Cholesterol-Dependent Kinase Activity Regulates Transmitter Release from Cerebellar Synapses

Abstract

Changes in membrane cholesterol content can alter protein kinase activity, however, it is not known whether kinases regulating transmitter release are sensitive to membrane cholesterol content. Here we have used the cholesterol extracting agent methyl-␤-cyclodextrin to measure the effects of acute cholesterol reduction on transmitter release from cultured cerebellar neurons. Cholesterol depletion increased the frequency of spontaneous transmitter release without altering the amplitude and time course of mEPSCs. Evoked transmitter release was decreased by cholesterol extraction and the paired pulse ratio was also decreased. Alterations in synaptic transmission were not associated with failure of action potential generation or changes in presynaptic Ca 2ϩ signaling. Both the increase in mEPSC frequency and the change in paired pulse ratio were blocked by the broad spectrum protein kinase inhibitor staurosporine. The increase in mEPSC frequency was also sensitive to selective inhibitors of PKC and PKA. Our results therefore demonstrate that the activity of presynaptic protein kinases that regulate spontaneous and evoked neurotransmitter release is sensitive to changes of membrane cholesterol content.

Cholesterol 24S-Hydroxylase Overexpression Inhibits the Liver X Receptor (LXR) Pathway by Activating Small Guanosine Triphosphate-Binding Proteins (sGTPases) in Neuronal Cells

“…In order to avoid cholesterol depletion, the cells activate cholesterol synthesis in parallel with a down-regulation of the LXR target genes related to cholesterol efflux (ABCA1 and ApoE). Acute cholesterol depletion by cyclodextrin treatment results in altered membrane properties that can affect synaptic transmission in Purkinje cells and wildtype hippocampal neurons [57,58]. On the other hand, Sodero and coworkers have suggested that a sudden rise in excitatory neurotransmission activate CYP46A1-dependent mild cholesterol loss mechanisms to protect themselves from neuronal death [59].…”

Vesicular Sterols Are Essential for Synaptic Vesicle Cycling

“…This has previously been used as a control to show cholesterolspecific effects of M␤CD (Suzuki et al, 2004;Smith et al, 2010). Sterol levels were increased in preparations incubated with this complex (Fig.…”

LTP-triggered cholesterol redistribution activates Cdc42 and drives AMPA receptor synaptic delivery

“…In fact, it is being increasingly recognized that dysregulation of cholesterol metabolism and homeostasis may have a role in neurological diseases, such as Alzheimer's (Ledesma and Dotti, 2006;Gamba et al, 2012;Suzuki et al, 2013) and Huntington's (Valenza et al, 2005). On the other hand, cholesterol may influence multiple aspects of synaptic transmission (Pfrieger, 2003), both presynaptically, acting on neurotransmitter vesicle fusion (Deutsch and Kelly, 1981;Linetti et al, 2010;Smith et al, 2010;Mercer et al, 2012), and postsynaptically, altering neurotransmitter receptor diffusion (Renner et al, 2009) and endosomal dynamics (Hering et al, 2003;Hou et al, 2008). However, it remains to be established whether cholesterol metabolism is regulated by neuronal activity under physiological conditions, and particularly, what the molecular mechanisms are that link changes in cholesterol to the regulation of synaptic strength during plasticity.…”