INVOLVEMENT OF DNA METHYLATION IN BINDING OF A HIGHLY REPETITIVE DNA COMPONENT TO NUCLEAR SCAFFOLD PROTEINS FROM RAT-LIVER

Experimental reduction of the amount of CpG methylation in a highly re petitive DNA component was achieved by growth of Ac2F cells in the pre sence of 5-aza-2'-deoxycytidine or procainamide, as judged by the resu lts of methyl-sensitive restriction endonuclease digestion and colony hybridization. Modification of genomic DNA with these DNA methylation inhibitors increased the release of 370-bp highly repetitive DNA from rat chromosomal DNA by HindIII digestion. This result indicated that h ighly repetitive DNA components in the nuclear scaffold fraction are h ypermethylated. On the other hand, methylated DNA was used for southwe stern analysis to investigate the protein(s) which bind specifically t o the DNA in the nuclear scaffold fraction. The introduction of additi onal methylated cytosines within a highly repetitive DNA component aff ected the binding of DNA to the nuclear scaffold proteins. Thus, cytos ine methylation may be involved in the regulation of gene expression a nd construction of the higher-order structure of chromatin. (C) 1998 A cademic Press.