A fln-2 mutation affects lethal pathology and lifespan in C. elegans

Yuan Zhao,Hongyuan Wang,Richard J Poole,David Gems

doi:10.1038/s41467-019-13062-z

Abstract

Differences in genetic background in model organisms can have complex effects on phenotypes of interest. We previously reported a difference in hermaphrodite lifespan between two wild-type lines widely used by C. elegans researchers (N2 hermaphrodite and male stocks). Here, using pathology-based approaches and genome sequencing, we identify the cause of this difference as a nonsense mutation in the filamin gene fln-2 in the male stock, which reduces early mortality caused by pharyngeal infection. We show how fln-2 variation explains previous discrepancies involving effects of sir-2.1 (sirtuin deacetylase) on ageing, and show that in a fln-2(+) background, sir-2.1 over-expression causes an FUDR (DNA synthesis inhibitor)-dependent reduction in pharyngeal infection and increase in lifespan. In addition we show how fln-2 variation confounds effects on lifespan of daf-2 (insulin/IGF-1 signalling), daf-12 (steroid hormone signalling), and eat-2 (putative dietary restriction). These findings underscore the importance of identifying and controlling genetic background variation.

Highlights

Differences in genetic background in model organisms can have complex effects on phenotypes of interest
We report that the longer lifespan of N2M is attributable to reduced P frequency that results from a single nonsense mutation in the X-linked gene fln-2, indicating that N2H is wild type and N2M mutant
We demonstrate how this has confounded research on C. elegans ageing, distorting experimental results, and causing confusion and controversy, issues that can be readily resolved

Summary

Introduction

Differences in genetic background in model organisms can have complex effects on phenotypes of interest. The importance of genetic variation in C. elegans strain backgrounds has become increasingly clear, partly arising from inadvertent selection acting on the wild type under laboratory conditions and/or random mutation accumulation[5,6,7]. Such variation may confound the effects of genes of interest. We previously noted that hermaphrodite lifespan is slightly but consistently longer in N2M than N2H (+11% median lifespan)[8] As both stocks have been used as wild type, it is possible that the stock difference may have confounded prior studies of gene effects on lifespan. We demonstrate the importance of controlling for fln-2 genotype by illustrating how it can confound investigations, using several examples of genes that have been the focus of many studies of ageing in C. elegans: sir-2.1, daf-2, daf-12 and eat-2

Methods

Results

Conclusion