Biography of Nancy Hopkins BIOGRAPHY

eneticist Nancy Hopkins, professor of biology at the Massachusetts Institute of G Technology (MIT; Cambridge, MA), has achieved unprecedented suc- cess in cloning vertebrate developmental genes by exploiting zebrafish as an ideal model organism. By using insertional mutagenesis, a technique pioneered in invertebrate animals such as Drosophila but long considered impossible to use in vertebrates, Hopkins’s laboratory has cloned hundreds of genes that play a role in creating a viable fish embryo. This research has earned her several accolades, including 1998 election to the American Academy of Arts and Sciences and 1999 election to the Institute of Medicine. Hopkins has gained addi- tional recognition for her revolutionary work on gender equity issues in science, including many awards and more than 400 requests to speak on the topic. GENETICS In 2004, Hopkins became a member of the National Academy of Sciences. In Nancy Hopkins her Inaugural Article (1), published in this issue of PNAS, she and her col- leagues describe 315 zebrafish genes es- about life,’’’ said Hopkins. ‘‘I also geneticist Mark Ptashne, a former sential for early development. Hopkins thought it was ultimately going to lead teaching assistant for one of Hopkins’s and members of her laboratory cloned to a cure for most human diseases.’’ classes at Harvard. these genes by using insertional mu- Hopkins quickly switched plans from ‘‘I couldn’t relate to the whole process tagenesis, and they estimate that they using applied science in medical school of just going to get a Ph.D. so you could have identified approximately 25% of to performing basic biological research. have some career. I was relating only to the genes essential for early zebrafish After the lecture, she raced to Watson’s solving particular research problems in development. The genes Hopkins’s team laboratory at Harvard to inquire about science,’’ she said. Regretful about leav- has identified not only reflect an ex- working there. For the next year and a ing Harvard, but heeding Watson’s ad- traordinary level of evolutionary conser- half, Hopkins finished her course work vice, Hopkins began a doctoral program vation from lower organisms, such as at Radcliffe while performing research at nearby Yale University in New Ha- yeast and Caenorhabditis elegans, but in Watson’s laboratory on bacterio- ven, CT. She soon found that no one at also they may play a vital part in identi- phage, a model organism considered to Yale was interested in isolating the re- fying the genetic basis for many human have the most accessible genes. Her pressor, which was then considered a diseases. work exposed her to many distinguished daunting task. Consequently, after a scientists who passed through the labo- year and a half, Hopkins left her pro- Masterful Mentors ratory, such as Francis Crick and Sydney gram without a degree to join Ptashne Hopkins was born in 1943 in New York, Brenner. Although women of Hopkins’s at Harvard and work as his technician. NY, into a family with several engineers generation were rarely encouraged to Ptashne successfully isolated the isotopi- and scientists; an uncle and a great un- pursue science as a career, Watson nur- cally labeled repressor about 6 months cle were both chemists, and another un- tured Hopkins’s interests and supported later (2). cle was an engineer. However, she did her strong scientific leanings. ‘‘He told Upon completion of her work with not seriously consider becoming a scien- me, ‘You should be a scientist. You Ptashne, Hopkins received a friendly tist until her undergraduate years at have a one-track mind, just like me,’’’ lecture from Watson. ‘‘Jim said, ‘Okay, Radcliffe College (Cambridge, MA), the she recalled. you’ve had your fun, now you have to go After she graduated from Radcliffe in formerly all-women annex of Harvard back to graduate school.’ The next day, 1964, Watson encouraged Hopkins to University. (Radcliffe College, now I was enrolled in Harvard,’’ she said. coed, is currently known as Harvard’s continue her education in graduate For the next several years, Hopkins con- Radcliffe Institute for Advanced Study.) school. However, she was reluctant to tinued to study the repressor, character- Fond of art, math, and science, Hopkins leave her friends and mentors in izing its properties and interactions with briefly considered architecture and med- Watson’s laboratory and the research operators. For her thesis, she used ge- icine as possible careers. Then, in her projects with which she had become junior year, she attended a lecture given deeply involved. At the time, her stron- by the famous geneticist James Watson. gest interest lay in a project to isolate This is a Biography of a recently elected member of the The topic of the day was DNA. ‘‘After 1 the lambda phage repressor, a protein National Academy of Sciences to accompany the member’s hour, I said, ‘That’s it; that’s going to that controls the expression of other Inaugural Article on page 12792. answer every question I’ve ever had lambda genes. The project was led by © 2004 by The National Academy of Sciences of the USA

www.pnas.org͞cgi͞doi͞10.1073͞pnas.0405554101 PNAS ͉ August 31, 2004 ͉ vol. 101 ͉ no. 35 ͉ 12789–12791 Downloaded by guest on September 28, 2021 netics to define the operators that the she was recruited by Salvador Luria and though many of the mechanisms of can- repressor binds to, and then she isolated David Baltimore, and she shared an of- cer had been elucidated based on RNA DNA from operator mutants. Her re- fice with the newly recruited Phil Sharp. tumor virus research, findings by Harold sults showed that various mutations af- All three of these scientists were Nobel Varmus, Mike Bishop, and others had fected the repressor protein’s ability to Prize winners, the latter two for work shown that oncogenes, and not viruses, bind to DNA (3, 4). Hopkins completed done at MIT. However, instead of con- were the major cause of human cancers. her Ph.D. in 1971. tinuing her research on DNA tumor vi- ‘‘The field of the molecular biology of ruses, Hopkins changed her focus to cancer was clearly in good hands, and A Dynamic Career RNA tumor viruses, considered then to I wanted to make a change,’’ said The accessibility of genes in lambda be a likely cause of many human can- Hopkins. phage originally drew Hopkins to genet- cers. Such a career shift would be diffi- After months of consideration, she ics. However, as her studies progressed cult for a junior faculty member to decided that her new focus would be the she became interested in applying her make today; switching tracks could genetics of vertebrate behavior, a field knowledge of genetics to a larger prob- alienate familiar funding sources or that had long interested her but was lit- lem. Inspired by the fear she had felt lengthen the time to achieve tenure. tle studied at the time. ‘‘From the day I when her mother contracted a mild ‘‘But back then, funding was easier to first heard about DNA in that classroom form of skin cancer when Hopkins was obtain, I suspect, and, to me, the two at Harvard, the three problems I wanted a child, she decided that her next step viruses seemed very similar and similar to work on were control of gene expres- would be to research the genetics of ani- even to phage lambda,’’ she said. ‘‘Intel- sion, cancer, and behavior,’’ she said. ‘‘I mal tumor viruses. Because of recent lectually, a virus is a virus.’’ just hadn’t known when the latter two successes in studying bacteriophage Hopkins and her students set out to would become accessible. So I decided genes, a small group of scientists was determine what features influence the to go and see if the genetics of behavior confident that cancer genes could even- host range for mouse RNA leukemia might have become accessible by now.’’ tually be just as accessible. viruses, an important factor in under- To begin her studies, Hopkins searched By the time Hopkins completed her standing why viruses cause cancer. Her for a suitable vertebrate model. In a Ph.D. at Harvard, Watson had estab- early studies in this area were some of stroke of luck, she heard at a cocktail lished the Cold Spring Harbor Laboratory the first genetic research on mouse party at Cold Spring Harbor that Ger- in Cold Spring Harbor, NY, particularly RNA tumor viruses. In a pivotal article man researcher Christiane Nusslein- for studying tumor viruses. ‘‘I don’t (5), published in the Journal of Virology Volhard had begun genetics studies on think I ever talked to him about my in- in 1977, Hopkins and her colleagues zebrafish. terest in tumor viruses. We were just obtained evidence that the viral capsid Hopkins had been awed when she independently on the same track,’’ said protein p30 was the determinant of the read about Nusslein-Volhard’s previous Hopkins. However, when she decided to B- or NB-tropism of murine leukemia discoveries on genes necessary for early begin tumor virus research at Cold viruses, determining whether the viruses development in the fruit fly, work that Spring Harbor, many colleagues in the could grow well just on type B mouse eventually earned her the Nobel Prize in phage field advised her against it. ‘‘A cells or on both type N and type B cells. Physiology or Medicine (8). Sensing that number of people who were still work- The result was surprising, because host Nusslein-Volhard’s nascent zebrafish ing on bacterial viruses said, ‘Goodbye, range was commonly thought to involve research held the key to performing we’ll never hear from you again,’ be- proteins located on the surface of a vertebrate genetics, Hopkins went to cause they thought cancer research is virus; the p30 protein was known to Germany in the late 1980s to plan be- the end of people’s careers, it isn’t ready reside deep inside the virus particle. havioral genetics studies on the new to be tackled. They told me that people Although Hopkins found this result fas- model. However, when she arrived, who go into cancer research are never cinating, she sensed that its mechanism Hopkins found that zebrafish genetics heard from again,’’ she said. ‘‘Fortu- in deciding host range would be difficult was not nearly as advanced as she had nately, they were wrong.’’ to elucidate, and she did not pursue this previously assumed. ‘‘I discovered that it Hopkins commuted to Cold Spring line of research. Her intuition was right; was just so primitive,’’ she said. She Harbor from Boston over the next 2 researchers are still working to solve this quickly abandoned the idea of doing years for her postdoctoral studies, problem. Interestingly, the capsid pro- behavioral genetics, deciding instead to spending part of each week analyzing tein was recently determined to confer focus on studying developmental genet- and characterizing DNA tumor viruses host range in the HIV and SIV viruses, ics in zebrafish. In a short time, Hop- before taking a 10-hour train ride home determining whether they infect monkey kins discovered that the fish held several to her husband. In 1973, she received a or human cells (6). advantages over previous vertebrate ge- call inviting her to become a faculty netics models: unlike mouse embryos, member at the newly constructed Cen- Fishing for a Model which are virtually inaccessible until ter for Cancer Research at MIT. For the next 15 years, members of Hop- birth, zebrafish mature outside the Thrilled at the opportunity, Hopkins kins’s laboratory continued to study the mother, remain transparent for a num- accepted. ‘‘The timing was just perfect mechanisms of host range and leukemo- ber of days, and become free-swimming, to provide the right facility in which to genesis by RNA tumor viruses, publish- feeding larvae in just 5 days. Thus, any work on cancer, the thing that I had ing more than 40 articles. Importantly, mutations that arise in the developing wanted to work on all my scientific life,’’ Hopkins identified transcriptional sig- fish are easily visible. she said. nals in RNA tumor viruses as a determi- However, the fish held some disad- After setting up her laboratory in the nant of the type of leukemia a virus in- vantages as well. With conventional summer of 1973, Hopkins reveled in the duces (7), a finding made without prior chemical or ␥-ray mutagenesis as the new research facility, built with an en- knowledge of the tissue specificity of only methods to produce mutations tire floor devoted to the study of tumor enhancers, which was discovered concur- within the germ line, cloning zebrafish viruses. Much like her experience at rently in other laboratories. However, genes was tedious and slow, taking up to Watson’s laboratory at Harvard, she was over time, Hopkins gradually felt that several years per gene. ‘‘I looked at this surrounded by the leaders in biology; she again wanted to change fields. Al- little animal and thought, ‘Oh, if only

12790 ͉ www.pnas.org͞cgi͞doi͞10.1073͞pnas.0405554101 Brownlee Downloaded by guest on September 28, 2021 we could get the genes for early devel- would the overall rate of mutagenesis be each mutation contributes to a specific BIOGRAPHY opment from this guy.’ But first, we had high enough to make a large screen fea- embryonic defect. Because this work to develop a method of mutagenesis sible? Subsequent studies published in requires understanding the development that would allow us to clone the genes 1996 and 1999, along with technological of many different organ systems in very quickly,’’ she said. Remembering innovations by her student and then depth, Hopkins has readily agreed to the P element insertional mutagenesis postdoctoral fellow Adam Amsterdam, collaborate with many additional labora- technique commonly used in Drosophila, showed that the answers were a defini- tories. ‘‘Our goal is to give these mu- Hopkins wondered whether a similar tive yes (11, 12). For the first time, Hop- tants away to as many people as possi- method could be developed in zebrafish. kins’s laboratories had succeeded in ble, because the more people who study Ironically, the method Hopkins’s labora- making insertional mutagenesis work in them, the faster the research will hap- tory ultimately developed involved in- a vertebrate model. pen,’’ she said. ‘‘Almost every mutant fecting germ-line cells with mouse retro- Over the past several years, Hopkins has a fascinating story to tell, once it viruses, the type of virus Hopkins had and her colleagues have used the tech- falls into the right hands.’’ previously studied in her cancer re- nique to perform a large-scale screen search. By inserting a retrovirus in the for all genes genetically essential for ze- Dual Interests germ line, insertional mutagenesis not brafish development. It is still a labori- Besides her zebrafish studies, Hopkins only creates a genetic mutation but also ous process: Hopkins’s team finds has been captivated in recent years by concurrently marks the mutation with important developmental genes by in- another academic interest: gender equity the virus’s own genes as a tag. fecting the zebrafish germ-line cells with in scientific research. During the mid- The possibility of using mouse retrovi- retroviruses, breeding the fish up to 1990s, she and other tenured female ruses to infect the fish germ line re- three generations, then examining devel- faculty members in science at MIT con- quired using viruses with extended host oping embryos under a microscope. ducted a wide-ranging study on poten- range, called pseudotyped viruses. How- Hopkins notes that only the gene clon- tial gender biases at the school. The ever, since their discovery some 20 years ing happens quickly: ‘‘We had hundreds findings were startling: among them, the earlier, these viruses had never been of thousands of fish pass through the lab fact that the School of Science had only grown to high enough titers to be useful in order to produce this work. It’sa 15 tenured women in 1994, compared

for such a purpose. Through another monumental undertaking.’’ The final with 197 tenured men. Women often GENETICS piece of good fortune, Hopkins learned results of these efforts, some 315 devel- also held significantly less laboratory that Ted Freedman of the University of opmental genes cloned, are revealed in space and often earned less pay than California at San Diego, motivated by her Inaugural Article (1). their male counterparts did. A summary his desire to use pseudotyped retrovi- According to Hopkins, many of the of the study published in 1999 (14) has ruses for human gene therapy, had suc- genes in her collection are the same been pivotal for inspiring change at MIT ceeded in growing these viruses to high genes that have proved genetically es- and many other institutions. Hopkins titers. ‘‘I said, ‘Oh my gosh,’ and I ran sential to development in C. elegans and has since taken a part-time position with to the telephone, called the lab, and to viability in yeast, reflecting a pro- the school’s higher administration to said, ‘Stop everything,’’’ she said. Hop- found level of genetic conservancy and work on achieving gender equity and kins quickly called Freedman and re- organization throughout evolution. Ad- greater faculty diversity within MIT. quested samples of the virus. When ditionally, as was found by other labora- In the future, Hopkins would like to Hopkins’s postdoctoral fellow, Shuo Lin, tories, many defects that were lethal to take more time outside her zebrafish injected the virus into 3-hour-old fish developing embryos are much like those work to explore again the feasibility of embryos, the virus was incorporated that plague humans, suggesting that sim- genetics research on behavior, including into germ-line cells, although at low fre- ilar genetic flaws are active in both spe- even gender inequalities in science and quencies (9). Hopkins’s graduate stu- cies. For example, Hopkins suspects that other forms of discrimination. However, dent, Nick Gaiano, was able to further mutations shown to cause cystic kidneys before she embarks on this new career increase virus titers about 100-fold, fi- in zebrafish lie in the same pathway as path she must choose an appropriate nally producing the first reliable infec- the those involved in human cystic kid- model: ‘‘I’m wondering whether or not tion rates (10). ney disease (13). it’s possible to study that problem with Two questions remained before the With this research published, Hopkins the fish, or whether you have to study it method could be used for genetics stud- says the next step will be to complete in humans,’’ she joked. ies: did retroviral infection cause muta- numerous shelf screens of the mutants, tions in the zebrafish germ line? And targeted searches to determine how Christen Brownlee, Science Writer

1. Amsterdam, A., Nissen, R. M., Sun, Z., Swindell, 7. Chatis, P. A., Holland, C. A., Hartley, J. W., Rowe, 12. Amsterdam, A., Burgess, S., Golling, G., Chen, E. C., Farrington, S. & Hopkins, N. (2004) W. P. & Hopkins, N. (1983) Proc. Natl. Acad. Sci. W., Sun, Z., Townsend, K., Farrington, S., Haldi, Proc. Natl. Acad. Sci. USA 101, 12792–12797. USA 80, 4408- 4411. M. & Hopkins, N. (1999) Genes Dev. 13, 2413– 2. Ptashne, M. (1967) Proc. Natl. Acad. Sci. USA 57, 8. Nusslein-Volhard, C., Wieschaus, E. & Klud- 2724. 306–313. ing, H. (1984) Roux’s Arch. Dev. Biol. 193, 13. Sun, Z., Amsterdam, A., Pazour, G. J., Cole, D. G., 3. Ptashne, M. & Hopkins, N. (1968) Proc. Natl. 267–282. Miller, M. S. & Hopkins, N. (2004) Development, Acad. Sci. USA 60, 1282–1287. 9. Lin, S., Gaiano, N., Culp, P., Burns, J. C., Fried- in press. 4. Hopkins, N. & Ptashne, M. (1971) in The Bacte- mann, T., Yee, J.-K. & Hopkins, N. (1994) Science 14. Chisholm, S. W., Friedman, J. I., Hopkins, N., riophage Lambda, ed. Hershey, A. D. (Cold Spring 265, 666–669. Harbor Lab. Press, Cold Spring Harbor, NY), pp. Kleitman, D., Matthews, J. L., Potter, M. C., 571–574. 10. Gaiano, N., Allende, M., Amsterdam, A., Rizzoli, P. M., Royden, L., Silbey, R. J., 5. Hopkins, N., Schindler, J. & Hynes, R. (1977) Kawakami, K. & Hopkins, N. (1996) Proc. Natl. Stubbe, J., et al. (1999) MIT Faculty Newsletter, J. Virol. 21, 309–318. Acad. Sci. USA 93, 7777–7782. Special Edition: A Study on the Status of Women 6. Stremlau, M., Owens, C. M., Perron, M. J., 11. Gaiano, N., Amsterdam, A., Allende, M., Faculty in Science at MIT. Issue 4, Vol. 11. Kiessling, M., Autissier, P. & Sodroski, J. (2004) Kawakami, K., Becker, T. & Hopkins, N. (1996) Available at http:͞͞web.mit.edu͞fnl͞women͞ Nature 427, 848–853. Nature 383, 829–832. women.html.

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