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Related Concept Videos

Epigenetic Regulation01:46

Epigenetic Regulation

Epigenetic mechanisms play an essential role in healthy development. Conversely, precisely regulated epigenetic mechanisms are disrupted in diseases like cancer.
Histone Modification02:32

Histone Modification

The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
DNA Topoisomerases02:02

DNA Topoisomerases

Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
Topoisomerases are divided into two main types.  Type I...
Base Excision Repair01:54

Base Excision Repair

One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing and strand breakage during replication. This type of damage causes minimal change to the DNA double helix structure and can be repaired by the base excision repair (BER) pathways. BER corrects damaged DNA sequences by removing the damaged base and restoring the original base sequence using the complementary strand as a template.
The first step of...
Epigenetic Regulation01:37

Epigenetic Regulation

Epigenetic changes alter the physical structure of the DNA without changing the genetic sequence and often regulate whether genes are turned on or off. This regulation ensures that each cell produces only proteins necessary for its function. For example, proteins that promote bone growth are not produced in muscle cells. Epigenetic mechanisms play an essential role in healthy development. Conversely, precisely regulated epigenetic mechanisms are disrupted in diseases like cancer.
X-chromosome...
Phase II Reactions: Methylation Reactions01:17

Phase II Reactions: Methylation Reactions

Methylation is a phase II biotransformation process involving the attachment of a methyl group to a substrate. Enzymes known as methyltransferases orchestrate this reaction.
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...

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Related Experiment Video

Updated: May 9, 2026

Immunostaining for DNA Modifications: Computational Analysis of Confocal Images
09:42

Immunostaining for DNA Modifications: Computational Analysis of Confocal Images

Published on: September 7, 2017

GADD45A does not promote DNA demethylation.

Seung-Gi Jin1, Cai Guo, Gerd P Pfeifer

  • 1Division of Biology, Beckman Research Institute of the City of Hope, Duarte, California, United States of America.

Plos Genetics
|March 29, 2008
PubMed
Summary

Growth arrest and DNA damage inducible protein GADD45A does not play a role in active DNA demethylation. The mechanism for removing methylated cytosines from DNA in mammals remains unknown, despite its importance in development and disease.

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Last Updated: May 9, 2026

Immunostaining for DNA Modifications: Computational Analysis of Confocal Images
09:42

Immunostaining for DNA Modifications: Computational Analysis of Confocal Images

Published on: September 7, 2017

Immunohistochemical Detection of 5-Methylcytosine and 5-Hydroxymethylcytosine in Developing and Postmitotic Mouse Retina
07:50

Immunohistochemical Detection of 5-Methylcytosine and 5-Hydroxymethylcytosine in Developing and Postmitotic Mouse Retina

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Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
06:07

Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors

Published on: August 5, 2022

Area of Science:

  • Epigenetics
  • Molecular Biology
  • Genetics

Background:

  • DNA methylation patterns are dynamic during development and disease.
  • Active DNA demethylation mechanisms remain largely unknown.
  • Previous research suggested a role for GADD45A in DNA demethylation.

Purpose of the Study:

  • To investigate the role of GADD45A in active DNA demethylation.
  • To clarify the mechanism of DNA demethylation in mammalian cells.

Main Methods:

  • Gene reactivation assays
  • DNA methylation assays

Main Results:

  • GADD45A was not found to be functionally involved in DNA demethylation.
  • Experimental results contradicted previous findings on GADD45A's role.

Conclusions:

  • The function of GADD45A in DNA demethylation could not be substantiated.
  • The mechanism of active DNA demethylation in mammals remains an open question.