2017/02/10

DNA methylation is directed by RNA

Cellular differentiation, adaptation and variation of organisms is directed by RNA, not DNA


Excerpt: "RNA-directed DNA methylation (RdDM) is a nuclear process in which small interfering RNAs (siRNAs) direct the cytosine methylation of DNA sequences that are complementary to the siRNAs. In plants, double stranded-RNAs (dsRNAs) generated by RNA-dependent RNA polymerase 2 (RDR2) serve as precursors for Dicer-like 3 dependent biogenesis of 24-nt siRNAs. Plant specific RNA polymerase IV (Pol IV) is presumed to generate the initial RNA transcripts that are substrates for RDR2. siRNAs are loaded onto an argonaute4-containing RISC (RNA-induced silencing complex) that targets the de novo DNA methyltransferase DRM2 to RdDM target loci."




My comment: There are only two chemical modifications discovered on the DNA; methylation and acetylation. But the list of different epigenetic markers on the RNA is remarkable; there are over one hundred of different chemical modifications discovered on the RNA. So far, most of these epigenetic tags are mysterious for science, but what is already found, is that genes don't regulate these tiny markers.

Instead, small interfering RNAs direct the cytosine methylation of DNA sequences and histones. The cell uses the cytosine and histone methylation for gene expression, it means at what level the genes are silenced or activated. This mechanism is the most significant factor in determining the outcome of an organism, the phenotype. SiRNAs are derived by the specific nucleotide cleavage of larger double-stranded RNAs, which means they are not copied from the DNA. Modern science is talking about target genes, not source genes.

The most significant share of biological information of an organism is utilized in RNA-mediated cellular mechanisms. Genes are just very rough libraries for these clever mechanisms. There is no such a thing as mutation driven evolution. These complex mechanisms point to Creation and Intelligent Design.