Important role of MAMs in bifurcation and coherence resonance of calcium oscillations

MAM (mitochondria-associated endoplasmic reticulum membrane complex) is kind of complexes formed between the endoplasmic reticulum (ER) and mitochondria, and it plays an important role in calcium signal transduction of cell. Coherence resonance is cooperative effect of noise and nonlinear system. In the field of life science, coherence resonance reflects the rhythm of life, so studying it by using the theory and method of nonlinear stochastic dynamics has very important biological significance. On the basis of the calcium oscillation model considering the role of MAMs proposed by Szopa et al., and taking two important indexes - the maximal permeability of the Ca2+ channels in the ER membrane (k(ch)) and the maximal permeability of MCU (mitochondrial calcium uniporter) at MAMs (k(MAM)) as the analysis parameters, this paper further studies the bifurcation characteristic of the system, including two-parameter bifurcation and one-parameter bifurcation, and theoretically expounds the reasons for the generation and disappearance of calcium oscillations. Then, on the basis of bifurcation analysis, we focus on the coherence resonance characteristic of calcium signals and its physiological significance when analysis parameters are affected by environmental noise. (c) 2017 Elsevier Ltd. All rights reserved.