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Cells rely on the centrosome to organize the microtubule cytoskeleton and form cilia used to sense and respond to the environment. Stearns uses genetics and advanced imaging to reveal the molecular logic underlying centrosome duplication and cilia assembly and how disruption of these processes leads to developmental disorders and cancer.

A finely regulated internal architecture underlies cell division, motility, and environmental responsiveness. Two small organelles, the centrosome and the cilium, are central to this organization. The centrosome organizes the microtubules that traffic components throughout the cell and that form the mitotic spindle. The centrosome also templates formation of the primary cilium, a sensor for external cues that is found on most human cells. Defects in either structure can disrupt development, impair signaling, and lead to disease, including cancer and inherited ciliopathies.

The Stearns lab has made many of the key discoveries that explain how centrosomes and cilia are built and maintained during the cell cycle, and disassembled at specific points in development. His laboratory identified γ-tubulin as the initiator of microtubule growth and defined the multiprotein complex that anchors it at the centrosome. The group showed that centrosomes duplicate only once per cell cycle because centrioles disengage at anaphase, a licensing step that ensures fidelity of division. They also discovered new members of the tubulin family and demonstrated their essential role in constructing the triplet microtubules that give centrioles their unique architecture

The lab has paired discovery with technical innovation. They were among the first to use GFP tagging to visualize microtubules and centrosomes in living cells, to apply BioID proximity labeling to map centrosome proteins, and to employ super-resolution and expansion microscopy to study organelle architecture. Recent work has revealed the structural basis of centriole appendages, tracked signaling proteins moving within cilia, and shown how transient cilia control the Hedgehog pathway and the cell cycle.

The Stearns lab also studies how specialized cells produce large numbers of cilia. In multiciliated tissues of the airway and brain, and in sensory neurons of the nose, they discovered mechanisms of centriole amplification and migration that allow cells to generate tens to hundreds of cilia for movement and detection. Expanding beyond classical model systems, they pioneered the use of chytrid fungi to study centrosomes and cilia in evolution, uncovering how centrioles remodel to match different stages of the organism’s life cycle.

These studies together define fundamental rules for how cells build and regulate centrosomes and cilia, and how disruption of these processes alters development and human health.

Stearns is also known for his deep commitment to education and mentorship. At Stanford he trained more than forty graduate students and postdocs, many of whom now lead independent laboratories. He has taught widely, from Cold Spring Harbor to courses in Africa and South America, and received a Howard Hughes Medical Institute Professor award for innovation in undergraduate education. Since joining Rockefeller in 2022, he has served as Dean of Graduate and Postgraduate Studies and Vice President for Educational Affairs, leading new initiatives in scientific training while continuing his research on the cellular dynamics of centrosomes and cilia.