Deoxyribonuclease, or DNase, is a family of enzymes that break down DNA molecules. These enzymes work by cleaving the chemical bonds within the DNA backbone, resulting in smaller fragments. The body must constantly break down DNA, both from the food we eat and the cells that die within us. This enzymatic activity is necessary for recycling the building blocks of life and for preventing cellular debris from triggering unwanted immune responses.
DNase I: Production for Digestive Processes
The primary production site for Deoxyribonuclease I (DNase I) is the pancreas. Pancreatic tissue synthesizes DNase I as a digestive enzyme and secretes it as a component of pancreatic juice into the small intestine. Its function is breaking down the genetic material consumed in the diet.
This digestive process ensures that long strands of DNA are broken down into individual components called nucleotides. These small, absorbable units are then taken up by the cells lining the small intestine and reused by the body. The salivary glands also produce DNase I, releasing it into the mouth to begin the breakdown of nucleic acids early in the digestive process.
DNase and Immune System Defense
DNase I also functions in the bloodstream and other body fluids, where it plays a role in immunity. It is a major nuclease responsible for the digestion of extracellular nucleoproteins. This cleanup function is important for preventing the accumulation of free-floating DNA that could trigger autoimmune reactions.
Neutrophils, a type of white blood cell, employ Neutrophil Extracellular Traps (NETs) to fight pathogens. Neutrophils release their internal DNA, decorated with antimicrobial proteins, to form a web-like structure that physically traps and kills invading microbes. Once the threat is neutralized, this externalized DNA must be cleared quickly. DNase I is the enzyme responsible for dissolving these NETs, preventing them from persisting in the tissues and causing inflammation or damage.
Managing DNA Inside the Cell
Deoxyribonuclease II (DNase II) is produced ubiquitously across the body for managing genetic material inside cells. This enzyme is primarily found within lysosomes, the cell’s specialized compartments for breaking down waste. DNase II operates optimally in the acidic environment characteristic of these cellular recycling centers.
Its main role is to break down the cell’s own DNA from cells that have died through programmed cell death, a process called apoptosis. When a cell dies, it is engulfed by a neighboring cell or a specialized phagocyte. The apoptotic cell’s nucleus is delivered to the lysosome of the engulfing cell, where DNase II breaks down this DNA, ensuring the genetic material is recycled.
When DNase Activity Goes Wrong
A deficiency or overactivity of DNase can have health consequences. When DNase activity is insufficient, the body fails to properly clear self-DNA, which can contribute to autoimmune conditions. For example, a failure to clear the DNA from dying cells or dissolved NETs can lead to the accumulation of circulating chromatin.
This uncleared self-DNA can trigger the production of autoantibodies, a characteristic feature of Systemic Lupus Erythematosus (SLE). The accumulation of extracellular DNA in the airways of patients with Cystic Fibrosis (CF) creates the thick, sticky mucus that characterizes the disease. In these cases, a recombinant form of human DNase I is used therapeutically, inhaled as a mist to break down the accumulated DNA and thin the mucus.