Protein teamwork drives successful cell division

Like a surgeon separating conjoined twins, cells have to be careful to get everything just right when they divide in two. Otherwise, the resulting daughter cells could be hobbled, particularly if they end up with too many or two few chromosomes. Successful cell division hangs on the formation of a dip called a cleavage furrow, a process that has remained mysterious. Now, researchers at Johns Hopkins have found that no single molecular architect directs the cleavage furrow’s formation; rather, it is a robust structure made of a suite of team players.

The finding is detailed in the March 2 issue of the journal Current Biology.

A cleavage furrow begins to separate a dividing cell into daughter cells. (Credit: Janet Effler/Johns Hopkins Medicine

A cleavage furrow begins to separate a dividing cell into daughter cells. (Credit: Janet Effler/Johns Hopkins Medicine

“We assumed the cleavage furrow was like a finely tuned Swiss watch, in that breaking a key component would bring it to a stop — we just didn’t know what that component was,” says Douglas Robinson, Ph.D., a professor of cell biology in the Institute for Basic Biomedical Sciences at the Johns Hopkins University School of Medicine, borrowing an analogy from the late Ray Rappaport, the founding father of modern cell division research. “But it turned out to be more like an old Maine fishing boat: almost indestructible.”

Cell division is how new cells form, both during development and throughout an organism’s life. To learn more about this process, Robinson and graduate student Vasudha Srivastava took the one-celled amoeba Dictyostelium as their model. One by one, they disabled genes for proteins known to be involved in the cleavage furrow to see whether doing so disrupted its assembly. But no matter which protein was taken out, other proteins still self-assembled to form the cleavage furrow.

“It’s not a house of cards — pulling out one protein doesn’t bring it down,” Srivastava says. Instead, she and Robinson found a robust process tuned not only by chemical signaling, but also by mechanical processes.

That makes sense, Robinson says, given the importance of the cleavage furrow to life itself. “Cells need to get division right in order to avoid ending up with the wrong number of chromosomes, which can be fatal,” he says.

The study was funded by the Hay Graduate Fellowship Fund, the National Institute for General Medical Sciences (grant number GM66817), the National Institutes of Health Office of the Director (grant number S10 OD016374) and the Johns Hopkins Physical Sciences-Oncology Center.

Douglas Robinson is an affiliated faculty member of Johns Hopkins Institute for NanoBioTechnology.

Reposted in its entirety from Johns Hopkins School of Medicine News.

For all press inquiries regarding INBT, its faculty and programs, contact Mary Spiro, mspiro@jhu.edu or 410-516-4802.

Q & A with Peter Devreotes

Back when the Johns Hopkins Institute for NanoBioTechnology first formed, we had an executive committee with faculty members from every University division to help guide our early footsteps. One of those memebers was Peter Devreotes, professor of cell biology at the School of Medicine.

Peter Devreotes with postdoctoral fellow Huaqing Cai. (Photo: Marty Katz)

Peter Devreotes with postdoctoral fellow Huaqing Cai. (Photo: Marty Katz)

Over the years Devreotes has advised and mentored students from the high school to postdoctoral level who are associated with INBT in his laboratory. Here, we have a short question and answer with Devreotes, produced for the Institute for Basic Biomedical Sciences newsletter. We e get to know a little bit about this faculty member, his personal and research interests and what inspires him.

How did you decide to study science?

DEVREOTES: I never thought about anything else. My father taught me a lot of math and took me on nature walks. I developed this fascination with everything in nature and wanted to know how it worked—I still do. I was actually a physics major in college—didn’t take a single biology class-but I decided to do a Ph.D. in biophysics, at Johns Hopkins’ Homewood campus. I was immediately fascinated by the mechanics of cells.

Follow this link to read more from this interview.

 

Studying cells in 3D, the way it should be

When scientists experiment on cells in a flat Petri dish, it’s more been a matter of convenience than anything that recapitulates what that cell experiences in real life. Johns Hopkins professor Denis Wirtz for some time has been growing and studying cells three dimensions, rather than the traditional two dimensions. And pretty much, he’s discovered that a lot of what we think we know about cells is dead wrong.

cancer-in-3d-impact_0

Cell in 3D. Image by Anjil Giri/Wirtz Lab

In this recent article by Johns Hopkins writer Dale Keiger, you will discover what Wirtz has discovered through his investigations. Furthermore, you will find out about the man behind these revolutionary ideas that are turning basic cell biology upside-down, as well as challenge a lot of what we thought we understood about diseases like cancer.

Wirtz directs the Johns Hopkins Physical-Sciences Oncology Center and is associate director and co-founder of Johns Hopkins Institute for NanoBioTechnology. He recently launched the Center for Digital Pathology. He is a the Theophilus Halley Smoot professor of chemical and biomolecular engineering.

You can read the entire magazine article “Moving cancer research out of the Petri dish and into the third dimension” online here at the JHU Hub.

Platelets, coagulation and cancer metastasis: a sticky situation in the blood

Owen McCarty

Join the Chemical and Biomolecular Engineering department for the first seminar of 2011: “Platelets, Coagulation and Cancer Metastasis: a Sticky Situation in the Blood” at 10:45 a.m., Thursday, March 3 in room 301 of Shaffer Hall at the Homewood campus of Johns Hopkins University. Owen J.T. McCarty of Oregon Health and Science University is the invited speaker.

McCarty serves as an assistant professor at OHSU in Portland in the departments of Biomedical Engineering and Cell and Developmental biology. He studies the interplay between cell biology and fluid mechanics in the cardiovascular system. His investigation into the balance between hydrodynamic shear forces and chemical adhesive interactions could shed light on the underlying processes of cancer, cardiovascular disease, and inflammation.

An alumnus of Johns Hopkins University, McCarty’s 2002 Ph.D. dissertation in Chemical and Biomolecular Engineering focused on the role of platelets in cancer metastasis and thrombosis. At the Department of Pharmacology, Oxford University and Centre for Cardiovascular Sciences, University of Birmingham, UK, he continued his research as a Wellcome Trust Postdoctoral Fellow in the area of thrombosis, examining the signaling pathways that rule platelet cytoskeletal reorganization. McCarty’s talk is co-sponsored by the Johns Hopkins Physical Sciences Oncology Center.

Johns Hopkins Physical Sciences Oncology Center