Current Research

Tim Stearns's research focuses on cell biology, particularly the microtubule cytoskeleton, a dynamic network of filaments and associated motors and organizing factors found in all eukaryotic cells. He will create a program that will train undergraduates to be the next generation of leaders in biological research through close interaction with faculty members in course work, research, and advising.

Dr. Stearns used his HHMI Professor grant to create a new educational program at Stanford University, the Pre-Grad Program, which sought to train a select group of undergraduates to be the next generation of leaders in biological research through close interaction with faculty members in course work, research, and advising.

The educational centerpiece of the program was a project lab course designed especially for students with an interest in pursuing research. Students in the program took a two-quarter course, the first part a lecture/discussion of what they will be doing in the lab, and the second the lab itself. Most of the students then chose a lab in which to do an honors thesis based on research in their junior and senior years.

Another important component is that the students were given the opportunity to attend a national science meeting. The experience with the Pre-Grad program has led to a complete revision of the undergraduate lab course taken by most biology-oriented Stanford undergraduates, so that it reflects the values of students doing real research with current technology, and participating in elements of experimental design.

Research in the Stearns Lab

Dr. Stearns' lab group is at the forefront of research on the structure, function, and duplication of the centrosome and ciium. In research on cell cycle control of centrosome duplication, they identified Cdk2/cyclin E as the cell cycle kinase responsible for initiating centrosome duplication at G1S and created an in vitro assay to demonstrate that centriole separation does not occur in the absence of Cdk2 activity. They also showed that components of the G1S ubiquitin proteolysis machinery are essential to the duplication process, and have recently identified a new regulatory module involved in controlling duplication.

Most recently, Dr. Stearns's lab group identified a regulatory mechanism that limits duplication to once per cell cycle in human cells, and they are now investigating how that regulation goes awry in cancer cells. In research on mechanisms of microtubule organization by the centrosome, Dr. Stearns and others have shown that a third member of the tubulin superfamily, gamma-tubulin, is important for microtubule nucleation and that gamma-tubulin is part of a large ring-shaped complex that includes five members of a novel protein family in addition to gamma-tubulin.

They also recently identified two new members of the tubulin superfamily in humans, delta-tubulin and epsilon-tubulin, and have shown that epsilon-tubulin is required for centrosome duplication. In research on biogenesis of the primary cilium, a critical eukarytotic signaling organelle, Dr. Stearns has found that asymmetry in the age of the centriole is linked to the timing of cilium formation after cell division, and has identified new components of the link between the centrosome, cilium and membrane trafficking. The dynamic polymerization and depolymerization of microtubules is essential to their function, and Dr. Stearns's lab was among the first to use green fluorescent protein-tubulin fusions to visualize microtubules in living cells and characterize the relationship between dynamics and spindle orientation.

As of May 2014

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