Joseph H. Bayle, Ph.D.
Ph.D., Princeton University
Postdoc: Stanford University School of Medicine
Academic Leadership - Faculty Mentor
Molecular Physiology and Physiology Graduate Program
MPCS Training Program
The phenotypes that result from a traditional gene knockout frequently give only snapshot's view of the effect of a gene's loss. However, mammalian development is highly dynamic and coordinated, and many proteins have multiple roles that can be obscured in a knockout. To permit the dynamic experimental control of gene function my laboratory develops conditional allele techniques that are rapid, reversible and function at the protein level. In these systems a target protein in mice is controlled rapidly and specifically with a generic high-affinity, cell-permeable small molecule rapamycin or derivatives called rapalogs in a mouse background that is resistant to the physiological effects of the drug.
In one scheme a small, destabilizing protein domain capable of binding to the small molecule is fused by a gene knock-in to the target. Addition of drug inducibly and reversibly stabilizes the structural integrity and function of the protein fusion. Current studies focus on the conditional chemical regulation of Pax6, a transcription factor that drives key patterning and cell fate decisions in several areas of the nervous system of the developing mouse including the eye, cerebral cortex, hindbrain, and spinal cord.
A second approach uses an engineered mouse we have developed, the 'exporter' mouse, to dock a nuclear target protein such as a transcription factor with a nuclear export signal when drug is added to the system. This mislocalizes the protein to rapidly and reversibly remove its nuclear function. This switch is rapid, on the order of tens of minutes. Please see the Snail1-Frb nuclear export video.
Another conditional protein allele technique developed by Yunguang Liu in the lab targets transmembrane receptors by driving the endocytosis of a targeted receptor in the presence of rapamycin. This switch is also efficient and rapid and can be broadly applied. Please see the video demonstrating regulated endocytosis of a Frb tagged receptor from the cell surface through Rab5 positive vesicles over a 45 minute timecourse.