negative regulation of gene expression obsolete gene silencing true OBSOLETE. Any process carried out at the cellular level that results in either long-term transcriptional repression via action on chromatin structure or RNA mediated, post-transcriptional repression of gene expression. This term was obsoleted because its definition was too broad, and not distinct from 'GO:0045814 negative regulation of gene expression, epigenetic'. biological_process GO:0016458 Wikipedia:Gene_silencing heterochromatin formation