Regulation of long distance neuropeptide signaling in aging
Final Report Abstract
The aim of this project was to investigate molecular mechanisms of neuropeptide release from aging mammalian neurons. For the release, neuropeptides are packaged in dense core vesicles (DCVs), which fuse with plasma membrane upon neuronal stimulation. Neuronal DCV fusion is regulated by a complex molecular machinery that is not well understood. In this project, I tested the role of several components of this machinery in the regulation of DCV fusion using overexpressed fluorescently tagged neuropeptide Y (NPY) as a DCV reporter in cultured mouse hippocampal neurons. One of the potential regulators of the DCV release is tomosyn (STXBP5), an evolutionary conserved SNARE-domain containing protein that acts as an inhibitor of synaptic vesicle fusion. I hypothesized that tomosyn negatively regulates fusion of neuronal DCV in a similar manner, and that loss of tomosyn would result in the increased neuropeptide secretion. Interestingly, loss of tomosyn did not affect fusion properties of neuronal DCVs, but, surprisingly, led to a strong reduction of the intracellular DCV pool and nearly complete loss of some DCV cargos, such as BDNF. In the absence of tomosyn, neurons failed to accumulate DCVs, even when spontaneous neuronal firing was silenced. During follow-up experiments, I found that tomosyn affects formation of DCVs at the early steps of secretory pathway via yet unidentified mechanism. Tomosyn is genetically associated with neurodevelopmental disorders in humans and was found to regulate lifespan in C. elegans. Thus, the newly identified function of tomosyn in the maintenance of intracellular neuropeptide stores may explain its implication in aging and disease. Future work is required for elucidation of the molecular mechanism of tomosyn’s action in the maintenance of DCV pool.
Publications
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Tomosyn affects dense core vesicle composition but not exocytosis in mammalian neurons. eLife. 2023; 12: e85561.
Aygul Subkhangulova, Miguel A Gonzalez-Lozano, Alexander JA Groffen, Jan RT van Weering, August B Smit, Ruud F Toonen, Matthijs Verhage
