Week In Science

An article in Nature Reviews Genetics 8, 35-46 (January 2007), entitled 'Heterochromatin revisited' and authored by Shiv I. S. Grewal and Songtao Jia, deals with heterochromatin; a hot news item of late. An article in Nature Cell Biology around March of this year (Gwen Lomberk, Debora Bensi, Martín E. Fernandez-Zapico & Raul Urrutia) detailed data related to a possible subcode within a histone code. Modification of heterochromatic proteins HP1, HP1 and the pan-nuclear HP1 were noted for effects on silencing of gene expression.

This current article notes that heterochromatin formation requires methylation of histone H3 and recruitment of chromodomain proteins like heterochromatin protein HP1 in referencing a model for epigenetic genomic control. The authors note that heterochromatin may serve "as a dynamic platform to recruit and spread a myriad of regulatory proteins across extended domains to control various chromosomal processes, including transcription, chromosome segregation and long-range chromatin interactions."

The dynamics of heterochromatin related regulatory effects have important implications for medicine but can also be viewed as particularly interesting with respect to evolutionary or ID models as they signal an important demarcation point between eukaryotic and prokaryotic organisms.