03-04-2019

Joan Barau joins IMB as a junior group leader

The Institute of Molecular Biology (IMB) is delighted to welcome Dr Joan Barau as a Junior Group Leader. Dr Barau investigates how the epigenetics of the germ cell lineage and intragenomic conflict impact mammalian fertility.

The blueprint for every living organism on Earth is coded into its genome in the form of DNA and made manifest through the activity of genes. Indeed, each genome can be viewed as its own environment. This environment is populated by genes whose specific behaviour gives each cell its own identity. Like any environment, a genome is subject to outside disruption, particularly through genetic parasites. These are chunks of foreign DNA that exploit a genome’s replication ability without giving any direct benefit to the cell or organism as a whole. This is particularly relevant for the genomes of cells involved in reproduction. Genetic parasites and their activity within a genome can threaten its stability and thus its ability to be inherited correctly by offspring.

These parasites – known as transposons – are prolific: more than 50% of a human’s genome derives from them. Transposons have the ability to move within a genome, hence their name. They maintain their presence not through their usefulness but through over-replication and increasing copy numbers. This disruptive invasion and increasing genetic burden does not go unchallenged. Genomes fight back through selection for mechanisms that allow the suppression and elimination of parasitic DNA. This self-propagating conflict has been shaping the sequence and structure of genomes for billions of years. It also provides fertile ground for the evolution of novel mechanisms of genome regulation that play essential roles in normal and pathological development.

In joining IMB, Dr Barau will bring his expertise in the various mechanisms genomes use to counteract the presence of transposons. His group will continue to investigate new mechanisms of transposon regulation at all levels of cell and organismal biology. In particular studying how and if these mechanisms are repurposed during normal and pathological development in mammals. As Dr Barau explains, “because the germ cell lineage represents a hotspot of transposon activity, our group will maintain a strong focus into germ cells and early embryos. We will also expand to other relevant physiological contexts including examples of their involvement in development, gene regulation and disease.”

Dr Barau explains he will focus on how mammals use classical modifications to DNA (epigenetic) to properly regulate the production of genomes in gamete cells while at the same time keeping transposons in check. “Cytosine methylation is a widespread epigenetic modification that mammalian genomes use to repress transposons and it has a crucial role for germline development and fertility. We are very interested in understanding how cells reprogramme this mark during gamete cell production ensuring it is absent from germline genes but placed back selectively at transposons. While scientists have known for over ten years that small RNAs are involved, the precise mechanisms and proteins behind this mechanism are still poorly understood.”

A PDF version of the press release can be found here