November 10, 2006

Speaker delves into cell cycle’s complexity

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Speaker delves into cell cycle's complexity

Harvard’s Marc Kirschner, Ph.D., delivers this week’s Discovery Lecture.
Photo by Susan Urmy

Harvard’s Marc Kirschner, Ph.D., delivers this week’s Discovery Lecture.
Photo by Susan Urmy

In the life cycle of a cell, as in many things in life, timing is everything, Marc Kirschner, Ph.D., told the audience at this week's Discovery Lecture.

Kirschner, professor and chair of Systems Biology at Harvard Medical School, detailed his laboratory's efforts to understand the intricate dance of proteins that regulate the cell cycle — the steps of cell division. His group has focused particularly on the role of protein degradation in controlling the timing of events in the cell cycle.

“I'm going to talk about something that goes down deep biochemically,” Kirschner said as he began his lecture. “It's a subject which is so complicated that mechanistic biochemistry isn't often done.”

Likening the cell cycle process to a Rube Goldberg machine — a complex device that performs tasks in a convoluted way — Kirschner said his team is after “how this machine really functions.

“That's something that typically we haven't really investigated, and here's an opportunity to do so,” he said.

Protein degradation plays a major role in the transitions between steps of the cell cycle. Kirschner explained how proteins are tagged for destruction by a process called “ubiquitination,” and described biochemical experiments to follow which proteins are tagged, and the order of those events.

This process of tagging proteins for destruction — and the complementary process of removing those ubiquitin tags — goes awry in a variety of human diseases, he said.

Kirschner is a member of the National Academy of Sciences and the American Academy of Arts and Sciences. He is a Foreign Member of the Royal Society of London and of the Academia Europaea.

In 2003, he received the E.B. Wilson Medal, the American Society of Cell Biology's highest honor, named for an early 20th century pioneer of American biology who advocated the chromosomal theory of inheritance. The award is given by scientific peers to those who have made significant and far-reaching contributions to cell biology over the course of a career.

In addition to being a featured Discovery Lecture Series speaker, Kirschner was also the Department of Cell and Developmental Biology Distinguished Faculty Lecturer and the Orrin Ingram Distinguished Lecturer.

The newly established Cell and Developmental Biology Distinguished Lecture Series honors the more than 80 years of excellence in research, teaching and service by the faculty in the department.

The Orrin Ingram Distinguished Lectureship Series features speakers who are conducting landmark work in the field of cancer science. It honors the chair of the Vanderbilt-Ingram Cancer Center's Board of Overseers for his leadership and generosity.

For a complete schedule of the Discovery Lecture Series and archived video of previous lectures, go to