Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


MDC and FMP Researchers Identify Edema Inhibitor

Researchers of the Max Delbrück Center (MDC) and the Leibniz Institute of Molecular Pharmacology (FMP) in Berlin-Buch, Germany, have now detected a substance that can prevent the accumulation of fluid in body tissue and thus edema formation.

The results of Dr. Jana Bogum (MDC/FMP) from the MDC research group led by Professor Walter Rosenthal and PD Dr. Enno Klußmann could be important in the future for the treatment of excessive fluid retention in patients with chronic heart failure. Using a novel approach, the researchers have also discovered a new molecular mechanism controlling water homeostasis in the kidneys (Journal of the American Society of Nephrology, doi:10.1681/ASN.2012030295)*.

Graphic of a renal cell with water channels (aquaporin-2, AQP2) in the cell (left image) and with aquaporin-2 in the plasma membrane (right image, above). For example, when a person is thirsty, the hormone AVP triggers a signaling cascade and thereby elicits the redistribution of the water channels from the cell interior to the plasma membrane. The cell then directs water from primary urine via other water channels (AQP3 and 4, Fig. on the right, the right side of the cell) into the bloodstream and tissues.
(Graphic: Enno Klußmann/ Copyright: MDC)

Renal principal cells with aquaporin-2 (blue) in the cell interior (image 1) and in the plasma membranes (image 2). The substance discovered by the MDC research group (4-acetyldiphyllin; image 3), prevents the redistribution of aquaporin-2 to the cell membrane. Nuclei are shown in green.

(Immunofluorescence microscopy: Jana Bogum, Kerstin Zühlke, Burkhard Wiesner, Jenny Eichhorst/ Copyright: MDC/FMP)

Every day around 1 500 liters of blood flow through the kidneys. Of this total volume, the kidneys initially filter 180 liters of primary urine, which they concentrate to two liters and then excrete as the final urine. A key regulatory step of the concentration mechanism is the release of the hormone AVP (arginine-vasopressin) from the brain. This hormone triggers a multi-step signaling cascade in the kidneys which affects water channels (aquaporins) and in particular aquaporin-2. “The water channels, specifically aquaporin-2, and their redistribution play a key role in the regulation of the water balance,” said Dr. Klußmann.

AVP, which is released from the brain upon thirst, induces aquaporin-2 located in the renal collecting duct principal cells to redistribute from the cell interior to the plasma membrane. The renal cells can then filter out the water from the primary urine flowing past the membrane via aquaporin-2. Dr. Klußmann explained: “To keep the renal cell from bursting and the body from dehydrating, the water is directed back via another group of water channels, aquaporin 3 and 4, into the bloodstream and body tissue. In contrast to aquaporin-2, these water channels are located in another domain of the plasma membrane in the renal principal cells and stay there permanently.” Once the thirst is quenched, the levels of the hormone AVP are reduced and aquaporin-2 is shuttled back into the interior of the renal cell until it is needed again.

However, if the AVP level is too high, as is the case in patients with chronic heart failure, aquaporin-2 remains permanently in the plasma membrane of the renal principal cell and directs the water continuously from the primary urine into the renal collecting duct principal cells. These cells funnel the excess water into the body tissue. “This process contributes to edema,” Dr. Klußmann said.

Discovery of how translocation of water channels can be inhibited
How can aquaporin-2 be prevented from settling permanently in the plasma membrane and thus triggering diseases or making them worse? Using a new research approach, the scientists were able to identify an inhibitor which prevents the translocation of the water channel aquaporin-2 into the cell membrane. At the same time they discovered a new regulatory mechanism of water homeostasis at the molecular level.

The researchers used “small molecules“, low molecular weight organic compounds, which penetrate well into cells. They tested 17 700 such substances in renal cells and ultimately filtered out a substance that blocks the redistribution of aquaporin-2 to the plasma membrane. The substance (4-acetyldiphyllin) prevents phosphorylation, an important biological and regulatory activation step. In particular, the compound prevents a phosphorylation reaction that is catalyzed by a protein termed protein kinase A. This protein is activated in the signaling cascade that is triggered by AVP in the renal principal cells. In the presence of 4-acetyldiphillin protein kinase A cannot add a phosphate group to aquaporin-2, with the result that the water channels can no longer redistribute to the plasma membrane.

The new research findings may not only be of interest for the treatment of edema but also for the treatment of depression. Here, by contrast, medical researchers are seeking a way to shuttle aquaporin-2 to the plasma membrane of the renal principal cell, because lithium, which is often used to treat depression, prevents aquaporin-2 from redistributing to the plasma membrane, thus causing diabetes insipidus. If AVP is not released from the brain, or if the receptor for AVP in the renal cell is defective, this likewise results in diabetes insipidus, as Professor Rosenthal discovered several years ago. The affected individuals excrete 20 liters of urine every day. A similar effect, but not quite as drastic, is caused by alcohol. Drinking lots of beer causes the body to excrete large amounts of urine. The reason – alcohol prevents the brain from releasing the hormone AVP and thus prevents the redistribution of aquaporin-2 to the plasma membrane.

*Small molecule screening to reveal mechanisms underlying aquaporin-2 trafficking

Jana Bogum1,2,3, Dorte Faust1, Kerstin Zuhlke1,2, Jenny Eichhorst2, Marie C. Moutty1,2, Jens Furkert2, Adeeb Eldahshan1, Martin Neuenschwander2, Jens Peter von Kries2, Burkhard Wiesner2, Christiane Trimpert4, Peter M.T. Deen4, Giovanna Valenti5, Walter Rosenthal1,6 and Enno Klussmann1

1Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
2Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany
3Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Germany
4Department of Physiology, RUNMC Nijmegen, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
5Department of General and Environmental Physiology, University of Bari, Italy
6Charité University Medicine Berlin, Germany

Barbara Bachtler
Press Department
Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch
in the Helmholtz Association
Robert-Rössle-Straße 10
13125 Berlin, Germany
Phone: +49 (0) 30 94 06 - 38 96
Fax: +49 (0) 30 94 06 - 38 33

Barbara Bachtler | Max-Delbrück-Centrum
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>