Ready, Reset, Go

By Karen Hopkin Ready, Reset, Go Rudolf Jaenisch enjoys climbing mountains, rafting rapids, and unraveling the secrets of pluripotency—knowledge that could someday lead to personalized regenerative medicine. RUDOLF JAENISCH Professor of Biology, MIT Member, Whitehead Institute F1000 Head of Faculty, Genomics & Genetics Porter Gifford It was a misbehaving virus that drew Rudolf Jaenisch to epigenetics. As a postdoc in Arnold Levine’s

Written byKaren Hopkin
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It was a misbehaving virus that drew Rudolf Jaenisch to epigenetics. As a postdoc in Arnold Levine’s lab in Princeton in the early 1970s, Jaenisch was studying the DNA tumor virus SV40. “The virus makes only skin tumors when you inject it into a mouse,” he says. “Not brain tumors or liver tumors. And I wondered why.” Two possible explanations came to mind: either the virus couldn’t infect brain cells, or it could infect them, but was then silenced so that it could not transform them. To figure out which was correct, Jaenisch needed a way to make sure the virus got into cells other than skin. That’s when he stumbled across the classic 1967 paper by developmental geneticist Beatrice Mintz of the Fox Chase Cancer Center. Mintz had managed to combine cells from two different embryos to form mice that were chimeric. “What blew me away was the idea ...

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