Related Experiment Videos
Hepatic binding of DNA is mediated by a receptor on nonparenchymal cells
1Department of Medicine, University of Washington, Seattle.
Abstract:
During cell death, nuclear material is released into the cellular environment and into the circulation. Studies in experimental animals have shown that circulating DNA is rapidly removed by the liver and broken down to oligonucleotides. The authors have used a perfused liver system in the mouse to study hepatic binding of single-stranded DNA. DNA binding to the liver was rapid and efficient, and did not require serum factors. Binding was saturable and temperature independent, suggesting a receptor-mediated process. Electron microscope autoradiography demonstrated DNA binding to sinusoidal lining cells, primarily Kupffer cells. In vitro studies with isolated cells confirmed that DNA bound to a trypsin-sensitive receptor on the adherent subset of hepatic nonparenchymal cells. The integrity of the perfused liver was confirmed by the demonstration of appropriate uptake and breakdown of asialoorosomucoid. Despite rapid binding of DNA, however, the perfused liver did not digest DNA or release DNA breakdown products. Infusion of DNAse at intervals after DNA perfusion demonstrated that significant amounts of DNA remained bound to the cell surface, and that serum nucleases were able to cleave this surface bound DNA. It is concluded that DNA binding to the liver is mediated by a receptor on Kupffer cells, but that DNA breakdown may occur at the cell surface or in circulation and may not require cell interiorization.
Insights
The liver rapidly binds circulating single-stranded DNA via Kupffer cell receptors. DNA breakdown occurs extracellularly, not requiring cell uptake.
Area of Science:
- Hepatology
- Immunology
- Molecular Biology
Background:
- Nuclear material, including DNA, is released during cell death.
- Circulating DNA is typically cleared by the liver in experimental models.
Purpose of the Study:
- To investigate the mechanism of hepatic binding and clearance of single-stranded DNA (ssDNA).
- To identify the specific liver cells and receptors involved in DNA uptake.
Main Methods:
- Utilized a mouse perfused liver system to study ssDNA binding.
- Employed electron microscope autoradiography and in vitro studies with isolated hepatic cells.
- Assessed liver function through asialoorosomucoid uptake and breakdown.
Main Results:
- Hepatic binding of ssDNA was rapid, efficient, saturable, and temperature-independent.
- DNA primarily bound to Kupffer cells via a trypsin-sensitive receptor.
- The liver did not internalize or degrade bound DNA; breakdown occurred extracellularly by serum nucleases.
Conclusions:
- Kupffer cells mediate DNA binding through cell surface receptors.
- Extracellular DNA breakdown, either on the cell surface or in circulation, is suggested.
- Cellular internalization is not required for DNA clearance by the liver.