Gene Found That Affects Cell Life Span

By SID PERKINS

UPI Science News

WASHINGTON, Aug. 7 (UPI) _ Scientists have found a new piece of the aging puzzle by identifying a gene that affects the life span of the human cell.

Reporting in the journal Science, John M. Sedivy and his colleagues at Brown University in Providence, R.I., found when a certain gene was deleted in human somatic, or nonreproductive, cells, those cells had an increased ``life span.''

Most cells die after a certain number of cell divisions. Sedivy says that in his study, the cells with the missing ``p21'' gene divided 20 to 30 additional times before they died.

Sedivy says the life span of a cell was measured in numbers of cell divisions, not in chronological time, because cell division slows down as the cell gets older.

Sedivy says the technology used to ``knock out'' the gene has been used to produce genetically modified mice but, until now, has never been adapted for use on normal human cells cultured in the laboratory. Previous research used individual cells taken from genetically altered animals, but Sedivy and his team were able to modify individual cells in the laboratory dish.

Sedivy says this development will be a boon to researchers because now scientists can study genetically altered human cells without having to genetically modify a human to get them.