Uncovering a novel mechanism in cell division

April 19, 2017 by Sarah Plumridge, Northwestern University
In cancer cells, defects in the bipolar spindle lead to pulling chromosomes in multiple directions during cell division. Credit: Northwestern University

Northwestern Medicine scientists have revealed the role amino-terminal methylation plays in a specific protein in the centromere, a region of the chromosome important in cell division, and how the dysregulation of this protein can affect the development of cancer cells. Methylation of amino acid side chains is well-documented, but the role of amino-terminal methylation is much less well understood.

Published in Nature Communications, the study showed this posttranslational modification of the , centromere protein A (CENP-A), distinguishes it from a similar protein that is found in the rest of the chromosome. CENP-A is a type of histone, a protein with DNA wrapped around it, and specifies the location of the centromere in the nucleus.

Lead author Daniel Foltz, '01 PhD, associate professor of Biochemistry and Molecular Genetics, and his team conducted functional analyses of the modifications on CENP-A, which they had previously identified.

"It's interesting because this is a novel type of modifications on histones and because we can go in and really show what function is being mediated by the amino-terminal methylation, which has not been previously well-defined for this type of modification," Foltz said.

The investigators discovered that CENP-A, when correctly methylated on its amino terminus, influences the recruitment of CCAN proteins, which are part of a large centromere complex of proteins. They showed that a subset of components of CCAN are dependent on this methylation. When the scientists blocked methylation from this process, they observed defects in chromosome segregation.

"We really defined a different arm of recruitment for the CCAN proteins than has been understood before," Foltz said.

Overexpression of CENP-A in Cancer

Next, the scientists studied hallmarks of cancer , including defects in and spindle polarity. A bipolar spindle is essential to equally segregate chromosomes into two separate cells during . In cancer cells, defects in the spindle lead to chromosomes that are pulled in multiple directions and can result in chromosome breakage and genomic instability. The scientists found that reducing the amount of methylation of CENP-A drives this process.

Foltz and the other investigators also found that in the absence of the p53, loss of CENP-A methylation promotes more rapid tumor formation.

Next, Foltz and his team want to study how tumor cells are using this pathway.

"What we've done in this paper is engineer this defect into cells to see what the phenotype is," Foltz said. "The next question is what happens to CENP-A methylation in , and when CENP-A is overexpressed, to what degree is it driving the genomic instability in cancers?"

Explore further: Scientists discover how crucial DNA sequences endure

More information: Kizhakke M. Sathyan et al. α-amino trimethylation of CENP-A by NRMT is required for full recruitment of the centromere, Nature Communications (2017). DOI: 10.1038/ncomms14678

Related Stories

Scientists discover how crucial DNA sequences endure

April 11, 2017

As cells divide, some of their DNA is rearranged, spurring the emergence of new traits that can dictate whether a species survives or flounders. But some stretches of DNA appear to be so crucial to the basic functioning of ...

Biologists identify proteins vital to chromosome segregation

December 24, 2012

New York University biologists have identified how a vital protein is loaded by others into the centromere, the part of the chromosome that plays a significant role in cell division. Their findings shed new light on genome ...

Recommended for you

The Swiss army knife of smoke screens

March 18, 2018

Setting off smoke bombs is more than good fun on the Fourth of July. The military uses smoke grenades in dangerous situations to provide cover for people and tanks on the move. But the smoke arms race is on. Increasingly, ...

Saving lives with platypus milk

March 15, 2018

A breakthrough by Australian scientists has brought the introduction of an unlikely hero in the global fight against antibiotic resistance a step closer; the humble platypus.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.