Cellular memory modules

Cellular memory modules are a form of epigenetic inheritance that allow cells to maintain their original identity after a series of cell divisions and developmental processes. Cellular memory modules implement these preserved characteristics into transferred environments through transcriptional memory. Cellular memory modules are primarily found in Drosophila.

History

Cellular memory modules were discovered by François Jacob and Jaques Monod in 1961 at the Pasteur Institute in Paris. The discovery led to Jacob and Monod, along with André Lwoff, receiving The Nobel Prize in Physiology or Medicine in 1965 for their discoveries regarding genetic control of enzyme and virus synthesis. These experimental results mapped the complex processes in which self-regulating processes express or suppress genes. Monod and Jacob proved how genetic information conversion during the construction of proteins was done through a messenger which evinced RNA. Lwoff aided in the experiment that won the Nobel Prize but did not work on the series of experiments that led to the discovery of cellular memory modules, which is why he remains uncredited in its discovery.

Locations and mechanisms: experiment overviews

Cellular memory modules have the same general process of genes undergoing transcription, these genes being transferred to an unfamiliar environment, and then these genes reverting to their original characteristics preserved through transcriptional memory. Cellular memory modules preserve repressed and active chromatin states in the Polycomb group (PcG) and trithorax group (trxG) proteins by using Polycomb- and trithorax response elements, which are just DNA sequences. Transcription resets and alters epigenetic marks on chromosomal memory elements that are regulated by PcG and trxG proteins.