Lamin Proteins, The ‘Steel Bars’ That Surround Our Cells

Researchers have provided new insights into how lamin proteins, which strengthen the envelope surrounding a cell nucleus, achieve their function.

AsianScientist (Sep. 21, 2016) – Using single molecule localization microscopy, researchers in Singapore have observed the cell’s cytoskeleton down to the molecular level. Their work was published in Current Biology.

The new description of the mammalian nuclear lamin proteins reveals a structure that is quite different from the textbook view generated 30 years ago from observations on amphibian lamins. The work is of particular significance since lamin defects impair the integrity of the cell nucleus, and give rise to a variety of human diseases, including muscle-wasting muscular dystrophy and cardiomyopathy, or chronic disease of heart muscle.

To visualize the organization of mammalian lamins, researchers led by Professor Brian Burke at the Institute of Medical Biology (IMB) built an in-house single molecule localization microscopy system, which achieves 20-50 nanometer resolution—up to 5,000 times smaller than a human hair. For comparison, the resolution of a normal light microscope is limited to 200 nanometers.

Their studies revealed that two different lamin species (A- and B-type) assemble into separate filament networks that come together as a large structure around the nuclear envelope. These large structures provide attachment sites for nuclear pore complexes, which control the transport of molecules in and out of the nucleus.

Dr. Xie Wei, senior research fellow at IMB, explained, “If the nucleus of a cell is a building, the nuclear envelope is its wall that separates the nucleus from other parts of the cell. The nuclear lamina, which is formed by lamin proteins, can be seen as the steel bars that strengthen the nuclear envelope wall.

“Structural problems occur when the steel bars are broken or defective. Understanding the disease-related protein is usually the first step towards understanding the disease itself, that one day could help in finally finding a cure.”



The article can be found at: Xie et al. (2016) A-type Lamins Form Distinct Filamentous Networks with Differential Nuclear Pore Complex Associations.

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Source: A*STAR; Photo: Shutterstock.
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