Role Reversal: Are Transcription Factors Responsible for Heterochromatin Formation?

Regions of eukaryotic chromosomes are classified into two distinct groups: euchromatin, which is generally less compacted and contains actively transcribed genes, and heterochromatin, which is typically more compacted and contains silent genes and the majority of the repeated DNA elements.  Transcription factors are generally thought of as proteins that are …


A potential role for 5hmC in RNA splicing and synaptic function in the brain

5-methylcytosine  (5-mC) is an epigenetic modification of DNA that is essential for normal development and is associated with a number of key cellular processes including genomic imprinting, X-chromosome inactivation, suppression of repetitive elements, and carcinogenesis.  5-mC can be further modified in cells to 5-hydroxymethylcytosine (5-hmC) through oxidization.  This novel epigenetic …


Chromatin Density Matters

Histone methylation mediated by polycomb repressive complex 2 (PRC2) is involved in numerous biological processes, including cell differentiation, proliferation, and stem cell plasticity. Enhancer of Zeste homolog 2 (Ezh2), a subunit of PRC2, is a histone methyltransferase that specifically methylates histone H3 on lysine 27 (H3K27) and regulates polycomb gene …


Epigenetic reprogramming key to normal development

Somatic cell nuclear transfer (SCNT) defines the process in which a somatic cell’s nucleus is removed and then introduced into an enucleated oocyte, or egg cell. Following transfer, the nucleus is reprogrammed by factors in the oocyte such that it now possesses the ability to mitotically divide and form totipotent …


Lost in translation? New findings suggest a critical role for cytosine methylation in tRNAs

While cytosine methylation in the DNA context will continue to be an important marker for epigenetic discoveries, current trends in the cytosine methylation game indicate diverse and critical roles of the modification in the RNA context. Much attention has been paid recently to findings in mRNA methylation, suggesting an important …

Mouse embryonic stem cells

How is DNA Methylation Maintained in ESCs and Differentiated Cells?

DNA methylation has been shown to be very important for development, differentiation, and aging.  But how is DNA methylation maintained?  When and how does de novo DNA methylation occur?  Are there specific DNA methyltransferases (Dnmts) involved in non-symmetric DNA methylation or DNA methylation outside of the CpG context?  There have …

5mC and 5hmC

Maternal instincts: Protection of 5mC?

DNA modification by 5-methylcytosine (5mC) was the only recognized DNA modification for many years in mammals and 5mC plays important roles in cell differentiation and development. Recently, a novel 5-hydroxymethylcytosine (5hmC) DNA modification has been reported and the balance between 5mC and 5hmC in the genome is a critical step …