High-throughput measurement of fibroblast rhythms reveals genetic heritability of circadian phenotypes in diversity outbred mice and their founder strains

Sam-Moon Kim,Ryan W Logan,Vivek M Philip,Chelsea A Vadnie,Kodavali V Chowdari,Elissa J Chesler,Colleen A Mcclung,Leona H Gagnon

doi:10.1038/s41598-021-82069-8

Sam-Moon Kim, Ryan W Logan + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-82069-8

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Abstract

Circadian variability is driven by genetics and Diversity Outbred (DO) mice is a powerful tool for examining the genetics of complex traits because their high genetic and phenotypic diversity compared to conventional mouse crosses. The DO population combines the genetic diversity of eight founder strains including five common inbred and three wild-derived strains. In DO mice and their founders, we established a high-throughput system to measure cellular rhythms using in vitro preparations of skin fibroblasts. Among the founders, we observed strong heritability for rhythm period, robustness, phase and amplitude. We also found significant sex and strain differences for these rhythms. Extreme differences in period for molecular and behavioral rhythms were found between the inbred A/J strain and the wild-derived CAST/EiJ strain, where A/J had the longest period and CAST/EiJ had the shortest. In addition, we measured cellular rhythms in 329 DO mice, which displayed far greater phenotypic variability than the founders—80% of founders compared to only 25% of DO mice had periods of ~ 24 h. Collectively, our findings demonstrate that genetic diversity contributes to phenotypic variability in circadian rhythms, and high-throughput characterization of fibroblast rhythms in DO mice is a tractable system for examining the genetics of circadian traits.

Highlights

Circadian variability is driven by genetics and Diversity Outbred (DO) mice is a powerful tool for examining the genetics of complex traits because their high genetic and phenotypic diversity compared to conventional mouse crosses
To investigate the association between genetic diversity and circadian rhythms, we measured molecular rhythms in primary skin fibroblast cultures derived from mice of the eight founder strains of the DO mouse population
Damping rate was the lowest at 13% (Table 1). While these heritability estimates were modest, our findings demonstrate that these founder strains capture genetic diversity that contributes to phenotypic variability in molecular rhythm phenotypes

Summary

Introduction

Circadian variability is driven by genetics and Diversity Outbred (DO) mice is a powerful tool for examining the genetics of complex traits because their high genetic and phenotypic diversity compared to conventional mouse crosses. Efforts to identify new genes or variants that modulate the amplitude, phase, or period of the clock have heavily relied on mice to leverage their genetic diversity and availability of genetics tools[3,4]. While these efforts have been valuable, many of these studies have used common inbred mouse strains or conventional inbred crosses that are constrained by their narrow genetic and phenotypic range. Uncovering novel genetic mechanisms of circadian rhythms may be translationally relevant for further understanding human circadian biology, as many circadian phenotypes (e.g., period) are heritable with few insights into their genetic bases[6,7,8,9]

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