Published in the July 29, 2004 issue of the journal Nature, the study utilized a sophisticated new form of mass spectrometry developed at the UCSD School of Medicine to determine how a protein called CENP-A, turns the normally flexible center section of a rod-shaped chromosome into a steel-like structure called a centromere.
A crucial player in the complicated process of cell division, the centromere is responsible for moving the correct number of chromosomes into a new cell. Learning how a centromere forms is an important step in understanding what goes wrong in cell division. When either too many or too few chromosomes end up in newly formed cells, the catastrophic result is often birth defects, spontaneous abortion, or cancer. For example, Down syndrome is a disorder caused by one too many copies of chromosome 21.
During cell division, each cell makes a duplicate copy of its chromosomes. Each pair of identical chromosomes forms a centromere that holds them together in the center, like a cinched waist in an "X". From opposite poles of the cell, microtubules called spindle fibers, extend down to the centromeres and act as ropes to pull the centromere and paired chromosome apart, so that half the centromere/chromosome moves to one side of the cell, while the other half goes to the opposite pole. Cell division follows, resulting in two identical daughter cells.
"Ever since Mendel's original genetic studies, we've wondered how it is that centromeres function to assure that chromosomes are faithfully inherited," said the study's senior au
Contact: Sue Pondrom
University of California - San Diego