Some Properties of the Silent Pool of Synaptic Vesicles and Further Characterisation of the Mode of Vesicular Exocytosis

Kuan, Tae Guen (2020) Some Properties of the Silent Pool of Synaptic Vesicles and Further Characterisation of the Mode of Vesicular Exocytosis. Doctoral thesis, University of Central Lancashire.

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Abstract

The research reported in this thesis concerns the properties of the three distinct pools of SVs that are present within nerve terminals; the readily releasable pool (RRP), the reserve pool (RP), and the silent pool (SP). Normally, the RRP and the RP can contribute to release during strong stimulation, however, the SP does not normally get released and so this has not been very well characterised. Herein, we have successfully managed to evoke the release of the SP of glutamate (GLU) containing SVs in cerebral cortical synaptosomes using Roscovitine (Cdk5 inhibitor) and Fluoxetine (widely used antidepressant drug). In addition, using western blotting of synaptosomes that had been stimulated under various conditions, preliminary experiments were performed to ascertain whether changes in specific phosphorylation sites on Synapsin I (Syn I) correlated with SP release in the presence of Roscovitine: the Cdk5 phosphorylated site at Ser-553 seemed to have reduced phosphorylation whilst the CaMKII phosphorylated site Ser-603 seemed to have and increase in phosphorylation.
Moreover, some further properties of Kiss-and-run (KR) and Full fusion (FF) mode of exocytosis have been characterised herein, including the role of Dynamin (Dyn), PKA, and Calcium channels and also the effect of actin cytoskeleton disassembly and stabilisation on the mode of exocytosis. These sections of the study determined the further difference between the Dyn dependent and the Non-muscle Myosin-II (NM-II) dependent KR modes. Such findings suggest that rather than one common KR mechanisms that can be regulated by either Dyn or NM-II, there is probably two distinct KR mechanisms that get activated by different stimulation conditions.


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