Markers of synaptic and neurotransmitter function
Fluid biomarkers | Biological function | Unspecified FTD | PSP | GRN | C9orf72 | MAPT | Ref. | |||
P | S | P | S | P | S | |||||
SNAP-25 | Vesicle fusion and release of neurotransmitters | – | 65 | |||||||
Synaptotagmin | Ca2+ sensor triggering vesicle fusion on calcium influx | – | 65 66 | |||||||
↓ | ||||||||||
Synaptophysin | Synaptic vesicle protein that regulates SNARE assembly and vesicle fusion | ↓ | 66 | |||||||
GAP-43 | Ca2+-dependent vesicle fusion | – | 66 | |||||||
Synapsin 1 | Vesicle trafficking | ↑ | 66 | |||||||
Neurogranin | Long-term potentiation and synaptic plasticity and regulates intracellular Ca2+ concentration | – | 65 66 | |||||||
↓ | ||||||||||
Synaptopodin | Regulates intracellular Ca2+ concentration | ↓ | 66 | |||||||
Reelin | Regulation of filopodia formation, dendrite growth and spine formation, and synaptogenesis, modulation of synaptic plasticity and neurotransmitter release | ↑ | 68 | |||||||
NPTXR | Organisation of excitatory and inhibitory synapses | ↓ | – | ↓ | – | ↓ | – | – | 69 | |
NPTX2 | Modulation of strength of excitatory synapses | – | ↓ | – | ↓ | – | – | 69 | ||
DA | Neurotransmitter | ↑ | 71 | |||||||
DOPAC | DA metabolite | ↓ | 71 |
Blue, in cerebrospinal fluid; green, in blood and cerebrospinal fluid; red, in blood; yellow, in neuron-derived exosomes from plasma.
– indicates (unchanged levels); ↑ indicates increased levels; ↓ indicates decreased levels; all compared with controls.
C9orf72, chromosome 9 open reading frame 72; DA, dopamine; DOPAC, 3,4-dihydroxyphenylacetic acid; FTD, frontotemporal dementia; GAP-43, growth associated protein, 43 kDa; GRN, progranulin; MAPT, microtubule-associated protein tau; NPTX2, neuronal pentraxin-2; NPTXR, neuronal pentraxin receptor; P, presymptomatic; PSP, progressive supranuclear palsy; Ref, reference; S, symptomatic; SNAP-25, synaptosomal-associated protein, 25 kDa; SNARE, soluble NSF attachment protein receptor.