Dare to challenge the silence? Telomeric gene silencing revisited

Gene silencing refers to position-dependent and promoter-independent repression of genes via the establishment and the maintenance of compacted heterochromatin. A very significant part of our knowledge on this phenomenon has been derived from studies in the yeasts S. cerevisiae and S. pombe. The gene silencing analyses in these species very often include the FOA-sensitivity assay, which detects the suppression of a reporter gene (URA3 in S. cerevisiae and URA4 in S. pombe) inserted at genomic locations of choice. Two recent studies have contested the validity of this assay and have set uneasy silence in the field. We are not certain how much of the previously acquired data truly deals with gene silencing. The current article comments on this challenge.