Frustration gave way to satisfaction when an experiment that seemed to foil St. Jude researchers actually brought them a step closer to understanding how the brain maintains healthy lines of communications among its nerves.
The researchers, headed by James Morgan, PhD, Developmental Neurobiology chair, were studying how the cerebellum - the lower, back part of the brain - maintains the structure and function of synapses. Synapses are the intimate connections between nerves that allow them to communicate with each other. Morgan had previously discovered that proteins called synaptrophins maintain countless millions of synapses in good working order.
In the current study, the St. Jude team focused on two synaptotrophins in the cerebellum, Cbln1 and Cbln3. The researchers found that nerves called granule cells secrete Cbln1 and Cbln3 bound together as a single unit. This pair of proteins then crosses over the synapse to its target nerves - the Purkinje cells.
Previously, Morgan's lab showed that mice lacking the genes for Cbln1 had abnormal connections between granule cells and Purkinje cells and were unsteady on their feet. Since Cbln1 and Cbln3 were always secreted as a team, the researchers thought that eliminating Cbln3 in mice would be just as damaging as eliminating Cbln1. But in the current study, eliminating Cbln3 had no apparent affect - much to the surprise of Dashi Bao, a former postdoctoral fellow who did much of this work.