Following a Different Track

By the time Tom Maniatis reached his senior year of high school in Denver, his future seemed set. Nobody in his family had attended college, and he didn’t plan to, either. Instead, he was going to become a firefighter. “That was my father’s dream” for me, he says.

However, his life took a detour when he traveled with his high school track team to the state finals at the University of Colorado, in Boulder. The meet itself wasn’t memorable. Maniatis, who ran the quarter mile and mile races, was no track star, he admits. But the visit afforded him plenty of time to explore the campus. “I’d never had any concept or experience of what college was,” he recalls. He was captivated by “the ambiance of the campus and listening to what people were saying. I said, ‘Wow, I think I would like that.’” When he got home, he decided to apply but discovered he had missed the deadline. A college guidance counselor helped him get admitted anyway.

Maniatis became one of the foremost molecular biologists. “He’s a deeply thoughtful, intense, almost obsessional scientist with a deep commitment to finding things out and getting things right,” says neuroscientist and Nobel laureate Richard Axel of Columbia University, who has known Maniatis for 50 years. Maniatis was one of the pioneers of molecular cloning, the techniques for isolating and studying individual genes. Although he didn’t originate the concept of cloning genes, he invented tools that made it possible, so that “even the least skilled among us could exploit the technology,” as one scientist put it. Maniatis’s work not only helped researchers tackle a host of basic science questions—including what specific genes do, how cells control genes’ activity, and how they are arrayed in the genome—but also was instrumental for the burgeoning biotechnology industry.

He also made a mark by co-writing one of the most important how-tos in biology: Molecular Cloning: A Laboratory Manual. First published in 1982, the book—which some researchers referred to as the Maniatis manual—taught readers how to clone genes, disseminating the techniques worldwide. “It had a profound impact on molecular biology,” says Angela Creager, a science historian at Princeton University who has written about the manual. For that dual legacy, Maniatis shared the 2012 Lasker~Koshland Special Achievement Award in Medical Science.

An Unlikely Scientist
Maniatis was born in Denver in 1943 and grew up there. His father, a firefighter, had attended a vocational high school. His mother hadn’t finished high school because of disruptions from the Great Depression and the Dust Bowl. Maniatis didn’t develop an interest in science until his senior year of high school, when he took chemistry from an inspirational teacher. “He made all the difference in me going to college,” Maniatis says. Still, he didn’t decide to abandon his firefighting plans until he attended the track meet.

The University of Colorado was building one of the country’s first molecular biology departments, Maniatis says, and “I was very fortunate to be there” at the time. In 1965, he read the newly published book Molecular Biology of the Gene, by James Watson, the Nobel Prize winner who had co-discovered the structure of DNA in 1953, and it persuaded him to pursue a career in the field. “The book was written and illustrated so clearly, and was so exciting, I knew then that I wanted to be a molecular biologist,” Maniatis says. His undergraduate adviser also offered a crucial boost, giving Maniatis the project that became his master’s degree research at Colorado. Maniatis used one of the first UV lasers to probe embryonic development in chickens. The project shaped his later career, he says, because “it really got me interested in technology and development of methods and tools to study biology.”

His next academic stop was Vanderbilt University, where he studied a compact form of DNA for his PhD. Maniatis finished his scientific apprenticeship as a postdoc in the lab of molecular biologist Mark Ptashne of Harvard University. Ptashne, winner of the 1997 Albert Lasker Basic Medical Research Award, was studying a type of virus to understand a genetic switch that turns genes on and off. Maniatis analyzed how key parts of the switch known as operators worked and then determined their DNA sequences. Even as a postdoc, Maniatis “already had a strong reputation [in the university’s biology labs] as a top-notch scientist,” says Argiris Efstratiadis, then a Harvard PhD student and now an emeritus molecular geneticist at Columbia University.

After Maniatis finished his postdoc, Harvard offered him a junior faculty position and the opportunity to start his own lab. He was about to make several pivotal discoveries. The work “changed the field from more observational to more mechanistic,” says immunologist Ed Fritsch of the Dana–Farber Cancer Institute, a former postdoc in Maniatis’s lab and co-author of the cloning manual. In the mid-1970s, scientists were eager to generate DNA segments known as complementary DNAs (cDNAs) that could serve as molecular probes for analyzing gene activity or identifying specific genes. Other researchers had gone part of the way. They had isolated messenger RNA (mRNA) molecules, which carry the instructions for synthesizing proteins, and then added an enzyme that creates a DNA version of the RNA. But the approach had yielded only partial cDNAs. Maniatis, Efstratiadis, and colleagues improved the method by incorporating more DNA building blocks into the mixture. “That was the key,” Maniatis says. In 1975, the scientists reported that they had produced the first full-length cDNAs by using the mRNA for rabbit β-globin, part of the hemoglobin protein, as a template. Unlike the double-stranded DNA in a human cell, the cDNAs that the scientists had created consisted of only a single strand. But later in 1975, the researchers filled in the matching strand.

Maniatis and colleagues wanted to go further and clone that sequence. Pulling it off would require them to insert the DNA into bacteria, which would act as molecular photocopiers. But work that involved mixing DNA from different organisms, yielding what is known as recombinant DNA, was controversial. Opponents worried that dangerous organisms could result. Maniatis says that students would confront him in the hallways at Harvard and chide him about his science. “It was seen as self-serving and morally unforgivable,” he recalls. In 1976, Cambridge, Massachusetts, where Maniatis’s Harvard lab was located, temporarily banned recombinant DNA research. At the time it was the only city in the world to take that action, Maniatis says. The cloning effort stalled. “We had everything ready, and we couldn’t do anything,” he says.

Watson then stepped in, offering the researchers space at the Cold Spring Harbor Laboratory (CSHL) in New York to conduct their experiments. The scientists achieved their goal in 1976, producing the first clones of their lab-made rabbit β-globin sequence. Methods for cloning cDNAs and full genes were indispensable in molecular biology for the next several decades, Fritsch says. “They were the most important technologies in the field until whole-genome sequencing came along.” For example, cloned cDNAs proved invaluable for producing recombinant proteins, including insulin, that were critical for the development of the biotechnology industry.

Going West
To his regret, Maniatis realized he would have to leave Harvard to continue his investigations. Although Cambridge had lifted its recombinant DNA moratorium, scientists had to perform the procedures in specialized containment facilities, which Harvard lacked. In 1977, he accepted an offer from the California Institute of Technology (Caltech), which had a containment facility. He and colleagues capitalized on their cDNA work to build genomic DNA libraries for several organisms, including humans. Each collection contained the entire genome, broken into pieces and packaged inside viruses. Scientists had previously made libraries for some organisms with relatively small genomes, such as fruit flies. But “people thought at that time that the same was not feasible for mammals because of the about 20-fold larger genome size,” Efstratiadis says. However, Maniatis and his team used a new approach of fragmenting the genome into small, random chunks. Although each virus contains only a small fraction of our DNA, Maniatis says, the library consists of billions of viruses, and together they carry all of the human genome.

The libraries were a boon because scientists could use them to clone and identify specific genes and map their relative positions. In 1980, for instance, Maniatis, Fritsch, and another postdoc, Richard Lawn, showed that humans carry five versions of the β-globin gene that reside close together on the same chromosome. Many other scientists also took advantage of those resources. “Loads of genes were isolated from these libraries,” says molecular biologist Nick Proudfoot of the University of Oxford, who was a postdoc in Maniatis’s lab at Caltech.

“They really opened up the recombinant DNA field.”

Years later, the international effort to sequence the human genome also relied on the library approach.

One reason that Maniatis was so influential, Proudfoot says, was that “he shared his results and ideas with anyone who was interested.” The libraries were a prime example. Maniatis says that he wanted to make them available but didn’t want to break the university’s rules on intellectual property. When he checked with Caltech’s intellectual property office, an employee told him, “Ah, I don’t see anything here,” he says. So he sent samples to any researchers who requested them without any strings attached.

Cambridge Redux
In 1980, Maniatis decided to return to Harvard, in part because the National Institutes of Health had relaxed its containment rules for recombinant DNA work. Once he had set up his new lab there, Maniatis helped scientists solve one of the big mysteries of the time. In the 1970s, molecular biologists Phillip Sharp of MIT and Richard Roberts of CSHL and their colleagues had discovered that genes contain extraneous sequences known as introns. When starting to synthesize a protein encoded by a particular gene, the cell first makes an RNA copy of the gene—which also contains the superfluous sequences. However, introns don’t code for portions of the final protein because the cell snips them out of the RNA and rejoins the remaining pieces in a process called splicing. For the discovery, Sharp earned the 1988 Albert Lasker Basic Medical Research Award, and he and Roberts shared the 1993 Nobel Prize in physiology or medicine.

When Maniatis turned his attention to splicing, researchers hadn’t figured out how it occurs, in part because splicing was hard to study in cells. Maniatis’s lab replicated the process in the test tube, a first that proved crucial for further research, Proudfoot says.

“It was the magic experimental tool that allowed the biology of splicing to be picked apart.”

Maniatis’s lab later helped uncover the mechanics of splicing and elucidated how cells can change where they cut and rejoin RNAs to produce different versions of proteins. “He provided the first evidence that splicing could be regulated to alter the properties and functions of genes,” Axel says.

Maniatis’s achievements stemmed from several qualities, say researchers who worked with him. He set high standards, Proudfoot says. “He expected people in his lab to think hard and to work hard.” At the same time, he drew out the best from colleagues and students because of his personality and desire to help, Fritsch says. “Tom is very humble. He’s very compassionate. He connects with people.”

Manual Labor

Maniatis’s other major contribution, the molecular cloning manual, grew out of a summer lab course that he and Fritsch taught at CSHL in 1980. Maniatis says that Watson, who “was not a person it was easy to say no to,” asked him to transform the course material they had amassed into a textbook. He, Fritsch, and Joseph Sambrook, then CSHL’s scientific director, started writing.

The manual they produced was so useful, Creager says, because even though researchers were performing molecular cloning at the time, “it was so darn hard to do.” The book offered tried and true procedures, she says. Moreover, the authors included plenty of background information. “It explains enough about why the techniques work that people could troubleshoot,” she says. As a consequence, even newbies with no one to teach them could learn how to clone. For a niche publication, the manual was a hit, selling more than 200,000 copies. And it wasn’t important just for molecular biology, Creager says: “Over time, it impacted all of biology.”

After the manual was published, Maniatis continued to teach and conduct research at Harvard for nearly 30 years before moving to Columbia University in 2010. One topic he and colleagues have probed is an identity system for brain cells. As the brain develops, neurons send out branches called dendrites that link with dendrites from other neurons to form neural circuits. But if two dendrites from the same cell meet, they recoil. Maniatis and colleagues found that distinctive proteins, known as protocadherins, on dendrites function like barcodes, allowing each branch to recognize and avoid other dendrites from the same cell. “Every neuron has a self-identity” specified by protocadherins, he says.

Maniatis also took his research in a new direction after his sister developed the neurodegenerative disease amyotrophic lateral sclerosis (ALS). His lab has been using molecular techniques to investigate what goes wrong in ALS, focusing on how brain cells known as astrocytes and microglia promote the deterioration of neurons. In addition, in 2011 he co-founded the New York Genome Center “as the means of bringing genomic technology to ALS research.”

Maniatis says his career has been “a never-ending, exciting run,” and he hopes to continue his work. “I have a deep fascination with complex biological mechanisms,” he says.

By Mitchell Leslie