Age-dependent structural reorganization of utricular ribbon synapses
2023
Susann Michanski | Susann Michanski | Susann Michanski | Timo Henneck | Mohona Mukhopadhyay | Anna M. Steyer | Anna M. Steyer | Paola Agüi Gonzalez | Katharina Grewe | Peter Ilgen | Peter Ilgen | Peter Ilgen | Mehmet Gültas | Eugenio F. Fornasiero | Stefan Jakobs | Stefan Jakobs | Stefan Jakobs | Wiebke Möbius | Wiebke Möbius | Christian Vogl | Christian Vogl | Christian Vogl | Tina Pangršič | Tina Pangršič | Tina Pangršič | Silvio O. Rizzoli | Carolin Wichmann | Carolin Wichmann | Carolin Wichmann
In mammals, spatial orientation is synaptically-encoded by sensory hair cells of the vestibular labyrinth. Vestibular hair cells (VHCs) harbor synaptic ribbons at their presynaptic active zones (AZs), which play a critical role in molecular scaffolding and facilitate synaptic release and vesicular replenishment. With advancing age, the prevalence of vestibular deficits increases; yet, the underlying mechanisms are not well understood and the possible accompanying morphological changes in the VHC synapses have not yet been systematically examined. We investigated the effects of maturation and aging on the ultrastructure of the ribbon-type AZs in murine utricles using various electron microscopic techniques and combined them with confocal and super-resolution light microscopy as well as metabolic imaging up to 1 year of age. In older animals, we detected predominantly in type I VHCs the formation of floating ribbon clusters, mostly consisting of newly synthesized ribbon material. Our findings suggest that VHC ribbon-type AZs undergo dramatic structural alterations upon aging.
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