Temporal feedback

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Within

platelet activation, and Xenopus oocyte maturation are examples for interlinked fast and slow multiple positive feedback systems.[1]

In biological systems, temporal feedback is a ubiquitous signal transduction motif that allows systems to convert graded inputs into decisive, all-or-none digital outputs. A system with interlinked fast and slow feedback loops produces a dual-time switch, which is rapidly inducible and robust to noise during stimulus. In contrast, a single fast or slow loop is separately responsible for the speed of switching and the stability of switches. Computer simulation studies have shown that linking two loops of the same kind brings no overall advantage over having a single loop, however the dual-loop switch performs in a monostable regime. Both single and dual loops can behave as a bistable switch.[1] Several computational models have been produced to demonstrate the responses of single and dual positive feedback loop switches to stimuli.[2][3]

Biological examples

The transcription factor

isoforms, I-κBα, -β, - ε has been computationally modeled. The model suggested that I-κBα results in robust negative feedback that leads to a fast turn off of NF-κB response. On the other hand, the oscillatory potential and stabilization of NF-κB during long stimulations has been shown to be reduced by I-κBβ and –ε.[4]

The outgrowth and progression is of limb

BMP4. The Shh signalling is activated independently of GREM1 and AER-FGFs. Propagation phase involves the control of distal progression during limb bud development. Finally termination of signalling system due to the widening gap between ZPA-SHH signalling and the Grem1 expression domain.[5] In mouse limb patterning, limb development is regulated by linking a fast GREM1 module to the slower SSH/FGF epithelial-mesenchymal feedback loop.[6]

Rev-Erb, the protein product of which, REV-ERB, represses transcription of Bmal. The repression of BMAL in vivo prevents the transactivation of Per-Cry, thereby completing the cycle in just over 24 hours.[7]

References

  1. ^
    PMID 16239477
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  2. PMID 17930288
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  3. PMID 19391966
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  4. S2CID 11834415
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  5. ^
    S2CID 31202624
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  6. S2CID 25309127
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  7. ^ Petrillo, Ezequiel; Sabrina E. Sanchez; Alberto R. Kornblihtt; Marcelo J. Yanovsky (2011). "Alternative Splicing Adds a New Loop to the Circadian Clock" (PDF). Communicative & Integrative Biology. 4:2.
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