Novel Structural Proteins Are Linked to Apoptosis Inhibition and Tumor Promotion

They used a suite of high tech methods including siRNA silencing and fluorescent cell sorting to manipulate and monitor the activity of various NSP isoforms. In particular, they were interested in the interaction between NSP isoform 5a3a and the nucleolar phosphoprotein B23, a multifunctional protein that is involved in cellular processes such as cell division, DNA repair, and apoptosis.

They reported in the June 15, 2008, issue of the journal Cell Cycle that reducing the expression of NSP5a3a did not affect the cell's viability or prevent it from proliferating. However, when B23 expression was lowered, most of the cells in the culture moved towards apoptosis. When the expression of both proteins was lowered simultaneously, no apoptosis occurred. Loss of apoptosis is a critical step in the transformation of normal to cancerous cells.

"So far, we have been able to confirm that two of the NSPs' four isoforms, called NSP 5a3a and NSP 5a3b, interact with a protein called B23, a multifunctional protein that is involved in cellular processes such as cell division, DNA repair and apoptosis,” said first author Dr. Luca D'Agostino, a research fellow at Temple University. "Eventually, we have to screen different types of cancers, different grades, and stages, to see if there is a difference in the expression of NSP5a3a and 5a3b, and if they have an application in the clinical field. With the 5a3a, if we see a pattern of expression when we do screenings of tissue biopsies, it could be useful as a diagnostic tool.”


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