A team of ISU researchers successfully cloned a fruit fly protein, discovering a link which could be important for the division of chromosomes.

Skeletor is a chromosomal protein which is present during mitosis, the process of cell division. It forms a nuclear spindle-like structure, thought to be important for assembling the microtubule spindle, which is also an important structure in the process of cell division.

Increased knowledge of cell division is important, said Kristen Johansen, associate professor of zoology and genetics. The equal separation of chromosomes into two separate cells in the nucleus is how cells pass on inherited information. She said many scientists have known the matrix-like structure played a role in this process but were not quite sure what it was.

“A microtubule spindle has been defined and has been known to be important for some time, but it wasn’t clear whether the nucleus played a role in establishing this structure,” Johansen said.

Skeletor is the first of two spindle structures to form, she said. Spindles are used as support by motor proteins to line up and then pull chromosomes apart during the metaphase stage of division. The nuclear spindle forms in the center of the nucleus during the pro-metaphase stage of mitosis before the microtubule spindle forms. “The co-alignment of the two spindles suggests the Skeletor spindle may play a role in helping to establish the microtubule spindle,” Johansen said.

She said scientists do not yet know if motor proteins use the microtubule spindle, the Skeletor spindle or both for support.

The main key in discovering this new protein was an antibody Johansen generated while carrying out her dissertation project at Yale University. The antibody didn’t recognize the protein she studied then, but she decided to keep the substance because of its significant distribution pattern with a different protein.

The antibody is now one tool which allows her to see the spindle matrix. Iowa State’s image analysis technology was another key in discovering Skeletor. The ISU biotechnology instrumentation facility houses a confocal microscope, equipped with four lasers, at the College of Veterinary Medicine. This scope excited different light wavelengths, and provided a 2-D plane in which 3-D reconstructions could be made using images captured in each plane of the samples, Johansen said.

The study was part of a five-year grant provided by the National Science Foundation and was published in the Dec. 25, 2000 edition of The Journal of Cell Biology.

Diana Walker, post doctorate resident associate in biochemistry, biophysics and molecular biology, did a large portion of the gene cloning in this project for her thesis while she was a graduate student.

“I cloned the gene that we had identified using this antibody,” she said. “I then analyzed DNA and the protein sequence of Skeletor. It’s overall a good example of how molecular and cell biology researchers can provide the pieces to a puzzle.”

Walker said it’s important to know how cells are able to divide and knowing more about cell division will provide more information about therapeutics like cancer targets for drugs.

The team included Johansen, Walker, Jorgen Johansen, professor of zoology and genetics, and graduate students Dong Wang, Uttama Rath and Yanming Wang.