A wave pinning model for spread of chromosomal inactivation

X chromosome inactivation (XCI) is a crucial process essential for achieving dosage compensation of X-linked genes in females. During XCI, most genes in the X chromosome are inactivated in a progressive manner following the transcription of the X-linked long noncoding RNA XIST. Recent experiments with transgenes showed that the spread of chromosomal inactivation can be restricted in autosomes even in the presence of XIST synthesis in cis, but the mechanism of controlling the spread remains unclear. In this work, we formulated a wave pinning model that elucidates chromosomal inactivation through a bistable reaction-diffusion system. In addition, we have developed an approach for integrating the discrete three-dimensional spatial arrangement of the X chromosome and autosomes into a continuous reaction-diffusion model. This method enables the investigation of spatiotemporal dynamics pertaining to the inactivation of the X chromosome and autosomes with varying degrees for spread of inactivation.