The findings provide a new focus for future therapies for the disease, for which there is currently no cure.
Dent’s disease is an extremely rare illness caused by a genetic mutation on the X chromosome. Affecting mostly men, its main symptom is kidney stones often followed by a deterioration of kidney function and in many cases chronic kidney failure. Treatment for the disease is focused on alleviating symptoms and can involve kidney transplant.
Scientists from the University’s Faculty of Biological Sciences have uncovered the role of a transporter protein, called CLC-5, which is known to be faulty in many sufferers of Dent’s disease.
Lead researcher Dr Jonathan Lippiat says, “This is a rare genetic disease so it’s impossible to know the exact number of sufferers worldwide. Dent’s disease could be the underlying cause of kidney stones or kidney failure for a larger number of people and it could be that a number of Dent’s sufferers go undiagnosed. The faulty gene itself has been known about for quite a while, but there’s been no concrete evidence about the function it fulfils. That’s why we’re excited by these findings – they provide us with a whole new area to examine in the search for therapies for Dent’s disease.”
In a research project supported by the Wellcome Trust, Dr Lippiat and his team have discovered that CLC-5 facilitates a crucial function by allowing certain ions to pass through cell membranes so they can reach the places they are needed.
The kidneys filter our blood, removing waste, but minerals and hormones that we need to remain healthy need to be reabsorbed. In order for the cells in the kidney to reabsorb effectively, a process called endocytosis takes place to allow larger molecules to travel through the cell membrane.
In endocytosis, a compartment is created in the cell membrane for the molecule to enter. This compartment – or endosome – needs to be acidic in order for the process to work effectively. The research findings show that CLC-5 delivers protons into endosomes, which causes acidification to occur, so when it CLC-5 is faulty, endocytosis cannot take place effectively.
“If endocytosis can’t take place we lose vital vitamins and hormones,” says Dr Lippiat. “CLC-5 is actually part of a family of proteins, some of which are implicated in other diseases, so these findings could have important consequences when we’re looking at the role of other proteins in the same family.”
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Notes to editors
- This research is published in a paper entitled Direct endosomal acidification by the outwardly rectifying CLC-5 Cl-/H+ exchanger in the hard copy of the Journal of Physiology, issue 588.12 (2010). A copy of the paper is available to journalists on request.
- The Faculty of Biological Sciences at the University of Leeds is one of the largest in the UK, with over 150 academic staff and over 400 postdoctoral fellows and postgraduate students. The Faculty is ranked 4th in the UK (Nature Journal, 457 (2009) doi :10.1038/457013a) based on results of the 2008 Research Assessment Exercise (RAE). The RAE feedback noted that “virtually all outputs were assessed as being recognized internationally, with many (60%) being internationally excellent or world-leading” in quality. The Faculty’s research grant portfolio totals some £60M and funders include charities, research councils, the European Union and industry. www.fbs.leeds.ac.uk
- The 2008 Research Assessment Exercise showed the University of Leeds to be the UK’s eighth biggest research powerhouse. The University is one of the largest higher education institutions in the UK and a member of the Russell Group of research-intensive universities. The University’s vision is to secure a place among the world’s top 50 by 2015. www.leeds.ac.uk
- The Wellcome Trust is a global charity dedicated to achieving extraordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust’s breadth of support includes public engagement, education and the application of research to improve health. It is independent of both political and commercial interests. www.wellcome.ac.uk