Sohyun Ahn: Thinking Things Through

JASON VARNEY | VARNEYPHOTO.COM

Commenting on the immaculate desk of Sohyun Ahn elicits an embarrassed giggle, but practically any other question gets a thoughtful look from behind her blue cat's-eye glasses. Throughout her career, Ahn has made a habit of stepping back and studying the situation before acting. "It's important to take a break and think about things," she says.

When faced with the choice of where to pursue her doctorate, Ahn trekked to see her family in Seoul, South Korea. Her choice: to study under a Johns Hopkins heavyweight or join David Ginty, so new he wasn't even listed in the graduate brochure. With her parents as sounding boards, finally she decided to go with a mentor who would be able to spend more time training her in lab techniques. Late one night, she tiptoed through her parent's house and dialed a Maryland phone number. When Ginty answered, she asked if he still had an empty bench.

It turned out to be a good decision. Ginty worked alongside her at the bench and helped focus her experiments on key questions. In five years she tracked CREB's role in stimulus-dependent transcription of c-fos and in mediating long-term effects of nerve growth factor. ¹ As she was ready to graduate, Ahn says she realized that the key questions now needed to be asked in vivo.

So Ahn chose a postdoc with Alexandra Joyner, a mouse genetics pioneer at the New York University School of Medicine. Ahn wondered how the sonic hedgehog (Shh) gradient influenced developing tissues. While other labs focused on the gradient itself, Ahn and Joyner designed a fate-mapping technique that genetically marked and tracked cells responding to Shh. Using this method, Ahn identified specific cell types that respond to the gradient. ²

Ahn still studies Shh in her lab at the National Institutes of Health and is trying to identify changes in Shh-mediated gene expression in stem cells versus non-stem cells. More recently, Ahn says she's been contemplating how the brain uses its regenerative cells and intends to develop a fate-mapping technique to map neural circuits formed by stem cells. She hopes these circuits are the key to forming new memories or to the learning process.

"Soyhun's an amazing scientist," says former colleague Mark Zervas at Brown University. "She has a knack for picking the critical experiment that gets at the heart of the question."

Ahn isn't too surprised at this compliment. In her postdoc days, she says, most of her eureka moments hit in the midst of her more tedious research chores and Zervas' bench was right next to the microtome.

Title: Investigator in the Unit of Developmental Neurogenetics, Laboratory of Mammalian Genes and Development,
National Institute of Child Health and Human Development, NIH
Age: 36
Representative Publications: