DNA repair #
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DNA repair is a collection of processes (Biological pathway) by which a cell identifies and corrects damage to the DNA molecules that encode its genome. (http://en.wikipedia.org/wiki/DNA_repair)

관련 유전자들은 이 페이지 참고 DNA repair-deficiency disorder

DNA damage and mutation
DNA repair mechanisms
Global response to DNA damage
Genes
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DNA damage and mutation #

Source of damage

Endogenous
1. Reactive oxygen species
2. Replication errors
Exogeneous
1. UV radiation
2. x-ray and gamma rays
3. hydrolysis or thermal disruption
4. certain plant toxins
5. human-made mutagenic chemicals, expecially compounds that act as DNA intercalating agents
6. viruses

Types of damage

oxidation of bases
alkylation of bases (methylation)
hydrolysis of bases (deamination, depurination, depyrimidination)
mismatche of bases
monoadduct damage cause by change in single nitrigenous base of DNA
disadduct damage

DNA repair mechanisms #

Direct reversal #

photoreactivation process directly reversed by phtolyase (not human)
methylation of G directly reversed by guanine methyl transferase (MGMT)
methylation of C and A

Single-strand damage #

Base excision repair (BER): single nitrogeneous base by glycosylase
Nucleotide excision repair (NER): pyrimidine dimerization cased by UV
DNA mismatch repair

Double-strand breaks (DSBs) #

It can make genome rearrangement

Non-homologous end joining (NHEJ): DNA Ligase IV, XRCC4 directly joins two ends -- can lead to deletion, insertion, translocation
Microhomology-mediated end joining (MMEJ): MRE11, PARP1 is required.
Homologous recombination

Translesion synthesis #

Translesion synthesis (TLS) is a DNA damage tolerance process that allows the DNA replication machinery to replicate past DNA lesions such as thymine dimers or AP sites.