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Chromatin is made up of DNA and histone protein, which forms the chromosome. It is present in two structures. One is euchromatin, which is less condensed and ready to transcribe. The second structure is heterochromatin, which is in a condensed form and cannot be transcribed.
Our DNA is not present in its natural form, it is present in a condensed and wrapped form, which is called chromatin. Through an electron microscope, chromatin can be seen as beads on chromosomes. These beads are known as nucleosomes and each nucleosome consists of DNA which is wrapped around the histone protein.
DNA repair is a set of procedures that a cell uses to detect and repair damaged DNA molecules. This can be damaged by both metabolic activities and external factors like radiation. These cause changes in the structure of DNA which halter the process of transcription of genes by the cell.
Targeting DNA repair and chromatin crosstalk in cancer therapy
DNA repair pathways are important to maintain the stability of genes, when the cells come in contact with any damaging agents such as ionising radiation, chemotherapeutic agents, DNA lesions, breaking of strands, which can cause mutations in the DNA. These instabilities in DNA and genes can cause cancer over time.
To overcome such situations, cells have developed a mechanism called (DDR) DNA damage response. It is a complicated network that helps in many ways to kill DNA lesions.
These ways are transcriptional regulation, apoptosis induction, And DNA repair pathways.
Deregulating mechanisms of DNA repair have been linked to cancer onset and progression. Ionising radiation and chemotherapeutic agents are the primary anti-cancer therapies, and they result in cell death through direct or indirect DNA damage. Dysregulation of the DNA damage response may contribute to cancer cells’ hypersensitivity or resistance to genotoxic agents. Targeting the DNA repair pathway can improve tumour sensitivity in treating cancer.
The targeted DNA repair pathways is said to be one of the best therapeutic ways to treat cancer. When one or even more histone modifications affect the insertion, deletion, or identification of another change, or when they work together to promote or repress gene transcription, this is known as crosstalk.
Chromatin crosstalk is the change in chromatin structure, which is necessary for regulating gene expression, and in the treatment of cancer. Both the targeted DNA repair and chromatin cross-talk are important because both help in repairing the DNA.
Chromatin and DNA repair
DNA repair involves the presence of chromatin because comedy changes and DNA repair are interlinked. The study of DNA repair has revealed some modification in a stone that happens after DSB is induced.
It has been discovered that many east in mammals helps in the modification of his tone when there is double standard break occurs. The enzyme is yH2AX.
The chromatin remodelers are also playing an important role in DNA repair. The complex NuRD HDAC has a chromatin remodeler subunit called (MTA1 or 2). This subunit is involved in the modification of his tone and remodelling of chromatin.
At DSBs, p400 (SWR1 in yeast) catalyses the transfer of the H2A variant H2A.Z onto the chromatin, resulting in a more open chromatin structure and promoting subsequent histone modifications at the damage site.
Conclusion
Chromatids in the compacted form of DNA are made up of histones, DNA and RNA. Chromatids have a highly complex structure because they get compacted in three steps. DNA repair is important because it leads to many harmful diseases. The modification of chromatin structure has played an important role in the repairing of damaged DNA. It has been seen that most of the enzymes are active in changing the structure of DNA during gene expression.
