Carolyn Widney “Carol” Greider (born April 15, 1961) is an American molecular biologist and Nobel laureate. She is a Bloomberg Distinguished Professor, Daniel Nathans Professor, and Director of Molecular Biology and Genetics at Johns Hopkins University. She discovered the enzyme telomerase in 1984, while she was a graduate student of Elizabeth Blackburn at the University of California, Berkeley. Greider pioneered research on the structure of telomeres, the ends of the chromosomes. She was awarded the 2009 Nobel Prize for Physiology or Medicine, along with Blackburn and Jack W. Szostak, for their discovery that telomeres are protected from progressive shortening by the enzyme telomerase.
Early life and education
Greider was born in San Diego, California. Her father, Kenneth Greider, was a physics professor. Her family moved from San Diego to Davis, California, where she spent many of her early years and graduated from Davis Senior High School in 1979. She graduated from the College of Creative Studies at the University of California, Santa Barbara, with a B.A. in biology in 1983. During this time she also studied at the University of Gttingen and made significant discoveries there.
Greider is dyslexic and states that her “compensatory skills also played a role in my success as a scientist because one has to intuit many different things that are going on at the same time and apply those to a particular problem” Greider initially suspected her dyslexia after seeing patterns of common mistakes such as backwards words when she received back graded work in the first grade. Greider started to memorize words and their spellings rather than attempting to sound out the spelling of words. Greider has worked significantly to overcome her dyslexia to become successful in her professional life, and credits her dyslexia as helping her appreciate differences and making unusual decisions such as the one to work with Tetrahymena, an unusual organism.
Greider initially had difficulty getting in to graduate school due to low GRE scores as a result of her dyslexia. U.C. Berkeleys graduate school admission office was able to focus on Greiders impressive experience and credentials and accepted her. Greider applied to thirteen grad schools and was only accepted to two, Caltech and U.C. Berkeley. She chose the University of California, Berkeley where she would be able to work with Elizabeth Blackburn and the two made their telomerase discovery.
Discovery of telomerase
She completed her Ph.D. in molecular biology in 1987 at the University of California, Berkeley, under Elizabeth Blackburn. While at UC Berkeley, Greider co-discovered telomerase, a key enzyme in cancer and anemia research, along with Blackburn.
Greider joined Blackburn’s laboratory in April 1984 looking for the enzyme that was hypothesized to add extra DNA bases to the ends of chromosomes. Without the extra bases, which are added as repeats of a six base pair motif, chromosomes are shortened during DNA replication, eventually resulting in chromosome deterioration and senescence or cancer-causing chromosome fusion. Blackburn and Greider looked for the enzyme in the model organism Tetrahymena thermophila, a fresh-water protozoan with a large number of telomeres.
On December 25, 1984, Greider first obtained results indicating that a particular enzyme was likely responsible. After six months of additional research Greider and Blackburn concluded that it was the enzyme responsible for telomere addition. They published their findings in the journal Cell in December, 1985. The enzyme, originally called “telomere terminal transferase,” is now known as telomerase. Telomerase rebuilds the tips of chromosomes and determines the life span of cells.
Greider’s additional research to confirm her discovery was largely focused on identifying the mechanism that telomerase uses for elongation. Greider chose to use RNA degrading enzymes and saw that the telomeres stopped extending, which was an indication that RNA was involved in the enzyme. Greider also used telomerase deficient mice and saw that her sixth generation of mice had become entirely sterile, she mated them with control mice and the telomerase deficient mice were able to regenerate their telomeres.
Greider then completed her postdoctoral work, and also held a faculty position, at the Cold Spring Harbor Laboratory, Long Island, New York. During this time, Greider, in collaboration with Ronald A. DePinho, produced the first telomerase knockout mouse, showing that although telomerase is dispensable for life, increasingly short telomeres result in various deleterious phenotypes, colloquially referred to as premature aging. In the mid-1990s, Greider was recruited by Michael D. West, founder of biotechnology company Geron (now CEO of AgeX Therapeutics) to join the company’s Scientific Advisory Board.
Greider, Blackburn and Jack Szostak, Ph.D., of Harvard Medical School, shared the 2006 Albert Lasker Award for Basic Medical Research for their work on telomeres.
Greider currently serves as director of and professor at the Department of Molecular Biology and Genetics at Johns Hopkins Medicine. Greider was first promoted to Daniel Nathans Professor at the Department of Molecular Biology and Genetics in 2004. Greider’s lab employs both student and post-doctoral trainees in order to further examine the relationships between the biology of telomeres and their connection to disease. Greider’s lab uses a variety of tools including yeast, mice, and biochemistry in order to look at progressive telomere shortening. Greider’s lab is also researching how tumor reformation can be controlled by the presence of short telomeres. The lab’s future work will focus more on identifying the processing and regulation of telomeres and telomere elongation.
Greider married Nathaniel C. Comfort, a fellow academic, in 1992. She has two children. Greider is divorced. Before Greider’s children were born, she competed in triathlons. She still bikes, runs, and swims for fitness.
Awards and honors
- Gairdner Foundation International Award (1998)
- Member of the American Society for Cell Biology (1999)
- Academy of Achievement Golden Plate Award (2000)
- Fellow of the American Academy of Arts and Sciences (2003)
- Member of the National Academy of Sciences (2003)
- Richard Lounsbery Award (2003), National Academy of Sciences
- Member of the American Society for Biochemistry and Molecular Biology (2004)
- Albert Lasker Award for Basic Medical Research (2006) (shared with Elizabeth Blackburn and Jack Szostak)
- Dickson Prize in Medicine (2006)
- Wiley Prize in Biomedical Sciences (2006) (shared with Elizabeth Blackburn)
- Louisa Gross Horwitz Prize of Columbia University (2007) (shared with Elizabeth Blackburn and Joseph G. Gall)
- Nobel Prize in Physiology or Medicine (2009) (shared with Elizabeth Blackburn and Jack Szostak)”
- Paul Ehrlich and Ludwig Darmstaedter Prize (2009) (shared with Elizabeth Blackburn)
- Member of the Institute of Medicine (2010) 
- Greider, C. W. & Blackburn, E. H. (1985). “Identification of a specific telomere terminal transferase activity in Tetrahymena extracts”. Cell. 43 (2 Pt. 1): 405-413. doi:10.1016/0092-8674(85)90170-9. PMID 3907856.
- Greider, C. W. & Blackburn, E. H. (1996). “Telomeres, Telomerase and Cancer”. Scientific American. 274 (2): 92-97. Bibcode:1996SciAm.274b..92G. doi:10.1038/scientificamerican0296-92. PMID 8560215.