Gasperini, RJ and Hou, X and Parkington, H and Coleman, H and Klaver, DW and Vincent, AJ and Foa, LC and Small, DH, TRPM8 and Nav 1.8 sodium channels are required for transthyretin-induced calcium influx in growth cones of small-diameter TrkA-positive sensory neurons, Molecular Neurodegeneration, 6, (19) pp. 1-12. ISSN 1750-1326 (2011) [Refereed Article]
© 2011 Gasperini et al; licensee BioMed Central Ltd.
Official URL: http://www.molecularneurodegeneration.com/content/...
Background: Familial amyloidotic polyneuropathy (FAP) is a peripheral neuropathy caused by the extracellular accumulation and deposition of insoluble transthyretin (TTR) aggregates. However the molecular mechanism that underlies TTR toxicity in peripheral nerves is unclear. Previous studies have suggested that amyloidogenic proteins can aggregate into oligomers which disrupt intracellular calcium homeostasis by increasing the permeability of the plasma membrane to extracellular calcium. The aim of the present study was to examine the effect of TTR on calcium influx in dorsal root ganglion neurons.
Results: Levels of intracellular cytosolic calcium were monitored in dorsal root ganglion (DRG) neurons isolated from embryonic rats using the calcium-sensitive fluorescent indicator Fluo4. An amyloidogenic mutant form of TTR, L55P, induced calcium influx into the growth cones of DRG neurons, whereas wild-type TTR had no significant effect. Atomic force microscopy and dynamic light scattering studies confirmed that the L55P TTR contained oligomeric species of TTR. The effect of L55P TTR was decreased by blockers of voltage-gated calcium channels (VGCC), as well as by blockers of Nav1.8 voltage-gated sodium channels and transient receptor potential M8 (TRPM8) channels. siRNA knockdown of TRPM8 channels using three different TRPM8 siRNAs strongly inhibited calcium influx in DRG growth cones.Conclusions: These data suggest that activation of TRPM8 channels triggers the activation of Nav1.8 channels which leads to calcium influx through VGCC. We suggest that TTR-induced calcium influx into DRG neurons may contribute to the pathophysiology of FAP. Furthermore, we speculate that similar mechanisms may mediate the toxic effects of other amyloidogenic proteins such as the β-amyloid protein of Alzheimer’s disease.
|Item Type:||Refereed Article|
|Keywords:||familial amyloidotic polyneuropathy, dorsal-root ganglion, Alzheimers disease, phosphatidyinositol 4,5-bisphosphate, calcium, cold sensitivity, fibril protein, in vitro, receptor, rat, oligomers|
|Research Division:||Biomedical and Clinical Sciences|
|Research Field:||Neurosciences not elsewhere classified|
|Objective Group:||Clinical health|
|Objective Field:||Clinical health not elsewhere classified|
|UTAS Author:||Gasperini, RJ (Dr Rob Gasperini)|
|UTAS Author:||Klaver, DW (Mr David Klaver)|
|UTAS Author:||Vincent, AJ (Dr Adele Vincent)|
|UTAS Author:||Foa, LC (Professor Lisa Foa)|
|UTAS Author:||Small, DH (Professor David Small)|
|Web of Science® Times Cited:||16|
|Deposited By:||Menzies Institute for Medical Research|
|Downloads:||495 View Download Statistics|
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