20170607 class lecture note part II

Bioinformatics : Epigenomics

Def : epigenetic modification을 연구하는 학문 > DNA or histones

Gene expression is controlled by Histone modifications, DNA modifications, RNA interference (trasmitted to next generation.. ) ... 

( Methylation is just a type of modifications, which is well studied.. )

- DNA Methylation > Hypo / Hyper - methylation ( 하이포 : 잘됨 / 하이퍼 : 잘 안됨 )

- DNA methyltrasferase (DNmt1 < most famous one)

using S-Adenosyl Methyonine. 

 

Natural Roles of DNA Methylation in Mammalian System..

> Imprinting

> X chromosome inactivation

> Heterochromatin ( compacted chromatin ) maintenance

> Developmental controls

> Tissue specific expression controls

 

Heterochromatin > if changed, become a cancer.. 암이 되기 위해서는 헤테로 크로마틴이 변형되어야 한다.

 

To make cancer.. 1. heterochromatin make open

                       2. de-activate some gene.. 

Methylation and Aging

: more methylation, older ... ?  > imprinting disorder, repeat-instability diseases, ect...

 

- Histone modification : Un or Acetylated histone. (un > nucleosome)

아세틸기가 붙으면 공간이 넓어져서 더 많이 transcipted 된다.

- RNAi (interference)

 

Bisulfite Sequencing

Methylation이 된 C는 U가 될 수 없다. 이렇게 되면 U가 된 RNA는 DNA에서 T로 바뀌지만 메틸레이션이 된 부분은 바뀌지 않는다.