Featured Research

from universities, journals, and other organizations

Clues point to cause of a rare fat-distribution disease

Date:
March 20, 2013
Source:
Johns Hopkins Medicine
Summary:
Studying a protein that gives structure to the nucleus of cells, researchers stumbled upon mutations associated with familial partial lipodystrophy (FPLD), a rare disease that disrupts normal patterns of fat distribution throughout the body.

Studying a protein that gives structure to the nucleus of cells, Johns Hopkins researchers stumbled upon mutations associated with familial partial lipodystrophy (FPLD), a rare disease that disrupts normal patterns of fat distribution throughout the body.

Related Articles


"Our findings open new paths for learning how and why fat cells are disproportionately affected by mutations in the protein lamin A, which is found in the nucleus of most cells of the body," says Katherine Wilson, Ph.D., professor of cell biology at the Johns Hopkins University School of Medicine.

According to the researchers, this is the first report that another protein, SUMO1, can attach to lamin A. Importantly, they found that FPLD-causing mutations in lamin A prevent this attachment. Details of the study were published in the Feb. 1 issue of the journal Molecular Biology of the Cell.

Wilson says lamin A is primarily known for giving shape to the nucleus. "It forms networks of strong 'cables' at the nuclear membrane and works with other proteins to create and maintain the three-dimensional environment in which chromosomes are properly organized, protected and expressed," she says.

When the Wilson group made their discovery, they were studying lamin A binding to another protein, actin. Actin can sometimes form a complex with certain SUMO proteins, small proteins often attached to other proteins to alter their functions, their locations and their interactions with additional proteins.

"Sometimes you go into an experiment looking for one thing but you find another," says Wilson. "We wanted to know if lamin A could bind to actin-SUMO1 complexes. Instead, we found that SUMO1 itself attaches to lamin A."

SUMO1 is usually attached to proteins at sites with certain properties; these sites can be predicted by the surrounding amino acids, the basic building blocks of proteins whose blueprints are found in genes. So the researchers searched lamin A's amino acid sequence for predicted binding sites and found five. Using targeted genetic techniques, they created lamin A variants, each with a mutation at a different predicted SUMO1 attachment site. They then added SUMO1 to the mutants and tested whether it could attach to them or not.

Two mutations significantly decreased SUMO1 attachment. One was at a predicted site; the other was unexpectedly in their comparison "control" variant. "Since the mutation site in our control variant was not a predicted SUMO1 attachment site, we were curious about it," explains Wilson. "Mutations in lamin A cause more than 15 different diseases, so we checked the genetic database to see if any diseases were associated with mutations near the SUMO1 attachment site, and FPLD leapt out like a neon sign."

FPLD is a very rare condition that starts around puberty. Fat on the legs of patients is reduced while it accumulates at other locations, including the neck and face. Patients can also become diabetic.

Twenty-four different mutations in lamin A can cause FPLD. To see if two other FPLD-causing mutations near the SUMO1 attachment site affected SUMO1 attachment, the team created these variants and tested them as before. One of the new variants did show decreased SUMO1 attachment. Based on the location of that mutation and one of the other SUMO1-disrupting mutations, the researchers were able to identify a "patch" on the surface of the lamin A protein that is important for SUMO1 attachment.

Exactly how lamin A and SUMO1 connect to FPLD is still a mystery. "We can only speculate on how lamin A and SUMO1 work together to regulate fat cells," says Wilson. "But these results raise new research questions that will hopefully move FPLD studies forward."

Other authors of the report include Dan Simon of the Johns Hopkins University School of Medicine and Tera Domaradzki and Wilma Hofmann of the University at Buffalo, The State University of New York.

This work was supported by grants from the National Institute of General Medical Sciences (RO1 GM048646) and the Department of Defense CDMRP (PC111523).


Story Source:

The above story is based on materials provided by Johns Hopkins Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. D. N. Simon, T. Domaradzki, W. A. Hofmann, K. L. Wilson. Lamin A tail modification by SUMO1 is disrupted by familial partial lipodystrophy-causing mutations. Molecular Biology of the Cell, 2012; 24 (3): 342 DOI: 10.1091/mbc.E12-07-0527

Cite This Page:

Johns Hopkins Medicine. "Clues point to cause of a rare fat-distribution disease." ScienceDaily. ScienceDaily, 20 March 2013. <www.sciencedaily.com/releases/2013/03/130320133233.htm>.
Johns Hopkins Medicine. (2013, March 20). Clues point to cause of a rare fat-distribution disease. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2013/03/130320133233.htm
Johns Hopkins Medicine. "Clues point to cause of a rare fat-distribution disease." ScienceDaily. www.sciencedaily.com/releases/2013/03/130320133233.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Bupa Eyes India Healthcare Opportunities

Bupa Eyes India Healthcare Opportunities

Reuters - Business Video Online (Mar. 5, 2015) Bupa is hoping to expand in India&apos;s fast-growing health insurance market, once a rule change on foreign investment is implemented. The British private healthcare group&apos;s CEO tells Grace Pascoe why it&apos;s so keen on the new opportunity. Video provided by Reuters
Powered by NewsLook.com
Doctor in Your Pocket Is Getting Smarter

Doctor in Your Pocket Is Getting Smarter

Reuters - Business Video Online (Mar. 5, 2015) Mobile apps are turning smartphones into a personal doctors, with users able to measure heart rate, blood pressure and even blood sugar. But will it change our behaviour? Ivor Bennett reports from the Mobile World Congress in Barcelona. Video provided by Reuters
Powered by NewsLook.com
AbbVie Inks $21B Deal To Buy Cancer Drugmaker Pharmacyclics

AbbVie Inks $21B Deal To Buy Cancer Drugmaker Pharmacyclics

Newsy (Mar. 5, 2015) AbbVie announced Wednesday it will buy cancer drugmaker Pharmacyclics in a $21 billion deal. Video provided by Newsy
Powered by NewsLook.com
Toddlers Drinking Coffee? Why You Shouldn't Share Your Joe

Toddlers Drinking Coffee? Why You Shouldn't Share Your Joe

Newsy (Mar. 5, 2015) A survey of Boston mothers and toddlers found that 15 percent of two-year-olds drink coffee and 2.5 percent of 1-year-olds. Video provided by Newsy
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:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

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