JAN 30, 2017 5:47 PM PST

Extracellular Fibers Observed Moving Through the Nucleus

WRITTEN BY: Carmen Leitch

The blueprint for our bodies is contained in our genes, but scientists have long wondered how our environment can in turn exert an effect on our genes. It was first proposed in the early 80s by Mina Bissell of the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) that cell fate and gene expression are influenced by a cell’s microenvironment or extracellular matrix. Bissell’s lab has now produced images that capture cytofilaments extending into the nucleus of a human breast cell. This research, published in the Journal of Cell Science, has demonstrated that it may be possible for the physical environment to impact the gene expression of a cell. Below is a three dimensional rendering of the cytofilament bundles tunneling through the nucelus of a cell, by Manfred Auer of the Berkeley Lab.

"There are somewhere between 30-70 trillion cells in our bodies, all with the same DNA sequence, so I've been saying since 1981 that something other than the sequence of the genes had to allow a nose to be a nose and not an elbow," said Bissell, co-corresponding author of the work and Distinguished Scientist at Berkeley Lab's Biological Systems and Engineering Division. "When the shape changes, biology changes."

Genes are generally seen as the primary drivers of cellular function, working with signaling molecules like hormones and transcription factors. The idea that the extracellular matrix (ECM) influences cellular processes has gained acceptance over many years of research. Work with breast cells of mice grown in a three-dimensional suspension supplemented with ECM showed that the right environment can influence cell behavior, in this case coaxing the cells to make milk.

The 3-D architecture of cytofilament bundles (in gold) tunneling through a cell's nucleus. The nuclear membrane is shown / Credit: Manfred Auer/Berkeley Lab

"We knew the extracellular matrix was affecting gene expression, but it wasn't understood until now that the cytoskeleton was actually able to connect inside the nucleus," said Bissell. "Now we know there's a direct connection to the nucleus. That's what we're showing here for the first time. This is absolutely novel."

Bissell worked with Berkeley Lab’s Manfred Auer, head of the Cell and Tissue Imaging Department in the Molecular Biophysics and Integrative Bioimaging Division, who is co-corresponding author of the report.

"It took advances in cryogenic sample preparation techniques and large-volume electron microscopy to come up with these images," said Auer. Another special technique, stochastic optical reconstruction microscopy, or STORM, was applied to this research by another study author Ke Xu, a Berkeley Lab faculty scientist and UC Berkeley Assistant Professor of Chemistry.

"We combined a record-breaking six different imaging techniques and hundreds of millions of data points to obtain these images," said Auer. "The integrative bioimaging approach involved three different optical light and three different electron microscopy imaging approaches, each with its own strengths. This new integration of imaging approaches is what allowed us to study something as complex as this cytofilaments system."

The incredible resolution of their imaging allowed the researchers to show that the cytoskeleton associates with a class of protein which functions in the connection between the nucleus and cytoplasm of a cell, SUN proteins. The detail in the images enabled detection of grooves and tunnels in the nucleus. Cytofilaments stuck to the membrane of the nucleus moved through the invaginations, creating an architecture of cytofibers extending from the ECM to and through the nucleus.

"This study establishes for the first time the long-postulated mechanical link between the cell's nucleus to adhesion complexes that allow communication with the surrounding extracellular matrix and other cells," said Auer.

"The reason we're excited is that it explains a whole lot of literature of how force and tension could be playing a role together with biochemical signals to bring about huge changes in a cell," concluded Bissell.

Above, this video features a talk with Bissell about the ECM and its influence on the cell.

 

Sources: AAAS/Eurekalert! via Berkeley Lab, Journal of Cell Science

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
OCT 05, 2020
Cell & Molecular Biology
Gaining Insight Into the Connection Between Depression and Stress
OCT 05, 2020
Gaining Insight Into the Connection Between Depression and Stress
Depression is a common mental illness, and stress is known to be an environmental influence that can increase the risk o ...
OCT 19, 2020
Genetics & Genomics
Early Childhood Trauma Affects Metabolism in the Next Generation
OCT 19, 2020
Early Childhood Trauma Affects Metabolism in the Next Generation
Traumatic experiences can have a lasting impact, and kids that suffer through them can feel the effects for a lifetime. ...
OCT 20, 2020
Genetics & Genomics
The Gene Behind the Glow of the Sea Pickle is ID'ed
OCT 20, 2020
The Gene Behind the Glow of the Sea Pickle is ID'ed
In this photo by OceanX, researchers off the coast of Brazil collected Pyrosoma atlanticum specimens with a special robo ...
OCT 22, 2020
Microbiology
SARS-CoV-2 Has Multiple Routes Into Cells
OCT 22, 2020
SARS-CoV-2 Has Multiple Routes Into Cells
Since the pandemic virus SARS-CoV-2 emerged on the scene late last year, it's left a trail of devastation around the glo ...
NOV 05, 2020
Cardiology
Investigating Platelet-Derived Extracellular Vesicles in Blood Clotting
NOV 05, 2020
Investigating Platelet-Derived Extracellular Vesicles in Blood Clotting
In our bodies, there are millions of signals and packages being sent and received every second. In the past several deca ...
NOV 14, 2020
Microbiology
The Structure of a Bacteriophage DNA Tube is Revealed
NOV 14, 2020
The Structure of a Bacteriophage DNA Tube is Revealed
Some viruses only infect bacteria; they care called bacteriophages or phages for short. As antibiotic-resistant bacteria ...
Loading Comments...