Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Scientists Discover Cells Reorganize Shape to Fit the Situation

Flip open any biology textbook and you're bound to see a complicated diagram of the inner workings of a cell, with its internal scaffolding, the cytoskeleton, and how it maintains a cell’s shape. Yet the fundamental question remains, which came first: the shape, or the skeleton?

Now a research team led by Phong Tran, PhD, Assistant Professor of Cell and Developmental Biology at the University of Pennsylvania School of Medicine, has the answer: Both.

The findings, published online this week in the journal Current Biology by co-senior authors Tran and Matthieu Piel of the Institut Curie, Paris, combine genetics, live-cell imaging, and microfluidics technology. They were able to force normally rod-shaped yeast cells to grow within tiny curved channels. Using the channels, they made rod-shaped cells deform into curved-shaped mutant cells and conversely, curved-shaped cells straighten out into a rod. The surprising finding: as the cells bend, they reorganize their cytoskeleton, and as they reorganize their internal skeletons, the cells further adjust their shape.

Cell shape gone awry has been implicated in some forms of cancer. In the future, one potential implication of Tran's findings is that it might be possible to rescue certain disease states via squeezing or otherwise applying mechanical pressure to tissues or organs. But that, he concedes, is “completely science fiction on my part.” Instead, he says at this point this study is pure, basic research. “It was just a cool experiment.”

The findings point to a type of feedback loop. “The cytoskeleton changes the shape of the cell and the shape of the cell also changes the organization of the cytoskeleton,” he says. “In fact they feed back on each other, so any perturbation on one system will change the other, and visa versa.”

The results validate a common belief among cell biologists, says Tran – that to cause a cell to form a branching projection, such as filopodia or dendrite, or new shape, simply adjust the cytoskeleton accordingly, and the shape will follow suit.

"Our demonstration is a conclusive and direct demonstration of that theory because we used normally rod-shaped cells, as opposed to indirect proof of the concept using mutant cell shapes,” he says.

At least five cellular components are required for making changes to the organization of the cytoskeleton and therefore the shape of a cell: microtubules, actin filaments, the cell membrane, and two protein complexes. Microtubules are hollow protein pipes that arrange themselves in bundles down the long axis of the cell. As they extend from the cell center towards the periphery, they carry with them one of the protein complexes, so that when they finally dock with a protein receptor at the cell membrane, the effect is to deliver the complex to the desired growth point. What follows is a cascade of events: This complex recruits the second protein complex, which in turn recruits the protein actin. Filaments of actin from this site bring the transport machinery necessary for new cell membrane to extend in the intended direction – generally, further along the long axis of the cell.

Essentially, what Tran's team, led by technician Courtney Terenna, found was that if normal yeast cells are forced to bend, their microtubules can no longer reach the old tip of the cell and so form new growth tips. Conversely, they also found that mutant yeast cells normally grow bent or round, if forced to grow in straight channels, will adopt cytoskeletal structures that are the normal rod-shape.

This, says Tran, could in theory partially explain why some cells from mouse knock-outs, when grown in two-dimensional tissue culture, have more severe problems than when grown in a three-dimensional animal. The researchers surmise that the three-dimensional architecture of a tissue inside a living organ rescues cytoskeletal abnormalities that otherwise arise in an artificial two-dimensional construct.

The study stems from an international collaboration between the microfluidics experts in Piel's group and the biology experts in Tran's. Co-first authors Terenna and Tatyana Makushok, a graduate student in Piel's group, funded by a Human Frontier Science Program (HFSP), an international organization funded by various countries, traveled to Paris and Philadelphia, respectively, to learn their counterpart's secrets so they could then proceed independently.

Now Tran's group is working to address several questions that arise from this research. First, how long can mutant cells maintain their wild-type phenotype once they are removed from the physical constraints of the microfluidic channel? How do the two protein complexes work together to affect cell shape? And, what effects do other environmental variables, such as temperature, have on cytoskeletal dynamics?

Tran’s lab is funded by the National Institutes of Health, the American Cancer Society, and the HFSP.

This release and related images can be found at:

PENN Medicine is a $3.6 billion enterprise dedicated to the related missions of medical education, biomedical research, and excellence in patient care. PENN Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.

Penn's School of Medicine is currently ranked #4 in the nation in U.S.News & World Report's survey of top research-oriented medical schools; and, according to most recent data from the National Institutes of Health, received over $379 million in NIH research funds in the 2006 fiscal year. Supporting 1,700 fulltime faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.

The University of Pennsylvania Health System (UPHS) includes its flagship hospital, the Hospital of the University of Pennsylvania, rated one of the nation’s top ten “Honor Roll” hospitals by U.S.News & World Report; Pennsylvania Hospital, the nation's first hospital; and Penn Presbyterian Medical Center. In addition UPHS includes a primary-care provider network; a faculty practice plan; home care, hospice, and nursing home; three multispecialty satellite facilities; as well as the Penn Medicine at Rittenhouse campus, which offers comprehensive inpatient rehabilitation facilities and outpatient services in multiple specialties.

Karen Kreeger | Newswise Science News
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 >>>