Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction.
Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction
Mariano Beguerisse-Díaz,R. Desikan,Mauricio Barahona
Published 2011 in Journal of the Royal Society Interface
ABSTRACT
PUBLICATION RECORD
- Publication year
2011
- Venue
Journal of the Royal Society Interface
- Publication date
2011-12-01
- Fields of study
Biology, Mathematics, Physics, Medicine
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- activation cascades
Sequential chains of protein activation triggered after an input signal is received.
Aliases: cascade, signaling cascade
- coarse-graining
The reduction of a detailed cascade into aggregated blocks or modules.
Aliases: lumping
- delay differential equations
Differential equations that include delayed terms used to model time-lagged dynamics.
Aliases: DDEs
- incomplete gamma function
A special mathematical function appearing in the closed-form cascade representation.
Aliases: gamma function with incomplete integral
- nonlinear module
A lumped analytical module used to represent the output of a cascade with fewer equations and parameters.
Aliases: lumped nonlinear module
- optimal gain cascades
A subclass of activation cascades in which the deactivation rates are identical.
Aliases: identical deactivation-rate cascades
- random deactivation rates
Deactivation rates treated as random variables to describe variability across cascades.
Aliases: random off-rates
REFERENCES
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