Determination of Epigenetic Changes

Epigenetics describes the study of heritable changes in genome function that occur without a change in DNA sequence. For example, it is not possible to explain the following facts with the sequence of our genome alone:

▪         a caterpillar and the resulting butterfly have the same genome but look very different

▪         humans have approximately 220 different kinds of cells and tissues with totally different functions, but all with the same genome

▪         Clone-sheep "Dolly" had the same genome as her mother but died very early of an age-related disease
 

These facts are explained by epigenetics:

In the nucleus of eukaryotic cells, genomic DNA is highly folded and compacted with histone and non-histone proteins into a dynamic polymer called chromatin. Gene expression, chromosome segregation, DNA replication, repair and recombination all act, not on DNA alone, but on this chromatin template. The discovery that enzymes can (re)organise chromatin into accessible and inaccessible configurations revealed epigenetic mechanisms that considerably extend the information potential of the genetic code.

The epigenetic code can be described by

▪         various histone modifications

▪         DNA-binding proteins and

▪         the methylation of cytosines

and is, unlike the genetic code, always being rewritten and erased. Epigenetic mistakes are involved not only in mutations in the genotype, but also in the development of abnormalities, cancer and other diseases and there are some manifestations of hereditary epigenetic changes.

My research in this field is focussed on the determination of the genome-wide methylation level by a method which was developed and is still being optimised in my research group. The analytical method is based on the isolation of DNA from blood or tissues, enzymatic hydrolysis to the nucleotides and chemical derivatisation with a carbodiimide and the fluorescence marker (BODIPY FL EDA) to phosphoramidates. The derivatisation mixture is then injected into the CE, where the phosphoramidates are separated by micellar electrokinetic chromatography and detected by laser-induced fluorescence.