Featured Research

from universities, journals, and other organizations

Unhealthy attachments: Deep look at the structure of myelin membranes

Date:
February 25, 2014
Source:
University of California - Santa Barbara
Summary:
Using the surface forces apparatus and an atomic force microscope, researchers have taken a molecular approach to myelin membrane interactions, leading to insights into demyelinating diseases, such as multiple sclerosis. For a healthy nervous system, axons -- the long projections of our nerve cells that run throughout our bodies -- must be properly insulated. Much like conventional power cords need electrical insulators around the conducting wires for efficient and effective transfer of current, axons rely on multiple bilayers of myelin to maintain a rapid and optimal transfer of impulses between, for instance, brain and organ, or spinal cord and muscle. However, even the slightest change in the composition of these myelin bilayers to affect their ability to insulate axons, the researchers found.

Myelin sheaths insulate the axon of a nerve cell and enable the rapid transmission of impulses.
Credit: Peter Allen Illustration

Using the surface forces apparatus and an atomic force microscope, researchers at UC Santa Barbara have taken a molecular approach to myelin membrane interactions, leading to insights into demyelinating diseases, such as multiple sclerosis. Their research is published in the Proceedings of the National Academy of the Sciences.

For a healthy nervous system, axons -- the long projections of our nerve cells that run throughout our bodies -- must be properly insulated. Much like conventional power cords need electrical insulators around the conducting wires for efficient and effective transfer of current, axons rely on multiple bilayers of myelin to maintain a rapid and optimal transfer of impulses between, for instance, brain and organ, or spinal cord and muscle. These bilayers are composed of lipids (fat molecules), protein and water.

"Basically, myelin is this multiple stacking of lipid bilayers," said Dong Woog Lee, a researcher in UCSB's Department of Chemical Engineering, and the study's lead author. "They need to be compact, and with very little water between the bilayers."

However, even the slightest change in the composition of these myelin bilayers to affect their ability to insulate axons, the researchers found. To observe and measure the characteristics and differences between healthy and diseased myelin bilayers, they studied the ability of these layers to adhere to each other.

On each of the two opposing surfaces of the surface forces apparatus -- a highly sensitive instrument that can measure interactions between membranes -- the researchers deposited a lipid bilayer on a mica substrate. Then they immersed the setup in a buffer solution containing myelin basic protein (MBP), a biomolecule commonly found in myelin that gives them adhesive properties and plays a role in maintaining the optimal structure of the myelin sheath. They brought the two bilayers close together, allowing them to stick to each other, and then pulled them apart, measuring the strength of the adhesion brought about by the MBP "glue" between the bilayers, and also the MBP's adsorption -- the ability of the MBP molecules to stick to the bilayers' surfaces. They performed this experiment with both healthy myelin and with "disease-like" myelin bilayers.

"A lipid bilayer simulating a normal or healthy myelin membrane adsorbs this protein much better than a lipid bilayer simulating a multiple sclerosis-type of myelin membrane," said UCSB researcher Kai Kristiansen, "meaning that the protein attaches more strongly to the lipid bilayer and can make two apposing lipid bilayers adhere more firmly to each other and at a smaller distance -- which is highly desirable for a well functioning myelin around a neuron."

One common characteristic of diseased myelin is swelling, due to various causes such as the autoimmune responses associated with MS and its variants, or in cases of infection or exposure to certain chemicals. Genetics also play a role in the health of myelin.

"When the disease progresses, people can see that they swell and eventually vesiculate, creating scars," said Lee. The MBP layer between the lipid bilayers also swells with water that seeps in between the double lipid layers. Instead of being a compact, molecule-thick film, the MBP layer becomes more gel-like.

"And since there's more water between the bilayers, their insulation property decreases," added Lee. From there, impulses slow down along the axon, or dissipate before they reach their destinations, causing paralysis and loss of function.

Disease-related changes in the lipid domain structures' size and distribution also causes irregular adsorption of MBP onto the lipid bilayers and weakens their adhesion properties, leading to lower nerve insulation. This in turn also leads to lower nerve insulation.

The molecular study of healthy and diseased myelin bilayers differs from conventional genetic, cellular or immunological approaches and may provide future insights into causes and mechanisms of demyelinating diseases.

The next step, according to Jacob Israelachvili, professor of chemical engineering and of materials at UCSB, is to develop a user-friendly bench-top instrument that could be used in hospitals and clinics to visualize the membranes of certain cells, both healthy and pathological, whose domain structure can be an indicator of the progression of a disease.

"We are currently planning a collaboration with a local hospital to provide us with such membranes, for example, from leukemic blood cells, that we would tag with a suitable fluorescent dye to enable this imaging," he said.


Story Source:

The above story is based on materials provided by University of California - Santa Barbara. The original article was written by Sonia Fernandez. Note: Materials may be edited for content and length.


Journal Reference:

  1. D. W. Lee, X. Banquy, K. Kristiansen, Y. Kaufman, J. M. Boggs, J. N. Israelachvili. Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers. Proceedings of the National Academy of Sciences, 2014; 111 (8): E768 DOI: 10.1073/pnas.1401165111

Cite This Page:

University of California - Santa Barbara. "Unhealthy attachments: Deep look at the structure of myelin membranes." ScienceDaily. ScienceDaily, 25 February 2014. <www.sciencedaily.com/releases/2014/02/140225143937.htm>.
University of California - Santa Barbara. (2014, February 25). Unhealthy attachments: Deep look at the structure of myelin membranes. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2014/02/140225143937.htm
University of California - Santa Barbara. "Unhealthy attachments: Deep look at the structure of myelin membranes." ScienceDaily. www.sciencedaily.com/releases/2014/02/140225143937.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins