life is long, or the pre-mRNA decay is fast, then feedback architecture I provides the best noise attenuation. In contrast, when the timescales of export, mRNA, and protein turnover are similar, then III is superior to both II and I. We finally discuss biological relevance of these findings in context of noise suppression in an HIV cell-fate decision circuit.


Genetics ◽  
1999 ◽  
Vol 153 (4) ◽  
pp. 1641-1654 ◽  
Author(s):  
Hanna Fares ◽  
Iva Greenwald

Abstract Ligands present on neighboring cells activate receptors of the LIN-12/Notch family by inducing a proteolytic cleavage event that releases the intracellular domain. Mutations that appear to eliminate sel-5 activity are able to suppress constitutive activity of lin-12(d) mutations that are point mutations in the extracellular domain of LIN-12, but cannot suppress lin-12(intra), the untethered intracellular domain. These results suggest that sel-5 acts prior to or during ligand-dependent release of the intracellular domain. In addition, sel-5 suppression of lin-12(d) mutations is tissue specific: loss of sel-5 activity can suppress defects in the anchor cell/ventral uterine precursor cell fate decision and a sex myoblast/coelomocyte decision, but cannot suppress defects in two different ventral hypodermal cell fate decisions in hermaphrodites and males. sel-5 encodes at least two proteins, from alternatively spliced mRNAs, that share an amino-terminal region and differ in the carboxy-terminal region. The amino-terminal region contains the hallmarks of a serine/threonine kinase domain, which is most similar to mammalian GAK1 and yeast Pak1p.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tim Liebisch ◽  
Armin Drusko ◽  
Biena Mathew ◽  
Ernst H. K. Stelzer ◽  
Sabine C. Fischer ◽  
...  

AbstractDuring the mammalian preimplantation phase, cells undergo two subsequent cell fate decisions. During the first decision, the trophectoderm and the inner cell mass are formed. Subsequently, the inner cell mass segregates into the epiblast and the primitive endoderm. Inner cell mass organoids represent an experimental model system, mimicking the second cell fate decision. It has been shown that cells of the same fate tend to cluster stronger than expected for random cell fate decisions. Three major processes are hypothesised to contribute to the cell fate arrangements: (1) chemical signalling; (2) cell sorting; and (3) cell proliferation. In order to quantify the influence of cell proliferation on the observed cell lineage type clustering, we developed an agent-based model accounting for mechanical cell–cell interaction, i.e. adhesion and repulsion, cell division, stochastic cell fate decision and cell fate heredity. The model supports the hypothesis that initial cell fate acquisition is a stochastically driven process, taking place in the early development of inner cell mass organoids. Further, we show that the observed neighbourhood structures can emerge solely due to cell fate heredity during cell division.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Xudong Zhu ◽  
Zhiyang Chen ◽  
Weiyan Shen ◽  
Gang Huang ◽  
John M. Sedivy ◽  
...  

AbstractRemarkable progress in ageing research has been achieved over the past decades. General perceptions and experimental evidence pinpoint that the decline of physical function often initiates by cell senescence and organ ageing. Epigenetic dynamics and immunometabolic reprogramming link to the alterations of cellular response to intrinsic and extrinsic stimuli, representing current hotspots as they not only (re-)shape the individual cell identity, but also involve in cell fate decision. This review focuses on the present findings and emerging concepts in epigenetic, inflammatory, and metabolic regulations and the consequences of the ageing process. Potential therapeutic interventions targeting cell senescence and regulatory mechanisms, using state-of-the-art techniques are also discussed.


1996 ◽  
Vol 25 ◽  
pp. S2
Author(s):  
Hideyuki Okano ◽  
Kazunobu Sawamoto ◽  
Masataka Okabe ◽  
Takao Imai ◽  
Shin-Ichi Sakakibara ◽  
...  

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