日時：	2025年8月14日（木）13：30～15：00
場所：	医生物学研究所 医生研３号館５階５０１室 Room 501, 5th floor, Bldg. #3 Institute for Life and Medical Sciences, Kyoto University
演者：	Je-Chiang Tsai Department of Mathematics, National Tsing Hua University, Taiwan
演題：	Noise-Induced Bimodality in Self-Regulated Gene Networks with Nonlinear Promoter Transitions and Fast Dimerization

講演要旨

We investigate noise-induced bimodal distributions in self-regulated gene
networks with fast dimerization, where dimerized proteins enhance gene
expression. Despite their fundamental role in gene regulation, the analytical
study of bimodal behavior in these networks is particularly challenging due
to the nonlinear features introduced by dimerization. To address this, we
reformulate the system as a self-regulated gene expression model that
approximates fast dimerization, where the transition rate from the promoteroff
to the promoter-on state depends nonlinearly on protein levels. We
introduce two key quantities: the promoter activity ratio, which quantifies
gene activation at a given protein level, and the mode detection ratio, which
identifies peaks in the probability distribution. Their governing recurrence
relations reveal how promoter activity modulates the steady-state
distribution, elucidating how stochastic effects drive multimodal protein
distributions in self-regulated gene expression. Our approach provides a
general framework for understanding noise-induced bimodality in gene
networks with nonlinear interactions without relying on exact probability
distributions, which are typically infeasible for nonlinear reaction rates,
particularly in our case. (Language: English)

Seminar20250814

contact: Atsushi Mochizuki
Laboratory of Mathematical Biology,
Institute for Life and Medical Sciences, Kyoto University
Email: mochi[@]infront.kyoto-u.ac.jp（＠）
Tel: 075-751-4612