Homeostatic controllers: robustness, temperature behaviors and oscillatory responses

16 October 2009

Peter Ruoff
Centre for Organelle Research
University of Stavanger, Norway, and
Dartmouth Medical School, Hanover, NH

Abstract

In this talk I will present approaches how to describe homeostatic mechanisms, discussing the concept of robustness, how the concept of 'integral feedback/integral control' can be reflected by kinetic conditions and how oscillations can arise in certain 'robust' homeostatic controllers. Starting point will be a brief description of the balancing approach [1-3] to describe temperature homeostasis of the period or fluxes for oscillatory or nonoscillatory networks, respectively. Then I will turn to robust perfect adaptation, how robust perfect adaptation sites may be identified [4], how integral control/integral feedback can be related to zero-order fluxes, state the need for robust inflow or outflow homeostatic control mechanisms, and how robust homeostatic controllers lead to 'almost robust' temperature compensation [5]. Under certain conditions harmonic oscillations are observed in an inflow homeostatic controller, and the suggestion is made that p53 oscillations may be the result of a homeostatic control mechanism becoming operative when p53 is upregulated.

References

1. P Ruoff, "Introducing temperature-compensation in any reaction kinetic oscillator model", J Interdiscipl Cycle Res 23:92-9 1992. PDF
2. P Ruoff, J J Loros, J C Dunlap, "The relationship between FRQ-protein stability and temperature compensation in the Neurospora circadian clock", PNAS 102:17681-6 2005. PubMed
3. P Ruoff, M Zakhartsev, H V Westerhoff, "Temperature compensation through systems biology", FEBS J, 274:940-50 2007. PubMed
4. T Drengstig, H R Ueda, P Ruoff, "Predicting perfect adaptation motifs in reaction kinetic networks", J Phys Chem B 112:16752-8 2008. PubMed
5. X Y Ni, T Drengstig, P Ruoff, "The control of the controller: molecular mechanisms for robust perfect adaptation and temperature compensation", Biophys J 97:1244-53 2009. PubMed
6. I W Jolma, X Y Ni, L Rensing, P Ruoff, "Harmonic oscillations in homeostatic controllers: dynamics of the p53 regulatory system", Biophys J, submitted, 2009.