Scientists at the University of California, Berkeley, have made a major breakthrough in our understanding of how DNA is organized within the cell. Their research, published in the journal Nature, reveals that DNA is not simply a long, continuous molecule, but rather is organized into a series of loops that are anchored to the nuclear membrane.
This new understanding of DNA organization has important implications for our understanding of how genes are regulated. Genes are specific regions of DNA that code for proteins, and the way that DNA is looped and anchored determines which genes are accessible to the cellular machinery that reads and transcribes them.
"This is a major paradigm shift in our understanding of how DNA is organized," said study lead author Erez Lieberman Aiden. "We used to think of DNA as a long, linear molecule, but now we know that it's actually a highly organized structure that is essential for gene regulation."
The researchers used a technique called Hi-C to map the interactions between different regions of DNA. Hi-C involves breaking up the DNA into small fragments, then sequencing the fragments and analyzing how they are linked together.
The Hi-C data revealed that DNA is organized into a series of loops that are anchored to the nuclear membrane. The loops range in size from a few thousand base pairs to several million base pairs, and they are organized into a hierarchical structure.
The largest loops are called topological domains, and they contain multiple smaller loops called subdomains. The subdomains are further divided into even smaller loops called contact domains.
The researchers found that the organization of DNA into loops is essential for gene regulation. The loops bring together regulatory elements, such as promoters and enhancers, with the genes they control. This allows the cell to control which genes are expressed and when.
The new understanding of DNA organization could lead to new insights into a variety of diseases, including cancer and developmental disorders. By understanding how DNA is organized, scientists may be able to develop new therapies that target specific genes or regulatory elements.
"This research opens up a whole new field of study in genetics," said Aiden. "We are now beginning to understand how the physical organization of DNA affects gene expression and cellular function."
