CSB neurobiologists identify switch that turns muscles on and off during sleep

CSB Professor John Peever, CSB PhD grad Zoltan Torontali and CSB RA Jimmy Fraigne have demonstrated a new link between arousal and muscle paralysis in mice using behavioral, electrophysiological, and chemogenetic strategies in a paper in Current Biology.
During REM sleep, muscle paralysis is induced by a region of the brain called the Sublaterodorsal Tegmental Nucleus (SLD). Involuntary muscle paralysis during wakefulness can occur in the natural phenomenon of cataplexy, whereas sleep is involuntarily induced in narcolepsy.
Prof Peever’s lab found that activation of SLD neurons in both narcoleptic and normal mice promotes cataplexy, whereas SLD silencing prevents cataplexy. This region of the brain therefore couples arousal state and motor activity during REM sleep and wakefulness.
This new understanding has the potential to treat muscular disorders in humans. In Parkinsons’s disease, the affected person’s muscles are in a continual state of rigour during wakefulness, but this rigour relaxes during REM sleep. Prof Peever dreams of helping Parkinson’s patients by applying this new understanding of the SLD to tune their muscle tension during wakefulness.
You can read more about this insight in a story from UofT News and in the Current Biology paper.

Prof Vince Tropepe’s lab using zebrafish as a vertebrate model for Usher Syndrome-linked blindness

The laboratory of CSB Chair Vincent Tropepe has received funding from Fighting Blindness Canada to conduct research using zebrafish to study Usher syndrome, a genetic condition that results in hearing and vision loss. Loss of vision in Usher syndrome is the result of retinal degeneration, but the mechanism through which degeneration happens in unknown.

Clues to the way retinal degeneration happens in Usher syndrome can be found in the zebrafish model organism. The gene that is altered in 20% of humans with Usher syndrome is also present in zebrafish, and mutations in zebrafish that mimic the Usher-linked changes in this ‘protocadherin’ gene can result in reduced hearing and vision.

When the zebrafish protocadherin protein Pcdh15b is mutated in the lab, the integrity of the outer segment of retinal cells, the region that captures light, is compromised. Mutants have a progressive loss of photoreceptor outer segments, which can be attenuated by darkness or exacerbated by light exposure.

The Tropepe lab will characterize the subcellular defects that underscore photoreceptor degeneration, identify Pcdh15b-binding proteins to reveal novel Pcdh15-dependent mechanisms for photoreceptor maintenance, and catalogue the different forms of Pcdh15b to identify ones that will prevent retinal degeneration as a potential gene therapy.

We are grateful to Fighting Blindness Canada for their support; you can read more about their funded research and also donate to them here.

Neuroscientist Dr Jessica Pressey joins CSB in 2020 as Assistant Professor, Teaching Stream

We are fortunate to have recruited Jessica Pressey to CSB as an Assistant Professor, Teaching-Stream (3-year CLTA) as of Jan 1, 2020. Professor Pressey graduated with a PhD from Dean Woodin’s lab in 2015 and completed postdoctoral research at INSERM’s Institut du Fer à Moulin in Paris, France.

Her field of expertise is synaptic transmission, neuroplasticity, and brain development and as such she will be a valuable addition to CSB’s Animal Physiology Major program and for CSB research project course students studying electrophysiology.

Congratulations, Professor Pressey!